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Seismic isolation for low-to-medium-rise buildings using granulated rubber-soil mixtures: Numerical study

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Abstract

This paper presents the preliminary research works on a potential seismic isolation method that makes use of scrap rubber tires for the protection of low‐to‐medium‐rise buildings. The method involves mixing shredded rubber tire particles with soil materials and placing the mixtures around building foundations, which provides a function similar to that of a cushion. Meanwhile, the stockpiling of scrap tires is a significant threat to our environment, and the engineering community has been looking for long‐term viable solutions to the recycling and reuse of rubber. A finite element program has been developed for modeling the time‐domain dynamic responses of soil–foundation–structure system, by which the effectiveness and robustness of the proposed method have been evaluated. In general, the structural responses, in terms of acceleration and inter‐story drift, can be reduced by 40–60%. Copyright © 2012 John Wiley & Sons, Ltd.

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... Tsang et al. [86] numerically model the time-domain seismic response of a structure, whose foundation was isolated by a layer of Fig. 25. Case study structure isolated by RNC Isolation system [54]. ...
... Frictional properties, self-lubricating, and wear behavior of Teflon-steel interface under different loads and sliding Fig. 29. Acceleration and Drift reduction of a system isolated with a composite rubber soil mixture along with the reduction percentage [86]. ...
... To replace the uneconomical and complex engineered isolation systems with locally available materials, Tsang [98] and Tsang et al. [86] presented the feasibility of using a mixture of sand and rubber beneath the foundation shown in Fig. 30, as an isolation layer for undeveloped countries and, gives the concluding remarks that the proposed composite isolation system not only reduces the horizontal vibrations but also greatly reduces the vertical acceleration response of the structure, which points out that this system can be used for a variety of earthquakes. Another advantage of the proposed method was the utilization of scrap tires, which leads toward a sustainable environment. ...
Article
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The historical development and practical implementation of structural base isolation systems that work on the principle of friction are discussed in the light of analytical, numerical, and experimental studies carried out by researchers. Various parameters such as sliding velocity, surface temperature, axial pressure, vertical excitation along with near-field and far-field excitations that influence the overall performance of the isolation system have been explored. Merits and demerits of using traditional isolation systems and newly introduced smart and adaptive multiple surface isolators such as double concave and triple friction pendulum system is also discussed. Advantages and problems associated with friction base isolation systems are briefly explained with some future research suggestions, including practical experimental work and numerical simulations to verify the behavior of friction base isolation systems. Design optimization and optimal design utilizing some new and smart materials to achieve adaptive base isolation systems particularly incorporating complex problems, such as pressure, velocity, and temperature dependency along with multi-directional loadings.
... Geotechnical Seismic Isolation (GSI) may be considered as an innovative method to reduce the seismic vulnerability of civil structures and infrastructures. The use of the GSI has been examined by several researchers (e.g., Tsang 2009;Tsang et al. 2012). Tsang (2009) introduced the definition of the GSI itself. ...
... Tsang (2009) introduced the definition of the GSI itself. In addition, Tsang et al. (2012) examined the use of rubber-soil mixtures on the acceleration and inter-story drift of low to medium rise buildings. Equivalent liner model was used to model the dynamic response of the soil and the GSI in Tsang et al. (2012) study, where the dynamic response of the soil was characterized using the secant shear modulus and the damping ratio. ...
... In addition, Tsang et al. (2012) examined the use of rubber-soil mixtures on the acceleration and inter-story drift of low to medium rise buildings. Equivalent liner model was used to model the dynamic response of the soil and the GSI in Tsang et al. (2012) study, where the dynamic response of the soil was characterized using the secant shear modulus and the damping ratio. Forcellini (2017) investigated the effect of the thickness of the GSI on the response of a bridge using different earthquake records with a PGA range of 0.3-0.9 ...
Article
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The seismic vulnerability of bridges may be reduced by the application of Geotechnical Seismic Isolation (GSI) below the foundations of the columns and the abutments. However , the role of GSI on the seismic response of bridges has been limitedly examined in literature. Therefore, this research has been conducted to study the effect of applying GSI on the seismic response of bridges to address the aforementioned gap in knowledge. Advanced nonlinear dynamic three-dimensional finite element analyses have been conducted using OpenSees to study the influence of the GSI. The cases of traditional and isolated bridges subjected to earthquakes have been considered to assess the GSI effects. The results showed that the GSI reduces the seismic effect on the column while its effect seems to be less significant for the abutments. In addition, fragility curves for the traditional and isolated cases have been developed and compared to provide insights with a probabilistic-based approach. The results of this paper provide a useful benchmark for design considerations regarding the use of GSI for bridges.
... Tsang et al. [11] conducted centrifuge tests, while Kaneko et al. [12] proposed hybrid simulations. Another typology of verifications consists of numerical simulations, such as in [13][14][15][16][17]. In particular, the authors of [13] investigated the application of granulated rubber-soil mixtures to the seismic isolation for low-to-medium-rise buildings. ...
... Another typology of verifications consists of numerical simulations, such as in [13][14][15][16][17]. In particular, the authors of [13] investigated the application of granulated rubber-soil mixtures to the seismic isolation for low-to-medium-rise buildings. Nonlinear models were proposed in [14] to study seismic isolation systems made of recycled tire-rubber. ...
... GSI was modelled in order to represent realistically a thin layer of deformable material, following the calibration proposed in [15], whose parameters are shown in Table 4. Some of these parameters (such as the density, Poisson's ratio) have little effect on the performance of GSI and were widely investigated by the authors of [13]. The soil was considered stiff, as it was demonstrated in [15] that the effectiveness of GSI depends on soil deformability. ...
Article
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Geotechnical seismic isolation (GSI) consists of an innovative technique to mitigate the effects of earthquakes based on interposing a superficial soil layer to filter the seismic energy from the soil to the structure. This approach is particularly applied in developing countries due to low-cost applications. In order to account the uncertainties, the presented paper aimed to develop fragility curves of 3D configurations performed by numerical finite element models. The mail goal is to assess and discuss the potentialities of GSI as a mitigation technique for several configurations. Opensees PL has been applied to perform the numerical analyses and to realistically reproduce the behaviour of GSI.
... Geotechnical seismic isolation (GSI) can be very promising and effective alternative isolation technique for low-to-medium rise buildings (Tsang, 2008;Tsang et. al., 2012;Goztepe, 2016). In the GSI concept, Rubber Soil Mixtures (RSM) is placed underneath the foundation and surrounds all the foundation of the building. ...
... Because of the fact that isolator contact with entire foundation of the structure in the GSI system, the GSI system is defined as distributed seismic isolation system. Recent studies support the feasibility of the implementation of sand-rubber mixtures as an effective seismic isolation layer below a structure's foundation (Tsang 2008;Tsang et al., (2012);Pistolas 2015;Goztepe, 2016;Brunet et al. 2016). Tsang (2008) and Tsang et al., (2012) are the one of the most important research in this issue. ...
... Recent studies support the feasibility of the implementation of sand-rubber mixtures as an effective seismic isolation layer below a structure's foundation (Tsang 2008;Tsang et al., (2012);Pistolas 2015;Goztepe, 2016;Brunet et al. 2016). Tsang (2008) and Tsang et al., (2012) are the one of the most important research in this issue. They investigated geotechnical seismic isolation for low to medium rise building using granulated rubber soil mixtures by numerical studies. ...
Article
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Processed waste tires can be used as additives for geotechnical applications in earthquake-prone areas. The increasing use of waste tires additives requires a better understanding of their dynamic behaviors. Processed waste tires as granular and fiber-shaped rubber particles under the same experimental conditions were not studied before. The main purpose of this study is to carry out these experiments to determine the effects of two different processing techniques on the shear modulus and damping ratios of the mixtures. It is also the first time that the effects of fiber-shaped rubber particle inclusions are determined in detail.In addition, the results of similar tests using different processed waste tires were evaluated. The effects of the processed waste tires are given by evaluating the literature and this study together. It has been found that depending on the size, aspect ratio and content of the rubber material, the type of processing can significantly affect the dynamic properties of the mixture.The tested materials may be suitable as base isolation material. Of all the studies evaluated, the highest damping ratio was obtained with granulated rubber inclusions.
... To tackle this issue of disposal, with a sustainable future in mind, research is being done to utilize the waste tires. Due to the inherent energy absorption and damping behavior of rubber, research has shown that waste tire in the form of crumbs can act as quite an effective base isolator [6]. Waste tire crumbs in mixture with soil have also been used as a lightweight backfill material and in retaining structures [7,8]. ...
... When a retaining wall which was subjected to sinusoidal dynamic excitations, it was observed that the horizontal displacement and incremental lateral earth pressures were significantly reduced when the retaining wall was included with tire chips as a cushion in between the wall and the fill [9]. With the help of a finite element program, another study found that the structural responses in terms of acceleration and inter-story drift of a low to medium rise building could be reduced by 40-60% [6]. Moreover, when sand-tire mixtures were subjected to undrained monotonic and cyclic triaxial tests, it was found that the undrained shear strength of the specimens tested increased with the inclusion of oven-dried, large-sized tire chips along with an improvement in liquefaction resistance [10]. ...
Chapter
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Unrecycled tire waste is an enormous global problem because of its non-biodegradability, flammability, and chemical composition. The production and disposal of tires have been on the rise ever since. Due to a shortage of natural resources and increase in waste disposal cost, waste tires in the form of crumbs are widely used as a lightweight material for the backfill in embankment construction. Due to the inherent energy absorption and damping behavior of rubber, research on sand-tire crumb mixtures has shown that there is increase in shear strength and energy absorption capacity. But, very few tests have been performed on soil-tire crumb mixtures. The primary objective of our study involves covering this gap by determining the shear strength and energy absorption characteristics of soil-tire crumb mixture (STCM) by performing direct shear and unconsolidated undrained (UU) triaxial test on disturbed soil samples collected from various site locations, by varying percentage of tire crumbs. Site response studies are done using DEEPSOIL software using both linear and nonlinear methods. Based on the result obtained, it is observed that there is an increase in shear strength in the range of 20–30%, increase in energy absorption 15–20%, and reduction in PGA by 10–15% for the optimum percentage of tire crumb which is site-specific.
... Tsang [2008] conducted a numerical study on the use of a rubber-soil mixture (RSM) as a low-cost base isolation system, and named it the GSI system. Following this work, numerous researchers have examined the behavior and performance of RSM through several numerical studies [Tsang, 2009] [Mavronicola et al., 2010] [Tsang et al., 2012] [Panjamani et al., 2015] [ Bandyopadhyay et al., 2015] [Pitilakis et al., 2015] [Brunet et al., 2016] [Forcellini, 2017] [ Tsiavos et al., 2019b] [Tsang and Pitilakis, 2019] [Forcellini, 2020] [Pistolas et al., 2020] [ Dhanya et al., 2020] [Hernández et al., 2020] and experimental studies [Xiong and Li, 2013] [Xiong et al., 2014] [Dhanya et al., 2019] [Tsiavos et al., 2019a] [Tsiavos et al., 2020b]. For example, Tsiavos et al. [2019a] experimentally tested a sliding layer consisting of a deformable sand-rubber granular mixture as a seismic isolation strategy for low-rise, smallfootprint buildings in developing countries. ...
... Although much effort has been invested in recent years in the development of suitable seismic base isolation in developing countries, not enough has been done to develop suitable numerical models to simulate seismic isolation. Some numerical models, whether presented as part of experimental studies or independently, can be found in [Mavronicola et al., 2010] [Tsang, 2012] [Pitilakis et al., 2015] [Brunet et al., 2016] [Zhao et al., 2016]. This paper presents and verifies the developed numerical model for dynamic analysis of planar structures with seismic base isolation using a layer of stone pebbles. ...
Article
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This paper presents a numerical model for the dynamic analysis of planar structures with seismic base isolation using a layer of stone pebbles. Following a brief presentation of the previously developed numerical model for structural analysis, the developed constitutive model for the stone pebble layer and the constitutive model for simulating the foundation-isolation layer coupling surface are presented. The model is based on a relatively small number of parameters, some of which were determined experimentally. The numerical model was verified by simulating the performed shake-table tests of simple structural models based on an aseismic layer of stone pebbles, and good agreement between the experimental and numerical results was observed. Finally, further verification and improvement of the presented constitutive models are outlined.
... In the past one and a half decades, numerical simulations and analytical modelling have been conducted by various researchers to demonstrate the effectiveness of GSI systems (Tsang et al. , 2012aPitilakis et al. 2015;Anbazhagan et al. 2015;Abdullah and Hazarika 2016;Brunet et al. 2016;Dhanya et al. 2020;Forcellini and Alzabeebee 2022). Experimental testing and field measurement have also been performed to confirm the isolation mechanism and to evaluate their performance (Kaneko et al. 2013;Nikitas et al. 2014;Nappa et al. 2016;Tsiavos et al. 2019;Tsang et al. 2021;Pitilakis et al. 2021). ...
... An ongoing study has indicated that a RSM layer of 2-m thick can support ordinary buildings of up to six to eight storeys without compromising serviceability requirements. Pile foundation can be used for taller or heavier buildings as investigated in Tsang et al. (2012a), whilst lower isolation effectiveness would be expected. ...
Article
Full-text available
Geotechnical Seismic Isolation (GSI) can be defined as a new category of seismic isolation techniques that involve the dynamic interaction between the structural system and geo-materials. Whilst the mechanism of various GSI systems and their performance have already been demonstrated through different research methods, there is a missing link between fundamental research and engineering practice. This paper aims to initiate the development in this direction. A new suite of equivalent-linear foundation stiffness and damping models under the same framework is proposed for four GSI configurations, one of which is a novel combination of two existing ones. The exact solutions for the equivalent dynamic properties of flexible-base systems have also been derived that explicitly include the foundation inertia and the strain-dependent equivalent damping of foundation materials, which are both significant for GSI systems. The application of the proposed analytical design models has been illustrated through response history analyses and a detailed hand-calculation design procedure has also been outlined and demonstrated.
... To extend the earthquakeresistant design strategy for masonry structures, public buildings that include schools, hospitals, residential structures, etc., the cost reduction and simplifi cation of the design principles are of great concern. As an alternative, several aseismic tools made of locally available inexpensive materials or lightweight materials have been proposed and investigated through experiment or fi nite element study by Kelly and Takhirov (2001), De la Llera et al. (2004), Turer and Özden (2007), Xiao et al. (2004), Tsang et al. (2012), Bandyopadhyay et al. (2015), Karayel et al. (2017) and Pistolas et al. (2020). The fi berreinforced elastomeric isolator (FREI), which uses fi ber reinforcement instead of steel shims, is a lightweight device and considered to off er a cost-eff ective design solution as proposed by Kelly (1999). ...
... Spizzuoco and Calabrese developed a recycled rubber-fi ber reinforced bearing using a tire granule binder mixture and demonstrated that it was more advantageous than the SREI or FREI in terms of energy dissipation, manufacturing cost, and had a lighter weight. A geotechnical isolation called the RSM system is proposed by Tsang et al. (2012), Bandyopadhyay et al. (2015), and Pistolas et al. (2020) and composed of shredded tires and sand and was found to be very eff ective in reducing the eff ect of ground motion. An experimental study performed by Mishra (2012Mishra ( , 2013aMishra ( and 2013b found that the STRP has an equivalent damping ratio of approximately 10%-22% and a vertical to horizontal stiff ness ratio in the range of 450-600 exceeding 150, the code specifi ed limits. ...
Article
The scrap tire rubber pad (STRP) made by natural or synthetic rubber and high strength reinforcing cords exhibits substantial vertical stiffness and horizontal flexibility, and these properties can be regarded as suitable for seismic isolators for structures. The use of environmentally burdensome scrap tires as STRP isolators might be convenient as an efficient and low-cost solution for the implementation of aseismic design philosophy for low-to-medium rise buildings, especially in developing countries. Finite element analyses of unbonded square and strip-shaped STRP isolators subjected to a combination of axial and lateral loads are conducted to investigate its lateral deformation performance under seismic loading. The rubber of the isolator is modelled with Mooney-Rivlin hyperelastic and Prony viscoelastic materials, including the Mullins material damage effect. The influence of the length-to-width ratio and bearing height on the isolator performance is assessed in terms of the force-displacement relationship, horizontal stiffness, damping, and isolation periods. It is shown that the dependence of stiffness on the length-to-width ratio is significant in the longitudinal direction and minor in the transverse direction. The STRP isolators following the proposed design criteria are shown to satisfy the performance requirement at different levels of seismic demand specified by the ASCE/SEI 7–2010 seismic provisions.
... However, both the burning and production of the rubber powder are not environmentally friendly and usually require extra energy to clean. More recently, the reuse of waste tires in the form of tire shreds and granulated rubber as new geo-materials or in the form of mixtures with soil has become a popular approach in the construction of civil engineering structures, such as lightweight embankment fill [3,4], lightweight retaining wall backfill [5,6], drainage layers for roads, landfills, and other applications [7][8][9], thermal insulation to limit frost penetration beneath roads, insulating backfill to limit heat loss from buildings and vibration damping layers for rail lines [10][11][12][13][14][15], which have great potential to alleviate the waste tire accumulation problems and are considered environmentally friendly methods [16]. ...
Article
Full-text available
Mixing soil with waste tire rubber granules or fibres is a practical and promising solution to the problem of global scrap tire pollution. Before successful applications, the mechanical behaviour of the soil–rubber mixture must be thoroughly investigated. Comprehensive laboratory studies (compaction, permeability, oedometer and triaxial tests) were conducted on the completely decomposed granite (CDG)–rubber mixtures, considering the effects of rubber type (rubber granules GR1 and rubber fibre FR2) and rubber content (0–30%). Results show that, for the CDG–rubber mixture, as the rubber content increases, the compaction curves become more rubber-like with less obvious optimum moisture content. The effect on permeability becomes clearer only when the rubber content is greater than 30%. The shape effect of rubber particles in compression is minimal. In triaxial shearing, the inclusion of rubber particles tends to reduce the stiffness of the mixtures. After adding GR1, the peak stress decreases with the increasing rubber content due to the participation of soft rubber particles in the force transmission, while the FR2 results in higher peak stress especially at higher rubber contents because of the reinforcement effect. For the CDG–GR1 mixture, the friction angle at the critical state (φ’cs) decreases with the increasing rubber content, mainly due to the lower inter-particle friction of the CDG–rubber interface compared to the pure CDG interface, while for the CDG–FR2 mixture, the φ’cs increases with the increasing rubber content, again mainly due to the reinforcement effect.
... An often-studied solution that involves the use of synthetic materials is the sand-rubber mixture. Several experimental studies have shown that thanks to the low shear modulus and high damping ratio values of this mixture, it is a valid alternative to the base isolation methods (Anastasiadis,Senetakis and Pitilakis 2012;Brunet, de la Llera, and Kausel 2016;Forcellini 2017;Tsang et al. 2012;Tsang and Pitilakis 2019), recently coupled to geogrids (Dhanya, Boominathan, and Banerjee 2020). ...
Article
This paper shows the experimental results of impact hammer tests conducted on sand and composite sand-polyurethane samples at different confining pressures. It was found that polyurethane can mitigate the propagation of waves generated by an impact, thereby influencing seismic isolation. Also, accelerations in the composite samples were reduced in relation to the percentage of polyurethane present. A theoretical lumped-mass model (calibrated based on the experimental results) interpreted the experimental results and enabled an in-depth parametric analysis. This analysis shows that the proposed isolation method is efficient, as the damping coefficient of the polyurethane and the soil/polyurethane impedance ratio increased.
... Typically, ELT-derived aggregates (in the form of chips, crumbs, granules and shreds -ASTM [27]) assorted with cohesionless granular soil (mainly sand) have found use as light-weight backfill materials for embankments and retaining walls, drainage systems, slope remediation, and landfill construction [28,29]. However, more recently, due to their superior strength and dynamic properties, soil-rubber mixtures have been proposed as free-draining energy-adsorption backfill material for retaining walls, underground horizontal and vertical layers for liquefaction mitigation [30,31] and geotechnical seismic-isolation systems for residential buildings [32][33][34][35]. ...
Article
Full-text available
End-of-life tires (ELTs) are tires, unusable in their original form, which go into a waste management scheme (for recycling and energy recovery purposes), or otherwise are disposed. In New Zealand, the annual disposal of 3.5 million ELTs is posing critical environmental and socio-economic issues, and the reuse of ELTs through large-volume recycling engineering projects is a necessity. In this study, gravel and recycled granulated rubber were mixed to explore the possibility of obtaining synthetic granular geomaterials (with adequate geotechnical and environmental characteristics) that are suitable as structural fills for geotechnical applications including foundation systems for low-rise light-weight residential buildings. Moreover, an original framework with a set of geo-environmental criteria is proposed for the acceptance of gravel–rubber mixtures (GRMs) as structural fills. It is shown that when gravel-size like rubber particles are used, GRMs with volumetric rubber content of 40% or less have adequate strength (ϕ’ > 30°), low compressibility (εv ≤ 3%), excellent energy adsorption properties, and acceptable leachate metal concentration values (e.g., Zn < 1 mg/L), making them ideal synthetic structural fill materials for many sustainable geotechnical applications.
... Tsang et al. (2012Tsang et al. ( , 2008 proposed the use of locally available materials for seismic176 isolation. They concluded that if a mixture of rubber and sand is used beneath the foundation,177 it would not only reduce the vertical acceleration response but would also reduce the 178 horizontal vibrations. ...
Preprint
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Masonry structures are frequently constructed in developing countries because of their affordability and ease of construction, despite the fact that they are vulnerable and perform poorly during earthquakes. Experimental and numerical studies were carried out to determine the optimum thickness of the isolation layer for a recently developed, low-cost seismic isolation system known as the Reinforced-Cut-Wall(RCW). The parameters of the isolation layer were optimized during the experimental and numerical investigation using hollow concrete blocks. Quasi-static cyclic tests were performed on 1:3 reduced-scale brick masonry wall, incorporating the RCW isolation scheme, validating the better performance of the proposed isolation technique.
... Moreover, the use of tire shreds was proposed in the design of embankments overlying soft soils to minimize the vertical stresses and settlements 24,28 and have been investigated experimentally in constructing a drainage layer based on their high hydraulic conductibility. 29,30 SRM suitability and advantages as GSI in the form of a layer underlying the foundation of a structure have been investigated numerically by many researchers, 13,[31][32][33][34][35][36][37][38] demonstrating the decrease of the foundation's horizontal and vertical motions. Additionally, it was stated that the low modulus of the SRM foundation layer contributes to the reduction of the rocking stiffness of the structures. ...
Article
We present the results of a large‐scale experimental campaign performed on the prototype structure of EuroProteas in Thessaloniki, Greece, to assess the effectiveness of gravel‐rubber mixture (GRM) layers underneath shallow foundations as a means of geotechnical seismic isolation (GSI). We found that the GSI of structures is optimized by increasing the rubber content of the soil‐rubber mixture up to 30% per mixture weight. The effectiveness of the GSI systems has been investigated numerically and in small‐scale experiments. This article seeks to fill the gap in the lack of full‐scale experimental studies on this subject. Three soil pits were excavated and backfilled with GRM of different rubber content per weight to serve as foundation soil. A large number of instruments were installed on the structure, the foundation, the soil surface, and inside the GRM layers beneath the foundation to fully monitor the GSI‐structure systems’ response in three dimensions. The experimental investigation included ambient noise, free‐ and forced‐vibration tests. Our results showed that a GSI layer composed of a GRM with 30% rubber content effectively isolates the structure. Even 0.5 m thickness (ie, B/6 of the foundation width) of the GSI system successfully cuts off practically all emitted waves at a (horizontal or vertical) distance of B/6 from the foundation. A significant reduction in the GSI‐structure system's stiffness was apparent, leading to a rocking‐dominant response. The rise in the system's damping and the substantial energy dissipation inside the GRM layer highlight its effectiveness as a GSI system.
... Senetakis et al. [38] reported that the maximum damping ratio of pure sand is less than 10%, whereas the corresponding value is up to 15% for sand-tire shred mixtures. Because of its high energy dissipation capacity, this mixture has been used in other engineering applications such as railway sub-ballast layers [39,40] and geotechnical seismic isolation [41][42][43]. Xiong and Li [44] showed that geotechnical seismic isolation could effectively mitigate seismic hazards. Dhanya et al. [45] showed that a 50% reduction in the seismic shear force of low-rise buildings could be achieved using geotechnical seismic isolation. ...
Article
Full-text available
Blasting is an unavoidable activity in geotechnical engineering, road and tunnel construction, and mining and quarrying. However, this activity can expose the environment to various hazards that are challenging to control and, at the same time, critical for the safety of site workers, equipment, and surrounding structures. This research aims to evaluate the ability of sand–tire shred mixtures to reduce peak blast pressure, which is the leading cause of damage to underground structures under surface explosion. ABAQUS software is used to model the material behavior under explosion and is validated using the results of previous studies and an empirical equation. Different scenarios are created by using mixture layers with different thicknesses (2, 4, and 6 m) and tire shred contents (10%, 20%, and 30%) that are subjected to various surface explosion charges (100, 500, 1000, and 5000 kg). The thickness of the mixture layer is found to be directly related to the dissipation of explosion energy. However, the percentage of the rubber content in the mixture is only significant in reducing peak blast pressure when a thick enough mixture layer is used. The results confirm the adequate performance of the correctly chosen sand–tire shred mixtures in reducing peak blast pressure and protecting the underground structure from surface explosion hazards.
... In the last decade, the concept of "Geotechnical Seismic Isolation" (GSI) has been introduced as an innovative base isolation method, where the use of devices such as isolators underneath the foundations is replaced by modifying the surficial layers of the foundation soil [17,18]. The object of the intervention for seismic risk mitigation is therefore the soil, and this choice is logical in thinking that the structures are damaged according to what the soil transmits [19]. ...
Article
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This paper analyses the effect of polyurethane injections on the seismic surficial response of cohesionless soils. For this purpose, dynamic finite element numerical analyses were performed through GiD + OpenSees. Both the soil and the composite material, resulted after the expansion of the injected polyurethane, are modelled with a nonlinear hysteretic constitutive model. Based on the polyurethane percentage, a homogenisation of the characteristics was considered for the composite material: linear for density and damping, and exponential (experimentally calibrated) for the stiffness. An expansion coefficient quantifies how much the injected polyurethane expands: three expansion coefficients were considered, each of them related to a different polyurethane density. For the evaluation of the foam stiffness, a linear stiffness–density correlation was used, derived after impact tests. Results showed that polyurethane reduces the surficial accelerations proportionally to the ratio of its seismic impedance and volumetric percentage with respect to the soil seismic impedance and total volume. This is a preliminary indication for the design of polyurethane injections in cohesionless soils for seismic acceleration reduction.
... Soil-rubber blends have also been proposed around foundations for absorbing seismic energy with a function similar to that of a cushion. The low cost of such GSI methods can greatly benefit residential buildings for which, otherwise, the use of expensive structural seismic isolation techniques is not feasible (Tsang, 2008;Tsang et al, 2012;Brunet et al., 2016;Triavos et al., 2019;Dhanya et al., 2019). ...
Conference Paper
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Worldwide, due to the large amount of end-of-life tyre (ELT) stockpiles, reusing and recycling of ELTs in civil engineering applications have become a priority, significantly contributing to lessen environmental and health issues related to the ever-growing ELT disposal. In this context, in Aotearoa New Zealand, ELT-derived granulated tyre rubber has been blended with gravel and concrete to form synthetic materials for use in the development of “eco-rubber geotechnical seismic-isolation (ERGSI) foundation systems” for medium-density low-rise residential buildings. The specific purpose of the study reported in this paper is to quantify the seismic mitigation provided by different percentage of rubber to gravel to create an optimum energy-dissipative layer placed beneath a fibre-reinforced rubberised concrete raft foundation. To do so, a prototype ERGSI foundation system placed on gravel-rubber layers with 0, 10%, 25%, and 40% of rubber (by volume) were tested in the laboratory by means of impact tests. By using the wave propagation theory and cross power spectral density frequency response function, modal parameters such as the natural frequency and damping ratio of the different layers were obtained. It was found that, at the foundation level, the peak acceleration decreased and the natural frequency increased with increasing the rubber content. This corresponds to an increase in both the damping and seismic-isolation effects, confirming the effectiveness of ERGSI systems. Considering also strength and compression requirements under static loads, it is proposed that the optimum seismic dissipative gravel-rubber layer for ERGSI foundation systems should have 25-30% rubber content.
... However, statistics suggest that to date only less than 10% of ELTs-derived rubber is currently being used for this purpose worldwide. More in-depth and coordinated investigations are certainly required to be carried out to broaden the available database that could include a wider range of soil types, rubber type and sizes and also refer to new promising applications such as geotechnical seismic isolation systems for residential buildings [13][14][15][16][17][18][19], countermeasures against soil liquefaction [20,21] and railways applications [22,23]. ...
Article
Full-text available
End-of-life tires (ELTs) represent a great source of readily available, low-cost and sustainable construction materials having excellent engineering properties. Their reuse (in the form of granulated rubber mixed with soils) in large-volume recycling civil (geotechnical) engineering applications would be beneficial and should be encouraged. It is estimated that at present worldwide only less than 10% of ELTs are reused in geotechnical applications, while nearly 40% are recycled as tire-derived fuel. Although many studies have focused on the material characterization of soil-rubber mixtures (SRMs), it appears that the results of such investigations have not been properly compiled and compared, making it difficult to fully understand the potential applicability of SRMs. In an attempt to provide useful insights facilitating the use of SRMs as geotechnical construction materials, this review paper presents a comprehensive review of published research on the engineering properties of granular soils (i.e., mainly sand and gravel) blended with various recycled rubber inclusions. Available experimental data are scrutinized, and the results of the analyses are presented and discussed primarily in terms of effects of rubber content and aspect ratio (ratio of rubber to gravel median particle sizes) on compaction, permeability, strength and compression properties along with dynamic and cyclic deformation characteristics of SRMs. This review paper may help to alleviate the concerns of designers and consumers and encourage and further promote the use of recycled rubber tires on a larger scale in civil engineering projects.
... A low cost method for developing countries which differs from the conventional base isolators would be the use of soil-scrap tyre mixture beneath the foundation (Mashiri et al.2010). Numerical studies on the dynamic response of soil-foundation system with rubber-soil mixture as seismic isolators were studied by Tsang et al. (2012). Apart from reducing the level of shaking in the horizontal direction, the distinctive advantage of the method is that it also significantly reduces the shaking level in the vertical direction. ...
Conference Paper
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The utilization of recycled scrap rubber tyre chips in seismic isolation of structure is a low cost earthquake mitigation technique which can potentially reduce the intensity of seismic shock propagation into the structure. The current paper deals with the seismic response of a typical structure which has layers of recycled scrap tyre mixtures placed underneath the footing. The intrusion of rubber tyre chips alters the damping properties of the soil by increasing energy dissipation. A finite element analysis of the isolation system was carried out by Flexible Volume Substructure Method using SASSI 2010. The time history of acceleration of Bhuj earthquake, India (2001) is used as a input motion in the analysis. It is found that the peak ground acceleration response is significantly reduced due to the damping effect caused by soil-rubber tyre isolators.
... earthquakes and hurricanes) have caused numerous property damages and casualties. 1,2 The development of technologies of structural vibration control [3][4][5][6] and structure retro¯t 7-10 can improve the seismic performance of structures. To mitigate the seismic response of structures, di®erent kinds of structural control systems [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] have been presented by researchers all over the world, including active, 28,29 semi-active, 19,[30][31][32] passive, 11,14,17,[22][23][24]33 and intelligent systems. ...
Article
Shape memory alloy (SMA) dampers are widely investigated passive control systems for structural vibration mitigation. However, the damping robustness of conventional austenite SMA dampers may be affected by environmental temperature. In this study, an innovative double SMA damper (DSD) system is presented to improve the temperature robustness of the SMA dampers. In the proposed system, double SMA hysteretic elements with different phase transition temperatures are arranged in parallel, where the SMA element with lower transition temperature behaves as austenite under room temperature, and the other with higher transition temperature behaves as martensite. To study the vibration control effect, both single-degree-of-freedom (SDOF) and multiple-degree-of-freedom (MDOF) structures with DSD systems are employed. The thermal and mechanical behaviors of the SMA elements and the working principle of DSD are also introduced. Thereon, the equivalent linearization method for SMA’s output force and the motion-governing equations for SDOF structure with DSD are derived. Moreover, parametric studies are conducted to investigate the performance of the proposed DSD system in both frequency and time domains. Also, numerical analysis for the MDOF structure with DSD systems is carried out to illustrate the trend in response reduction with an increasing number of degrees of freedom. The analytical results show that the DSD can mitigate the structural seismic response more effectively than the conventional one with acceptable residual deformation, and is capable of delaying the degradation of SMA’s energy dissipation capacity. Less SMA material is required for the proposed DSD to fulfill the same mitigation requirement, and it is suitable for general applications for temperature robustness.
... SRM suitability and advantages as GSI in the form of a layer underlying the foundation of a structure have been investigated numerically by many researchers [13,[31][32][33][34][35][36][37][38], demonstrating the decrease of the foundation's horizontal and vertical motions. Additionally, it was stated that the low modulus of the SRM foundation layer contributes to the reduction of the rocking stiffness of the structures. ...
Chapter
We present the results of an extensive large-scale experimental campaign on the dynamic response of rubber–gravel mixtures as an innovative seismic isolation material. In the first series of experiments, the foundation soil immediately below the prototype structure of EUROPROTEAS was replaced only with gravel to serve as benchmark tests, while in the following tests two rubber–gravel mixtures with increasing rubber content per mixture weight were used. The experimental campaign included free- and forced-vibration tests. A large number of instruments of various types (accelerometers, seismometers, shape-acceleration arrays, and laser sensors) were installed on the structure, in the foundation soil and at the adjacent soil surface in order to obtain a well-instrumented 3D set of recordings to study the response of the structure and wave propagation in soil media. In this study, we seek to investigate the isolation capability of the rubber–gravel mixtures under dynamic loading. Our primary goal is to assess the effect of the rubber content of the improved foundation soil in the stiffness and the damping of the soil-structure system.
... Regarding the content and applicability of the method; it was also underlined that factors such as nonlinear soil behavior, resonance effects of the soil, liquefaction, ground settlement, and environmental effects should be evaluated. In subsequent studies, comprehensive numerical and experimental studies were carried out on the seismic isolation capacity of RSM layers formed with varying rubber contents [1,[5][6][7][8][9][10]. [1] Another example of the GSI method is developing an isolation layer using geosynthetic material with or without an RSM layer. ...
... The high damping and energy absorption capacity of rubber is well established in the past, making it an ideal material in vibration mitigation studies (Hazarika et al. 2008;Kaneko et al. 2013). The recycled tyres in the form of rubber chips, crumb rubber, and shredded rubber mixed with sand are recently adopted in vibration isolation studies for earthquake protection of buildings in recent years (Tsang et al. 2012). Sand-Rubber Mixtures (SRM) are found to have low dry density, stiffness, shear modulus, and high damping ratio (Senetakis et al. 2009). ...
Chapter
Ground vibrations arising from construction and industrial activities and road/rail traffic can induce settlement issues, cracks, and severe damage to adjacent and remote structures. One of the well-established methods to eliminate such unwanted ground-borne vibrations is to incorporate trench barriers between the source of vibration and the structure to be protected. Recently, the use of shredded rubber from recycled tires has gained prominence in various geotechnical applications. The high energy absorption capacity of rubber is well established in the past, making it an ideal material in vibration mitigation studies. In the present study, 2D finite element analysis was carried out to investigate the use of sand–rubber tire mixture (SRM) infill trench barriers for the screening of ground-borne vibration due to vertical ground vibrations. In the present study, the typical soil profile from the Indo-Gangetic plain region is considered. 1 m width open and SRM infill trenches with a depth of 1–3 m are considered. The rubber content in the SRM fill trenches was chosen as 30% and 50%. The hyper elastic material model was adopted for the modeling of the SRM infill trench, while the soil medium was modeled using the hypoelastic constitutive model. The ground excitation was created by applying sinusoidal vertical motion with 2 m/s amplitude and a frequency of 50 Hz at the ground surface away from the trench. During the excitation, the vibration levels were computed at different locations in front of and away from the trenches. It was found that SRM infill trench with 50% rubber content performs similar to the open trenches to reduce the vertical vibration amplitude.
... Aimed at providing a sustainable engineering solution to the ELT disposal in New Zealand, the authors have conducted a feasibility study on the use of ELT-derived aggregates (in the form of granulated rubber) blended with gravelly soils as an effective energy-absorption layer for geotechnical seismic-isolation (GSI) with energy dissipation foundation systems for low-rise light-weight residen-tial buildings. Low-shear modulus and high damping materials such as sand-rubber mixtures (SRMs) have been previously proposed for use as GSI layers (Tsang, 2008(Tsang, , 2009Tsang et al., 2012). However, the compressible nature of SRMs in the GSI layer leads to low bearing capacity and unacceptable high settlement of foundations (Dhanya et al., 2018(Dhanya et al., , 2020. ...
Article
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In this paper, a newly developed 3-dimentional discrete element model (DEM) for gravel-rubber mixtures (GRMs), namely DEM4GRM, that is capable of accurately describing the macro-scale shear response (from small to large deformation) of GRMs in a direct shear box apparatus is presented. Rigid gravel grains are modelled as simple multi-shape clumps, while soft rubber particles are modeled by using deformable 35-ball body-centered-cubic clusters. Mixtures are prepared with different volumetric rubber content (VRC) at 0, 10, 25, 40 and 100%, statically compressed under 30, 60 and 100 kPa vertical stress and then sheared, by closely simulating a reference laboratory test procedure. The variation of micro-scale factors such as fabric, normal and tangential force anisotropy is carefully examined throughout the shearing process and described by means of novel micro-mechanical relationships valid for GRMs. Moreover , strong-force chains are scrutinized to identify the transition from rigid to soft granular skeleton and gain insights on the load transfer and deformation mechanisms of GRMs. It is shown that the development of the fabric and force anisotropy during shearing is closely related to the macro-scale shear strength of GRMs, and strongly depends on the VRC. Besides, strong-force chains appear to be primarily formed by gravel-gravel contacts (resulting in a rigid-like mechanical behavior) up to VRC = 30%, and by rubber-rubber contacts (causing a soft-like mechanical response) beyond VRC = 60%. Alternatively, at 30% < VRC < 60%, gravel-rubber contacts are predominant in the strong-force network and an intermediate mechanical behavior is observed. This is consistent with the behavioral trends observed in the macro-and micro-mechanical responses.
... To extend the earthquake-resistant design strategies for masonry structures, residential and public buildings, the cost reduction and simplicity of the design principles are of great concern. As an alternative, numerous innovative aseismic tools made with locally available and inexpensive materials have been proposed (Kelly & Takhirov, 2002;Llera et al., 2004;Xiao et al., 2004;Turer & Özden, 2007;Tsang et al., 2012). The fiber-reinforced elastomeric isolator, which is called FREI, was proposed by Kelly (Kelly, 1999). ...
Article
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Automobile tires are made by vulcanizing natural or synthetic rubber with high-strength steel cords. The scrap tire rubber pad, called the STRP isolator, is made from scrap automobile tires. It is expected to be a low-cost isolator and have mechanical properties similar to widely used elastomeric bearings. This article investigated the seismic protection effectiveness of the STRP base isolation system in comparison with the conventional steel-reinforced elastomeric isolation method. A hypothetical four-story building is modelled with four different sub-structure systems: (i) bonded STRP isolator (B-STRP), (ii) unbonded STRP isolator (U-STRP), (iii) steel-reinforced elastomeric isolator (SREI), and (iv) fixed-base system (FB), and is analyzed under the designed based earthquake (DBE) and maximum considered earthquake (MCE) acceleration. The SREI and STRP isolators are assumed to be geometrically comparable, and their fidelity is verified by comparing the numerical results with the past experimental results. The finding reveals that the seismic performance of the B-STRP base-isolated building is similar to that of the SREI system. The seismic performance of the U-STRP base-isolated building was found to be superior to that of the SREI, B-STRP, and FB base conditions. The U-STRP isolators are stable at the DBE level input while there is slippage at the MCE level input.
... While the widespread SSI systems (Skinner et al., 1993;Naeim & Kelly, 1999;Kelly, 1997) use either the sliding or flexible interfaces between the structure and its foundation, the GSI systems directly employ natural earth materials and/or man-made reinforced earth materials (Tsang et al., 2012) for seismic mitigation. ...
Conference Paper
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The paper examines the effects of removing the lateral ground connection between embedded foundations and surrounding soil on the dynamic soil-structure interaction. The lateral disconnection produces (i) a reduction in the overall stiffness leading to a decrease in the seismic actions; (ii) a shrinkage of the interaction domain of the foundation. In order to take into account both these factors the method introduced by Wolf was used to assess the actions at the structure level; the reduction in the bearing capacity due to the disconnection was estimated by suitably employing the limit analysis; finally, both the pseudo-static and the pushover methods of analysis were adopted. The proposed procedure was applied to a one-story building and a parametric analysis was carried out varying both the dimensions of the lateral disconnec-tion and the stiffness of the foundation soil. In order to show the effectiveness of the proposed intervention, the obtained results are presented for two selected cases.
... increasing the thickness or depth of RSm layer. Similar findings were shown in full-scale models with RSm using finite element analysis in which the RSm layer thickness was the main factor affecting the stress wave attenuation (Tsang and Pitilakis, 2019;Brunet et al., 2016;Tsang et al., 2012). ...
Conference Paper
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A Geotechnical Seismic Isolation (GSI) system is proposed in this study based on the use of Rubber-Soil mixtures (RSm) to facilitate the benefits of dynamic soil-foundation structure interaction. The latter is possible due to the lower stiffness and greater capacity to dissipate energy of RSm. However, the research done on RSm has been limited to the element scale context. In this study, the dynamic response of a modified soil foundation has been investigated by adding soft zones comprising RSm. A 1g shaking table was used to apply a sequence of sinusoidal excitations to a soil-lumped mass system. The results have shown that the rubber addition results in a reduction of the amplification at frequencies higher than the system natural frequency. This change in the dynamic response is due to the shift in the natural frequency and the dampening of the peak output accelerations. This study shows thus that an alternative design consideration with bagged soft zones, adjacent to the soil foundation, can offset the incoming disturbances and hence could protect both new and existing constructions.
... Earthquake energy can also be dissipated by reducing the rocking stiffness (Tsang and Pitilakis 2019), taking the advantages of rocking isolation, which is a well-known seismic isolation technique (Anastasopoulos et al. 2012;Acikgoz and DeJong 2014;Bantilas et al. 2021;Makris 2014;Shang et al. 2020;Sorace and Terenzi 2015). Researchers have used various types of low-modulus material, such as sand (Anastasopoulos et al. 2012;Banović et al. 2018b;Patil et al. 2016;Radnić et al. 2015), sand-bitumen mixtures (Kuvat and Sadoglu 2020), gravel (Pecker 2003;Pecker et al. 2001;Steenfelt et al. 2015), stone pebbles (Banović et al. 2018a(Banović et al. , 2019(Banović et al. , 2020a(Banović et al. , 2020bBanović 2021), rubber-soil mixtures (Brunet et al. 2016;Forcellini 2017, Forcellini 2020Forcellini 2021;Hernández et al. 2020;Mavronicola et al. 2010;Pitilakis et al. 2021;Tsang 2008;Tsang 2009;Tsang et al. 2012;Tsang et al. 2020;Tsiavos et al. 2019aTsiavos et al. , 2019bTsiavos et al. , 2020a, geofoam (Murillo et al. 2009;Azinović et al. 2014;Azzam et al. 2018;Gatto et al. 2020;Gatto et al. 2021a;Gatto et al. 2021b;Gatto et al. 2022;Hadad et al. 2017;Karatzia et al. 2017;Koren and Kilar 2016;Xue et al. 2021), and some hybrid solutions (Ali et al. 2022;Tsiavos et al. 2020bTsiavos et al. , 2021aTsiavos et al. , 2021bYuan et al. 2021;). The base isolation concept was categorized by Tsang (2008) as a "Geotechnical Seismic Isolation (GSI) system" and also adopted by Brunet et al. (2016), Forcellini (2017), and Banović et al. (2019). ...
Article
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This paper presents the findings of an experimental investigation of the efficiency of several low-cost frictional geotechnical seismic isolation methods on a rigid building model. A total of eleven different aseismic layers were considered. One layer was made of stone pebbles only, whereas the remaining ten layers were composites containing combinations of stone pebbles with different types and positions of “sliding” elements/materials (geogrid, geomembrane, and limestone sand layers). All the samples were exposed to four earthquake accelerograms of different durations and predominant periods, with three levels of peak ground acceleration (PGA): 0.2, 0.4, and 0.6 g. The test results confirm that the composite aseismic layers can significantly reduce the inertial/earthquake forces of the rigid building model relative to the stone pebble layer, depending on the type of earthquake and PGA. The need for further research on this issue on real building models is highlighted.
... Regarding the content and applicability of the method; it was also underlined that factors such as nonlinear soil behavior, resonance effects of the soil, liquefaction, ground settlement, and environmental effects should be evaluated. In subsequent studies, comprehensive numerical and experimental studies were carried out on the seismic isolation capacity of RSM layers formed with varying rubber contents [1,[5][6][7][8][9][10]. [1] Another example of the GSI method is developing an isolation layer using geosynthetic material with or without an RSM layer. ...
Article
Full-text available
Seismic isolation is a method of protecting buildings from earthquake-induced deformations by using isolators and devices under the superstructure. The purpose of the seismic isolation method is to reduce the earthquake forces transferred from the ground to the structure by placing energy-absorbing elements between the foundation and superstructure. Especially in developing countries, the "Geotechnical Seismic Isolation (GSI)" system has been proposed as an isolation method to reduce earthquake-induced damages on buildings. This study, it is aimed to reduce the effects of earthquakes in a multi-story building with an isolation layer formed by a rubber-sand mixture (RSM). For this purpose, a 10-story reinforced concrete building was numerically modeled. Beneath the foundation of the building model, a seismic energy absorbent RSM layer was placed and its contact with the natural soil was interrupted by using geosynthetic liners. The model was subjected to the 1992 Erzincan (EW) Earthquake motion and its performance has been evaluated in terms of lateral displacements and accelerations. The numerical studies indicated a substantial improvement due to the use of the RSM layer. The accelerations measured by the superstructure decreased up to 48% by employing the isolation layer. The numerical analysis was carried out using the dynamic module of the PLAXIS 2D finite element analysis program.
... In an attempt to overcome the aforementioned limitations, Tsang (2008) and Tsang et al. (2012) investigated numerically the use of a sand-rubber foundation layer for the seismic isolation of structures in developing countries. This investigation has paved the way for the use of durable, locally available and recyclable materials as a means of a more economical and sustainable approach for the seismic protection of structures in developing countries. ...
Article
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The aim of this paper is to demonstrate the efficiency of a low-cost and sustainable timber-based energy dissipation system with recentering ability, which can be used as a seismic isolation system or a tuned mass damper for the seismic protection of structures in developing or developed countries. The system, defined as Dovetail with SPrings (Dove-SP), utilizes the attractive properties of timber to store CO 2 , thus reducing the carbon footprint of the existing energy dissipation systems: It comprises two timber slabs that are designed to slide against each other in a motion that is restrained by a dovetail sliding joint. Two sliding interfaces that allow this sliding motion at an attractively low friction coefficient are experimentally investigated: A PVC sand-wich (PVC-s) sliding interface, comprising a thin layer of sand that is sand-wiched between two PVC layers and a timber sand-wich sliding interface consisting of a thin layer of sand encapsulated between two beech timber surfaces. A set of low-cost steel springs is designed and installed on both sides of the dovetail joint to recenter the structure back to its original position after the end of an earthquake ground motion excitation. A novel, low-cost and deformable wood material fabricated from delignified balsa wood is used to reduce the pounding effects before the activation of the steel springs. The seismic behavior and the recentering ability of the novel timber-based energy dissipation system subjected to an ensemble of recorded earthquake ground motion excitations was experimentally investigated through a large-scale shaking table investigation at ETH Zurich.
... Vulnerable structures that are not dilapidated could be sufficiently protected by reducing the seismic acceleration, i.e. the so-called peak ground acceleration (PGA) which acts directly on them. Since PGA strongly depends on the soil type through the site effects, on this issue the scientific literature includes both structural and geotechnical solutions: the first mainly regard the base isolation techniques (;arone et al. 2019;De Domenico et al. 2020;Eröz & DesRoches 2018), while the second are referred to as "Geotechnical Seismic Isolation" (GSI) and consist of interventions aimed at improving the dynamic properties of the foundation soil (Tsang et al. 2012;Tsiavos et al. 2020;Tsang et al. 2021). Despite the scientific evidence of the efficiency of GSI techniques in the seismic risk mitigation, there are often doubts concerning their feasibility, almost exclusively possible underneath new buildings, and secondary effects, e.g. on mechanical aspects, such as settlements because of the materials' deformability. ...
... Even more recent is the direct intervention in the soil, defined by Tsang (2008) and Tsang et al. (2012) as geotechnical seismic isolation (GSI), which is receiving growing interest. These techniques can be used to reduce earthquake-induced loads acting on superstructures, allowing to protect them from the potential effects of earthquakes. ...
Article
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The paper focuses on the detailed analysis of the dynamic characterisation of polyurethane to evaluate the effects of polyurethane injections into soil with the aim of geotechnical seismic isolation. To determine the dynamic properties, resonant column (RC) tests were performed at the University Kore of Enna (Italy) on specimens of pure polyurethane with different values of density and subjected to different mean confining pressures. The results obtained by means of RC tests, in terms of shear modulus G and the damping ratio D as a function of shear strain γ c , allowed to develop an analytical formulation for G-γ c and D-γ c curves, taking into account the linear relationship with density, of both the maximum value of shear modulus G max and the minimum value of damping ratio D min . The analytical formulation derived from the experimental results is applied for ground response seismic analyses of cohesive soils injected with polyurethane, using a finite element code. The numerical results show that the polyurethane injections reduce the value of maximum acceleration on the ground surface and the reduction varies with the thickness of the soil modified by polyurethane injections.
Chapter
The extensive generation of end-of-life (ELT) tires worldwide has resulted in adverse environmental effects and threats to public health and safety including tire fires and leaching of contaminants into the soil environment, groundwater, and surface water. It is becoming imperative to investigate more sustainable and large-scale opportunities for the reuse of ELTs. One novel engineering solution is their reuse in structures with enhanced seismic resilience. This is particularly important in countries such as New Zealand and Japan where past earthquakes have caused widespread damage and socioeconomic loss. Research is being carried out to investigate a seismic-resilient engineered foundation-soil system for low-to-medium-density low-rise residential housing composed of a layer of granulated tire rubber (GTR) and gravel, and a flexible rubber–concrete raft foundation. It is essential to ensure that such innovations do not result in long-term negative impacts on the environment as tires contain hazardous compounds used in their manufacturing and the steel fiber within the tires can leach heavy metals (e.g., zinc, manganese, lead, cadmium). Preliminary batch leaching tests undertaken on (1) GTR and (2) GTR: gravel mixtures (20–40% rubber content by volume) indicated leaching of calcium (Ca), sodium (Na), magnesium (Mg), and potassium (K) which was contributed to the gravel and low levels of zinc (Zn), which were attributed to the tires.
Article
An innovative seismic isolation technique known as the flat-spring friction system (FFS) for seismic isolation was developed in this study. This novel isolation technique has some distinct features, such as improved uplift-restraint safety, higher vertical sustaining force, extended environmental duration, and variable frequency, which can be intuitively observed by readers. A series of analytical and numerical investigations were conducted to verify the seismic isolation performance of the FFS. An algorithm for the FFS was developed, and a multi-storey structural model was established. Seven earthquake records were selected as the input to shake the structural model. The numerical simulation results showed that the structural response could be significantly reduced when the FFS was installed as isolators.
Article
The primary purpose of this work is to evaluate the viability of using waste rubber particles as buried pipe backfill. By applying confined compression test and model test, this research studied the compressibility of sand and rubber-sand mixtures (RSM) and also, investigated the behavior of pipe surrounded by sand and RSM subjected to impact loading. The findings are as follows: 1) The vertical elastic strain and plastic strain of compression test samples increase with rubber content, and the elastic strain and plastic strain of saturated samples are greater than those of dry samples. 2) The settlement of RSM model soil is greater than that of pure sand model soil subjected to impact loading. The addition of rubber particles to pure sand reduces the earth pressure increment. The cumulative strain of pipe surrounded by dry RSM is less than that surrounded by dry pure sand. However, the cumulative strain of pipe surrounded by saturated RSM is greater than that surrounded by saturated pure sand. This investigation provides an environmentally friendly approach for recycling waste tire particles in geotechnical engineering.
Article
Dynamic behavior of sand-bitumen mixtures was investigated using a series of dynamic hollow cylinder tests. The effects of different parameters including bitumen content, loading frequency and bitumen viscosity on shear modulus and damping ratio of the mixtures were evaluated in detail. The results showed the added bitumen increased shear modulus of the mixture up to about 20% for bitumen content of 3.5% in the range of shear strains between 0.01% and 0.1%. Such an increase was negligible at shear strains beyond 0.3%. Moreover, the added bitumen boosted damping ratio of the mixtures up to about 10% for bitumen content of 3.5% at shear strains beyond 0.3% while this increase was only about 5% at shear strains less than about 0.1%. Damping ratio and shear modulus of the mixtures changed with the frequency of applied loading mainly due to the viscous behavior of the bitumen. It was also found that using more viscous bitumen augmented damping ratio and shear modulus of the mixtures.
Thesis
The problem under consideration is the earthquake impact on structures. The subject of the performed research is the efficiency of seismic base isolation using layers of predominantly natural materials below the foundation, as well as the development of a numerical model for seismic analysis of structures with such isolation. The aseismic layers below foundation are made of limestone sand - ASL-1, stone pebbles - ASL-2, and stone pebbles combined with layers of geogrid and geomembrane - ASL-3. The experimental research methodology is based on the use of shake-table and other modern equipment for dynamic and static testing of structures. Experiments were conducted on the basis of detailed research plan and program. Efficiency of the limestone sand layer - ASL-1 was tested on cantilever concrete columns, under seismic excitations up to failure, varying the sand thickness and intensity of seismic excitation. Influence of several layer parameters on the efficiency of stone pebble layer - ASL-2 was investigated. For each considered layer parameter, a rigid model M0 was exposed to four different accelerograms, with three levels of peak ground acceleration (0.2 g, 0.4 g and 0.6 g), while all other layer parameters were kept constant. On the basis of test results, the optimal pebble layer was adopted. Afterwards, the optimal ASL-2 efficiency was tested on various model parameters: stiffness (deformable models M1-M4), foundation size (small and large), excitation type (four earthquake accelerograms), and stress level in the model (elastic and up to failure). In the ASL-3 composite aseismic layer, the optimal ASL-2 is combined with a thin additional layer of sliding material (geogrid, geomembrane above limestone sand layer), in order to achieve greater efficiency of this layer than that of the ASL-2. A total of eleven different aseismic layers were considered. To determine the optimal ASL-3, the M0 model was used, like for the ASL-2. On the basis of test results, the optimal ASL-3 layer was adopted (one higher strength geogrid at the pebble layer top). The optimal ASL-3 is tested on various model parameters, analogous to the optimal ASL-2. A numerical model for reliable seismic analysis of concrete, steel, and masonry structures with seismic base isolation using ASL-2 was developed, with innovative constitutive model for seismic isolation. The model can simulate the main nonlinear effects of mentioned materials, and was verified on performed experimental tests. In relation to the rigid base - RB without seismic isolation, model based on the ASL-1 had an average reduction in seismic force and strain/stress by approximately 10% at lower PGA levels and approximately 14% at model failure. Due to the effect of sand calcification over time, the long-term seismic efficiency of such a layer is questionable. It was concluded that the aseismic layers ASL-2 and ASL-3 are not suitable for models of medium-stiff structure M3 and soft structure M4. In relation to the RB without seismic isolation, the M1 (very stiff structure) and M2 (stiff structure) based on the ASL-2 had an average reduction in seismic force and strain/stress by approximately 13% at lower PGA levels and approximately 25% at model failure. In relation to the RB without seismic isolation, the M1 and M2 based on the ASL-3 had an average reduction in seismic force and strain/stress by approximately 25% at lower PGA levels and approximately 34% at model failure. In relation to the RB without seismic isolation, the ASL-2 and ASL-3 did not result in major M1 and M2 model displacements, which was also favourable. It is concluded that the ASL-2 and especially ASL-3 have great potential for seismic base isolation of very stiff and stiff structures, as well as small bridges based on solid ground, but further research is needed. In addition, it was concluded that the developed numerical model has great potential for practical application. Finally, further verification of the created numerical model on the results of other experimental tests is needed, but also improvement of the developed constitutive models
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To make full use of advantages of waste steel slag and old rubber particles, the steel slag and rubber particles were mixed into the mucky clay to form the mucky clay-steel slag-rubber particles admixtures (MCSRA) to improve the engineering properties of mucky clay. Dynamic tests have been carried out by resonant column apparatus to investigate the influence of steel slag content, rubber particle content, rubber particle size and confining pressure on small-strain dynamic shear properties of MCSRA. The results showed that the dynamic properties of MCSRA were significantly improved compared with those of the mucky clay. It also revealed that as steel slag content increased, the shear modulus increased and the damping ratio decreased. In addition, as rubber particle content and rubber particle size increased, the shear modulus decreased and the damping ratio increased, and as confining pressure increased, the shear modulus increased and the damping ratio decreased. Moreover, an improved dynamic model was built based on the Hardin-Drnevich model to describe the dynamic performance of MCSRA. By comparing the dynamic characteristics of MCSRA with those of the mucky clay-steel slag admixtures, the Fujian standard sand and the Nanjing fine sand, the MCSRA could be applied to replace the mucky clay improved with the steel slag and Nanjing fine sand in some practical engineering.
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The micromechanical behaviour of sand-rubber mixtures (SRMs) under monotonic triaxial shear were investigated using X-ray micro-tomography. The localisation of sand particle rotations that occurred in a pure sand sample under shear was inhibited in the sand mixed with 30% rubber grains by mass. Meanwhile, the SRMs exhibited an evolution of sand-sand contact coordination number that is not negatively correlated with sample porosity, dramatically different from that was observed in pure sands. Substantially increasing anisotropy degree of sand-rubber contacts compared with minor changes of sandsand contact fabric was observed, implying the increasingly important role of sand-rubber contacts in the transmission of deviatoric loads as the shear of SRMs progressed.
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The increase in the volume of scrap tires has led to environmental concerns in different locations of the world, particularly in the coastlines. Managing this solid waste, including reuse in civil engineering applications (e.g. geotechnical projects) can be an effective solution to solve the problem. A series of drained triaxial tests was performed on Qeshm calcareous soil obtained from Qeshm Island. Specimens were prepared at loose and dense relative densities and mixed with different percentages of tire crumbs (TCs), including 0%, 10%, 20%, 30%, and 50%. The variation ratio parameter was introduced to evaluate the effect of TCs on the engineering properties of the soil-tire mixture. Based on the results, the stress–strain behavior of the calcareous soil was strongly influenced by TCs contents. As the tire content (TC) increases, the stress transfer mechanism changes from particle-particle to tire-tire, which results in a shear strength reduction. For an example, the addition of 50% of TCs to the calcareous soil resulted in a 64% reduction in the maximum deviatoric stress under a confining pressure of 600 kPa. In addition, the secant modulus at maximum deviatoric strength of the soil-tire mixture with 50% of TCs decreased about 80%.
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As reuse materials, waste tires mixed with soils are valuable materials to be used for many purposes in geotechnical projects that may be subjected to dynamic loads. The aim of this study is to assess the efficacy of using waste tires in buried pipe protection. To achieve this purpose, a series of laboratory model tests were carried out to investigate the dynamic responses of pipe buried in pure soil and rubber soil mixtures with volume content of 10%, 20% and 30% rubber particles. Test results such as earth pressure and strain of buried pipe are discussed in this study. The results indicate that inclusion of 20%-30% rubber particles in the mixtures leads to a change in earth pressure increment distribution, and these mixtures leads to obvious reductions in earth pressure increments. For the mixtures with 20%-30% rubber particles, the pipe has lower strain under the dynamic loading. Compared with pure soil, the mixtures with 20%-30% rubber particles exhibit better performances in regards to responses of pipe-soil system. Hence, the research undertaken in this paper provides a viable approach to protect the buried pipe subjected to dynamic loading.
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Geotechnical Seismic Isolation (GSI) is an emerging category of earthquake protection systems that involve dynamic interaction between the structure and geomaterials. This new field of study has diversified and gained momentum through a decade of research. This paper attempts to consolidate the collective research efforts at a high level and put forward a vision plan for global collaboration amongst GSI researchers and for multi-sectoral engagement with end-users including governments, non-governmental organisations, builders, engineering professionals and local communities. Finally, resilience, sustainability and universality, as the three overarching goals of GSI, are highlighted.
Chapter
Comparative Analysis of Utilization of Salts for Stabilization of Black Cotton Soil .
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Traditionally, seismic isolation is a flexible or sliding interface positioned between a structure and its foundation for the purpose of decoupling the motions of the ground from that of the structure. In recent years, novel seismic isolation methods have been proposed, in which the flexible or sliding interface is in direct contact with geological sediments and the isolation mechanism primarily involves geotechnics. Smooth synthetic liners have been proposed beneath foundations or between soil layers for dissipating seismic energy through sliding. Rubber-soil mixtures have also been proposed around foundations for absorbing seismic energy with a function similar to that of a cushion. The low cost of these proposed seismic isolation methods can greatly benefit developing countries where resources and technology are not adequate for earthquake mitigation using well-developed, yet expensive, techniques. In this chapter, the background and principles of these new methods will be introduced, followed by the latest research findings. Potential problems and further research directions will be identified and discussed.
Conference Paper
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This paper considers the potential usage of a rubber-soil mixture beneath the foundation of a building in order to reduce the induced seismic loads. The appropriateness of replacing backfill soil by a granulated rubber-soil mixture, as a kind of distributed seismic isolation system, is assessed through numerical simulations using the finite element method. Specifically, the effect of utilizing rubber-soil mixtures in the foundation soil of a 5-storey building on its seismic behaviour is studied by comparing the computed seismic responses with those calculated using the corresponding system without the replacement of the foundation soil. Numerical simulations and parametric analyses are conducted, using a commercially available software (SAP2000), in order to study the effect of certain soil parameters and earthquake characteristics. The effectiveness of using a rubbersoil mixture on the dynamic response of the simulated structure is discussed in terms of peak absolute top-floor accelerations.
Article
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This paper describes the design and construction of a twelve storey office building which has base isolators (i.e. energy dissipators) and external cross bracing to resist lateral loads. The computer analysis techniques used are described and some comparisons are made with non-base isolated structures. The system shows a practical method of using base isolation and energy dissipation techniques in a multi-storey structure. The construction of the building has proved the system to be advantageous in terms of both cost and construction time.
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Processed waste tires mixed with soils are applicable in lightweight fills for slopes, retaining walls, and embankments that may be subjected to seismic loads. Rubber's high damping capacity permits consideration of granulated rubber/soil mixtures as part of a damping system to reduce vibration. The dynamic properties of granulated rubber/soil mixtures are essential for the design of such systems. This research investigates the shear modulus and damping ratio of granulated rubber/sand mixtures using a torsional resonant column. Specimens were constructed using different percentages of granulated tire rubber and Ottawa sand at several different percentages. The maximum shear modulus and minimum damping ratio are presented with the percentage of granulated rubber. It is shown that reference strain can be used to normalize the shear modulus into a less scattered band for granulated rubber/sand mixtures. The normalized shear modulus reduction for 50% granulated rubber (by volume) is close to a typical saturated cohesive soil. Empirical estimation of maximum shear modulus of soil/rubber mixtures can be achieved by treating the volume of rubber as voids.
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The primary objective of the research described herein is to assess the pertinent engineering properties for reusing shredded scrap tires as a construction material for light-weight fill material in highway construction, for drainage material in highway and landfill construction, and for other similar applications. Reuse of scrap tires would not only provide a means of disposing of them but would also help solve difficult economical and technical problems. This paper presents the characteristics of shredded scrap tires and their engineering properties and behavior alone or when mixed with soils. The properties considered include compaction, compressibility, strength and deformability, and hydraulic conductivity. Described are new test procedures or modification of existing methods developed to characterize this unusual material.
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The United States Environmental Protection Agency (USEPA) estimates that over 279 million discarded tires are being added annually to the already existing stockpile of two billion tires. Current disposal and stacking methods of waste tires are not acceptable due to the possibility of fire and health hazards. Several states and the federal government have issued legislation that encourages or mandates the recycling of discarded tires. One application where shredded tires can be used is as a lightweight fill material behind retaining walls or in highway embankments over weak or compressible soils. This paper presents the engineering properties of shredded tires, Ottawa sand, and a mixture of 50% Ottawa sand and 50% shredded tires by volume (70% Ottawa sand and 30% shredded tires by weight). The maximum size of the tire chips used was 4.75 mm. Gradation, specific gravity, void ratio, density, permeability, and consolidated-drained (CD) triaxial tests were performed as part of the testing program. Although the data obtained were limited to the above three mixes, the results indicate that the use of shredded tires/Ottawa sand mixes as a lightweight fill material is very promising. However, long-term impact of leachates from tires on groundwater quality should be investigated.
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The growing interest in utilizing waste materials in civil engineering applications has opened the possibility of constructing reinforced soil structures with unconventional backfills. Scrap tires are a high-profile waste material for which several uses have been studied, including the use of shredded tires as backfill. A triaxial testing program was conducted to investigate the stress-strain relationship and strength of tire chips and a mixture of sand and tire chips. The test results and additional information from the literature were used in the numerical modeling of wall backfills, both unreinforced and reinforced with geosynthetics. The numerical modeling results suggest tire shreds, particularly when mixed with sand, may be effectively used as a backfill.
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Masonry infill walls are widely used as partitions worldwide. Field evidence has shown that continuous infill masonry walls can help reduce the vulnerability of a reinforced concrete structure. In order to test this hypothesis, a full-scale three-story flat-plate structure was strengthened with infill brick walls and tested under displacement reversals. The results of this test were compared with results from a previous experiment in which the same building was tested without infill walls. In the initial test, the structure experienced a punching shear failure at a slab-column connection. The addition of infill walls helped to prevent slab collapse and increased the stiffness and strength of the structure. The measured drift capacity of the repaired structure was 1.5 %. A numerical model of the test structure was calibrated to match experimental results. Numerical simulations of the response of the strengthened structure to several scaled ground motion records suggest that the measured drift capacity would not be reached during strong ground motion.
Conference Paper
The stockpiling of scrap tires is a significant threat to our environment and has been a hot topic amongst the engineering community which has been looking for long term viable solutions to the recycling and reuse of rubber tires. This paper proposes a new method of utilizing scrap tires for applications in infrastructure protection forming part of the solution strategy. The method involves mixing scrap tire particles with soil materials and placing the mixtures around civil engineering systems, for vibration absorption. The inexpensive nature of the proposed method can be of great benefits to developing countries where there are affordability issues with employing expensive resources and state-of-the-art technology for infrastructure protection. The interaction of compacted soil with interlocking rubber components exploits the well known reinforced earth principles. This study employs conventional soil-structure interaction analysis techniques for quantifying the effectiveness of rubber-soil mixtures in terms of its ability to dissipate energy and control vibrations. While deriving closed-form analytical expressions for such heterogeneous conditions remains to be a difficult task, the potential of the proposed method has been demonstrated by numerical modeling to show its effectiveness and robustness as a means of protecting low-to-medium-rise buildings in an earthquake.
Article
An acoustic model employing sound waves in a fluid medium was used to evaluate the use of rows of piles as passive isolation barriers to reduce ground vibrations. The results of experimental measurements indicate that the effectiveness of the barriers is highly dependent on the mismatch between pile and soil material properties, with greater mismatch resulting in greater effectiveness. Pile-to-pile aperture spacing of 0. 4 times the wavelength was found to be the upper bound for a barrier to have some effectiveness, and a minor dependence of effectiveness on the pile diameter was also observed. The extrapolation of the model studies to actual field problems is considered.
Article
Tire chips made from waste tires have a compacted dry unit weight of 40 pcf (0.64 Mg/m3) and a specific gravity of 1.05 making their use as lightweight fill for highway embankments over compressible soils very advantageous. A large scale compressibility apparatus with the capability to measure side friction and horizontal stress was fabricated. Compressibility tests showed that tire chips were very compressible at low stresses but that compressibility decreased significantly at higher stresses. The coefficient of lateral earth pressure at rest was about 0.40 at low stresses and about 0.94 at high stresses. Preliminary finite element studies showed the importance of the thickness and modulus of the subbase overlying the tire chips on pavement deflections.
Article
In this study, an experimental investigation program on a newly proposed seismic isolation technique, namely “Geotechnical Seismic Isolation (GSI) system”, is conducted with an aim of simulating its dynamic performance during earthquakes. The testing procedure is three-fold: (1) A series of cyclic simple shear tests is conducted on the key constituent material of the proposed GSI system, i.e., rubber-sand mixture (RSM) in order to understand its behavior under cyclic loadings. (2) The GSI system is then subjected to a series of shaking table tests with different levels of input ground shakings. (3) By varying the controlling parameters such as percentage of rubber in RSM, thickness of RSM layer, coupled with the weight of superstructure, a comprehensive parametric study is performed. This experimental survey demonstrates the excellent performance of the GSI system for potential seismic hazard mitigation.
Article
The effects of seismic base isolation on the response of structures supported on pile foundations are discussed. The benefit of seismic isolation is achieved by means of flexible piles that may be partially embedded in an inelastic material and that direct substantial energy dissipation and radiation into the surrounding soil. The resulting dynamic characteristics of such a system are found to be considerably different from those of the structure with a fixed base. Using a finite element model developed in a companion paper, the influence of the key parameters affecting the response are studied. A lumped-mass building model with a variety of subsurface conditions is analyzed for free vibration, under constantamplitude ground acceleration, and under horizontal ground accelerations from representative earthquakes. The studies reveal that the interactive flexible-pile system is effective as a base-isolation mechanism.
Conference Paper
This paper presents a promising earthquake protection method by placing rubber-soil mixtures (RSM) around underground tunnels for absorbing vibration energy and exerting a function similar to that of a cushion. The validity of the method will be demonstrated by numerical simulations using various recorded earthquake ground motions. The use of scrap tires as the rubber material can provide an alternative way of consuming huge stockpiles of scrap tires from all over the world. Moreover, the low cost of this proposed method can greatly benefit developing countries where resources and technology are not adequate for earthquake mitigation using welldeveloped, yet expensive, techniques.
Article
Subsoil interventions to enhance the static soil resistance and reduce deformations may alter significantly the seismic response of the complex soil-foundation-structure system. The aim of this article is to have an insight in the physics of the problems encountered and to validate an adequate numerical modeling procedure to study these effects of the intervention in the global response of the system. Validation concerns wave propagation, site effects, and dynamic soil-structure-interaction issues including the intervention beneath the foundation. Theoretical models-expressions and experimental results from centrifuge tests have been used. The proposed numerical model is proven very efficient to describe the complex dynamic phenomenon and anticipate the seismic response after the employment of subsoil interventions.
Article
The feasibility of constructing buildings on horizontally flexible foundations to mitigate the effects of earthquakes is investigated. The flexibility is achieved by inserting a soft spring between the building superstructure and the soil foundation. The use of slender piles enclosed in sleeves is found to permit flexural distortion. The piles are designed by a simple procedure using smoothed response spectra. The performance of building-foundation systems so designed are then studied using histories of actual ground motions. It is shown that the simple design procedure is adequate and that the concept achieves the desired result of greatly reducing seismic forces. The maximum seismic forces on the building may be reduced to a level which is so low that the forces probably do not affect the design of the superstructure. The economic feasibility of the concept is analyzed and it is shown that the additional foundation cost can be justified on the basis of savings in initial superstructure cost and in probable future damage costs.
Article
A study on the influence of the plasticity index (PI) on the cyclic stress-strain parameters of saturated soils needed for site-response evaluations and seismic microzonation is presented. Ready-to-use charts are included, showing the effect of PI on the location of the modulus reduction curve G/G(max) versus cyclic shear strain-gamma-c, and on the material damping ration gamma-versus-lambda-c curve. The charts are based on experimental data from 16 publications encompassing normally and overconsolidated clays (OCR = 1-15), as well as sands. It is shown that PI is the main factor controlling G/G(max) and lambda for a wide variety of soils; if for a given gamma-c PI increases, G/G(max) rises and lambda is reduced. Similar evidence is presented showing the influence of PI on the rate of modulus degradation with the number of cycles in normally consolidated clays. It is concluded that soils with higher plasticity tend to have a more linear cyclic stress-strain response at small strains and to degrade less at larger gamma-c than soils with a lower PI. Possible reasons for this behavior are discussed. A parametric study is presented showing the influence of the plasticity index on the seismic response of clay sites excited by the accelerations recorded on rock in Mexico City during the 1985 earthquake.
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Design Example for a High-Damping Rubber Bearing Design Example for a Lead-Plug Bearing
Article
A series of large-scale underwater shaking table tests was performed on a gravity type model caisson protected by a cushioning technique using tire chips (scrap tire derived recycled product). The function of the tire chips cushion is to reduce the load and restricting the permanent displacement of such waterfront retaining structures during earthquakes by exploiting the compressibility, the ductility and the energy absorbing capacity of tire chips. The seismic performance of such earthquake resistant techniques was evaluated by subjecting the soil-structure system into three different earthquake loadings (two actual earthquake records and one synthetic earthquake), and measuring the respective responses. The results demonstrated that the seismic load against the caisson quay wall could be substantially reduced using the proposed technique. In addition, the presence of the protective tire chips cushion could significantly reduce the earthquake-induced residual displacement of the caisson quay wall.
Article
A synthetic liner consisting of a nonwoven geotextile over an ultrahigh molecular weight polyethylene, geotextile/UHMWPE, placed within a soil profile can dissipate seismic energy transmitted to the overlying soil layer and structure. This concept of soil isolation can be an effective and inexpensive way of reducing seismic ground motions through slip displacements. Shaking table tests on soil layers isolated using cylindrical and tub-shaped liners were conducted using harmonic and earthquake base excitations. The results show that an isolation liner can significantly reduce the accelerations at the surface of the isolated soil mass. Accompanying such a reduction in accelerations are slip displacements that manifest around the perimeter of the isolated soil. Because of the curved nature of the liner, permanent slips are minimized by the restoring effect of the gravitational forces of the isolated soil mass. Analytical results under field scale conditions indicate that a soil isolation liner can dramatically reduce the peak and spectral accelerations of a vertically propagating shear wave. Such a reduction can provide seismic protection to a structure founded on soil-isolated ground.
Article
Smooth synthetic materials placed underneath foundations of structures can provide seismic protection by absorbing energy through sliding. Cyclic and shaking table tests were conducted on a variety of synthetic interfaces to identify a suitable liner for use as foundation isolation. It was concluded that a high strength, nonwoven geotextile placed over an ultrahigh molecular weight polyethylene, UHMWPE (geotextile/UHMWPE) constitutes a liner that is well suited for this application. The static friction coefficient of the interface (between the geotextile and the UHMWPE) is about 0.1. The dynamic coefficient is about 0.07 and is insensitive to changes in slip rate and normal stress. A single-story structural model with and without foundation isolation was tested using a shaker table. The results demonstrate the role of foundation isolation in substantially reducing the seismic shear forces in the model. Accompanying this reduction in shear forces are slip displacements along the isolation liner. Permanent slip (final location of the structure relative to its initial position) can be reduced through the use of a small restoring force that could be provided through passive soil resistance. Peak-to-peak slip (maximum slip during shaking) needs to be permitted for foundation isolation to be effective. The experimental and analytical research results demonstrate the technical feasibility of using a smooth synthetic liner in earthquake hazard mitigation.
Article
Tunnels are used to convey transportation in dense urban areas, especially by underground trains. Underground trains radiate noise and vibration by airborne sound and by transmission of vibration through the rails to the surrounding ground. The acoustic wave propagates through the ground, being transmitted by soil–structure interactions to nearby buildings. The transportation induced vibrations add to the static and other types of loads, and their specific spectral features are well distinguished and perceived as nuisance to people. The disturbing effect caused by these solid borne vibrations can be significantly mitigated by soil replacement of the material under the rails. This technique, which was described in previous publications by the authors, is further developed and analyzed here by modeling and numerical analysis, for underground applications. Illustrative examples show through spectral analysis the role of soil replacement, avoiding sound bridges. In this context, the required thickness of the soil replacement layer was considered. It is shown that a 0.5m thick layer may be sufficient for most practical purposes.
Article
A finite element model to study the effects of seismic base isolation on the response of structures supported on pile foundations is presented. The model takes into account both pile flexibility and energy dissipation and radiation, realized through the mechanism of soil-pile-structure interaction. The resulting dynamic characteristics are considerably different from those of the structure with a fixed base. The model is applied to study the influence of soil-pile-structure interaction on the response of structures, including nonlinear pile-soil effects. To incorporate nonlinearities in the soil-pile system that might arise from large deformations under severe earthquake loading, the piles are modeled as beam-column finite elements with material and geometric nonlinearities, while the soil is idealized by nonlinear springs and dashpots uniformly attached to the piles along their length. For the soil springs, a modified Ramberg-Osgood model is employed. For the material damping of the soil, a simple relationship between the shear modulus and the damping is utilized. To simulate radiation damping effects in the soil, viscous dampers are attached to the pile. The model is tested against documented solutions for verification.
Article
A method to cover a tunnel lining with a soft and thin coating is discussed herein as a possible measure for mitigating seismic damage to tunnels. Long-term earthquake observations at different tunnel sites within a variety of alluvial soil deposits have demonstrated that a circular tunnel is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately. Narrowing down vibration modes, in order to discuss this particular and the most important mode, any of the essential items of the soil–tunnel system, namely the soil, the coating and the tunnel lining, has only one degree of freedom, allowing the coating effect to be simply evaluated in terms of a limited number of key parameters. Copyright © 2001 John Wiley & Sons, Ltd.
Book
1 Seismic Isolation for Earthquake-Resistant Design.- 1.1 Introduction.- 2 Vibration Isolation.- 2.1 Introduction.- 2.2 Theory of Vibration Isolation.- 2.3 Frictional Vibration Isolators.- 3 Seismic Isolation.- 3.1 Review of Fixed-Base Structural Analysis.- 3.2 Linear Theory of Base Isolation.- 3.3 Isolation of Very Flexible Structures.- 4 Extension of Theory to Buildings.- 4.1 M-Degree-of-Freedom Equations of Motion.- 4.2 Modal Analysis of M-DOF System.- 4.3 Estimates of Displacements and Forces for M-DOF System.- 5 Earthquake Regulations for Seismically Isolated Structures.- 5.1 Introduction.- 5.2 1994 Uniform Building Code.- 5.3 Design Methods.- 5.4 Static Analysis.- 5.5 Dynamic Analysis.- 5.6 Computer Programs for Analysis of Seismically Isolated Structures.- 5.7 Other Requirements for Nonstructural Components.- 5.8 Review.- 5.9 Design Requirements for Isolators.- 5.10 Base-Isolated Structures under Extreme Earthquake Loading.- 6 Coupled Lateral-Torsional Response of Seismically Isolated Buildings.- 6.1 Introduction.- 6.2 Case I: Three Close Frequencies.- 6.3 Case II: Equal Lateral Frequencies, Distinct Torsional Frequency.- 7 Behavior of M?ltilayered Bearings Under Compression and Bending.- 7.1 Introduction.- 7.2 Shear Stresses Produced by Compression.- 7.3 Bending Stiffness of a Single Pad.- 7.4 Pure Compression of Single Pads with Large Shape Factors.- 7.5 Compression Stiffness for Circular Pads with Large Shape Factors.- 7.6 Compression Stiffness for Square Pads with Large Shape Factors.- 7.7 Bending Stiffness of Single Pads with Large Shape Factors.- 8 Buckling Behavior of Elastomeric Bearings.- 8.1 Stability Analysis of Bearings.- 8.2 Stability of Annular Bearings.- 8.3 Influence of Vertical Load on Horizontal Stiffness.- 8.4 Downward Displacement of the Top of a Bearing.- 8.5 A Simple Mechanical Model for Bearing Buckling.- 8.6 Postbuckling Behavior.- 8.7 Influence of Compressive Load on Bearing Damping Properties.- 8.8 Rollout Stability.- 9 Design Process for Multilayered Elastomeric Bearings.- 9.1 Preliminary Bearing Design Process.- 9.2 Experimental Studies of Elastomeric Isolator Performance.- 9.3 Compact Design Bearings.- Afterword.- References.- Appendix A.- A.I Base-Isolated Buildings and Projects in the United States.- A.2 Retrofit Base-Isolated Buildings and Projects in the United States.- Appendix B.- B.I N-PAD.- B.2 3D-BASIS.- B.3 SADSAP.- B.4 General Nonlinear Three-Dimensional Analysis Programs.
Article
In the present article the effect of subsoil interventions on the response of soil-structure systems under strong earthquake shaking is studied. Several idealized configurations of commonly applied as well as innovative intervention techniques are examined, referring to increased or reduced stiffness of the initial subsoil conditions of the subsoil-foundation-structure system. Numerical analysis utilizing validated simulation procedures covers a large spectrum of structures and soil conditions. A parametric investigation of several key factors is also conducted. A comparative evaluation of the results in time and frequency domain is aiming in generalizing the conclusions to several earthquake and soil-structure combinations. Obtained results reveal a rather detrimental effect of the stiffness-increasing methods, whereas techniques related to modification of oscillation dynamic properties with flexible subsoil intervention schemes, present promising alternatives for an efficient mitigation of structural response to strong earthquakes.
Article
This study describes the development of a simple, heuristic manual calculation procedure for estimating the site period-shift factor and soil damping ratio, with appropriate considerations for the level of shaking, impedance contrast between soil and bedrock interface and the plasticity of the soil layers. Essentially, the analogy of a building shear-frame has been used to represent the seismic response behaviour of a soil column. The proposed procedure has been verified by comparing the predictions with results obtained directly from non-linear shear wave analyses of soil column models. Copyright © 2006 John Wiley & Sons, Ltd.
Article
This paper proposes a promising seismic isolation method particularly suitable for developing countries, which makes use of rubber–soil mixtures. Apart from reducing the level of shaking in the horizontal direction, the distinctive advantage of the proposed method is that it can also significantly reduce the shaking level of vertical ground motion, to which an increasing attention has been paid in the earthquake engineering community. On the other hand, the use of scrap tires as the rubber material can provide an alternative way to consume the huge stockpile of scrap tires all over the world. Moreover, the low cost of this proposed seismic protection scheme can greatly benefit those developing countries where resources and technology are not adequate for earthquake mitigation with well-developed, yet expensive, techniques. The proposed method has been demonstrated through a series of numerical simulations and a parametric study has also been carried out. Lastly, five important issues regarding the concept and feasibility have been discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Article
The areas that experienced large strains and differential motions in the soil (indicated by breaks in the water and gas pipe distribution systems) and the areas with severely damaged buildings showed remarkable separation during the March 10, 1933, Long Beach, California earthquake. With analogous results for the 1994 Northridge, California earthquake [Soil Dynam. Earthquake Engng. 17 (1998) 41], the observations summarized in this paper show the fallacy of simplistic and popular interpretations, such as those that hold that in the near field the damage to buildings is caused by 'soft' or 'bad ground' conditions. In fact, significant reduction in the potential damage to buildings may be expected in the areas where the soil experiences 'moderate to large' strains.
Article
The spatial relationship between areas with severely damaged (red-tagged) buildings and areas with large strains in the soil (indicated by reported breaks in the water distribution system), observed during the 1994 Northridge earthquake, is analysed. It is shown that these areas can be separated almost everywhere. Minimal overlapping is observed only in the regions with very large amplitudes of shaking (peak ground velocity exceeding about 150 cm s−1). One explanation for this remarkable separation is that the buildings on ‘soft’ soils, which experienced nonlinear strain levels, were damaged to a lesser degree, possibly because the soil absorbed a significant portion of the incident seismic wave energy. As a result, the total number of severely damaged (red-tagged) buildings in San Fernando Valley, Los Angeles and Santa Monica may have been reduced by a factor of two or more. This interpretation is consistent with the recorded peak accelerations of strong motion in the same area. It is concluded that significant reduction in the potential damage to wood frame single family dwellings may be expected in areas where the soil experiences ‘large’ strains (beyond the linear range) during strong earthquake shaking, but not significant differential motions, settlement or lateral spreading, near the surface.
Article
http://deepblue.lib.umich.edu/bitstream/2027.42/8349/5/bad6526.0001.001.pdf http://deepblue.lib.umich.edu/bitstream/2027.42/8349/4/bad6526.0001.001.txt
Earthquake protection of low-to-medium-rise buildings using rubber-soil mixtures
  • X Xu
  • Tsang
  • Al
Xu X. Earthquake protection of low-to-medium-rise buildings using rubber-soil mixtures. MPhil Thesis, Department of Civil Engineering, The University of Hong Kong, Hong Kong, 2009. 35 40 45 50 55 60 65 70 H.-H. TSANG ET AL.
Dynamic response of SDOF systems on soil replaced with sand/rubber mixture
  • K Senetakis
  • A Anastasiadis
  • K Trevlopoulos
  • K Pitilakis
Senetakis K, Anastasiadis A, Trevlopoulos K, Pitilakis K. Dynamic response of SDOF systems on soil replaced with sand/rubber mixture. Proceedings of the ECOMAS Thematic Conference on Computation Methods in Structural Dynamics and Earthquake Engineering, Rhodes, Greece, June 22-24, 2009.
Earthquake Engineering: New Research
  • H H Tsang
Tsang HH. Geotechnical seismic isolation. Earthquake Engineering: New Research. Nova Science Publishers, Inc.: New York, U.S., 2009, pp. 55-87.
MH The effectiveness of Chinese seismic design codes on the protection of masonry buildings against the great Wenchuan earthquake
  • Rkl Su
  • Chu
  • Cheng
Su RKL, Chu ML, Cheng MH. The effectiveness of Chinese seismic design codes on the protection of masonry buildings against the great Wenchuan earthquake, Proceedings of the Australian Earthquake Engineering Society Conference, Ballarat, Victoria, Australia, November 21-23, 2008.
Experimental study on innovative geotechnical seismic isolation system
  • W Xiong
  • H H Tsang
  • S P Shang
  • H D Wang
  • F Y Zhou
  • J B Yan
Xiong W, Tsang HH, Shang SP, Wang HD, Zhou FY, Yan JB. Experimental study on innovative geotechnical seismic isolation system. Journal of Building Structures 2010; 31(S2):39-45. (in Chinese)
Geotechnical seismic isolation by rubber-soil mixtures
  • H H Tsang
  • X Xu
  • S H Lo
  • Ntk Lam
Tsang HH, Xu X, Lo SH, Lam NTK. Geotechnical seismic isolation by rubber-soil mixtures. Proceedings of the 11th World Conference on Seismic Isolation, Energy Dissipation and Active Vibrations Control of Structures, Guangzhou, China, November 17-21, 2009.
Protecting underground tunnel by rubber-soil mixtures
  • H H Tsang
  • Jyk Lam
  • S Yaghmaei-Sabegh
  • S H Lo
Tsang HH, Lam JYK, Yaghmaei-Sabegh S, Lo SH. Protecting underground tunnel by rubber-soil mixtures. Proceedings of the 7th International Conference on Lifeline Earthquake Engineering, ASCE-TCLEE, Oakland, California, U.S., June 28 -July 1, 2009.
Simple models for estimating period-shift and damping in soil
  • H H Tsang
  • A M Chandler
  • Ntk Lam
Tsang HH, Chandler AM, Lam NTK. Simple models for estimating period-shift and damping in soil. Earthquake Engineering and Structural Dynamics 2006; 35(15):1925-1947.
Subsoil interventions effect on structural seismic response. Part I: validation of numerical simulations
  • Kirtas
Subsoil interventions effect on structural seismic response. Part II: parametric investigation
  • Kirtas