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Seismic Evaluation and Retrofit of Concrete Buildings: A Practical Overview of the ATC 40 Document
Abstract
The Applied Technology Council (ATC), with funding from the California Seismic Safety Commission developed the document, Seismic Evaluation and Retrofit of Concrete Buildings, commonly referred to as ATC 40. This two-volume, 612-page report provides a recommended procedure for the seismic evaluation and retrofit of concrete buildings. Although the focus is specifically on concrete buildings, the document provides information on emerging techniques applicable to most building types. This paper provides an introduction and overview of the document. The conceptual basis of the procedures is performance-based design using nonlinear static structural analysis. The ATC 40 document comprises a practical guide to the entire evaluation and retrofit process. Topics include performance objectives, seismic hazard, determination of deficiencies, retrofit strategies, quality assurance procedures, nonlinear static analysis using the capacity spectrum method, modeling recommendations, foundation effects, and response limits.
... Capacity Spectrum Method was adopted for the evaluation of capacity curves (Comartin et al., 2000) in the ADRS format (Acceleration-Displacement Response Spectra) (Lin and Chang, 2003) and intersection points corresponding to specific damage state were obtained for determining data points for the seismic vulnerability relationship (Figure 3) (Comartin et al., 2000). The method adopted in this study implements the procedures of ASCE-41: Seismic Rehabilitation of Existing Buildings (ASCE-41, 2006), Pre-standard and Commentary for the Seismic Rehabilitation of Buildings (FEMA-356, 2000); Seismic evaluation and retrofit of concrete buildings (ATC-40, 1996). ...
... Capacity Spectrum Method was adopted for the evaluation of capacity curves (Comartin et al., 2000) in the ADRS format (Acceleration-Displacement Response Spectra) (Lin and Chang, 2003) and intersection points corresponding to specific damage state were obtained for determining data points for the seismic vulnerability relationship (Figure 3) (Comartin et al., 2000). The method adopted in this study implements the procedures of ASCE-41: Seismic Rehabilitation of Existing Buildings (ASCE-41, 2006), Pre-standard and Commentary for the Seismic Rehabilitation of Buildings (FEMA-356, 2000); Seismic evaluation and retrofit of concrete buildings (ATC-40, 1996). ...
... The method adopted in this study implements the procedures of ASCE-41: Seismic Rehabilitation of Existing Buildings (ASCE-41, 2006), Pre-standard and Commentary for the Seismic Rehabilitation of Buildings (FEMA-356, 2000); Seismic evaluation and retrofit of concrete buildings (ATC-40, 1996). (Comartin et al., 2000) Demand spectra was based on response spectrum from IS-1893IS- (2002. Inter-storey drift ratios for various performance levels like 'IO', 'LS', and 'CP' were defined based on damage state parameters (ASCE-41, 2006), as global displacement limits as shown in Table 1. ...
Due to adverse environmental exposure, buildings in coastal regions often experience extensive deterioration during their service life. If these buildings are located in high seismic regions such as the Andaman & Nicobar Islands, their seismic vulnerability may vary considerably from the time of construction. Characteristic deficiencies in design and construction can further exacerbate the vulnerability. This paper discusses the temporal variations in seismic vulnerability of degrading reinforced concrete frame building considering the effect of corrosion of reinforcement bars. Typical low-rise concrete buildings located in the Andaman & Nicobar Islands have been considered. The quality of materials used are often inferior due to the geographical remoteness of the islands from mainland India. Constructions are also often carried out by untrained personnel. A typical symmetrical three storied reinforced concrete framed building with masonry infills is modeled with inherent (construction) and temporal (corrosion) deficiencies. Inherent deficiencies considered include insufficient anchorage length of beam reinforcement into the beam-column joint and insufficient lap splice length in the column reinforcements. Temporal (time dependent) deficiencies considered the loss of bond stress and loss of cross-sectional area of reinforcement due to corrosion. Nonlinear static analyses have been used to estimate the vulnerability functions. It is shown that the rate of degradation is an important parameter in increase in seismic vulnerability and can be used as the basis to estimate the safety of such buildings.
... Figure 2 depicts the conventional and optimal approaches to the general design process (Arora 2004). Whilst both approaches require iterations, the main difference is the manner that guides the design updating. ...
... Comparison of (a) conventional and (b) optimal design method(Arora 2004). ...
Viscous dampers enhance the seismic performance of buildings by increasing the capacity for energy dissipation, or damping. Many placement optimisation algorithms currently exist, though they often do not align with code-based verification procedures nor consider optimising performance at multiple seismic hazard levels, at serviceability and ultimate limits. This paper proposes new damper placement algorithms and compares them against eight existing methods on seismic performance at different hazard levels, design iterations required and total computation effort. The comparison is conducted by means of numerical case studies. All methods are applied to a ten-storey reinforced concrete (RC) moment resisting frame (MRF) building, initially meeting the design requirements of typical buildings in a moderate seismic zone in New Zealand. The result showed that the proposed methods and two existing methods can generate a solution that dominates solutions of other existing methods in at least one aspect (e.g. the objective at a hazard level or running time).
... Two principal approaches were proposed, the first one using the damping, as in ATC 40 (Comartin et al, 2000), and the second one the ductility, as in the Eurocode 8 (Fajfar, 2000). Taking into account their development, which was separated at the origin, and the iterative nature of the solutions which were proposed in the frame of ATC 40, they still does not exist practical "simple" comparisons allowing in particular to point out the importance of the parameter "energy to be dissipated" which should appear in these approaches. ...
... We will see further (paragraph 4) that, for a better understanding of the importance of the parameter eff (effective damping), which corresponds to an energy to be dissipated, it is interesting to introduce the demand and the capacity on the same diagram eff -S d or eff -, being the ductility (see Mouroux , 2002et AFPS, 2006. , 1996, -Comartin et al, 2000 3. Approach using ductility : Eurocode 8 ...
... Several approaches have evolved in developing the seismic fragility curves for a given intensity measure with respective advantages and limitations [9][10][11]. In this study Capacity Spectrum Method (CSM) specified by ATC-40 [12] and Incremental Dynamic Analysis (IDA) developed by Cornell [13] has been used for developing the fragility curves. CSM approach is simple to implement and gives sufficiently accurate results in case of regular structural configurations. ...
... Considering the IDA curves generated, the fragility parameters (i.e., the mean 'μ' and standard deviation 'σ' values) are computed as per ATC 40 [12] for different damage states are shown in Table 3, which are further used to compute the probability of exceedance as per the equation is given below: ...
Reinforced concrete frame buildings with Open Ground Story (OGS) are one of the most common building configurations in urban habitat. These configurations are known to be vulnerable to seismic excitations, primarily due to the sudden loss in strength in the ground story and differential stiffness distribution throughout the structure. The differential stiffness distribution is attributed primarily to the interaction of non-structural infill wall with the moment-resisting frame. Hence, the interaction of infill wall needs to be accounted in estimating the seismic vulnerability. Therefore, the present investigation is focused on understanding the impact of utilizing real ground motion records on the performance assessment of RC buildings with and without consideration of infill walls. Fragility curves were developed for low and mid-rise structural models using Capacity Spectrum Method (CSM) specified by ATC-40 and with Incremental Dynamic Analysis (IDA). CSM uses the response spectrum specified by the respective code, unlike IDA where an ensemble of spectrum compatible real ground motion accelerograms satisfying the necessary site conditions is used in assessing the performance. Further, significant variations observed in the developed fragility curves by CSM and IDA emphasizes the sensitivity of real ground motion data in performance assessment.
... Ignoring foundation deformations in such cases results in mischaracterization of dynamic properties such as the fundamental mode frequency and the damping ratio (e.g., Veletsos and Nair 1975;Stewart et al., 1999), which biases the engineering characterization of seismic demand. Moreover, Comartin et al. (2000) showed how ignoring foundation compliance could cause an engineer to mischaracterize seismic structural performance to such an extent that the wrong portion of a building would be retrofit. ...
... It is well documented that structural performance can be significantly affected by the nonlinear behavior of shallow foundations (e.g., Comartin et al. 2000). As compared to the yielding of the structural elements, the yielding behavior at the foundation-soil interface dissipates energy with a self-centering mechanism that can help reduce residual drift. ...
For stiff structural systems, such as shear walls and braced frames, deformations that occur at the
soil-foundation interface can represent a significant component of the overall soil-foundationstructure
system flexibility. Practical guidelines have been available for many years to
characterize these soil-structure interaction (SSI) effects when structural analyses are performed
using simplified pseudo-static force-based or pushover-type procedures. Those guidelines are
typically based in large part on representing the soil-foundation interaction in terms of elastic
impedance functions that describe stiffness and damping characteristics. Such approaches are not
able to capture the nonlinear behavior at the foundation level, which may involve formation of a
temporary gap between the footing and soil, the settlement of the foundation, sliding, or energy
dissipation from the hysteretic effects.
Due to the importance of these effects, reliable characterization of structural system
response within a performance-based design framework requires improved tools for modeling of
the soil-foundation interaction. In this work, two such tools have been developed. The first,
referred to as the beam-on-nonlinear-Winkler-foundation (BNWF) model, consists of a system of
closely spaced independent nonlinear inelastic springs that are capable of capturing gapping and
radiation damping. Vertical springs distributed along the base of the footing are used to capture
the rocking, uplift, and settlement, while horizontal springs attached to the sides of the footing
capture the resistance to sliding. The second tool is referred to as the contact interface model
(CIM). The CIM provides nonlinear constitutive relations between cyclic loads and
displacements at the footing-soil interface of a shallow rigid foundation that is subjected to
combined moment, shear, and axial loading.
The major distinguishing characteristics of the two models are that (1) the BNWF model
directly captures the behavior of structural footing elements with user-specified levels of
stiffness and strength, whereas the CIM assumes a rigid footing and (2) the BNWF model does
not couple foundation response in the vertical direction (in response to vertical loads and
moments) with horizontal response, whereas the CIM does couple these responses. Accordingly,
the BNWF model is preferred when simulation results are to be used to design footing elements
and for complex foundation systems consisting of variable-stiffness elements (such as wall
footings and columns footings). Conversely, the CIM is preferred when moment and shear
iv
response are highly coupled. Some applications may involve a combination of CIM elements
beneath wall footings and BNWF elements beneath other foundation components of a given
structure.
Both models are described by a series of parameters that are categorized as being userdefined
or hard-wired. User-defined parameters include those that are directly defined by
foundation geometry or by conventional material properties such as shear strength and soil
stiffness. Hard-wired parameters describe details of the cyclic or monotonic response and are
coded into the computer codes. Both sets of parameters are fully described in this report and a
consistent set of parameter selection protocols is provided. These protocols are intended to
facilitate straightforward application of these codes in OpenSees.
The models are applied with the parameter selection protocols to a hypothetical shear
wall building resting on clayey foundation soils and to shear wall and column systems supported
on clean, dry, sand foundation soils tested in the centrifuge. Both models are shown to capture
relatively complex moment-rotation behavior that occurs coincident with shear-sliding and
settlement. Moment-rotation behavior predicted by the two models is generally consistent with
each other and the available experimental data. Shear-sliding behavior can deviate depending on
the degree of foundation uplift with coincident loss of foundation shear capacity. This can
significantly affect isolated footings for shear walls or braced frames, but is less significant for
multi-component, interconnected foundation systems such as are commonly used in buildings.
Settlement response of footings tends to increase with the overall level of nonlinearity.
Accordingly, in the absence of significant sliding, settlement responses tend to be consistent
between the two models and with experimental data. However, conditions leading to sliding
cause different settlement responses. For conditions giving rise to significant coupling between
moment and shear responses (resulting in shear-sliding), CIM elements provide improved
comparisons to data and their use is preferred.
This work has advanced the BNWF model and CIM from research tools used principally
by the Ph.D. students that wrote the codes to working OpenSees models with well-defined (and
at least partially validated) parameter selection protocols. We recognize that further validation
against full-scale field performance data would be valuable to gain additional insights and
confidence in the models. In the meantime, we encourage the application of these models, in
parallel with more conventional methods of analysis, with the recognition that the simulation
v
results from both established and new procedures should be interpreted with appropriate
engineering judgment as part of the design process.
At present, many building engineers are reluctant to allow significant rocking rotations
and soil nonlinearity at the soil-foundation interface. It is hoped that the availability of
procedures that are able to reliably predict displacements caused by cyclic moment, shear, and
axial loading will empower engineers to consider rocking of shallow foundations as an
acceptable mechanism of yielding and energy dissipation in a soil-foundation-structure system.
In some cases, the allowance of foundation nonlinearity may lead to economies in construction
and improvements in performance.
... However, the structure may experience severe pressures and deformations as a result. An alternate tactic is multi-story isolation, which effectively separates the upper floors from the lower ones in terms of seismic vibration by permitting controlled movement at different levels [60]. During seismic occurrences, precautions must be taken to prevent rooftop components from becoming hazardous by falling and potentially damaging the primary structure or neighboring buildings. ...
Architectural planners must give due consideration to seismic events as they present substantial hazards to both critical infrastructure and human well-being. This research investigates the fundamental concepts and methodologies employed by architects to enhance seismic resilience in buildings and ensure the safety of occupants. It emphasizes the importance of seismic hazard assessment, design standards, structural systems, and cutting-edge technology in reducing earthquake-related dangers. A mixed method has been adopted: surveying the literature, applying inductive reasoning, and conducting a case study. This research highlights the value of interdisciplinary cooperation between structural engineers, geotechnical experts, and architects to design resilient built environments that can survive the pressures unleashed by seismic occurrences. The findings demonstrated that architectural design solutions and approaches might significantly impact earthquake risk reduction techniques in seismic and non-seismic locations. In the cases taken, different techniques—in some cases multiple techniques—had been applied based on the buildings’ geographical locations, sizes, and shapes. Finally, we prepared a checklist for these strategies, including mass distribution, openings, rooftop structures, and other considerations to be applied by architects to make the solutions easier.
... The results are expressed probabilistically as a performance function, and this process is referred to as the PEER methodology. The calculation is performed using Equation (1) [30]. ...
The performance-based seismic design pretends to take care of the lives of the occupants and reduce the cost of damage caused by earthquakes. Several ways of estimating damage and economic losses have been developed, but most of them lack objectivity and have great dispersion in the results. In the last decade, the advancement of technology has allowed the appearance of new methodologies, such as the one developed by the Pacific Earthquake Engineering Research Center (PEER methodology). However, the information regarding application and scope is scarce. In the present investigation, the economic seismic performance for a steel building was determined by applying the PEER methodology with different levels of seismic intensity. A multi-family residential model of special moment frames (SMF) was used, and the structure was designed by means of modal analysis. Spectral, incremental dynamic non-linear analysis was performed where the structural response was determined, with the help of the PACT software. The seismic performance, expressed as the repair costs, repair times, deaths, and injuries, was defined. The results obtained indicate that buildings designed with traditional structural standards can be demolished after the action of an earthquake because the repair costs exceed 40% of the replacement cost. Rare and very rare seismic events can cause the total suspension of the service and a considerable number of deaths and injuries.
... Both capacity spectrum and response spectrum should be defined in the ADRS (Acceleration Displacement Response Spectrum) format. The fundamentals of CSM are described in Comartin et al. (2000) "Seismic Evaluation and Retrofit of Concrete Buildings" and FEMA-440 "Improvement of Nonlinear Static Seismic Analysis Procedures" (FEMA 2005). Content courtesy of Springer Nature, terms of use apply. ...
Earthquakes are a major cause of damage and human losses to the built environment, including cultural heritages, monumental buildings and historical centers. In the last decades, the seismic performance of buildings has received special attention due to the interest in the built heritage conservation and protection of human life, particularly with respect to masonry structures which have shown evidence of poor behavior once subjected to seismic loads. The present work contributes to the seismic safety assessment of the out-of-plane behavior of unreinforced masonry walls through a displacement-based approach, providing the capacity for different out-of-plane geometric indexes and its seismic response in different earthquake-prone regions. The analyses are conducted using a seismic probabilistic framework, considering the most common out-of-plane mechanisms, different material properties, various slenderness ratios, and a wide range of seismicity levels to cover the seismic hazard in Europe. The results presented can be useful for seismic safety assessment and to incorporate vulnerability models for seismic risk analysis.
... Colombia is located on the Pacific Ring of Fire, an area with the highest concentration of earthquakes in the world (Comartin et al., 2000). The country lies at the intersection of three tectonic plates: the Caribbean, the South American, and the Nazca plates. ...
At certain depths, the elastic properties of the ground are not affected by seismic waves. However, as they reach the surface, the soil density decreases and so does its elastic limit. This means that the expected ground motion acting at the foundation of a structure cannot be adequately described without considering the inelastic response of the soil near the surface. Therefore, one of the key elements in characterizing the seismic response of civil structures is the site effect. These depend mainly on the parameters of the soil beneath the structure and the features of the ground motion acting at the depth, where non-linear effects are negligible. Therefore, the main objective of this paper is to find an intensity measure that incorporates the information provided by the soil profile under the structure and the ground motion acting at the bedrock level. Due to the random nature of both elements, a probabilistic framework using Monte Carlo simulation has been developed to analyze this problem. For this purpose, random soil profiles have been generated to obtain a representative sample of likely scenarios of the study area. A large database of Colombian ground motion records has been used to model the seismic hazard. Finally, power functions capable of relating the input variables to the dynamic response of a large set of reinforced concrete structures have been derived by considering multi-regression analysis. It has been observed that, in several cases, intensity measures extracted from the displacement spectrum appear in the mathematical arrangements. These functions could be used to improve the efficiency of seismic risk prediction at the urban level.
... The structural ductility ratio (μ) can be defined as (Comartin et al., 2000): ...
Most design codes assume the nonlinear seismic performance of structures using response reduction/modification factor (R). The R factor is sensitive to a variety of factors in terms of overall ductility and over-strength. This research assesses the actual R factor for vertical irregularity cases for RC bare buildings with moment-resisting frames (MRF) systems. Also, this research derives a significant relationship between R values and identified vertical irregularity index calculated from relative stiffness between adjacent stories. Three-dimensional numerical models are carried out for the soft story and setback irregularity scenarios using ETABS. Modal pushover analysis (MPA) is selected to obtain the inelastic seismic capacity. The obtained results demonstrate that vertical irregular buildings have weak inelastic seismic capacities compared to regular one. So, the response modification factor (R) should be scaled down before the design stage by 15% to 40% for single and combined vertical irregularity scenarios. Structures with a combined asymmetric setback with a soft ground story experience the worst R factor. Also, R factors are sensitive to the identified vertical irregularity index (Vtm) that has 80% regression percent. So, it may be used to specify the allowable vertical irregularity ratio, location, and combination for each seismic zone.
... where y max 5 y s;α y s;β for Probabilistic method Fuzzy method [41] where V j is the total lateral shear force demand in the jth story and P j is the total gravity load acting at that story. ...
... The load was applied under displacement control. The incremental displacement amplitude was applied based on the recommendation by ACI committee 374.1-05 (ATC 1996) [92] in a half-cyclic trend pattern, as depicted in Fig. 11. The amplitude increments commenced at 2 mm and gradually increased by 2 mm until failure. ...
This study proposed a new scheme for the retrofitting of Reinforced Concrete (RC) beams using Carbon Fiber Reinforced (CFRP) rods restrained using steel plates and anchorage bolts called the mechanical anchorage system (MAS). This system also employed an external concrete jacket to cover the MAS and CFRP rods. The performance of the proposed technique was experimentally assessed using the four-point flexural testing of retrofitted beams under incremental cyclic load using a dynamic actuator. A total of eight beams were cast and tested in different configurations to determine the effectiveness of the design parameters including the number of CFRP rods, the contribution of MAS, and concrete jacketing (CJ) in terms of load capacity, cracking, failure mode, and ductility. The results revealed that the efficiency of the proposed retrofitting system was achieved by increasing the load capacity of retrofitted beams and preventing the premature debonding failure of CFRP rods. Although de-bonding can occur on the surface between the old and new concrete, the utilization of a perfect adhesive epoxy on the concrete contact surface led to sufficient bonding between the two surfaces. Therefore, overall, the proposed strengthening technique can be considered a reliable method to enhance the performance of RC beams without the risk of de-bonding.
... The schematic of conversion of foundation into equivalent vertical stiffness for end and middle zone is shown in Figure 9. The vertical translational stiffness intensities for end and middle zone is given by [26]: ...
The purpose of the current research work is to investigate the free vibration control characteristics of a Terfenol-D layered functionally graded fluid-conveying pipe when subjected to partial two-parameter foundation, viscoelastic supports, and multi-span length. The integration of differential quadrature method with domain decomposition and the delta point approach, as well as Terfenol-D layer actuation with viscoelastic supports, distinguishes the current study effort. The equivalent spring stiffness for the two-parameter partial foundation is determined methodically for various elastic soil materials. The effect of varied spans with viscoelastic supports on the stability of fluid conveying pipes is also explored.
... In the JBDPA-2002, the shear mechanism, connecting methods, calculating equations and design procedures are well concluded, which provides a significant basis for the further external retrofitting research and application in practice. In 2008, Matteis et al. [215] adopted the capacity spectrum method provided in the ATC 40 [216] to retrofit the existing RC building by means of the external steel-aluminum shear panels. The simplified analytical relationships were given to determine the geometrical configurations of the applied shear panels, and the full-scale experiments were performed, confirming the superior improvements in the seismic behaviors after retrofitting. ...
Earthquakes cause serious damage to buildings and result in heavy losses to society, therefore, it is necessary to enhance the seismic capacity of existing buildings via structural retrofitting. The traditional retrofitting approaches are based on the component-level, but their improvement effect for the overall structure is not obvious. The ultimate goal of seismic retrofitting is to improve the overall seismic performance of the whole structure, thus a variety of external sub-structure retrofitting methods have been developed at home and abroad since the 1970s. The external sub-structure is connected with the existing structure as a whole on the structural-system-level, and it is of great significance for lifeline projects or non-interrupted buildings. At this stage, the external sub-structure retrofitting technology has received wide attention in the seismic community and is still developing in bloom. This paper gives a state of the art review of the advances and research interests of the external sub-structure retrofitting technology. First, the general concepts of the external sub-structure retrofitting technology are given, including (1) retrofitting principle and (2) retrofitting superiority. Then, the typical types of the external sub-structure retrofitting technology are summarized, including (1) external frame sub-structures, (2) external frame-brace sub-structures, (3) external wall sub-structures and (4) other external sub-structures. Finally, some critical issues of the external sub-structure retrofitting technology are extracted, including (1) interfacial shear transferring mechanism, (2) joint property and connection performance, (3) combination with precast-assembly technology, (4) combination with prestress technology, (5) numerical approach and assessment indicators, (6) optimization strategy and design procedure, (7) environment interaction and maintenance cost, and (8) application in practical engineering. The future perspectives of the external sub-structure retrofitting technology are also pointed out, and the contents can provide some reference for the subsequent research as well as the developing trend in the future.
... In this method, structures are usually subjected to invariant lateral load, whose magnitude gradually increases until the control node reaching the predefined target displacement. Various versions of pushover methods have been proposed in extensive research, such as the capacity spectrum method [11,12] and the N2 method [13]. However, the response estimated by these methods is not that accurate for large-scale and irregular structures [14], since the lateral load pattern remains invariant, and the stiffness degradation and inertia redistribution effect are ignored. ...
Seismic responses of tall pier bridges are usually estimated with nonlinear time history analysis (NLTHA) since it is able to provide rigorous results while the time consumption is acceptable with the improvement of computers. Note that parallel computing employing multiple computers might be required to facilitate estimating the performance of numerous bridges in highway networks after earthquakes. Recently, deep learning techniques have been recognized as promising alternatives for predicting structural responses in earthquake engineering with significantly improved time efficiency. Therefore, this paper develops a fast seismic performance estimation methodology using deep learning procedures to rapidly predict the seismic demands of tall pier bridges. The efficiency of the employed techniques is verified through illustrative examples, by comparing the predicted responses with those obtained from NLTHA under several types of input motions. The results show that when trained following appropriate steps, the deep learning models could provide satisfactory prediction for shear force, bending moment, as well as section curvature ductility. Additionally, the time efficiency of deep learning models is shown increased by about 97% compared with NLTHA, which might be further improved for more complex structural systems. Further parametric analysis reveals that the efficiency of selecting proper input variables for deep learning models could be significantly improved by considering the physical characteristics of structures; e.g., structural dynamic properties and interaction between structure and ground motion. This methodology is believed especially favored evaluating the seismic performance/post-earthquake resilience of highway networks containing thousands of bridges, in which conducting NLTHA for each bridge is prohibitively computational demanding and might delay rescue operations.
... In this paper, the earthquake loss estimation process is based on the seismic damage assessment approach developed for Algerian existing buildings (Boukri et al. 2013(Boukri et al. , 2014b. It is adapted from HAZUS methodology (FEMA 2002), which relies on the capacity spectrum method (Mahaney et al. 1993, ATC-40 1996, Comartin et al. 2000, Chopra and Goël 1999, Fajfar 1999Lagomarsino, Cattari, and Calderini 2012). It requires, as seismic input, the specific soil conditions and their dynamic properties: definition of the probable or real earthquake scenario (magnitude, epicentre, focal depth), the soil conditions and site effects (seismic microzoning studies, response spectrum) (Brando et al. 2020), as well as the specific material properties and the structural types since they govern the structural dynamic response (seismic output). ...
The present work develops an integrated rapid loss assessment model aiming to quickly estimate the expected damages and their spatial distribution for the Algerian urban heritage context. It predicts the expected damages for a given earthquake scenario, i.e. an historic event or a reference scenario. Furthermore, in the immediate aftermath of an earthquake, the model updates the damages according to the seismic signals either recorded in the zone of interest or derived quickly from the GMPE (Ground Motion Prediction Equations). It combines a seismic damage assessment approach developed for existing building in Algeria and a GIS system, in order to automatically generate relevant damage maps for decision-making and rescue purposes. It is implemented and run for a real case of Blida city, located in the central northern part of Algeria, which is a highly dense urban area (3070 inhabitants/km²) containing an important architectural and historical heritage.
For calibration purposes, the model is implemented and run in order to generate the seismic damage GIS maps for a set of 23,000 buildings, for a potential earthquake Mw = 7, consistent with the area seismicity.
The results show that serious damages and complete destruction are expected in particular areas, mainly the oldest districts with an urban heritage consisting of old unreinforced masonry buildings dating from the XVI to the middle of the XX centuries. Less important damages are expected for newly erected constructions built during and after the last half of the XX century, as they meet the structural design standards and built on adequate soils.
... Among these we have the linear and non-linear procedures, considering static and dynamic loads. The static nonlinear is considered in several methodologies such as: capacity spectrum, developed in ATC-40 [21], FEMA displacement coefficient [22]; and, Hazus [23], which bases its evaluation on a static non-linear model with variation of the earthquake and capacity of the structure. In the present study, the Hazus alternative was used. ...
Ecuador is located in the Pacific Ring of Fire, a country with high risk and seismic sensitivity, evidenced by the 6.8-degree earthquake in Ambato in 1949, which left approximately 6000 dead, the 7.8-degree earthquake in Manabí and Esmeraldas in the year 2016 with 663 victims and 29672 buildings without the possibility of use. Currently there is a problem about seismic performance in reinforced concrete buildings, since many were built with old regulations; so, it is necessary to assess their vulnerability. Quito, Guayaquil and Cuenca, large cities in Ecuador, have formal studies of seismic vulnerability, mostly carried out by university students and teachers. In contrast, most small cities do not have these studies; or, they need to be updated to validate their results. This is the case of the city of Azogues. The objective of this research is to evaluate the vulnerability of structures using the Hazus methodology, adapted to Ecuador, in the downtown area of the city of Azogues, in structures located around the Central Park, to establish the seismic performance in reinforced concrete buildings. The Hazus methodology, which determines the vulnerability of buildings from fragility curves, which are entered with inputs as the capacity, performance level and drift curves calculated through Ecuadorian models. The capacity curves, depending on various aspects such as: the material, number of floors, spans between columns, among others; they vary from building to building. In this sense, capacity curves were defined for sets of buildings with similar characteristics, coinciding with the Hazus methodology. The performance levels and the displacements were calculated with the ETABS computer package. For fragility curves, the model that most real simulates the response of a structure is the non-linear analysis, because it considers the decrease in stiffness in columns and beams, as well as the deterioration of the properties of the materials. In this sense, there are fragility curves of Ecuadorian buildings for four levels. The earthquake readings enable the construction of a demand spectrum, which, when contrasted with the capacity spectrum, leads to the performance point. Its position sometimes varies per the elastic demand spectrum, which is diminished by its inelastic behavior. As the demand spectrum decreases, the damage will increase. Once the coordinates of the performance point are known, the fragility curves are used; and, the possible damages are defined, quantifying them in percentage.
... To this end, ATC-40 has recommended that a coefficient of ¼ be applied to static hysteretic energy, so that the cyclic effect of the inelastic spectrum is considered in calculation of hysteretic energy. In other words, by applying the aforementioned coefficient to the hysteretic energy obtained from plastic analysis, it would be modified to include the cyclic effects in nonlinear analyses (Comartin et al. 2000;Terapathana 2012). ...
This study presents an energy-based procedure for the design of RC frames under earthquake strong motions. For this purpose, three RC frames having 4, 8, and 12 stories that were used in FEMA P695 were selected. The code-based designed frames were analyzed and redesigned employing the proposed energy-based procedure. A comparison was conducted between the performance of the code-based and energy-based designed models. Results reveal that the energy-based models appeared to perform more effectively under strong ground motions in terms of more optimized use of beam capacity for dissipation of energy, higher ductility values, and more uniform distribution of plastic hinges in height of structure. Comparison of pushover curves showed that ductility value in energy-based frames increases nearly 1.5–2.0 times the ductility of code-based frames. Calculated hysteretic energy demand in energy-based frames is also proved to decline by 50% in lower stories and, instead, the contribution of upper stories is increased. The same pattern for distribution of interstory drift ratio is also observed.
... With the advancement in earthquake engineering, the concept of performance-based earthquake engineering has gained popularity, which considers the entire range of seismic structural behaviors, including nonlinear behavior up to collapse. Standard performance levels put forward by the Applied Technology Council [1] and Federal Emergency Management Agency [2] include operational, immediate occupancy, life safety, and collapse prevention. Collapse prevention is the performance level where the structure may experience large damage to the structural components without collapsing. ...
Special concentrically braced frames (SCBFs) located in regions close to earthquake faults may be subjected to near-fault ground motions, often characterized by pulses with long periods. These near-fault pulses could impose additional seismic demands on structures and increase the risk for structural collapse. Currently, there is limited research on the seismic collapse risk of SCBFs under near-fault earthquakes. This paper uses a general simulation-based framework to assess the seismic collapse risk of SCBFs under near-fault earthquakes. To quantify the large variability and uncertainty associated with the seismic hazard, a stochastic ground motion (SGM) model is used where the near-fault pulse characteristics are explicitly incorporated. The uncertainties in the SGM model parameters (including the near-fault pulse characteristics) are addressed through appropriate selection of probability distribution functions. To accurately predict the occurrence of collapse, numerical models capable of capturing the nonlinear and collapse behavior are established and used. Efficient stochastic simulation approaches are proposed to estimate the seismic collapse risk with or without considering the near-fault pulse. As an illustration, the seismic collapse risks of two SCBFs are investigated and compared. Probabilistic sensitivity analysis is also carried out to investigate the importance of uncertain model parameters within the SGM towards the seismic collapse risk.
... Accordingly, a number of numerical and experimental studies have been conducted to compute energy dissipation in RC elements under cyclic loading. However, none of these studies were accurate and their findings were based on the type of material and did not consider design parameters (Comartin et al. 2000;FEMA 2000;Lin et al. 2003;Medhekar and Kennedy 2000). Recently, Eom and Park (2010) carried out a study on the mechanism of input energy dissipation via RC structures. ...
Shear walls are lateral load-resisting systems that provide lateral strength and stiffness in order to reduce the horizontal sway of a building. Over recent years, composite shear walls with steel-encased profiles (CSRCWs) have attracted increasing attention. This paper aims to numerically investigate the impact of axial loads on the seismic behavior of shear walls. Numerical modeling was carried out via OpenSees. Five composite shear walls with different shapes of steel-encased profile and one typical reinforced concrete (RC) shear wall subjected to lateral cyclic displacements and different levels of axial load in the range of 10%-40% of axial load capacity were investigated. The findings revealed that increasing the axial compressive load ratio has a negative effect on the seismic behavior of shear walls. In addition, the results showed that shear walls with steel-encased profiles have more flexibility, stiffness, and energy dissipation compared with typical RC shear walls under the same axial load.
... Specific reduction factors [44] have been considered to opportunely account for the effect of openings, by limiting the strength and lateral stiffness of the panels. The capacity spectrum method (CSM) [45] implementing the N2 approach [46] has been applied to derive the EDPs associated to the reference limit states (ZL, OP, and DC) and the corresponding spectral accelerations at the fundamental period T*. In this optic, non-linear static analyses (push-over) have been performed in the two principal (X-and Y-) directions of each archetype building, considering a linear force distribution (Figures 5-7). ...
Comprehensive methodologies based on a fully probabilistic approach (i.e., the performance-based earthquake engineering approach, PBEE), represent a refined and accurate tool for the seismic performance assessment of structures. However, those procedures are suitable for building-specific evaluations, appearing extremely time-consuming if applied at the urban scale. In the proposed contribution, simplified loss assessment procedure will be applied at the urban scale with reference to the residential building stock of the center of Potenza. After the identification of the main reinforced concrete (RC) structural typologies and the definition of specific archetype building numerical models, the direct estimation of expected annual loss (DEAL) methodology will be applied to derive the EAL (i.e., expected annual loss) of RC buildings, deriving information on the effectively seismic quality (or seismic resilience) of the aforementioned built heritage at urban scale. Similarly, the monetary losses associated with downtime are evaluated. Preliminary considerations on the socio-economic effects of seismic scenarios on the territorial scale are also proposed.
... This factor is estimated considering the expected ductility reached by the structure. Note that this approach is analogous to the one presented in ATC-40 [82]. The response spectra of the selected earthquakes (see Fig. 8) are used as seismic demand. ...
In Costa Rica, typical dwelling constructions are generally built with reinforced concrete masonry walls. This construction practice became one of the most common during the second half of the last century in Costa Rica. These kinds of structures exhibit high lateral stiffness and shear capacity, which makes them susceptible to semi-ductile failure or torsion if they are not correctly designed and constructed or the walls are not well distributed. However, recent research has shown that this type of masonry exhibits adequate capacity to dissipate plastic energy if the latter requirements are controlled. In this study, the seismic behavior of a recently designed and built reinforced concrete masonry structure is studied from a probabilistic perspective. Experimental results have been used to calibrate the probabilistic model. This structure was designed using the response spectrum method according to the Costa Rican Seismic Code. To verify its expected behavior considering more advanced analysis, it is analyzed through probabilistic incremental nonlinear static and dynamic computational-based methods. The aim is to obtain probabilistic damage curves in a series of permutations between the mechanical properties and the nonlinear behavior of the walls. Three different Damage Indices are estimated. Specifically, the Park & Ang damage index is used as a reference for two approximations that employ the capacity curve as input. Results indicate that the behavior of the analyzed structure is suitable for the seismic demand provided by the Costa Rican Seismic Code. Finally, correlations between input and output variables are calculated to analyze what are the variables governing the structural response. A strong relationship between masonry compression strength, Young's module, and the post yielding slope (input variables) and all the output variables has been observed.
... In the past few decades, a more accurate seismic design method based on inelastic analyses called displacementbased seismic design (DBD) has been developed. In this method, an earthquake is applied in the form of an equivalent displacement at the roof level of the structure (Comartin et al. 2000;Prestandard 2000). In the DBD, the structural behavior with an emphasis on the performance of each member in the inelastic range is performed, and the structure should be designed in an inelastic range, appropriate to its expected performance level. ...
Force-based and displacement-based methods are two conventional approaches for the seismic design of structures. Recently, the advantages and disadvantages of these methods have activated the researchers to combine them and to introduce the hybrid force–displacement (HFD) seismic design methods. In this paper, a new method named “modified seismic coefficient” for steel moment frames (MRFs) is presented. For this purpose, the seismic behavior factor and response spectrum of the structure are determined based on actual structural response and also the fundamental period of the structure. For practical examples, at first, a series of three (3, 6, and 9-story) MRFs is designed based on the proposed method and a classic HFD method, and then, their seismic responses are evaluated using nonlinear time-history analyses. For satisfying life safety (LS) performance level, it is observed that the proposed method reduces structural weight as 27, 22, and 24% for 3, 6, and 9-story frames, respectively.
... It is an important theoretical basis for evaluating the seismic risk loss of a bridge and making decision. HAZUS and ATC-40 [29] are graded to assess the damage. e macroscopical descriptions of the damage at all levels are given, as shown in Table 4. Table 4, the damage grade of the structure is divided into no damage, slight damage, moderate damage, extensive damage, and complete damage. ...
In the traditional bridge seismic fragility analysis, the criterion for judging the structural damage state is clear. That is to say, when the damage index exceeds a specific value, the structure is judged to enter the new damage state. However, the actual condition is that the boundary of structural damage is not clear but fuzzy. Taking a three-span V-shaped continuous girder bridge as an example, the damage process of the structure is described by fuzzy mathematics. Considering the uncertainties of ground motion and structure itself, a seismic fragility analysis method is established, which can consider the randomness of bridge itself, seismic load, and structural failure fuzziness simultaneously. Finally, the improved product of conditional marginal (I-PCM) method for fragility analysis of bridge system is further optimized and improved. The new improved method is used to form the seismic fragility curves of bridge structure system. The results show that it is possible to underestimate the potential seismic fragility of bridge components and system without considering the structural fuzzy failure criteria; the fragility curves formed by different membership functions are obviously different; the new system fragility analysis method can significantly improve the analysis accuracy.
... The main findings from early linear elastic analyses were that the increased damping and increased flexibility from rocking and sliding of the foundation causes a modification to behaviour with its overall effect being dictated by the frequency content of the earthquake record. There have been several studies into linear SFSI with non-linear structures, such as Comartin et al. (2000) demonstrating that ignorance of SFSI can result in the wrong part of the structure being retro-fitted. Studies by Nakhaei and Ali Ghannad (2008) showed that by modelling SFSI the structure will generally suffer more damage compared to a fixed based equivalent when the super-structure period is less than the predominant period of the record and vice-versa. ...
The uptake of a performance-based design methodology requires a consideration of not just the performance of the superstructure but the supporting soil and foundation as well. Case studies throughout history (eg. Kobe, Kocaeli & Christchurch earthquakes) demonstrate that a poor performance at the foundation level can result in a full demolition of the structure. For designers to have confidence that their design satisfies the given performance levels they must first understand how the soil-foundation interaction affects the performance and secondly have tools available to adequately account for it in their design. This paper firstly provides an overview of the effects and mechanisms of soil-foundation-structure-interaction especially in relation to the non-linear effects. Following this a performance-based design framework is presented which addresses all of the discussed effects and is supported with a design example of a six storey building.
... Early numerical and analytical studies using linear elastic analysis showed that the increased damping and increased flexibility from rocking and sliding of the foundation caused a modification to behaviour with the overall effect being dictated by the frequency content of the earthquake record relative to the main frequency of the structural-foundation system. There have been several studies into linear SFSI with non-linear structures, such as Comartin et al. (2000), which demonstrated that ignoring SFSI could result in the wrong part of the structure being retro-fitted. Studies by Nakhaei and Ali Ghannad (2008) showed that by modelling SFSI the structure would generally suffer more damage compared to a fixed based equivalent when the super-structure period was less than the predominant period of the record and vice-versa. ...
A rigorous performance-based design methodology should not just consider the performance of the superstructure but the supporting foundation system as well. Case studies throughout history (eg. Kobe 1995, Kocaeli 1999 and Christchurch earthquakes 2010-2011) have demonstrated that a poor performance at the foundation level can result in a full demolition of the structure and, in general terms, that the extent of damage to, and repairability of, the building system as a whole, is given by the combination of the damage to the soil, foundation and superstructure. The lack of consideration of the modifying factors of soil-foundation-structure interaction (SFSI) and an absence of intuitive performance levels for controlling foundation and soil behaviour under seismic loads has resulted in inadequate designs for buildings sited on soft soil. For engineers to be satisfied that their designs meet the given performance levels they must first, understand how the soil-foundation interaction affects the overall system performance and secondly have tools available to adequately account for it in their design/assessment. This paper presents performance-based design considerations based on a de-aggregation of superstructure and foundation performance. Several effects and mechanisms of non-linear SFSI are discussed and related to design parameters (super-structure drift and foundation rotation). Following this a performance-based design framework is presented which addresses the discussed effects and is supported with a design example of a six-storey building.
... For the P-M-M hinge, an interaction (yield) surface should be specified in the three-dimensional P-M2-M3 space that represents the first yielding location for different combinations of axial force P, minor moment M2, and major moment M3. In the SAP2000 program, the builtin default hinge properties for steel members are provided based on FEMA-356 criteria [32], and the built-in default hinge properties for concrete members are generally based on ATC-40 criteria [33]. For the user-defined plastic hinges, XTRACT [34] software is generally utilized to determine the moment-rotation curves for beam and P-M-M interaction curves for columns. ...
SAP2000 software was used to build the finite element model of a six-storey-three-span reinforced concrete (RC) frame structure. The numerical simulation of the seismic performance of the RC frame structure incorporating different levels of rebar corrosion was conducted using pushover analysis method. The degradation characteristics of the seismic performance of the corroded structure under severe earthquake were also analyzed. The results show that the seismic performance of the RC frame decreased significantly due to corrosion of the longitudinal rebars. And the interstory drift ratios increase dramatically with the increasing of the corrosion rate. At the same time, the formation and development of plastic hinges (beam hinges or column hinges) will accelerate, which leads to a more aggravated deformation of the structure under rare earthquake action, resulting in a negative effect to the seismic bearing capacity of the structure.
... Understanding the nonlinear behavior of shallow building foundations under large amplitude loading is an important aspect of performancebased design. The 1997 Federal Emergency Management Agency NEHRP Guidelines for the seismic retrofit of buildings [12] and the associated Applied Technology Council document (ATC 40) [2] discuss alternative design issues associated with the response of shear walls when subjected to lateral earthquake induced rocking. Geotechnical components of the foundation are known to have a significant effect on the building response to seismic shaking. ...
Shallow foundations supporting building
structures might be loaded well into their nonlinear range
during intense earthquake loading. The nonlinearity of the
soil may act as an energy dissipation mechanism, potentially
reducing shaking demands exerted on the building. This
nonlinearity, however, may result in permanent
deformations that also cause damage to the building. Five
series of tests on a large centrifuge, including 41 models of
shear wall footings, were performed to study the nonlinear
load-deformation characteristics during cyclic and
earthquake loading. Footing dimensions, depth of
embedment, wall weight, factor of safety, soil density, and
soil type (dry sand and saturated clay) were systematically
varied. The behavior of the wall-footing-soil system is
analyzed in terms of the resultant of the vertical, horizontal,
and moment load acting at the center of the base of the
footing and the corresponding displacements (settlement,
sliding and rotation). For the soils tested, the moment
capacity was not observed to degrade with cycling, but due
to rounding of the interface and uplift associated with large
rotations, stiffness degradation was observed. Permanent
deformations beneath the footing continue to accumulate
with the number of cycles of loading, though the rate of
accumulation of settlement decreases as the footing embeds
itself.
In this study, the inelastic displacement ratio (IDR) for far-field earthquake ground motions is statistically evaluated by the modified energy damage indices, known as hysteresis energy to input energy ratio, to estimate the target displacement in performance-based design theory with an energy approach. The suggested damage model can consider the effect of the frequency content, earthquake amplitude, and ground motion duration by accounting for whole energy aspects, including kinematic energy, damping energy, hysteresis energy, and input energy, without complex parameters in its structure. The IDR is statistically determined in six damage levels, four hysteresis models, and 30 periods of vibration by performing 216,000 dynamic analyses on 300 far-field ground motions. Moreover, the effect of the period, magnitude, source-to-site distance, and soil classes are investigated. Hence, a simplified mathematical equation is proposed based on the CDI−T−DI
function to estimate the target displacement in different damage levels for performance-based design. Finally, the proposed method and formula are verified by target inelastic displacements gained from dynamic time history analysis. Statistical results showed that the coefficient of variation (COV) is not too high, and the influence of record-to-record characteristics on the IDR ratio is negligible. Additionally, the proposed equation could estimate the inelastic target displacement in different damage levels and periods of vibration appropriately.
Earthquakes are a major cause of damage and human losses to the built environment, including cultural heritages, monumental buildings and historical centers. In the last decades the seismic performance of buildings has received special attention due to the interest in the built heritage conservation and protection of human life, particularly with respect to masonry structures which have shown evidence of poor behavior once subjected to seismic loads. The present work contributes to the seismic safety assessment of the out-of-plane behavior of unreinforced masonry walls through a displacement-based approach, providing the capacity for different out-of-plane geometric indexes and its seismic response in different earthquake-prone regions. The analyses are conducted using a seismic probabilistic framework, considering the most common out-of-plane mechanisms, different material properties, various slenderness ratios, and a wide range of seismicity levels to cover the seismic hazard in Europe. The results presented can be useful for seismic safety assessment and to incorporate vulnerability models for seismic risk analysis.
Earthquakes are one of the most extinctive natural unpredictable disaster. The major reason of most of the earthquakes are the movement of Tectonic plates and excitation in the earth’s crust. It is observed that many conventional buildings have constructed without considering seismic provisions given by Indian standard codes to escape the disastrous effect of earthquakes which results into the collapse and disintegration of buildings. Therefore, the concept of earthquake resistant building design came into consideration and this is the most crucial aspect when a structure is to be designed for sloping terrain or for the hilly area. This research is carried out to examine the response of structures during the ground oscillations in terms of storey drift, base shear and storey displacement. For research work, 8storey, 12 storey and 16 storey frames are considered which are constructed on plain ground and sloping ground and 20°, 30°and 45° slopes and zone V are considered. All the frames are designed and analyzed using pushover analysis in finite element based software ETABS v-19. Response reduction factor is also calculated for several frames and compared the calculated values with the values given in IS 1893:2016(part- I).
In recent years, several earthquakes have drawn the attention of researchers to the effectiveness of antiseismic devices (AD) and structural designs. These elements certainly influence building safety, but they also impact the environment. Hence, the overall ecological footprint of a building is varied by the size of the structural elements and the inventory of construction materials used. Since both parameters (safety and environmental footprint) are currently key factors in the building sector, this paper aims to compare the ecological impact produced for each of the three most common antiseismic devices: chevron braces, shear walls and energy dissipators. For such a purpose, a 15-storey building was modelled whose structure was sized by setting a similar base shear capacity (i.e. approx. 2500 kN), regardless of the incorporated antiseismic device. Besides this, with the aim of determining the influence of reinforcement ratios, three different ratios (from 3 to 8%) were chosen for each case. Thus, four different structures (including a bare frame as a control case) were assessed in terms of the mechanical response (i.e. modal parameters, pushover curves and time history analysis) and environmental impact (i.e. life cycle impact assessment method). The results showed that the use of energy dissipators provides the most satisfactory mechanical performance and leads to minimise both ecosystem quality and resource scarcity. Although the use of shear walls certainly shows the lowest impact on the human health category, dynamic calculations demonstrate that this solution greatly increases the rigidity, which hinders the effectiveness of such antiseismic devices. The results provide comprehensive guidance for building designers, showing the main advantages of each AD, in terms of safety, damage control and environmental impact.
Many countries are undertaking changes in earthquake design codes, the main reason for it is that the existing building codes do not specify the performance criteria of individual structural elements under various levels of shaking. Even though some buildings performed well in life safety aspects, many of those failed in safeguarding the building from high extent of structural damage under severe shaking. Retrofitting had also proved to be uneconomical for the buildings to perform better under severe shaking. In the current earthquake codes, the displacements and forces are within the elastic limit i.e., the assumed behaviour is linear. But the response of a structure to the major earthquakes is not elastic. There is a high chance of yielding and the development of plastic hinges in the members. Therefore, it is required to perform the non-linear analysis for assessing the inelastic behaviour of the structure. In the present study non-linear static analysis was adopted to assess the seismic performance of an irregular building in plan with re-entrant corners using the capacity spectrum method. If either the drift limit of the structure or the response of the hinges is exceeding the desired level of performance, the structure is fed with supplemental damping to ensure the required performance. It was observed that the formation of hinges crossed life safety level and entered the collapse prevention state. As the response exceeded the desired level of performance a methodology to calculate the required supplemental damping for the structure is proposed. Depending on the level of safety of the structure, an appropriate supplemental damping value can be obtained from the proposed performance plots.
Adobe bricks have been used in construction since ancient times, due to their low cost, good performance and the ease of assembly and elaboration of these elements in construction. However, the low ductility and resistance of adobe could harm the structural behaviour of buildings, especially taller buildings. The addition of additives, in the form of abundant high-density polyethylene (HDPE) fibres, could improve the mechanical properties from a seismic and structural point of view. These improved adobes could replace factory bricks, whose mechanical deficiencies are similar to adobe (stiffness and flexural strength), and they could reduce the high cost of buildings today. This work analyses and compares the performance and structural performance that these elements acquire in framed buildings, compared to traditional adobe, incorporating different percentages of high-density polyethylene fibres (HDPE) in low-rise buildings (of 2 and 4 storeys), which are very abundant in areas of high seismicity. For this, models of structural frames are analysed, adding adobe walls using the mechanical results carried out in a laboratory at the University of Talca (Chile). The addition of a small percentage (0.6% and 1.2%) of HDPE in the traditional adobe, improves the ductility and the structural performance of the frames.
Pushover method for underground structure is a seismic analysis method with high calculation accuracy and simple implementation process, which has been widely used in seismic design and scientific research, however, the influence of different soil-structure flexibility ratios on the accuracy of this method is not clear. This paper takes the cross section of Daikai subway station as the research object, and 12 finite element analysis models with different soil-structure flexibility ratios are established by ABAQUS, and all models were computed by dynamic time-history method or pushover method. Th dynamic time-history solution result was taken as the standard solution, and the precision and application of pushover analysis method are discussed based on the parameters of peak interlayer displacement and peak internal force of middle column section. The results show that the soil-structure flexibility ratio has significant influence on the calculation accuracy of pushover method, the calculation accuracy of this method is the most ideal when the soil-structure flexibility is equal to 1. The research results can provide some references for the seismic design of underground structures or the improvement of simplified seismic analysis methods.
Hydraulic fracturing is a key technology in the development of unconventional oil and gas reservoirs. With the continuous industrialization and large-scale development of shale gas production in China, the workload of hydraulic fracturing is also increasing rapidly, and the induced seismic events are also increasing gradually, resulting in different degrees of damage to the surrounding ancillary buildings. In order to study the impact of hydraulic fracturing on ancillary buildings, the finite element software ABAQUS was used to establish a three-dimensional model of middle and high-rise isolated structures to simulate the earthquake triggered by hydraulic fracturing. Then, considering the SSI (soil-structure interaction) effect of soil-based structure, the nonlinear dynamic response of the structure under the action of ground motion was analyzed. Through the adoption of different types of soil and the foundation depth, the influence of various parameters is discussed. The study found that in the case of not considering SSI, basal shear force, and displacement between floors of the seismic-isolation structure significantly greater than considering SSI, using hard soil layer, base shear displacement is greater than the soft soil layer and interlayer, shows that due to the effect of hydraulic fracturing, making fluid diffusion in soil, the seismic energy dissipation effect. It is also found that the period, base shear, peak displacement, and interlayer displacement of deep foundation pit are increased compared with shallow foundation pit considering SSI effect.
A Case study of Liquefaction-induced Damages to a Port Building Supported on Pile Foundation and
Analysis of laterally loaded single pile in cohedionless soil considering Nonlinear SSI.
The 9-m and 1-m radius geotechnical centrifuges at the Natural Hazards Engineering Research Infrastructure (NHERI) facility at the University of California at Davis provide the national research community with open access to unique and versatile modeling capabilities for advancing methods to predict and improve the performance of soil and soil-structure systems affected by earthquake, wave, wind, and storm surge loadings. Large-scale centrifuge models are particularly effective for the building of basic science knowledge, the validation of advanced computational models from the component to the holistic system level, and the validation of innovative soil remediation strategies. The capabilities and unique role of large-scale centrifuge modeling are illustrated using three example research projects from the shared-use NHERI facility. Education impacts stemming from operations activities and coordination of activities by the center’s user base are discussed. Future directions and opportunities for research using the NHERI facilities are discussed.
Earthquake events have been demonstrated to be a major threat to building in Indonesia. It was found that many building failures occurred due to design shortage or construction shortcomings. This research is intended to propose the evaluation method for the concrete building against the possible earthquake. Pushover analysis was performed to study the nonlinear behaviour of a concrete building. A total of two types of concrete buildings, designed for seismic and designed for gravity load only, were investigated. The results show that the concrete building designed for seismic has better performance in both local and global response than that of the concrete building designed for gravity.
Current research works and observations have shown that the parts of the Kingdom of Saudi Arabia are considered as low to moderate seismic zone. However, most of the residential buildings were designed for gravity loading only and lack of detailed to resist the seismic load. This research focused on the seismic evaluation of an existing typical residential building that was assumed to be located in different regions (Makkah, Jeddah, Gizan and Haql). This was accomplished by conducting a pushover analysis to simulate the nonlinear behaviour of the building. The analysis results in the failure mechanism of the building so that the weak elements can be monitored. These results help engineers to take any action for rehabilitation and strengthening work.
Seismic vulnerability assessment methods have been used by engineers and policy-makers as a tool for various engineering and economic applications during the last several decades. These methods were developed for building typologies representing a building stock. Member deficiencies due to poor quality of design, construction or maintenance are not explicitly taken into account in most of these methods. This paper quantifies the influence of member-level deficiencies due to corrosion on the seismic vulnerability of a low-rise, poorly constructed RCC building. Typical design and construction practice prevalent in Andaman and Nicobar Islands have been considered, which is both a highly seismic zone and has highly corrosive environment due to the saline and humid environment.
Chapter four focused on demonstration the basics of structural dynamic and explain the fundamental process to determine structural seismic response. In order to have a clear comprehending of the highlighted concepts within this book, it is tried to present the application of theories and calculation processes in a real buildings in all sections. Therefore, a 6 story building is considered and in the second section of this chapter the architectural plans and structure details are demonstrated. The third part of this chapter describes the response spectrum analysis and the analytical model for the multi degree-of-freedom (MDOF) structure. The shear force for every mode is computed from the natural frequency and eigenvalue analysis of the structure. The square root of the sum of squares (SRSS) technique and complete quadratic combination (CQC) technique are employed to determine the critical seismic responses for considered structures using maximum modal responses. In the last section, the procedure for nonlinear static analysis is demonstrated after describing the concept for plastic hinge occurring in the structural member. The nonlinear static analysis technique is considered as one of the mainly applicable techniques for nonlinear analysis of the structures subjected to lateral load.
En ingénierie sismique, il est admis que le comportement d’une structure soumise à de forts séismes soit caractérisé par des boucles d’hystérésis qui peuvent être amples ou étroites selon le type de structure impactée. La prise en compte de ce type de comportement non-linéaire dans un calcul temporel présente des difficultés liées à l’identification des paramètres, au coût numérique élevé, au risque de non-convergence. Dans ce contexte, la méthode de linéarisation équivalente, a été introduite en géotechnique dès les années 70. Elle reste peu utilisée dans le domaine des structures malgré les efforts de nombreux auteurs. Ce travail de thèse a pour objet l’étude du comportement linéaire équivalent dans le contexte des méthodes simplifiées d'évaluation de la réponse non-linéaire d'une structure en ingénierie sismique. Nous passons en revue les critères de linéarisation adoptés par les différentes méthodes qui recherchent l’équivalence (1) du déplacement maximum ou (2) de la quantité d’énergie dissipée ou (3) de la force de rappel. Nos analyses montrent que ces trois critères ne sont pas pertinents et/ou efficaces, conduisant à des méthodes peu robustes qui conduisent dans certains cas à des résultats inexplicables. Nous montrons le rôle important, négligé par toutes les méthodes disponibles, du contenu fréquentiel respectif des signaux et du système dans la détermination de la ductilité appelée. Sur cette constatation, nous introduisons une nouvelle méthode de linéarisation équivalente basée sur la fonction de transfert. Nous utilisons cette méthode pour explorer un plan d’expérience numérique dans lequel nous calculons les caractéristiques de fréquence et d’amortissement équivalents en fonction de la ductilité appelée pour différente configurations caractérisées par (a) le rapport entre fréquence de l’oscillateur et fréquence centrale du signal excitateur, (b) la pente d’écrouissage et (c) le modèle de comportement qui varie continument de élastoplastique à endommageant. Nous proposons deux nouvelles approches du comportement linéaire équivalent. La première, visant à améliorer la procédure statique non-linéaire de l’ATC40, utilise la rigidité sécante et le déplacement maximal. Elle fait intervenir une estimation de l’amortissement différente de celle de l’ATC40. Sa pertinence est établie par le fait qu’elle permet d’évaluer avec exactitude le déplacement maximal de systèmes canoniques non-linéaires. La seconde consiste à restituer la dynamique de la réponse d'un oscillateur non-linéaire au travers de la fonction de transfert. Sa pertinence est démontrée au travers des critères d’Anderson, avec notamment un critère relatif au spectre transféré. La détermination du comportement linéaire équivalent par fonction de transfert est validée sur des structures réelles au travers des essais sur voiles en béton armé (SAFE) et sur systèmes des tuyauteries (BARC et EPRI)
This study focuses on the soft-storey behavior of RC structures with lead core rubber bearing (LRB) isolation systems under near and far-fault motions. Under near-fault ground motions, seismic isolation devices might perform poorly because of large isolator displacements caused by large velocity and displacement pulses associated with such strong motions. In this study, four different structural models have been designed to study the effect of soft-storey behavior under near-fault and far-fault motions. The seismic analysis for isolated reinforced concrete buildings is carried out using a nonlinear time history analysis method. Inter-story drifts, absolute acceleration, displacement, base shear forces, hysteretic loops and the distribution of plastic hinges are examined as a result of the analysis. These results show that the performance of a base isolated RC structure is more affected by increasing the height of a story under nearfault motion than under far-fault motion.
PreambleBackground to Current DevelopmentsPerformance-Based MethodologyCurrent Analysis ProceduresSecond Generation Tools for PBSEReferences
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