Seismic Vulnerability Research Articles

Assessment of the Seismic Vulnerability of Florence (Italy) Through Macro-Seismic Methods

In recent years, the assessment of damage scenarios in urban communities has become one of the central themes in local government policies, aimed at promoting effective seismic risk mitigation and improving the efficiency of rescue systems to manage emergencies. In Italy, the seismic hazard has become a topical issue since the 1982 Irpinia earthquake, and several ventures have been promoted to face the seismic mitigation of complex residential districts. The objective of this research is to define the damage scenarios of the city of Florence, where 97% of the building stock is designed without anti-seismic prescriptions. The urban vulnerability of Florence has been assessed based on the current approaches available in the technical literature, combined with the knowledge provided by the recent investigation on the subsoil. Once the possible damage scenarios have been defined, the resilience of the area has been determined, and the population involved in the evacuation has been estimated.

Seismic Vulnerability Assessment of the Cliff-Attached Buildings Equipped with Energy Dissipation Devices Under Obliquely Incident Seismic Waves

Cliff-attached structures are structures attached to slopes and connected tightly, which is particularly complex to analyze due to the foundations’ unequal grounding and the lateral stiffness’ irregularity. In rare earthquakes, seismic waves are usually obliquely incident on the foundation at a certain angle. Therefore, it is not appropriate to consider only seismic waves’ vertical incidence, and it is necessary to consider multi-angle oblique incidence. In this paper, based on the theory of viscous-spring artificial boundary and the principle of equivalent nodes at the interface of oblique incidence of ground shaking P-waves, and combined with the dynamic properties related to Buckling-Restrained Brace, the numerical models of slopes and two kinds of cliff-attached structures considering the slope amplification effect and soil-structure interaction are established. The dynamic response of the obliquely incident seismic waves under the action of the cliff-attached vibration reduction structure is studied in depth, and the additional effective damping ratios of the nonlinear energy-dissipated units based on the deformation energy are compared and analyzed. It is shown that under the four oblique incidence angles of incidence (compression waves in the vertical plane) studied in this paper, the seismic dynamic response and damage degree peaked at an angle of incidence of 60°, with a tendency to increase and then decrease with increasing angles of incidence. The ability of an energy-dissipating vibration reduction device to change structural vibration characteristics decreases with an increase in incidence angle. The difference between the total strain energy of the structure in the X-direction (Transverse slope direction) and Y-direction (Down-slope direction) and the total energy dissipation of the dissipative components is obvious, with the X-direction being about 10 times that of the Y-direction.

MODIFICATION OF THE ATTENUATION EQUATION FOR PEAK GROUND ACCELERATION (PGA) IN THE NORTH SUMATERA REGION

Prediction of the empirical formula for ground acceleration is an important thing to analyze for seismic estimation in an area. This needs to be done to reduce the negative impact of earthquakes as a more appropriate mitigation effort in planning and designing earthquake-resistant buildings. Therefore, the empirical formulation from Zhaou, et al is used, which is well adapted to the seismotectonic conditions of the North Sumatra region, which has high seismic vulnerability, considering that this region is located in an active subduction zone. This advantage allows the model to more accurately predict the maximum ground acceleration (PGA) produced by earthquakes in the region. The purpose of this research is to obtain an empirical formulation of the maximum ground acceleration value based on seismic parameters such as distance, depth, and magnitude. It will also show the relationship between these parameters and the value of maximum ground acceleration or peak ground acceleration (PGA) in the North Sumatra region. This study modifies the empirical formulation of Zhao, et al data sourced from the Meteorology Climatology and Geophysics Agency (BMKG) of North Sumatra in 2017-2023 with a magnitude of 3 - 6 Mw. This research uses non-linear regression with the least squares method. The results of the analysis of the empirical formula produce the constant value sought a = 1.4703 b = -0.0025, c = 20.7441, d = 0.0196, e = 0.0015, S_SS = -2.0843, and S_SL = -0.0529. An empirical formula was obtained for the North Sumatra region based on the research results. This equation can be used on a scale of 3.0 - 6.0 Mw and a distance to the earthquake source between 0 - 300 km. The relationship between each parameter of this empirical formula is that the PGA value will increase with the magnitude, and the PGA value will decrease as the epicentre distance increases.

Analysis of the Seismic Vulnerability of a Masonry Pagoda Based on Increasing Dynamic Analysis

ABSTRACTFor the seismic vulnerability analysis method of masonry pagodas, the dynamic characteristic of the Bayun Pagoda in China was conducted by using environmental excitation technology. A numerical model of the masonry pagoda was established with the finite element software Abaqus. Ten seismic waves were selected as excitation signals to conduct incremental dynamic analysis (IDA) on the pagoda. The Sa(T1,5%) served as the seismic intensity indicator, whereas the damage factor (d) and relative stress () were employed as damage indicators for seismic vulnerability analysis of the pagoda. The failure probability of the structure reaching the limit state under different seismic intensities was determined. The results indicate that, comparing the IDA curves and seismic vulnerability curves under two different damage indicators, the Sa(T1,5%) range required for the IDA curves under the damage factor (d) is smaller than the relative stress (), with lower dispersion. Additionally, the failure probability of the pagoda reaching different limit states is higher under the damage factor (d). Considering the existing damage status of the masonry pagoda, the damage factor (d) is more reasonable as the damage indicator.

Seismic Vulnerability Along the Kaur-South OKU Highway in Bengkulu, Indonesia: Planning for More Resilient and Safer Cities

Seismic Vulnerability Along the Kaur-South OKU Highway in Bengkulu, Indonesia: Planning for More Resilient and Safer Cities

A methodology to assess and select seismic fragility curves: Calibration from expert survey and fuzzy analysis

Fragility curves (FCs) are extended decision-making tools for estimating the structural performance of systems exposed to seismic hazards. However, selecting an inappropriate FC can significantly affect the accuracy of loss and damage calculations in seismic risk assessments.This article enhances the “Select.FC” method, a recently proposed novel approach that allows the selection of FCs with a higher degree of reliability. This method utilizes a multidimensional index incorporating a comprehensive set of variables about various aspects of FCs. A calibration and validation process is conducted on the variable scores of this multidimensional index based on a worldwide survey of experts. The implementation of the fuzzy analytic hierarchy process (FAHP) method further enhances the objectivity and dependability of the scores calculated from the experts' responses.The proposed approach not only allows for the evaluation of FCs but also provides a practical tool for researchers. This evaluation of FCs is crucial, as it enhances the accuracy and reliability of seismic vulnerability and risk assessments.The results obtained from the expert survey and the FAHP reveal several discrepancies between the calibrated new scores assigned to specific variables and those proposed in the original methodology. However, in the aggregate, these discrepancies disappear. Therefore, the “Select.FC” method and its proposed classification of FCs into six categories based on the score obtained in the final multidimensional index seem quite robust regarding important changes in the weights of some of the variables.

Development and Validation of a New Approach to Assess the Seismic Vulnerability of Masonry Structures Based on the CARTIS Form

ABSTRACT Rapid methodologies for seismic vulnerability assessment are crucial for implementing effective seismic risk mitigation strategies over large areas. This paper addresses data accuracy and specificity uncertainties in vulnerability indices by introducing a novel rapid methodology built upon the CARTIS form. To transition from typology identification to vulnerability analysis, the study proposes a new Informed Vulnerability Index for Structures (In.V.I.S.) calibrated upon a hybrid vulnerability index formulation based on the GNDT II level approach, and specifically tailored to fit the main CARTIS form fields. Collaboration with local experts, as required by the CARTIS form, aids in identifying representative building typologies within urban centres, informed by historical data and expert knowledge. The In.V.I.S. is computed based on the distinctive characteristics of these building typologies to accurately reflect vulnerability levels. The feasibility of this approach is proved by its application to six municipalities in the Garfagnana area (Lucca, Italy). Finally, vulnerability and fragility curves are proposed for the main building typologies, as a demonstration of the potential applications of the proposed index. Overall, this research underscores the importance of integrating local expertise, historical context and rapid vulnerability assessment methodologies to enhance the accuracy and effectiveness of seismic vulnerability assessments.

New Methodology for Assessing Seismic Ground Vulnerability Based on Microtremor and Taiwan Seismic Intensity Scale

ABSTRACT The Taiwan Ground Deformation Index (TGDI) is proposed to quantify site vulnerability using a non-linear soil deformation model, PGA parameters from the Taiwan seismic intensity scale, and microtremor analysis. Site vulnerability is graded into four levels: low (TGDI < 2.4), moderate (2.4 ≤ TGDI < 4.2), high (4.2 ≤ TGDI < 7.4), and very high (TGDI ≥ 7.4), based on susceptibility to seismic damage. Validating TGDI with 13 disaster events in Tainan during the 2016 Meinong earthquake showed 12 cases of moderate-to-high vulnerability. Since weak ground and strong amplification properties favor TGDI increases, this index serves as an early warning parameter for disasters.

MICROTREMOR ANALYSIS IN DETERMINING LANDSLIDE POTENTIAL IN SEMBAHE VILLAGE, SIBOLANGIT DISTRICT, DELI SERDANG REGENCY

Sembahe Village is an area that is highly vulnerable to landslides. This is caused by steep topographic conditions and high rainfall. This research is intended to understand the characteristics and distribution of dominant frequencies, amplification factors and seismic vulnerability index on the possibility of landslides. Microtremor measurements were carried out in Hamlet 3 Sembahe Village at 2 location points which were measured using a portable seismograph / Pegasus for 2 hours with a sampling frequency. 100 Hz. Microtremor data was processed using Geopsy software using the Horizontal to Vertical Spectral Ratio (HVSR) method and each parameter was weighted using the Analytical Hierarchy Process (AHP) statistical method in determining potential landslide areas. The results obtained show that the distribution of dominant frequency values (F0) is 5.36 Hz – 5.33 Hz, amplification (A0) is 1.84 – 1.59, seismic vulnerability index (Kg) is 0.63 x 10-3s2 / cm - 0.47 x 10-3 s2/cm. Based on weight analysis using the AHP statistical method, the location point that has the highest potential for landslides is point 1.

Android-based framework for condition assessment of existing RC hospital buildings

Rapid visual screening (RVS) is a practically viable tool implemented all over the world to rank structures based on their seismic vulnerability. Seismic assessment of hospital buildings is essential in seismic-prone regions to ensure their structural integrity and readiness to provide emergency care and medical treatment after significant seismic events. Therefore, in the current study, an approach is developed that is similar to the proven methodologies reported in the literature, for the seismic evaluation of structural and non-structural elements of hospital buildings in a metropolitan city like Karachi. Karachi is located in the southwest of Pakistan and is vulnerable to earthquake and tsunami hazards. To this end, an android-based RVS system has been developed for large-scale seismic risk mapping of hospital buildings. The proposed system acquires the physical status of the building features in real time and identifies the building performance obtained from the calculated seismic risk index. Moreover, three case study hospital buildings were employed and analysed through the proposed RVS system. Results illustrate the performance of case study hospital buildings at organisational, structural and non-structural levels based on seismic risk indices.

A framework for rapid seismic performance and fragility analysis of earth slopes considering uncertainties

It is acknowledged that various sources of uncertainties play a vital role in the seismic vulnerability of slope systems, while many studies ignore these sources in seismic assessments. This is because seismic performance and fragility evaluation of large soil-structure systems is challenging and computationally intensive by conventional nonlinear dynamic analysis methods, especially when the modeling uncertainties are considered. To address this challenge, this paper proposes a new framework for addressing uncertainties in the seismic evaluation of earth slopes using the Endurance Time Analysis (ETA) method. The ETA method is a dynamic pushover procedure in which the slope is subjected to a limited number of artificial intensifying records, and seismic responses are obtained over a continuous range of seismic intensities. For the purpose of this study, probabilistic two-dimensional numerical simulations of earth slopes are created using the FLAC software by considering the soil parameters uncertainty. Latine Hypercube Sampling is employed to generate random simulations. The models are then subjected to the intensifying prefabricated excitations based on the ETA method, and the fragility curves of the slope are obtained in three damage states by considering and not considering uncertainties. The results indicate that as the endurance time, which is a kind of intensity measure, increases, the uncertainties of seismic responses also increase. This shows that the effects of uncertainties become more significant when the slope is subjected to strong ground motions. Additionally, the influence of modeling uncertainty is negligible in the slight damage state, but significant in the extensive damage state. The proposed framework provides an effective and rapid way for performing the fragility and associated risk analysis of earth slopes considering uncertainties.

Effects of wire rope isolators on seismic life-cycle cost of UHV bypass switch

The seismic isolation devices reduce the seismic vulnerability of the electrical equipment. Accurately assessing the seismic life-cycle cost (SLCC) of the electrical equipment is beneficial in guiding the design and enhancing the seismic resilience of electrical substations and converter stations. To evaluate the effects of the isolator devices on the seismic life-cycle cost of electrical equipment, a SLCC evaluation model was proposed in this study, and the evaluation was conducted on an ultra-high voltage (UHV) bypass switch (BPS) with wire rope isolators (WRI). The model takes into account equipment purchase, maintenance, transportation and installation costs and indirect losses caused by power outages. Afterward, the SLCC and break-even time of the UHV BPS with and without WRIs in different regions were analyzed. The results indicate that beyond the break-even time, the BPS with WRIs becomes more economically viable. Moreover, its economic viability increases as the service life extends. Therefore, in high seismic cost risk areas, it is recommended to adopt seismic isolation devices to ensure the secure and economically efficient operation of electrical equipment.

Seismic vulnerability assessment and strengthening of an existing typical Indian unreinforced masonry building in a high-risk seismic zone-a comprehensive application

Seismic vulnerability assessment and strengthening of an existing typical Indian unreinforced masonry building in a high-risk seismic zone-a comprehensive application

Influence of masonry infills on seismic performance of BRB‐retrofitted low‐ductile RC frames

AbstractReinforced concrete (RC) frames with masonry infills represent a prevalent construction typology across the globe, including moderate to high seismic regions. Such structures are often characterized by high seismic vulnerability, and consequently, there is an urgent need for retrofit solutions to effectively improve their seismic performance. Buckling‐restrained braces (BRBs) represent one such solution. They are a type of dissipative device that can be included within the frames of an existing structure to increase its strength, stiffness, and energy dissipation capacity. Although a substantial amount of research has already been performed to understand the effectiveness of BRBs as a retrofit strategy, these studies have often neglected the contribution of masonry infills and the interactions between the infills and the BRBs. While masonry infills are usually overlooked in the analysis and design stage (owing to their brittle nature), past studies indicated that their strength and stiffness may significantly alter the structure's seismic performance, leading to undesirable and unexpected results. This study presents a detailed investigation of the impact of masonry infills on the seismic response and fragility of BRB‐retrofitted RC frames. A three‐story, three‐bay, low‐ductile RC frame has been selected for case study purposes. High‐fidelity finite element models are developed in OpenSees for combinations of infilled and non‐infilled structures—with and without BRBs. Nonlinear static and dynamic analyses are performed to evaluate the seismic response of the different configurations at local and global levels. Successively, cloud analyses are conducted by considering a set of 150 ground motion records to account for the record‐to‐record variability and develop seismic fragility curves. The present study sheds some light on the mutual interaction between the infill panels and BRBs retrofit intervention and highlights the critical aspects that must be considered in the design.

Integrated Framework for Analyzing Seismic Hazard, Exposure, and Vulnerability in Damage and Loss Assessment of Water Network System

Integrated Framework for Analyzing Seismic Hazard, Exposure, and Vulnerability in Damage and Loss Assessment of Water Network System

Evaluating Seismic Vulnerability and Enhancing Resilience of Road Infrastructure: A Comprehensive Bibliometric Analysis

Evaluating Seismic Vulnerability and Enhancing Resilience of Road Infrastructure: A Comprehensive Bibliometric Analysis

Comparison between Design Methods for Seismic Retrofit of Reinforced Concrete Frames Using Dissipative Bracing Systems

Braces equipped with dissipative devices are among the most widespread methods for the seismic strengthening of seismically prone reinforced concrete (RC) frames. It allows for high reductions in seismic vulnerability with inexpensive, quickly executed interventions. They can often be carried out mainly at the exterior, resulting in interruptions of use that are limited both in time and to only small portions of the building. The design methods of dissipative devices are based on the extensive use of pushover analyses (POA). POA is capable of highlighting the structural deficiencies of the building and comparing the performances of design performed according to different methods and sizing criteria. In the present work, with reference to a case study represented by a four-story spatial frame having characteristics representative of design and construction common practice of the 1970s in Southern European countries, the performances of three different design methods were evaluated and compared. The examined procedures differ, including the following: (i) methods for estimating the peak displacement response of the nonlinear systems, namely (i1) the well-known equal displacement rule and (i2) the equivalent (secant) stiffness and damping rule, and (ii) criteria for distributing stiffness and strength of the braces along the height, namely (ii1) the distribution of stiffness and strength proportionally to those of the frame and (ii2) methods that vary the stiffness and strength along the height in order to minimize the eventual irregularity in elevation of the bare frame. The effectiveness of the procedures was checked by both POA and nonlinear response history analysis, the latter performed assuming both unidirectional and bidirectional input. The stiffness was found to increase by about 10 times and the strength between 7.5 to 3.7 times depending on the design method, and reduction in the displacements ranged between 31% and 42% compared to the values of the original frame. The pros and cons of each procedure are summarized, as all procedures are able to provide brace designs that meet the performance requirements set during the design phase.

Seismic resonance vulnerability assessment for different structural systems through soil characterization: application in Guadalajara city, Mexico

Seismic resonance vulnerability assessment for different structural systems through soil characterization: application in Guadalajara city, Mexico

Assessment of the seismic vulnerability of structures using: the N2 method, taking into account soil-structure interaction

Assessment of the seismic vulnerability of structures using: the N2 method, taking into account soil-structure interaction

Seismic vulnerability assessment and fragility analysis of tunnels in Oman: Development of risk matrices and functionality guidelines

Past seismic events worldwide inflicted severe damage on tunneling and underground infrastructure projects and resulted in considerable socioeconomic loss. In this study, the seismic vulnerability of tunnels in the Sultanate of Oman is assessed, accounting for tunnel typology and localized site conditions. Seismic Fragility Curves (SFCs) were developed for two seismic zones (Zone 1 and Zone 2) based on the proposed intensity-response relationship, incorporating two different lining properties. Results consistently indicated a 39.56 % decrease in raking ratio for every 15 m/s reduction in shear wave velocity (VSST) across all tunnel models, spanning soft to stiff strata conditions. Employing the fragility functions developed for the Sultanate of Oman, project-specific risk matrices and operational route maps for Al-Sharqiyah Expressway Tunnel-2 (AST2) were formulated, along with an assessment of post-seismic operational accessibility. The insights garnered from this investigation provide fundamental guidance for engineers, designers, and consultants involved in seismic analysis and design of underground structures, encompassing both new constructions and retrofitting endeavors. Furthermore, the data generated herein offers valuable input for governmental stakeholders, facilitating policy formulation and the establishment of national-level design directives concerning tunneling projects within the Sultanate of Oman.