Seismic Vulnerability Of Structures Research Articles

Seismic risk model for regional buildings that considers the influence of temperature and intensity measures

Probability-based seismic risk and random ground motion theories are used to develop high-precision seismic risk functions and models of regional building portfolios. Seismic intensity measures and structural demand parameters are critical in developing seismic fragility models for building clusters. Earthquake damage data indicate that ambient temperature may influence structural fragility, but the effect of temperature on seismic risk is commonly ignored. A method for quantifying seismic intensity is proposed in this study and optimized using 450,000 acceleration records detected by 15 stations during the Luding earthquake in Sichuan, China, on September 5, 2022. Considering the influence of different temperature fields, the proposed seismic intensity quantification method was used to evaluate structural damage during two destructive earthquakes in Xinjiang, China (the Aktao earthquake on September 2, 2003 and the Zhaosu earthquake on December 1, 2003). Three structural empirical seismic risk matrices and cloud maps were developed, and a vulnerability membership curve was generated using fuzzy decision-making, a membership algorithm, and nonlinear regression. A structural seismic risk index function was proposed, and vulnerability cloud diagrams and curves based on actual structural seismic vulnerability datasets were generated. Together, these analyses demonstrated the impact of temperature and intensity measures on the seismic risk to regional buildings. A model was established to evaluate the seismic risk to typical structures and was validated using historical earthquake damage data from China. This method improves the accuracy of earthquake risk and vulnerability assessments for typical building clusters given the influence of temperature. The developed seismic risk prediction model enables the evaluation of vulnerability and resilience of typical structures under low and high temperatures.

Efficient seismic fragility assessment method for a frictional isolated bridge constrained by shape memory alloy cables under pulse-like ground motion

Utilizing shape memory alloy (SMA) cables to constrain frictional isolated bridges is considered an efficient approach to limit bearing displacement and prevent serious earthquake damage. Accurate seismic fragility assessments of this kind of structure are crucial for aseismic decision making. However, traditional assessment methods cannot quantitatively describe the impact of the pulse effect on pulse-type seismic motions, which may lead to inaccurate assessment results. Therefore, this study deduced a novel equation for seismic fragility assessment that considers the pulse effect. Firstly, the impact of the pulse effect is quantified. Then, a multivariable probabilistic seismic demand model (MV-PSDM) is developed that is conditioned on the pulse period, peak ground velocity, structural period, maximum friction coefficient and SMA consumption. Based on the MV-PSDM, an effective approach for predicting structural seismic vulnerability is recommended, which does not require finite element modeling or nonlinear time-history analysis. Finally, a novel equation for calculating the intensity measure corresponding to 50% damage probability is deduced. The results indicate that increased friction coefficients and SMA consumption can enhance structural seismic safety under pulse-type ground motions. However, when the ratio of pulse period to structural period is too small, increased friction coefficients or SMA consumption have no meaningful effect on the seismic fragility of the structure.

Social and seismic structural vulnerability in Zihuatanejo, Guerrero, Mexico

The spatial distribution of the social and seismic structural vulnerabilities in Zihuatanejo (ZIH), Guerrero, Mexico, was estimated. Social vulnerability was assessed considering twelve indicators, including parameters such as access to health services, education, housing, employment, and unfavorable family conditions. Seismic structural vulnerability was evaluated characterizing the structural features of local houses, assessing the type and age of construction, and the quality of building materials. Surveyed households were randomly selected from a statistically significant sample. Our findings indicate that in the western and eastern areas of ZIH the population has high and very high social vulnerability. The main factors that condition these levels of social vulnerability are low-income, female-headed families, and households with marginal access to information technology, such as internet and telephone. Although seismic ground amplification in ZIH is relatively low, the regions to the west and southwest of the city are zones where the impact of strong earthquakes to constructions may be greater than in other areas. In particular, the districts of Lázaro Cárdenas, Benito Juárez, Cuauhtémoc, Emiliano Zapata, Las Mesas, Buenos Aires, Lomas del Quebrachal, and Lomas del Riscal would be affected. In general, houses vulnerable to the impact of earthquakes are in regions where the population is socially more vulnerable. More than 50% of the population and 30% of the houses have high and very high level of social and structural vulnerability, respectively. Our results provide information to the local and federal authorities to strengthen their civil protection and mitigation plans.

Fragility Assesment of Mid-Rise RC Building using HAZUS Method in High Seismic Zone

Earthquake is a pounding that caused by a released energy of ground motion. The earthquake in high seismic zone caused damages and loss of live. Thus, there was important to evaluate the seismic vulnerability of structure before an earthquake was occurred to prevent the damage and safe of lives. The seismic vulnerability can be described by using fragility curves. These fragility curves was developed by HAZUS method that present the probability of the structure damage due to various ground shaking or lateral displacement of the building. This paper addresses the performance based design method to consider the building capacity due to Padang ground motion. Therefore, the damage probability was calculated by using the lognormal distribution with the probabilistic parameter was acquired by HAZUS engineering building module. Then, the fragility assesment of the building was compared in transverse and longitudinal direction. The result reveals that the building is vulnerable to collapse due to Padang ground motion.

A Review of Studies on the Seismic Vulnerability of Structures in China

The performance-based seismic vulnerability analysis is the basis for evaluating the seismic reliability of structures, which is of great significance to the prediction of seismic damage and the establishment of seismic design codes based on the reliability theory. In this paper, a comprehensive review of the methods of seismic vulnerability analysis, the current research status, and the remaining problems in this field is presented. Firstly, the methods of structural seismic vulnerability analysis are categorized, and the advantages and disadvantages of each method are summarized, and the research progress in this field is discussed in detail; Finally, it is concluded that the research on the seismic vulnerability of structures in China has not yet produced research results of practical engineering significance. A set of more effective seismic vulnerability analysis theories should be established to directly guide the performance-based seismic design of structures by reasonably and accurately quantifying relevant factors such as ground shaking input parameters and performance level damage indicators.

Study of seismic vulnerability of steel frame structures on soft ground considering group effect

Earthquakes have caused increasingly severe casualties and economic losses in coastal urban areas where soft soils are widely distributed. To mitigate disaster losses, this paper aims to investigate the mechanism of the group effect, the interaction between a group of buildings (at least three) through the foundation, on seismic vulnerability in coastal urban areas. Firstly, the analysis models are established, and the validity is subsequently verified. Meanwhile, a self-built automatic iterative calculation program for multilayer soils is adopted to consider the nonlinearity of the soft soils. On this basis, probabilistic seismic demand analyses are further performed using ten earthquake ground motions. The seismic vulnerability formulas of the structures are obtained in combination with the probabilistic seismic demand models. Finally, the influence of the group effect on the seismic performance of the structures is evaluated from different perspectives based on the vulnerability formulas. The results indicate that the group effect of the steel frame structures makes the performance margin ratio (PMR) significantly higher and reduces the seismic vulnerability of the structures in coastal urban areas. The mechanism revealed in this paper presents a more accurate way to conduct earthquake-resistant design, provides guidelines for setting the criteria, and is likewise instructive to the seismic design of other structural forms.

Classification of buildings' potential for seismic damage using a machine learning model with auto hyperparameter tuning

The research on the application of machine learning (ML) methods in the field of earthquake engineering shows a continuous and rapid progress in the last two decades. ML methods and models belonging to the category of supervised, unsupervised and semi-supervised learning are applied for the assessment of seismic vulnerability of structures and estimation of the expected level of seismic damage. These models lead to the classification of seismic damage into predefined classes through the extraction of patterns from data collected from various sources. However, the lack of detailed knowledge can affect their performance and ultimately reduce their reliability, as well as the generalizability that should characterize them. Towards this direction, the present paper attempts to compare and evaluate for the first time the ability of an extensive number of ML methods in the correct classification of R/C buildings at the first stage pre- and post-seismic inspection considering three seismic damage categories. A database consisting of 5850 training samples is used for this evaluation. This database is generated by solving 90 R/C buildings for 65 actual seismic excitations applying nonlinear time history analyses. For each one of the training samples the maximum interstory drift ratio is calculated as a damage index. In addition, a major contribution of this paper is the presentation and extensive documentation of the procedures required for the preprocessing of the data. Finally, an auto hyperparameter tuning method for the winning algorithm is proposed, so that the hyperparameters are automatically optimized utilizing Bayesian Optimization. The most significant conclusion extracted is that the studied ML algorithms extract very different classification results. In addition, the Support Vector Machine - Gaussian Kernel algorithm extracted the most accurate results of all the studied ML algorithms.

A Simplified Prediction Model of Structural Seismic Vulnerability Considering a Multivariate Fuzzy Membership Algorithm

ABSTRACT Fuzzy decision-making and analytic hierarchical processes are ubiquitously used to predict the seismic damage and vulnerability of building clusters. However, the factors affecting the seismic vulnerability of building structures are diversification, cognitive uncertainty, and complex fuzziness. To probe the impact of multiple fuzzy influencing factors on the vulnerability of regional buildings and the degree of membership between them, the development of a structural vulnerability prediction model based on fuzzy decision-making and a hierarchical system with multiple factors has strong theoretical and practical significance. This study proposes a novel method for rapidly predicting structural vulnerability based on a multivariate fuzzy membership index. Rapid fragility prediction models of fiv4e typical structures considering the multivariate fuzzy membership index are established. A new approach is proposed based on the relationship model between the empirical vulnerability index and seven fuzzy membership parameters. Five types of typical structural vulnerability index rapid prediction innovation models are developed. The new prediction model is compared and verified using the quantitative value of China’s macrointensity standard and the structural seismic loss observation data (98,050 × 104 m2 and 995,000 buildings) of 213 typical earthquakes to establish an empirical vulnerability index belt model. The proposed prediction model comprehensively considers multiple fuzzy membership parameters and the empirical structural earthquake damage database. The model analysis and validation results indicate that the proposed model can be further used for the seismic damage evaluation of typical structures and rapid fragility prediction.

Fragility Comparison for Soft Storey Infill Reduced Structures by Incremental Dynamic Analysis

A keen understanding of how a structure behaves when it is exposed to earthquake scenarios is required in order to foresee and avert the adverse effects and consequences when such a incident occurs, with the current rate of development in our country the construction of mid and high rise residential apartments are rapidly increasing but the data to understand such structures is insufficient, this data includes seismic vulnerability of structures, hazard maps of earthquake prone areas, seismic risks involved for a structure, this data provides the insight of what magnitude of risks are at hand when a earthquake scenario occurs and how to avert or minimize the losses with those risks [1]. In the present study, an effort is made to determine the behavior of soft Storey structures for various parameters when it is exposed to an earthquake ground motion; this includes the development of models analytically with the existence of soft Storey in them with different infill reductions and analyzing them, two models with varying heights and plot areas are considered for this study, this four models are modeled in such a way that different variations of soft Storey existence depending on the location of walls, percentage of infill reductions among different walls are done, a total of eight variety of models are been analyzed in both the X and Y directions. It is concluded that in all the models the fragility is higher in the models with lower lateral dimensions, as the length of the side decreases the fragility of that side is increasing. The Model without reduction performed efficiently showing less probability to collapse and that height and plan dimensions of the model are dependent on each other for the increase or decrease of fragility in a structure. If the height increases with the same model plan dimensions, the fragility of the structure also increases, if the plan dimension increases the fragility of the structure decreases.

Utilizing Google Street View for Rapid Seismic Vulnerability Assessment: Case Study in the City of Manila, Philippines

Earthquake Impact Reduction Study for Metro Manila (MMEIRS) estimated that around 40% of the total number of residential buildings within Metro Manila will either collapse or be affected by the M7.2 generated by the West Valley Fault. Need arises to evaluate the seismic vulnerability of structures in the area to enhance the city’s resilience to seismic hazards. Rapid seismic vulnerability assessments are typically conducted by means of sidewalk surveys. However, advances in digital technologies such as Google Street View (GSV) provide the potential to do remote assessments, particularly amid mobility restrictions brought about by the COVID-19 pandemic. This paper aims to demonstrate the usefulness of GSV in collecting data needed for rapid seismic vulnerability assessments through the case of buildings in the City of Manila. Six 300 m x 300 m blocks were evaluated using GSV for identifying seismic-related building parameters. Results show the ease of use of GSV in data collection on areas encompassing commercial and residential zones within the city and poses difficulty for blocks dominated by informal settlements. Among the challenges observed in formal zones include blockages in views due to fences, trees, and/or vehicles parked in front. For informal settlements, much of the buildings are not visible in GSV for evaluation thereby necessitating supplemental data collection. Overall, GSV demonstrates usefulness, and has the potential to speed up seismic vulnerability assessments in urban areas in conjunction with existing in situ assessments currently conducted.

The assessment of the interaction between base isolation (BI) technique and soil structure interaction (SSI) effects with 3D numerical simulations

Base Isolation (BI) is a well-known technique that aims to reduce the seismic vulnerability of structures by increasing the structural deformability and the damping. However, these beneficial effects are significantly reduced when the system is founded on deformable soils and then Soil Structure Interaction (SSI) effects are considered. Even if both BI and SSI have been extensively studied in literature, the mutual effects of the two mechanisms are still object of discussion and this paper aims to fill this gap by performing 3D numerical simulations. Several structural systems of different soil conditions are herein modeled in order to account the period elongation and damping increase of the isolated systems. In particular, the paper proposes relationships to calculate these two effects to be used for preliminary estimations avoiding complex and time-consuming analyses. The models have been performed with Opensees to reproduce non-linear hysteretic materials and advanced soil models and consider the non-linear structural performance.

Challenges of emergency evacuation of residential areas caused by chemical release due to the earthquake: a Natech event scenario.

:Background:In recent decades, earthquakes, as natural hazards that caused direct effects both on communities and the chemical industry, produced many Natech events. Natech term is utilizing to describe the technological disasters caused by natural hazards. This study was conducted on the emergency evacuation challenges of residential areas adjacent to a refinery near Tehran based on H2S toxic gas release following a possible earthquake scenario.Methods:This Research was an applied study at two phases in 2020. In the first phase, a review study was conducted to identify the community's previous experiences on emergency evacuation following Natech events. In the second phase, the challenges of emergency evacuation were analyzed based on the scenario of a possible earthquake and gas release from the refinery.Results:Due to the high seismic vulnerability of structures in the area affected Natech risk, the total Resident population in this area would be affected simultaneously by an earthquake and H2S gas release in concentration 30 ppm as the result of the earthquake impact on chemical facilities. Emergency evacuation would be inevitable. The existing evacuation places are very unsafe and dangerous due to having open spaces. The nearest suitable evacuation places were found in the north direction for more than 38 % of the exposed population and in the east, west, and south direction for more than 61% of them.Conclusions:The emergency evacuation challenges were discussed in 4 viewpoints, disrupted or interrupted rescue and firefighting operation, unnecessary evacuation, frequent evacuation, and evacuation behavior. The measures such as revising and updating emergency evacuation maps; public informing, training, preparedness; providing protocols and training for operational and therapeutic response teams; and coordination improvement can help resilience increasing to such disasters.

Examination of Longitudinal Seismic Vulnerability of Shield Tunnels Utilizing Incremental Dynamic Analysis

In order to study the longitudinal seismic capacity of shield tunnels, this work applies the structural seismic vulnerability analysis, based on incremental dynamic analysis (IDA), to a shield tunnel and explores the ground motion intensity measure suitable for the shield tunnel in different site types. The failure probability of the structure at each earthquake intensity is calculated by combining the probabilistic seismic demand model with the limits on the engineering demand parameters to establish the seismic vulnerability curve of the structure. The results indicate that the peak ground velocity (PGV) is the ground motion intensity measure suitable for the longitudinal seismic performance of the shield tunnel. The site type has the most profound influence on the extent of the longitudinal damage to the shield tunnel, and site type IV is the most dangerous under an earthquake. Further, the tunnel has stronger seismic resistance in the elastoplastic stage. The low-grade bolts between the rings damage more severely than the high-grade bolts. A tunnel with either a great depth of burial or a large cross section is more dangerous than the one with either a small depth of burial or a small cross section. The risk of the axial tension-compression failure of the shield tunnel is higher than that of the horizontal transverse shear failure.

Seismic fragility analysis of sea-crossing continuous rigid frame bridges based on fuzzy failure

The bridges play an important transportation hub in the transportation lifeline system. The sea-crossing bridges located in earthquake-prone areas may be subjected to earthquake and wave action during their lifetime. This paper mainly investigates the seismic performance of continuous rigid frame bridges supported by group pile foundations based on the seismic fragility analysis. Based on the OpenSees software, the three-dimensional finite element model of the sea-crossing bridge is developed, where the pile-water interaction and pile-soil interaction are simulated by added mass method and p-y curve method, respectively. The uniform input ground motions are used by applying the displacement of the surface ground motion on all spring supports. Based on the traditional structural seismic vulnerability analysis and introducing the theory of reliability, the damage index is reduced by a half-trapezoidal distribution membership function, and the structural damage boundary is fuzzy analyzed to obtain the fuzzy components. Further, the damage limit about the vulnerability of the full bridge system is discussed. Finally, the influence of wave force on structural seismic vulnerability and the vulnerability of the full bridge model under different earthquake types, such as far-field, near-field pulse, and near-field non-pulse types, are analyzed.

Research on the disaster prevention mechanism of mega-sub controlled structural system by vulnerability analysis

The mega-sub controlled structural system (MSCSS) is a new structural system that combines structural response control theory with the construction principle of mega frame structure (MFS), and has significant response control effects. It is of practical significance to study the method which accurately evaluate the seismic vulnerability of structures. In this paper, Multiple Stripes Analysis (MSA) and Incremental Dynamic Analysis (IDA) are used to evaluate the vulnerability of MSCSS structure. The comparison between these two methods certify the accuracy of MSCSS vulnerability evaluation along with the impact of the number of stripes used in MSA method. In addition, through the comparative analysis of structural vulnerability analysis results, it is found that under limit state LS4, the failure probability of MSCSS is 30% lower than that of MFS, and the exceeding probability of megastructure is 50% lower than that of substructure, indicating that MSCSS structure has advanced disaster prevention design concept. Afterward, by introducing the seismic damage index used for regional structural seismic damage assessment into the vulnerability assessment, an intuitive seismic risk assessment method for buildings is anticipated by combining the seismic damage index and the beta distribution function, which can provide a reference for the risk assessment of super high-rise buildings.

Challenges in Evaluating Seismic Collapse Risk for RC Buildings

The development of fragility functions that express the probability of collapse of a building as a function of some ground motion intensity measure is an effective tool to assess seismic vulnerability of structures. However, a number of factors ranging from ground motion selection to modeling decisions can influence the quantification of collapse probability. A methodical investigation was carried out to examine the effects of component modeling and ground motion selection in establishing demand and collapse risk of a typical reinforced concrete frame building. The primary system considered in this study is a modern 6-story RC moment frame building that was designed to current code provisions in a seismically active region. Both concentrated and distributed plasticity beam–column elements were used to model the building frame and several options were considered in constitutive modeling for both options. Incremental dynamic analyses (IDA) were carried out using two suites of ground motions—the first set comprised site-dependent ground motions, while the second set was a compilation of hazard-consistent motions using the conditional scenario spectra approach. Findings from the study highlight the influence of modeling decisions and ground motion selection in the development of seismic collapse fragility functions and the characterization of risk for various demand levels.

A Proposed Theoretical Approach for the Estimation of Seismic Structural Vulnerability of Wastewater Treatment Plants

The assessment of seismic vulnerability is critical for lifelines such as wastewater treatment plants (WTPs) because failures may result in environmental degradation, deterioration of water quality and human diseases development. The main scope of this research is the testing and application of a rapid, simple methodology for assessing the seismic structural vulnerability (SSV) of WTPs (according to the qualitative method Rapid Visual Screening), using structural variables as indices of these infrastructures. An original new method involving the assessment of the SSV of thirteen steps (four for a sample set of WTPs and nine for an individual one) is introduced following systematic literature retrieval. The analysis highlights twenty one factors that may determine the SSV of WTPs: three factors involving general characteristics, five factors involving seismicity and geotechnical data, six factors involving technical data (including structural data) and seven additional factors about WTPs’ materials (concrete and the steel reinforcement of concrete frames). The structural data is analyzed to six additional factors. The implementation of the proposed methodology constitutes a simple, rapid methodological approach for assessing the SSV of WTPs using unique factors that were pinpointed and identified for the first time in this study.

Effect of ground motion characteristics on seismic fragility of subway station

Seismic fragility analysis of structure is fundamental in performance-based seismic design. The ground motion record set used in the analysis may have a characteristic effect on the fragility curves of a subway station structure. In this paper, fragility data have been developed by conducting the incremental dynamic analysis of subway station structure subjected to far-field record set (FFRS), near-field record set (NFRS), and near-filed record set with a pulse (NFRS + P). The dynamic analysis was conducted employing 2-D finite element models that account for soil nonlinearity and structural plastic damage. The vulnerability curves were derived utilizing the inter-story drift ratio as the damage measure (DM) and the peaks of ground acceleration as the intensity measure (IM). The results show that the second story was more prone to damage than the first story. The fragility curves derived from the data of the second story exhibited widely varying features for three ground motion record sets. The subway station sustained higher damage conditional probability when subjected to NFRS compared to NFRS + P and FFRS ground motions. The difference in the free field response under the three ground motion records sets directly correlates to the difference in the structural seismic vulnerability analysis. These results add to the rapidly expanding field of subway station performance-based seismic design.

Seismic vulnerability assessment of multi-storey subway station structure

The safety of underground structure under seismic load is an important basis of the normal operation of underground rail transit system. Structural seismic vulnerability assessment based on incremental dynamic analysis method can evaluate the probability of the structure exceeding a certain limit state under a specific seismic intensity in terms of probability. In this paper, the seismic vulnerability of a multi-storey subway station structure is evaluated using this method, and a two-dimensional finite element model of both soil and structure is established by finite element software ABAQUS. The vulnerability curve is obtained through incremental dynamic analysis and mathematical statistics. Based on this curve, the probabilities of the structure exceeding four seismic limit states are obtained under the design seismic intensity and the rarely occurred seismic intensity at 7 degree. Results show that this station may attain slight damage under design seismic intensity of 7 degree, and may attain life safety at the rarely occurred seismic intensity at 7 degree.

Analytical fragility curves of shallow-founded structures subjected to Soil-Structure Interaction (SSI) effects

Soil structure interaction (SSI) may affect significantly the seismic vulnerability of structures with several mechanisms that depend on the mutual effects of soil properties and structural characteristics. A probabilistic-based approach is here applied to evaluate the effects of SSI on the fragility assessment of two selected benchmark buildings: a Reinforced Concrete with Infill Masonry Walls (RCIMW) and a Reinforced Concrete (RC). Analytical fragility curves were developed by performing non-linear 3D numerical simulations with Opensees that implements hysteretic materials and advanced plasticity models for representing non-linear soil conditions and structural configurations. The effects of soil deformability and structural flexibility on the non-linear response of the system (soil-foundation-structure) were assessed and discussed by referring to four limit states (slight, moderate, extensive and collapse) with respect to the maximum inter storey drifts.