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Seismic isolation using granulated tire-soil mixtures for less-developed regions: Experimental validation

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Seismic isolation using granulated tire-soil mixtures for less-developed regions: Experimental validation

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Abstract

In this study, shaking‐table experiments were conducted with a novel seismic isolation system (Geotechnical Seismic Isolation, GSI) to validate its dynamic performance during earthquakes. This isolation technique uses shredded rubber–soil mixtures to reduce the structural response to earthquakes, and thus may not only provide economical structural safety for buildings in less‐developed regions, but could also consume a large amount of waste tires worldwide. The present experimental results show that the GSI system has potential to significantly mitigate seismic hazards. Copyright © 2013 John Wiley & Sons, Ltd.

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... In Tsang et al. (2012), 2D finite element simulations were conducted to calculate the soil-foundation-structure interaction in response to input seismic motions. An equivalent linear approach was adopted to simulate dynamic soil properties adopted from experimental testing undertaken by Zheng-Yi and Sutter (2000) and Xiong and Li (2013). The parameters considered for evaluating the effectiveness of the system were a) thickness of RSm foundation, b) ...
... To conclude, this chapter should be seen as an initial experimental study that explores the feasibility of an alternative design to improve the structural response against cyclic loading. Despite the high isolation efficiency shown in previous studies by implementing RSm isolating layers (Xiong and Li, 2013;Bandyopadhyay et al., 2015), a unique design configuration has been proposed whereby horizontal layers are installed before the superstructure. Hence, the vertical disposition of the soft zones herein proposed would allow its application to any existing and new infrastructure whilst minimizing the limitation associated with foundation settlement. ...
... Therefore, results from this study support the view that incident vibrations are more attenuated as damping increases, as established in existing research (Xiong and Li, 2013;Bandyopadhyay et al., 2015). The main discrepancy between this and previous studies stems from the basis to explain energy dissipation at lab/field scale. ...
Thesis
Full-text available
The disposal of scrap tyres has become a major environmental problem around the world. For its recovery, a geomaterial has been used as part of civil constructions, commonly known as Rubber-Soil mixture (RSm). The use of RSm has the potential to be used as geotechnical seismic isolation system and hence provide protection against earthquakes. However, the static and dynamic behaviour of RSm is not well understood. Various bulk (macro), particle (micro) properties, and the test conditions affect its characterisation. Whilst addressing this knowledge gap, the aim of this study was to understand the response of RSm under cyclic loading and evaluate its effectiveness in attenuating accelerations when used to retrofit a soil foundation. An experimental programme was chosen for this research and is divided into three scales; particle, element and 1g model scales. Plain strain visualisations, oedometer, and x-ray tomographic tests were performed to elucidate RSm particulate behaviour. To understand RSm dynamic behaviour, the evolution in stiffness and damping of the mixture was analysed from small-to-large deformations whilst altering rubber content and number of cycles. A sweep analysis was also performed via 1g shaking table tests to evaluate the cyclic performance of a scaled foundation-modified soil with RSm. The findings in this thesis revealed that the macro behaviour of RSm is highly influenced by the particle properties, including rubber mass, size, shape, stiffness and its interaction with sand particles. Tests showed a greater change in void ratio of mixtures containing shredded rubber compared to crumb rubber. 3D x-ray tomographic images revealed an increase in contact and a decrease in rubber volume of RSm under loading. This demonstrated that the high RSm compressibility is the result of both particle re-arrangement and rubber distortion. At an element scale, liquefaction resistance increased and mixtures did not liquefy by adding 20% rubber. The addition of rubber led to a reduction in soil stiffness whilst it increased the mixture resilience against cyclic loading, ameliorating the cyclic effect on stiffness and damping degradation. Material damping increased with rubber content at small-to-medium strains, whereas an upper value was revealed by adding 10% rubber at larger deformations. Test results supported the basis that energy dissipation in RSm is generated through particle sliding and rubber deformation, which takes over the dissipation mode after several cycles. Altering a host soil system by adding vertical discrete zones with RSm showed a lower amplification ratio and as a result mitigated part of the incident vibrations. The increase in damping capacity at a model scale was postulated to be the result of combining geometrical and material damping. The vertical disposition of the soft zone herein proposed could allow its application to both existing and new infrastructure.
... The seismic isolation in the GSI system is attained by using engineered soils, with high damping property and low-shear modulus, surrounding the building foundation for a limited depth [11][12][13][14]. The primary benefit of this method is that the partial energy dissipation happens within the soil itself before the vibrations reach the foundation and the superstructure [10,15,16]. Lately, studies on the GSI techniques have gradually broadened to seismic protection of bridge configurations and pile-supported bridge piers [14,17]. ...
... Limited experimental studies using shaking-table setup with SRM as isolation material placed below concrete/rigid block further confirm its suitability for seismic isolation [12,16,32]. However, experimental test on the seismic response of model building placed on SRM layer are not available in the literature. ...
Article
The Geotechnical Seismic Isolation (GSI) is recently recommended as an innovative base isolation system placed below the foundation of the superstructure for protection from earthquake damages. Low-shear modulus and high damping material such as Sand-Rubber Mixture (SRM) is used for the GSI layer. However, the compressible nature of SRM in the GSI layer leads to low bearing capacity and high settlement of foundations. In view of this, a GSI system consisting of SRM and geogrid reinforcement is proposed for low-rise buildings in the present study. Finite element based two-dimensional numerical investigation on the seismic performance of a two-storied building supported on raft footing resting on the proposed GSI system was carried out considering the soil–structure interaction. The nonlinearities of the subsurface materials were duly considered using hypoelastic formulations to account for the strain-dependent response. The effectiveness of geogrid reinforcement for the GSI system is demonstrated through seismic settlement analysis based on which optimum geogrid layers were chosen. Effect of various factors such as the thickness of GSI layer, frequency content of earthquake input motions on the seismic demand of the framed structure resting on the proposed GSI system was investigated. While the contribution of SRM was predominant in reducing the peak ground acceleration experienced by the building, the contribution of geogrids was evident in reducing the seismic settlement and lateral deformations on the structure. The results demonstrate the suitability of using the proposed GSI system with a thickness of 0.1B–0.2B (B is the footing width) with double layered geogrid reinforcement in significantly reducing the seismic demands of low-rise building.
... The rubber is a non-biodegradable material and its accumulation causes serious environmental imbalances. It is known as 'black pollutant' (Xiong and Li 2013). Hence, the utilization of scrap rubber tires is of paramount importance. ...
... Numerical studies carried out by Tsang et al. (2012) and Pitilakis et al. (2015) as well as shake table studies by Xiong and Li (2013) also points out the potential use of sand-rubber tire shred mixtures in effective earthquake protection. Apart from earthquake energy dissipation by GBI layers due to the vibration damping nature of rubber present in it, the high durability and non-biodegradable nature of rubber makes the GBI system an eco-friendly and sustainable solution for costly base isolation techniques. ...
Conference Paper
It is a known fact that the earthquakes cause huge loss to life and property. By and large, the seismic isolation systems are employed for massive structures mostly in developed countries. But the ordinary residential and commercial buildings remain vulnerable to the destructive effects of ground motions. It is necessary that the common masses of developing and underdeveloped nations should also have a method and means to protect their houses from the earthquakes given the fact that the existing seismic isolation systems are extremely expensive. On the other side, the generation of scrap rubber tires and their free disposal is a severe environmental problem. However, it is a known fact that the rubber is a very good damping material. A single shot solution to the above problems of earthquake hazard, unavailability of an affordable, effective seismic isolation system, rapid production of scrap rubber tires and exploiting the good damping property of rubber tires, would be to consider sand-rubber tire shred mixtures. In the first part of this study the static and dynamic characterization of sand-rubber tire shred mixtures are carried out to assess their suitability for seismic base isolation of low-rise buildings. The rubber tire shreds tailored to fine size are mixed with poorly graded sand in various gravimetric proportions. The static shear strength is determined using monotonic triaxial shear tests and the dynamic shear properties are assessed using strain controlled advanced cyclic triaxial tests under both dry and consolidated undrained conditions. The results of laboratory tests show that sand-rubber tire shred mixtures possess adequate static and dynamic properties required for seismic isolation of low-rise buildings. In the second part of the study, to demonstrate the effective use of sand-tire mixture as an isolating base layer for buildings, seismic response of typical buildings on sand-tire mixture isolator is carried out using finite element code ABAQUS. It is found that the geo-isolation layer made of sand-tire mixture effectively reduces the peak spectral acceleration and shifts the frequency content causing period lengthening depending on the thickness of the layer.
... 8 Waste tyre rubber has been considered as a desirable candidate for making RSM, 9 rendering GSI system an environmentally sound and low-cost technology that is affordable for the impoverished parts of the world, where earthquake disasters often exacerbate poverty. [10][11][12] All these contribute to various United Nations Sustainable Development Goals in relation to resilient infrastructure and cities, sustainable resource consumption and waste management, as well as reduction of poverty and inequality. ...
... Smallscale 1-g shaking table tests were conducted on lumped-mass models sitting on mixtures of sand and shredded rubber tyre. 10,37 It was found that GSI-RSM system could achieve a greater response reduction with higher percentage of rubber, thicker layer of RSM or at higher shaking levels. Shimamura 4 has developed two composite materials based on mixing soil-cement slurry with ductile nylon fibres and tyre rubber chips or high-damping rubber chips for backfilling around the peripheral of the foundation. ...
Article
Geotechnical seismic isolation (GSI) system involves the dynamic interaction between structure and low‐modulus foundation material, such as rubber‐soil mixtures (RSM). Whilst numerical studies have been carried out to demonstrate the potential benefits of GSI‐RSM system, experimental research is indispensable for confirming its isolation mechanism and effectiveness in reducing structural demand. In this regard, centrifuge modelling with an earthquake shaker under an acceleration field of 50 g adopted in this study can mimic the actual nonlinear dynamic response characteristics of RSM and subsoil in a coupled soil‐foundation‐structure system. This is the first time the performance of GSI‐RSM system was examined in a geotechnical centrifuge. It was found that an average of 40‐50% reduction of structural demand can be achieved. The increase in both the horizontal and rotation responses of the foundation was also evidenced. The unique augmented rocking mechanism with reversible foundation rotation was highlighted.
... Radnić et al. [6,7] found from shake table tests that a thin layer of plain sand under the foundation can reduce seismic forces to a cantilever concrete column by over 10%. Xiong and Li [8] analyzed seismic base isolation using rubber-soil mixtures (RMSs) based on shake table tests and a parametric numerical study in [9]. e effectiveness of utilizing a rubber-sand mixture (RSM) in the foundation soil of different momentresisting frame (MRF) typologies was assessed through numerical simulations in [10]. ...
Article
Full-text available
The results of a shake table study of the efficiency of a seismic base isolation using a layer of natural stone pebbles are presented. Models of stiff and medium-stiff buildings were tested. Case studies were conducted with the foundation of model on the rigid base and on four different layers of pebbles (thin and thick layer with small and large pebbles). Four different horizontal accelerograms were applied, and the characteristic displacements, accelerations, and strains were measured. Strains/stresses of the tested models remained in the elastic area. It was concluded that the effectiveness of the stone pebble layer under the foundation, i.e., the reduction in the seismic forces and stresses in the structure compared to the classical solution of foundation, significantly depends on the type of the applied excitation and depends relatively little on the layer thickness and pebble fraction. The results of the study showed that a layer of pebbles can significantly reduce the peak acceleration and strains/stresses of the model, with acceptable displacements. Further research is expected to confirm the effectiveness of this low-cost and low-tech seismic base isolation and to pave the way to its practical application.
... The GBI can attenuate the incoming earthquake waves and reduce structural responses like conventional base isolation systems. Shredded scrap tire-sand mixtures placed below the foundation can act as earthquake protection layers (Tsang et al. 2012;Xiong and Li 2013;Pitilakis et al. 2015). The use of a GBI layer has been found to partially dissipate earthquake energy within the soil itself before it propagates to the foundation and the superstructure. ...
Article
To mitigate earthquake-related damage to buildings, a simple alternative method to conventional base isolation techniques is to provide a geo-base isolation (GBI) system, composed of a scrap tire-sand mixture, between the base of the building foundation and the supporting soil medium. The GBI system should possess adequate dynamic stiffness and damping properties, as well as enough shear strength to resist both static and seismic loads. This study focused on the use of geogrid reinforcement to improve the bearing capacity, settlement, and rotational aspects of a shallow foundation resting on a GBI layer under static loading. Load tests were carried out on a model footing resting on GBI layer with and without geogrid reinforcement in a sand-bed tank setup. Finite-element-based numerical modeling of the footing on the GBI system with geogrid was also carried out, and the computed results were compared with those measured from the experiments. Parametric studies were carried out using the developed finite-element model to arrive at an optimum thickness of the GBI layer, number of geogrid layers, depth of placement of first geogrid, and length of geogrids. The results from the study indicate that the bearing capacity of the GBI layer can be increased up to three times by providing double-layered geogrid reinforcements with a substantial reduction in the settlement.
... Over the last decade, the effectiveness of GSI system based on RSM has been evaluated through numerical modeling [4,[29][30][31][32][33][34][35][36], shake table testing [14,[37][38][39], field tests [40,41], and hybrid simulation (also known as online pseudodynamic test) [13]. These studies have generally demonstrated the good performance and feasibility of the GSI concept. ...
Article
The innovative concept of geotechnical seismic isolation (GSI) system with the use of a continuous layer of low-modulus materials, such as rubber-soil mixtures (RSM), surrounding the foundation of structure has attracted considerable research interest on its performance at both system and material levels, since it was first proposed over a decade ago. The performance of the GSI system has been studied through a number of numerical, physical and hybrid modeling techniques; but due to the complexity of the problem, the isolation mechanism has not been thoroughly investigated. Hence, this article aims at initiating this aspect of development. A simple and efficient lumped-parameter analytical model is developed for analyzing the dynamic soil-foundation-structure interaction (SFSI) of the GSI system. Considering the importance of various nonlinearities involved, a theoretical approach for estimating effective shear strain is derived for capturing the nonlinearity of subsurface materials by the equivalent-linear method. The effectiveness of the analytical model is then demonstrated through a representative case study, based on which the main features of the isolation mechanism are investigated. The seismic isolation capability of the GSI system is founded on the reduced lateral stiffness of the RSM layer and the lower modulus of RSM that reduces the rocking stiffness. The proposed system could take advantage of the rocking isolation mechanism with reversible foundation deformations due to the higher elasticity of the RSM material.
... Tsang et al. [15] proposed RSM around the foundation of structures for absorbing seismic energy and exerting a function similar to that of a cushion. Further work dealing with RSM can be found in [16][17][18][19]. Experimental studies based on shake-table tests by providing geotextiles and a smooth marble frictional base isolation system at the plinth level of a brick masonry building were performed by Nanda et al. [20][21][22][23]. ...
Article
Full-text available
Using a shake-table, the effects of several stone pebble layer parameters (the layer thickness, the fraction of pebbles, the pebble compaction, the pebble moisture, the vertical contact stress below the foundation, and the effect of repeated excitations) on layer aseismic efficiency were investigated. For each considered parameter, a model of a rigid building on an aseismic layer was exposed to four different accelerograms, with three levels of peak ground acceleration (PGA), while all other layer parameters were kept constant. For each test, the characteristic displacements and accelerations were measured. Based on the test results, the main conclusions regarding the effect of the considered parameters on the effectiveness of the adopted aseismic layer are given.
... The rubber is a nonbiodegradable material and its accumulation causes serious environmental imbalances. It is known as 'black pollutant' (Xiong and Li 2013). Hence, the utilization of scrap rubber tires is of paramount importance. ...
Article
Full-text available
This paper deals with the characterization of dry sand-rubber tire shred mixtures to find shear strength and dynamic properties. A series of ordinary triaxial shear tests, direct shear tests and dynamic triaxial tests were performed on dense dry sand-rubber tire shred mixtures for various rubber replacement levels such as 0, 10, 30, 50 and 100% by weight. The effects of rubber content, confining pressures and rates of shearing on the angle of internal friction of the mixtures were investigated. Also, the influence of rubber content and the rate of horizontal displacement on the volumetric strain is presented. In addition, this paper proposes an appropriate method to find the angle of repose of dry sand-rubber tire shred mixtures. The angle of repose of the mixtures is compared with the angles of internal friction obtained from triaxial shear and direct shear tests. Finally, the effects of saturation, rubber content, axial strain, frequency and number of cycles of loading on the strain-dependent stiffness and damping properties of these mixtures were studied.
... The accumulation of rubber causes serious environmental imbalances. It is known as 'black pollutant' (Xiong and Li 2013). Hence, there is a need to find ways to efficiently utilize these scrap tires and in particular for geotechnical engineering purposes. ...
Conference Paper
The dynamic simple shear condition serves as the best field stress condition during seismic shaking. Conventional simple shear equipment comprises the specimens within the confines of stacked rings or wire reinforced membrane. This study employs a new dynamic simple shear apparatus capable of applying confining pressures similar to the triaxial testing equipment. The strain controlled dynamic simple shear tests were conducted on various proportions of rubber tire shreds and sand mixtures by weight under undrained conditions. The tests were performed on consolidated samples under effective confining pressures of 50, 100 and 200kPa at 1Hz frequency. This present study describes the pore pressure responses of rubber tire shred- sand mixtures at above mentioned testing conditions. It is found that the pore pressure development recedes with the introduction of rubber tire shreds into the sand matrix. The pore water pressures were found to increase with increase in the total vertical stresses. This characteristic of the rubber tire shred-sand mixtures can be harnessed for their use as seismic isolation materials of buildings.
... Prema dostupnim informacijama, do sada je objavljeno vrlo malo radova u kojima se istraživala "jeftina" seizmička izolacija osnove građevine pomoću prirodnih materijala. Rezultati nekih dosadašnjih istraživanja mogu se naći u [1][2][3][4]. U ovom su radu prikazani rezultati eksperimentalne studije o efikasnosti primjene sloja od prirodnih kamenih oblutaka ispod temelja na smanjenje potresnih sila na konstrukcije. Konačan cilj je praktična primjena takvog rješenja u budućnosti pri gradnji srednje visokih zgrada i manjih mostova u seizmičkim područjima. ...
... In the following years, it has been determined both experimentally and numerically by many researchers that this method is quite effective [6][7][8][9]. Though SRM mixtures significantly reduce the earthquake effect, Xiong and Li (2013) [10] stated that the mixtures containing more than 35% rubber by volume may cause stability problems in the superstructure. Similarly, Bandyopadhyay et al. (2015) [11] stated that the SRM mixtures containing 50% shredded rubber by weight reduced significantly base movement, but mixtures containing more rubber would initiate rocking mode in the structure and would result in stability problems in the foundation. ...
Article
Geotechnical seismic isolation (GSI) has been emerged as an economical and alternative method in recent years that reduces earthquake that will affect the superstructure. Crumb rubber-granular soil mixtures (SRM) are generally used as damping geomaterial in this method. However, the major disadvantage of SRM is that the addition of rubber leads to significant reduction in stiffness of the granular soil. In this study, dynamic properties (secant shear modulus (Gsec) and damping ratio (D)) of sand and bitumen mixtures (SB) which can be used as damping materials in GSI systems were determined by cyclic triaxial tests. In addition, monotonic triaxial tests were performed to determine the pre- and post-cyclic behavior of the mixtures. In the cyclic tests, the effect of bitumen penetration and content on the energy absorption capacity of the bituminous specimens was examined depending on cyclic stress ratio (CSR), cell pressure and loading frequency. According to the findings, it was determined that higher bitumen penetration and (CSR) result in decrease of Gsec and increase of D, yet the in-crease in confining pressure and the increase in loading frequency have the opposite effect. For the specimens prepared with both bitumen types, it was specified that the D increased depending on the increase of bitumen content, and the highest Gsec value was observed to be bitumen content of 8%. Moreover, the findings obtained from the monotonic triaxial tests showed that after a high number of cyclic loading, the peak deviatoric stresses of the SB samples increase slightly.
... e application of passive seismic isolation for buildings that was primarily practiced in the United States is discussed in [10]. e analysis of an innovative earthquake protection method by placing rubber-soil mixtures (RSMs) around the foundation of structures to absorb seismic energy based on shaking table experimental tests is presented in [11] and based on parametric numerical study in [12]. e devices used in practice are of different complexities, efficiencies, and costs. ...
Article
Full-text available
The possibility of the use of a layer of natural material under foundations for seismic base isolation was investigated. The dissipation of seismic energy of a low-cost natural material with adequate thickness, bearing capacity, and lateral and vertical stiffness, which can serve as an optimal solution for seismic base isolation under the foundations of many structures, was tested. This paper presents the results of a brief experimental study to determine the effectiveness of ordinary limestone sand under the foundation of a cantilever concrete column to increase its seismic resistance. The behavior of small-scale columns with three substrates below the foundation (rigid base, the thin layer of limestone sand, and the thick layer of limestone sand) was investigated by the shake table. The column was exposed to a set of horizontal base accelerations until structure collapse. It was concluded that a layer of limestone sand of appropriate thickness and compressibility can serve as the means a seismic base isolation. The nonlinear numerical model for the dynamic analysis of planar concrete structures coupled with soil is briefly presented and verified by the performed experimental tests.
... The use of rubber as base bearings is a commonly adopted solution due to its capacity to mitigate the impact of strong ground motions (Tsang, 2008). However, this sophisticated seismic isolation method is expensive and presents major technical difficulties related to the design and installation, precluding its installation to low-to-medium rise buildings in earthquakeprone developing countries (Tsang et al., 2012;Xiong & Li, 2013). Therefore, there is a need to develop low cost, easy deployment techniques for mitigation of earthquake damage in developing countries unable to afford the high cost of advanced base seismic isolations systems. ...
Conference Paper
Full-text available
Residential buildings in high population density areas are seismically vulnerable to the action of major seismic events. The high cost and technical difficulties related to the use of advanced seismic isolations systems precludes its installation to low-to-medium rise buildings in the developing world. The environmental issues attributed to the stockpiling of scrap tires and its use as tire derived fuel has led research to explore viable recycling solutions in civil engineering projects. Several authors have proposed a novel seismic isolation system by mixing recycled rubber tires with sand particles. However, research to date has been mainly focused on the dynamic properties of this mixture in the low-to-medium strain range at a specific loading cycle. This paper has studied the dynamic properties in the medium-to-large shear strain amplitude (0.05%-1%) of shredded rubber-soil mixtures (ShRm). The influence of the rubber percentage, size ratio, shear strain amplitude and number of cycles have been evaluated. The shear modulus decreases at larger rubber percentages and strain amplitudes. The damping ratio has been found to increase by adding 10% rubber but it decays at greater rubber percentages. The results show that the dynamic properties of ShRm are affected by the number of cycles at the strain amplitude assessed in this paper. However, the addition of up to 30% of shredded rubber particles increase significantly the resilience of sand particles against cyclic loading leading to a reduction in the stiffness and damping degradation.
... This isolation technique is cost-effective and eco-friendly, making it especially suitable for financially distressed developing countries. The GSI was later studied numerically [21] and experimentally [22]. With the same aim of providing an effective and robust seismic isolation system for less developed regions, Yao et al. [23] introduced the steel-asphalt composite layer system. ...
... To address vibration isolation using trench barriers, numerous analytical approaches (White 1958;Knopoff 1959a;Knopoff 1959b;Mal and Knopoff 1965;Thau and Pao 1966;Lee 1982;Avilés and Sanchez-Sesma 1983), two and three-dimensional investigations using finite element method (FEM) (Saikia and Das 2014;Younesian and Sadri 2014;Esmaeili et al. 2013;Zakeri et al. 2014;Yang and Hung 1997;Bo et al. 2014;Liyanapathirana and Ekanayake 2016;Jesmani et al. 2012;Jesmani et al. 2011;Jesmani et al. 2008;Hamdan et al. 2015;François et al. 2012;Shrivastava and Rao 2002), boundary element method (BEM) (Al-Hussaini and Ahmad 1996;Al-Hussaini and Ahmad 1991;Ahmad and Al-Hussaini 1991;Leung et al. 1991;Dasgupta et al. 1990), and other numerical methods (Sivakumar Babu et al. 2010), as well as laboratory and field studies (Murillo et al. 2009;Ulgen and Toygar 2015;Xiong and Li 2013;Coulier et al. 2014;Alzawi and El Naggar 2011;Connolly 2013;Çelebi et al. 2009), have been conducted on both open and infilled trenches. Laboratory and field studies are limited; thus, investigations employing numerical methods are most frequently utilized. ...
Article
Full-text available
Abstract This paper provides a review of various investigations concerned with vibration isolation using trench barriers and factors affecting their performance, also extracts design recommendations, because there is no exact conclusion of researches in this field. Vibrations induced by different sources can be seriously harmful to structures and occupants. Geometrical parameters, soil characteristics, and filling material properties can affect a barrier’s performance. Investigators have applied analytical approach, finite element, boundary element, experimental, and field studies to identify relevant factors. Various geometrical parameters affecting trench’s isolation level were examined, among which depth of trench was found to be the most important, but in most cases, the width of the trench and source-barrier distance have a low effect. Shear-wave velocity ratio of filling material and surrounding soil has the most significant role of all material properties. Using high-energy-absorbing materials can lead to better isolation. The majority of studies consider soil and filling material’s behavior to be elastic, so changes in loading amplitude have no effect on vibration reduction. Finally, among special cases in vibration isolation by trenches, non-rectangular and multiple ones found to be economically satisfying and wellisolating barriers. Keywords Trench barrier . Vibration isolation . Open and infilled trench . Ground borne vibrations
... To address the isolation of vibration using barriers, numerous analytical approaches (White, 1958;Knopoff, 1959aKnopoff, , 1959bMal & Knopoff, 1965;Thau & Pao, 1966;Lee, 1982;Avilés & Sanchez-Sesma, 1983), two-and three-dimensional (2D and 3D) investigations using the finite-element method (FEM) (Yang & Hung, 1997;Jesmani et al., 2008;Rahman & Orr, 2008;Jesmani et al., 2011Jesmani et al., , 2012Esmaeili et al., 2013;Bo et al., 2014;Saikia, 2014;Saikia & Das, 2014;Younesian & Sadri, 2014;Zakeri et al., 2014;Hamdan et al., 2015;Liyanapathirana & Ekanayake, 2016), boundary element method (BEM) Leung et al., 1991;Al-Hussaini & Ahmad, 1996) and other numerical methods (Sivakumar Babu et al., 2010) have been conducted on both open and in-filled trenches. However, laboratory and field studies (Çelebi et al., 2009;Murillo et al., 2009;Sivakumar Babu et al., 2010;Alzawi & El Naggar, 2011;François et al., 2012;Connolly et al., 2013;Xiong & Li, 2013;Coulier et al., 2014;Ulgen & Toygar, 2015) are very limited owing to the difficulty and expense involved in conducting them. According to the literature, it is known that open trenches offer better performance than filled ones (Alzawi & El Naggar, 2011;Bo et al., 2014;Saikia, 2014;Saikia & Das, 2014;Ulgen & Toygar, 2015) but, for the following reasons, it is necessary to use filled trenches. ...
Article
Vibration induced by different sources can be seriously harmful to structures and occupants and their isolation has gained importance during recent years with rapid urbanisation. Trench barriers (open or filled) have been used for isolating such unwanted vibrations, but few experimental studies have investigated the effects of different parameters on vibration reduction. This paper provides results of a series of full-scale field experiments conducted to investigate the effect of open and filled trenches on vibration screening. A sand–rubber mixture (SRM) was used to fill the trench as a lightweight, high-energy-absorbing and environmentally friendly material. Results confirmed that the SRM-filled trench can be used as an efficient, low-cost and easily constructed system for reducing ground vibration. In some cases, the performance level of SRM-filled trenches was close to that of open ones. The use of geophones that could record vibrations in three dimensions demonstrated that trench barriers can isolate vertical vibrations better than horizontal and transversal ones.
... Tsang [15] presented the geotechnical seismic isolation (GSI) system as an efficient, cost-effective and eco-friendly seismic isolation for earthquakeprone developing countries. By using granulated or stripped tire-soil mixtures as an isolation layer, this GSI system exhibited good seismic isolation in both the horizontal and vertical directions, as demonstrated in subsequent numerical studies [16] and experimental surveys [17]. Another system with circular cone-type surface, called the ball-in-cone isolator, was introduced by Kasalanti et al. [18] and subsequently studied by Chang and Spencer [19] and Harvey et al. [20][21][22]. ...
Article
This work introduces an innovative seismic isolation system named the convex friction system (CFS). This newly introduced isolation system has a sliding concavity with a circular cone-type surface, and exhibits some distinct features compared to conventional isolation techniques, such as increased uplift stability, improved self-centring capacity, and resonance dodge when subjected to near-fault earthquakes. A series of comprehensive analytical and numerical investigations are performed to verify these features of the CFS. First, the force-displacement relation of the CFS is established to describe the underlying philosophy of the system. The analytical model is then incorporated into numerical simulations to evaluate the seismic isolation performance of the CFS. Various ground accelerations, such as near-fault shakings, are included in these numerical calculations. Furthermore, the numerical results are rigorously investigated to illustrate the feasibility of the CFS. Finally, the limitations of the CFS study are discussed, and conclusions are drawn. The analytical and numerical results show that the CFS performs well in seismic isolation applications. The structural response can be reduced by approximately 30% with the CFS when compared to that with the Curved Surface Slider (CSS) with a spherical-surface concavity for some near-fault earthquakes, which verifies the aforementioned advantages of the CFS.
... Soil reinforced with rubber demonstrates an increase in energy dissipation capability (Edil and Bosscher, 1994). The feasibility of using shredded rubber mixed with sand (RSM) as a natural base isolator was investigated experimentally by Xiong and Li (2013) and theoretically by Gray et al. (1983), Doudoumis et al. (2002), Tsang (2008), Kirtas et al. (2009), Kirtas and Pitilakis (2009), Mavronicola et al. (2010), and Tsang et al. (2012. ...
Article
Full-text available
The performance of a well-designed layer of sand, geo-grid, geo-textiles and composites like layer of sand mixed with shredded tyre (rubber) as low-cost base isolators is studied in shake table tests in the laboratory. The building foundation is modelled by a 200 mm × 200 mm and 40 mm thick, rigid plexi-glass block. The block is placed in the middle of a 1 m × 1 m tank filled with sand. The selected base isolator is placed between the block and the sand foundation. Accelerometers are placed on top of the footing and foundation sand layer. The displacement of the footing is also measured by transducers. The whole set-up is mounted on the shake table and subjected to sinusoidal motion with varying amplitude and frequency. Sand is found to be effective only at very high amplitude (>0.65 g) of motion. Among all the different materials tested, the performance of a composite consisting of sand and 50% shredded rubber tyre placed under the footing is found to be the most promising as a low-cost, effective base isolator.
... Soil reinforced with rubber demonstrates an increase in energy dissipation capability (Edil and Bosscher, 1994). The feasibility of using shredded rubber mixed with sand (RSM) as a natural base isolator was investigated experimentally by Xiong and Li (2013) and theoretically by Gray et al. (1983), Doudoumis et al. (2002), Tsang (2008), Kirtas et al. (2009), Kirtas and Pitilakis (2009), Mavronicola et al. (2010), and Tsang et al. (2012. ...
Article
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The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building foundation is modeled by a 200 mm by 200 mm and 40 mm thick rigid plexi-glass block. The block is placed in the middle of a 1m by 1m tank filled with sand. The selected base isolator is placed between the block and the sand foundation. Accelerometers are placed on top of the footing and foundation sand layer. The displacement of the footing is also measured by LVDT. The whole setup is mounted on a shake table and subjected to sinusoidal motions with varying amplitude and frequency. Sand is found to be effective only at very high amplitude (> 0.65 g) of motions. The performance of a composite consisting of sand and 50% shredded rubber tire placed under the footing is found to be most promising as a low-cost effective base isolator. © 2015, Institute of Engineering Mechanics, China Earthquake Administration and Springer-Verlag Berlin Heidelberg.
... Over the last decade, the effectiveness of GSI system based on RSM has been evaluated through numerical modeling [4,[29][30][31][32][33][34][35][36], shake table testing [14,[37][38][39], field tests [40,41], and hybrid simulation (also known as online pseudodynamic test) [13]. These studies have generally demonstrated the good performance and feasibility of the GSI concept. ...
Conference Paper
Scrap tyre stockpile has been a significant disposal problem around the world. Significant research attention has been devoted in recent years to find new beneficial ways to recycle and reuse the huge stockpile. This paper proposes a new method of utilizing scrap tyres for infrastructure protection. The method involves mixing scrap tyres with soil materials and placing the mixtures around foundations for vibration absorption. This method provides two major benefits: (i) the low-cost would make it accessible to developing countries and rural areas of developed countries where resources and technology are not adequate for earthquake mitigation with well developed, expensive, techniques and (ii) potential to consume the huge stockpiles of scrap tyres all over the world. However, the success of the proposed method depends on the static and dynamic properties of scrap tyre soil mixtures. This paper presents results of recent experimental investigations on tyre (tyre crumbs)-soil mixtures carried out at University of Wollongong.
... The GBI can attenuate the incoming earthquake waves and reduce structural responses like conventional base isolation systems. Shredded scrap tire-sand mixtures placed below the foundation can act as earthquake protection layers (Tsang et al. 2012;Xiong and Li 2013;Pitilakis et al. 2015). The use of a GBI layer has been found to partially dissipate earthquake energy within the soil itself before it propagates to the foundation and the superstructure. ...
... Another type of vulnerable construction is one-to-two-storey houses that are typical in rural areas. Various GSI research groups have targeted this vulnerable type of housing in different parts of the world (Xiong and Li 2013;Nikitas et al. 2014;Tsiavos et al. 2019). The second case study building configuration can be built around this type. ...
Conference Paper
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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.
... In addition, as a siding isolation system, geotechnical seismic isolation techniques using locally available materials such as limestone sand [13], sand-bitumen mixtures [14] and rubber-soil mixtures [15] were developed for structural seismic response mitigation. These techniques are characterized by low cost and simple construction and are of particular significance in developing countries [16][17][18]. ...
Article
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Previous studies have proven that adding an inerter to a sliding isolation structure can reduce the isolation displacement without compromising the control effect of the superstructure. However, due to the strong nonlinearity of the sliding isolator, approximate methods or numerical analyses are adopted to investigate inerter-added sliding isolation structures, which hinders the understanding of the inherent working mechanisms of such structures. This study derives exact analytical solutions during both sliding and stick motion states of inerter-added sliding isolation structures under harmonic ground motions and investigates the influence of an additional inerter on the motion states and responses of such structures. The main novelties of this paper are the employment of the inerter technique in a sliding system for performance improvement and explicit expressions of the dynamic responses and motion modes for inerter-added sliding isolation structures that assist in understanding the role of the additional inerter. Differential equations are established for both the stick and sliding motions of inerter-added sliding isolation structures subjected to harmonic ground excitations. The dynamic characteristics of the structure are analyzed, and accurate analytical solutions are derived for structural responses. The explicit forms for the occurrence conditions of three fundamental modes (i.e., the stick-stick, stick-slip and slip-slip modes) for the motion of the inerter-added sliding isolation structures are presented. Based on the derived analytical solutions, extensive parametric analyses are conducted to investigate the influences of the added inerter on the motion modes and responses of sliding isolation structures. By adding an inerter, a decreased natural frequency, a decreased damping ratio and a reduction in ground motion excitation are observed for the vibration of the superstructure in the inerter-added sliding isolation structure compared to that in the sliding isolation structure without an inerter. Furthermore, the inerter causes the slip-slip mode to occur more easily, which is preferred for sliding isolation structures when sliding occurs. An increasing inertance of the inerter is beneficial for reducing isolation displacement in general but contrary to reducing maximum acceleration in some frequency ranges and excitations with large amplitudes. The trade-off between the reduction of isolation displacement and acceleration is recommended for determining the inertance of the inerter in sliding isolation structures.
... GSI has been studied by following two main approaches. First, researchers conducted experimentally investigations [24][25][26][27][28][29][30][31]. In particular, Reference [24] assessed the efficiency of seismic base isolation using natural stone pebbles below the foundation by experimental shake table tests with the aim to propose practical applications in the construction of low-cost buildings and smaller bridges in seismically active regions. ...
Article
Full-text available
Geotechnical seismic isolation (GSI) has emerged as a potential technique to mitigate the effects of earthquakes, with many applications to structural configurations, such as bridges and buildings. It consists of absorbing the seismic energy from the soil to the superstructure by interposing a superficial soil layer in order to reduce the accelerations that filter from the soil to the structure. This mitigation technique is particularly suitable in developing countries since GSIs are low-cost seismic isolation systems that through relatively simple manufacturing processes allow to safe costs and stimulate many applications. The presented study aimed to perform 3D numerical finite element models that overcome the previous contributions by performing several structural configurations. Several historical earthquakes are considered in this paper, and the results may be applied to drive general assessments of the technique in case of future seismic hazards.
... Whilst the concept of GSI is not limited to a particular choice of materials, RSM were chosen because: (i) rubber has been widely used in vibration damping and isolation, and both the static and dynamic properties of RSM were available in the literature, and (ii) waste tyres are available in abundance with an urgent need of recycling, which also provides a green and economical source for RSM (Tsang 2012, Xiong & Li 2013, Tsiavos et al. 2019, Chiaro et al. 2019. Granulated RSM are characterised by nonlinearity and high damping in the mediumto-high strain range, with properties that can be adjusted via rubber content . ...
... 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
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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.
... 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
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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.
... On the other side, due to the level of its novelty, GSI applications required many experiments to prove their reliability. In this regard, experimental tests were conducted on shaking tables [8,9]. Tsiavos et al. [10] performed direct shear tests and small-scale 1 g shaking table tests. ...
Article
Full-text available
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.
... 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. ...
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.
... 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. ...
... Another advantage of the proposed method was the utilization of scrap tires, which leads toward a sustainable environment. Xiong and Li [99] experimentally validate the use of a granulated tire-soil mixture layer beneath the foundation of the structure as an isolation. The isolation layers of different thicknesses and with two different rubber percentage, 35%, and 50% was tested. ...
Article
Full-text available
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.
... This GSI system could not only bring a promising isolation tool to the developing countries, but also consume a large number of wasted tires, which was quite eco-friendly. This study was further extended by numerical study [14] and experimental investigation [15]. More details can be found in Refs. ...
Article
A series of comprehensive parametric studies are conducted on a steel-frame structure Finite-Element (FE) model with the Multangular-Pyramid Concave Friction System (MPCFS) installed as isolators. This new introduced MPCFS system has some distinctive features when compared with conventional isolation techniques, such as increased uplift stability, improved self-centering capacity, non-resonance when subjected to near-fault earthquakes, and so on. The FE model of the MPCFS is first established and evaluated by comparison between numerical and theoretical results. The MPCFS FE model is then incorporated in a steel-frame structural model, which is subjected to three chosen earthquakes, to verify its seismic isolation. Further, parametric study with varying controlling parameters, such as isolation foundation, inclination angle, friction coefficient, and earthquake input, is carried out to extract more detailed dynamic response of the MPCFS structure. Finally, limitations of this study are discussed, and conclusions are made. The simulations testify the significant seismic isolation of the MPCFS. This indicates the MPCFS, viewed as the beneficial complementary of the existing well-established and matured isolation techniques, may be a promising tool for seismic isolation of near-fault earthquake prone zones. This verified MPCFS FE model can be incorporated in future FE analysis. The results in this research can also guide future optimal parameter design of the MPCFS.
... The concept of GSI has gained a lot of momentum in the past few years. Current GSI efforts are mainly focused on soil replacement by rubber-soil mixtures [Tsang, 2009] [Tsang et al., 2012] [Xiong and Li, 2013] [Xiong et al., 2014] [Bandyopadhyay et al., 2015] [Panjamani et al., 2015] [Brunet et al., 2016] [Forcellini, 2017] [Hadad et al., 2017] [Tsiavos et al. 2019] or geofoam [Murillo et al., 2009] [Azinović et al., 2014[Azinović et al., , 2016 [Karatzia and Mylonakis, 2017] [Azzam et al., 2018]. Relatively fewer works concern the sliding mechanism [Banović et al., 2018b[Banović et al., , 2019. ...
Article
Full-text available
The effect of structural stiffness on the efficiency of seismic base isolation using layers of stone pebbles is experimentally investigated by shake-table. The efficiency of the adopted layers is tested on four models with different stiffness, under four different earthquake accelerograms. A part of the study was carried out for one-time accelerations of the shake-table with strains in elastic range, and another part, for the most unfavourable accelerogram, was carried out by successive increase in the acceleration to the collapse of the model. It is concluded that efficiency of the considered seismic isolations systems decreased with decrease of model stiffness and that this concept shows great potential in increase of structural seismic resistance
... The mechanisms of the multiphase mixture material and its properties have been well investigated and are becoming increasingly available in the literature (Lee et al., 2014;Pistolas et al., 2018aPistolas et al., , 2018bShariatmadari et al., 2018;Fonseca et al., 2019). The seismic isolation capabilities of RSM have also been widely acknowledged through numerical and experimental investigations by a number of researchers over the years (Tsang, 2008;Mavronicola et al., 2010;Tsang et al., 2012;Xiong and Li, 2013;Brunet et al., 2016;Bandyopadhyay et al., 2018). A variety of applications have been proposed; when used as a geotechnical seismic isolation system, certain conclusions can be drawn, by analyzing the aspects governing the soil-structure interaction problem (Veletsos and Meek, 1974;Wolf, 1985). ...
Article
View-only link: https://rdcu.be/b5D5i This study examines the use of granular soils mixed with tire derived aggregates (TDA) as an underlying soil layer for surface foundations. The benefit of this geotechnical seismic isolation (GSI) scheme is threefold: the seismic force and displacement are significantly reduced; the construction is similar to that of a regular compacted granular fill and the re-use of scrap tires has an assertive environmental impact. These features highlight the rubber/soil mixtures (RSM) as a promising seismic isolation technique for infrastructure and large-scale structures. The seismic isolation capabilities of a rubber-soil foundation layer are investigated, using well defined material properties, and the direct analysis method of the soil-structure system, in the form of a simple oscillator on a soil profile. The influence of the RSM layer on the fundamental variables of the seismic response, namely the base shear and the total drift displacement of the structure on deformable soil, is examined. The structure’s overall stability is studied by means of monotonic lateral load analysis and incremental dynamic analysis, varying the slenderness of the structure and the synthesis of the mixture. The effectiveness and capabilities of the RSM isolation scheme are presented and discussed.
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.
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.
Article
Large stock of scrap tyres in waste disposal ground is a huge threat to the environment. In many civil engineering applications, potential of using scrap tyres have been explored in the last two decades. In this paper, effectiveness of Un-bonded Scrap Tyre Isolator (U-STI), as a seismic isolation system, has been evaluated by both experimental and numerical studies. Simple design approach of low-cost U-STI for seismic response control of the test model is outlined first. The mechanical properties of U-STI, under simultaneous action of horizontal cyclic displacement and vertical load, have been determined. Shake table testing of 1/5th scale two-storey masonry building supported on U-STIs has been carried out. Shake table testing confirmed that transmissibility of peak ground acceleration to the test model is reduced to a large extent and the peak floor accelerations are of the order of 12%–15% of the peak table accelerations, which establishes the effectiveness of the U-STI in controlling the seismic response of the test model. Results of the numerical analysis of the test model, using SAP 2000 v.19, have been validated by the experimental results. The U-STIs have been modelled using multi-linear pivot hysteretic plasticity model. Comparison of acceleration and displacement responses at various floor levels obtained from numerical analysis is done with that obtained from shake table tests. Results from the numerical tests are found to be in reasonably good agreement with those obtained from the experimental tests under the action of considered ground motions. It is concluded from the study that low-cost U-STIs are effective in reducing the seismic response of low-rise masonry building test models.
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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The effect of the foundation size on the efficiency of seismic base isolation using a layer of stone pebbles is experimentally investigated. Four scaled models of buildings with different stiffnesses (from very stiff to soft) were tested, each with the so-called small and large foundation, and exposed to four different accelerograms (different predominant periods and durations). Tests were conducted so that the strains in the model remained elastic and afterwards the models were tested until collapse. Each model was tested for the case of the foundation being supported on a rigid base and on an aseismic layer. Compared to the smaller foundation, the larger foundation results in a reduced rocking effect, higher earthquake forces and lower bearing capacity of the tested models, with respectable efficiency (reduced strain/stress, displacement and increase of the ultimate bearing capacity of the model) for the considered seismic base isolation compared to the foundation on a rigid base.
Article
An innovative yet extremely simple approach to reduce the seismic vulnerability of existing buildings on shallow foundations is to remove the lateral contact between the embedded foundation and the surrounding soil. This paper compares the dynamic response of two identical one-degree-of-freedom reduced-scale model sway frames tested in a geotechnical centrifuge. One of the models was founded on fully embedded shallow strip footings, whereas the foundations of the other were disconnected from the soil laterally. Both models were constructed in dry medium density sand whose strength and small strain shear stiffness profiles were obtained by cone penetration and air hammer tests carried out in flight. Various tools were used to monitor the displacements and accelerations both in the structure and in the soil, including micro-electro-mechanical systems (MEMS) accelerometers, piezoelectric accelerometers, LVDTs, and a high-frequency camera. The experimental results demonstrate that the lateral disconnection of the foundation from the adjacent soil significantly reduces the foundation translational and rotational stiffness, which results in a larger predominant period of the structure and a reduction of the absolute floor accelerations obtained for different sinusoidal input signals. The lateral disconnection also mitigates floor drift and story shear forces. The trade-off is the lower radiative damping observed for the laterally disconnected foundation, which results in a larger number of post-earthquake oscillations of the structure.
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Buildings in towns and villages suffer heavy damages and losses during earthquakes. In this study, six types tire–granular material composite foundations were fabricated and tested under cyclic reversed loading to investigate the energy absorption and dissipation effects of such composite foundations applied to village buildings. The effects of different axial loads (100, 200 and 300 kPa), tire arrangement and transverse connection between layers on the dynamic performance of the tire–granular material composite foundations were examined. The failure patterns of the composite foundation were obtained. The effects of the aforementioned design parameters on the dynamic performance of the composite foundation, characterised by the hysteresis loops, skeleton curves, stiffness degradation curves and energy dissipation capacity, were analysed. The hysteresis loops were full, indicating good seismic performance. The results demonstrated that using a staggered lap joint arrangement and adding a fibre mesh improved the horizontal bearing capacity and lateral stiffness of the composite foundation and enhance its overall damping capacity. Therefore, adding space connections between tires can improve the energy dissipation capacity of the foundation.
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Properties of the polyurethane-rubber composites obtained from used products were studied. The influence of the amount of polyurethane glue and amount of isocyanate diphenylmethane 4,4 '-diisocyanate (MDI) on composites selected properties was observed. The dynamic thermo-mechanical analysis allowed us to determine the glass transition temperature Tg and the course of the relaxation processes in the composites. The analysis of the changes in the storage module E ' and loss module E-'' as a function of temperature enabled the calculation of the activation energy for relaxation processes of various polyurethane glues and polyurethane-rubber composites.
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The isolation effectiveness of the Geotechnical Seismic Isolation (GSI) system was further investigated via a series of prescribed shaking-table tests. The dynamic response of GSI system was also evaluated in detail of this work. A parametric study for assessment of the isolation performance of GSI was conducted by varying experimental key parameters, such as rubber percentage of rubber-sand mixtures (RSM), configuration of the foundation, storey number of the superstructure, and different kinds of seismic acceleration inputs. From the parametric survey, it can be concluded that the GSI system can to some extent attenuate the dynamic response of the superstructure under big earthquake shakings.
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Following the 1994 Northridge earthquake, the areas with a high density of reported breaks in water pipes in typical residential areas in San Fernando Valley and in Los Angeles often did not coincide with the areas having a high density of severely damaged (red-tagged) buildings. As the former is an indicator of large strains and nonlinear soil response, this observation suggests that the damage to buildings in some areas may have been smaller than expected because the soil dissipated part of the energy of the ground motion by nonlinear response. This paper presents an attempt to quantify this relationship between the density of red-tagged buildings, N (per km 2 ), and the severity of shaking (via peak horizontal ground velocity, v max, or modified Mercalli intensity, IMM), including the density of breaks in water pipes, n (per km 2 ), as a variable specifying the level of strain in the soil. Approximate empirical relationships for N = f(vmax, n) and N = f(IMM, n) are presented. The trends in the data indicate that, for vmax in the range from ;35 to ;125 cm/s, the rate of growth of N versus vmax tends to decrease at sites with large strain in the soil (i.e., large n). For vmax beyond ;150 cm/s, the beneficial effects of nonlinear soil response seem to fade out, as large differential motions associated with soil failure begin to contribute to the damage of structures. Assuming fairly uniform density and quality of building stock and of water pipes in the areas studied, the derived relationships are then used to map vmax and IMM in San Fernando Valley and in Los Angeles. The resulting maps are more detailed than what could be obtained from the density of strong motion stations and of sites with reports on felt intensity.
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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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Current design guidelines for shallow foundations supporting building and bridge structures discourage footing rocking or sliding during seismic loading. Recent research indicates that footing rocking has the potential to reduce ductility demands on structures by dissipating earthquake energy at the footing-soil interface. Concerns over cyclic and permanent displacements of the foundation during rocking and sliding along with the dependence of foundation capacity on uncertain soil properties hinder the use of footing rocking in practice. This paper presents the findings of a series of centrifuge experiments conducted on shear wall-footing structures supported by dry dense to medium dense sand foundations that are subjected to lateral cyclic loading. Two key parameters, static vertical factor of safety (FSV), and the applied normalized moment-to-shear ratio (M/(H·L)) at the footing-soil interface, along with other parameters, were varied systematically and the effects of these parameters on footing-soil system behavior are presented. As expected, the ratio of moment to the horizontal load affects the relative magnitude of rotational and sliding displacement of the footing. Results also show that, for a particular FSV, footings with a large moment to shear ratio dissipate considerably more energy through rocking and suffer less permanent settlement than footings with a low moment to shear ratio. The ratio of actual footing area (A) to the area required to support the vertical and shear loads (Ac), called the critical contact area ratio (A/Ac ), is used to correlate results from tests with different moment to shear ratio. It is found that footings with similar A/Ac display similar relationships between cyclic moment-rotation and cumulative settlement, irrespective of the moment-to-shear ratio. It is suggested that shallow foundations with a sufficiently large A/Ac suffer small permanent settlements and have a well defined moment capacity; hence they may be used as effective energy dissipation devices that limit loads transmitted to the superstructure.
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The effectiveness of structural fuse mechanisms used to improve the performance of buildings during seismic loading depends on their capacity, ductility, energy dissipation, isolation, and self-centering characteristics. Although rocking shallow footings could also be designed to possess many of these desirable characteristics, current civil engineering practice often avoids nonlinear behavior of soil in design, due to the lack of confidence and knowledge about cyclic rocking. Several centrifuge experiments were conducted to study the rocking behavior of shallow footings, supported by sand and clay soil stratums, during slow lateral cyclic loading and dynamic shaking. The ratio of the footing area to the footing contact area required to support the applied vertical loads (A/A(c)), related to the factor of safety with respect to vertical loading, is correlated with moment capacity, energy dissipation, and permanent settlement measured in centrifuge and 1 g model tests. Results show that a footing with large A/A(c) ratio (about 10) possesses a moment capacity that is insensitive to soil properties, does not suffer large permanent settlements, has a self-centering characteristic associated with uplift and gap closure, and dissipates seismic energy that corresponds to about 20% damping ratio. Thus, there is promise to use rocking footings in place of, or in combination with, structural base isolation and energy dissipation devices to improve the performance of the structure during seismic loading.
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In this, the second of a two-part paper, the analysis of the apparent frequency of a seven-story reinforced-concrete hotel building in Van Nuys, Calif., is extended to consider its time-dependent changes, both short and long term. The instantaneous apparent frequency is measured by two methods: windowed Fourier analysis and zero-crossings analysis. The results show that it changes from earthquake to earthquake and during a particular earthquake. The results also suggest "self healing" believed to result from settlement of the soil with time and dynamic compaction from aftershock shaking. Implications of such high variability of the system frequency on structural health monitoring, control of response, as well as on the design codes are discussed. Nonlinear response of the foundation soil acts as a sink of the incident seismic wave energy. It is suggested that it could be exploited in future designs to serve as a powerful and inexpensive energy-dissipation mechanism.
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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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This paper describes an experimental and theoretical study of the feasibility of using fiber reinforcement to produce lightweight low-cost elastomeric isolators for application to housing, schools and other public buildings in highly seismic areas of the developing world. The theoretical analysis covers the mechanical characteristics of multi-layer elastomeric isolation bearings where the reinforcing elements, normally steel plates, are replaced by a fiber reinforcement. The fiber in the fiber-reinforced isolator, in contrast to the steel in the conventional isolator (which is assumed to be rigid both in extension and flexure), is assumed to be flexible in extension, but completely without flexure rigidity. This leads to an extension of the theoretical analysis on which the design of steel-reinforced isolators is which accommodates the stretching of the fiber-reinforcement. Several examples of isolators in the form of long strips were tested at the Earthquake Engineering Research Center Laboratory. The tested isolators had significantly large shape factors, large enough that for conventional isolators the effects of material compressibility would need to be included. The theoretical analysis is extended to include compressibility and the competing influences of reinforcement flexibility and compressibility are studied. The theoretical analysis suggests and the test results confirm that it is possible to produce a fiber-reinforced strip isolator that matches the behavior of a steel-reinforced isolator. The fiber-reinforced isolator is significantly lighter and can be made by a much less labor-intensive manufacturing process. The advantage of the strip isolator is that it can be easily used in buildings with masonry walls. The intention of this research is to provide a low-cost lightweight isolation system for housing and public buildings in developing countries.
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Designing earthquake-resistant low-to medium-rise structures is problematic in that their fundamental frequency of vibration is in the range of frequencies where earthquake energy is the strongest, so the building acts as an amplifier of the ground vibrations, with the floor accelerations increasing over the height of the building. Ultimately, the seismic design should reduce the accelerations in buildings to below the level of the ground accelerations. To do this the building must be flexible. Incorporating flexibility in a structural frame can cause problems, however: windows may fall out due to wind loads, partition walls may crack and floors may vibrate under foot. For a low-or medium-rise building, the necessary flexibility can only be achieved by using base isolation at the foundation level. A number of buildings have been built in the US using this innovative technology; this review will highlight a few of them.
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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.
Over 300 Million Waste Tires Each Year
  • Crawford Renewable Energy
Crawford Renewable Energy. Over 300 Million Waste Tires Each Year. Available from: http://www. crawfordrenewableenergy.com/about-us/the-problem-of-waste-tires/ [11 November 2012].