Methodology For Seismic Assessment Research Articles

Case study for a performance based rapid seismic assessment methodology (PERA2019) based on actual earthquake damages

Case study for a performance based rapid seismic assessment methodology (PERA2019) based on actual earthquake damages

Non-linear modeling parameters for new construction RC columns

Modeling parameters (MP) of reinforced concrete columns are a critical component of performance-based seismic assessment methodologies because in these approaches damage is estimated based on element deformations calculated using non-linear models. To ensure model fidelity and consistency of assessment results, performance-based seismic assessment methods in ASCE 41, ACI 369.1, and ACI 374.3R prescribe modeling parameters calibrated using experimental data. This paper introduces a new set of equations to calculate reinforced concrete column non-linear modeling parameters optimized for design verification of new buildings using response history analysis. Unlike modeling parameters provided in ACI 369.1 and ASCE 41, intended for columns of older non-ductile buildings, the equations for modeling parameters anl and bnl presented in this study were calibrated to simulate the load-deformation envelope of reinforced concrete columns that meet the detailing requirements of modern seismic design codes. Specifically, the proposed equations are intended for use with provisions in ACI 374.3R, Chapter 18 and Appendix A of ACI 318-19 and Chapter 16 of ASCE/SEI 7-16. The proposed equations were calibrated using the ACI Committee 369 column database, which includes column configuration parameters, material properties, and deformation capacity modeling parameters inferred from the measured response of columns under load reversals. Dimension reduction techniques were applied to visualize different clusters of data in 2D space using the negative log-likelihood score. This technique allowed decreasing the non-linearity of the problem by identifying a subset of columns with load-deformation behavior representative of new construction conforming to current codes requirements. A Neural Network model (NN) was calibrated and used to perform parametric variations to identify the most relevant input parameters and characterize their effect on modeling parameters, and to stablish the degree of non-linearity between each input variable and the model output. Developing equations for modeling parameters applicable to a wide range of columns is challenging, so this research considered subsets of the database representative of new construction columns to calibrate simple practical equations. Linear regression models including the most relevant features from the parametric study were calibrated for rectangular and circular columns. The proposed linear regression equations were found to provide better estimates of new construction column modeling parameters than the available tables in ACI 374.3R and ASCE 41-13, and the equations ASCE 41-17.

Assessment and Retrofitting of Building Structures: Experimental Testing and Modelling—Editorial

Collapse of, or severe damage to, existing buildings during strong earthquakes has resulted in significant economic losses, severe injuries, and casualties. Progress made over the last few decades has had a considerable impact on the seismic safety of modern buildings designed according to new standards. However, the majority of existing buildings in southern European countries do not meet the safety requirements set by the Eurocodes. Thus, the assessment of existing buildings not designed with modern codes and the development of effective retrofitting techniques are currently of paramount importance to society. The use of accurate modelling strategies and appropriate seismic assessment methodologies is crucial to understand the behaviour of existing buildings and to develop efficient and proper mitigation measures, thus, preventing future damage, casualties, and economic losses. The effect of non-structural elements should not be neglected, since they could play a vital role in buildings’ structural performance. Another major challenge is to ensure the sustainability of renovation schemes in terms of both the environmental burden (i.e., CO2) and economic investment in seismic regions. The sustainable renovation of existing buildings typically focuses on reducing operational energy consumption and using low-carbon materials in the refurbishment process, without accounting for structural deficiencies that could leave the building exceptionally unsafe and hamper the refurbishment investment, particularly in areas prone to seismic activity. This Special Issue focuses on innovations in the context of assessment and retrofitting of building structures: experimental testing and modelling.

A Framework and Tool for Knowledge-Based Seismic Risk Assessment of School Buildings: SLaMA-School

When dealing with seismic risk assessment at a large scale, the collection of relevant building data is still deemed a challenging task, often leading to limited building knowledge and, consequently, high uncertainties. Therefore, innovative yet standardized frameworks and adaptive tools are needed to support the seismic risk assessment of buildings. Towards this goal, this paper proposes a simplified multi-knowledge seismic assessment methodology involving the analytical-mechanical SLaMA (Simple Lateral Mechanism Analysis) method. An ad-hoc data collection form is first developed to identify the building vulnerabilities by merging and building on existing institutional forms at the international level and integrating new input data. The data are then used to implement the SLaMA-based methodology, at different building knowledge levels, to assess the seismic safety and the economic losses of buildings. The proposed data structure and approach is planned to be included in the “Seismic-Response” module for PELL (Public Energy Living Lab)-School platform, aiming to become a standardized and interoperable database for relevant data of Italian schools and a dashboard for allowing stakeholders to continuously monitor their energetic and static/seismic conditions. The paper discusses the potential and effectiveness of the proposed procedure for large-scale applications and its integration into platforms assessing the energy efficiency of buildings.

Damage Index Seismic Assessment Methodologies of URM Buildings: A State-of-the-Art Review

Damage Index Seismic Assessment Methodologies of URM Buildings: A State-of-the-Art Review

Performance-based seismic assessment of capacity enhancement of building infrastructure and its cost-benefit evaluation

Excessive damage to building infrastructure has been witnessed in some major earthquakes in Pakistan and hence requires to better understand their potential vulnerability. Some basic data was gathered in terms of features such as number of stories, age of building and construction typology, as a part of this study to evaluate seismic risk in Abbottabad city (in the North of Pakistan), Relevant study is scarce in the literature so far on the vulnerability study of Pakistan building infrastructure with and without strengthening (capacity enhancement), using performance based seismic assessment methodology. This is first of its kind of study done on the structures in Pakistan that describes the different attributes and performance in detail. To measure the seismic vulnerability of building infrastructure, the induced damage due to increased shaking force is determined. This description of the structure's vulnerability, in conjunction with the hazard, permits well informed, risk-based conclusions that can be done using performance metrics for instance collapse prevention and economic effects. Numerical modeling was performed by using available data, collected during field survey to represent exactly, the actual response of building infrastructure. Two sets of building fragility curves, before and after capacity enhancement (strengthening), are employed to describe the seismic behavior of the building infrastructure in all the cases. To calculate the losses, an inventory was composed using field survey data that contains all the structural and non-structural components.

Reliability-based seismic performance of masonry arch bridges

Seismic structural assessment of masonry arch bridges is essential due to their cultural, economic and strategic importance and vulnerability. A realistic and rigorous structural assessment is necessary in order to protect the bridges and use resources carefully. At this time, there are no standardised or widely accepted assessment procedures, and the performance criteria for masonry arch bridges are not available. This study presents an overarching reliability-based seismic assessment methodology based on analytical modelling, laboratory testing and probabilistic assessment. It investigates the performance criteria concept and proposes performance limit states. The methodology is applied to a historical masonry arch bridge in Turkey. To consider rigorously the uncertainties in material properties and seismic input, probabilistic nonlinear analyses are conducted using a detailed 3D finite element model. The results are combined with the proposed limit state definitions to generate the capacity and demand distributions. Both distributions are used in Monte Carlo simulation and First-Order Reliability Method (FORM) to estimate the probability of exceedance and reliability indexes for each limit state. The proposed probabilistic assessment methodology will be a useful approach to obtaining more reliable information about masonry arch bridges' expected seismic performance and for better-informed decision-making, especially when designing intervention actions and post-earthquake scenarios.

Ranking the Seismic Vulnerability of Masonry School Buildings according to the EC8-3 by Using Performance Curves

ABSTRACT A simple methodology for seismic assessment of masonry building, which allows the ranking of the seismic safety of buildings according to principles and rules that are established in Part 3 of the Eurocode 8 (EC8), is presented in this work. This approach uses the concept of “performance curve”, which consists in the representation of all possible performance points (the target displacements of the EC8) associated with a given capacity curve and a response spectrum. This allows a better comparison of the overall seismic behaviour, namely a comparison of the seismic safety associated with all limit states at once, which makes the task of ranking the urgency for seismic retrofitting measures easier. This methodology was used for ranking a set of primary school masonry buildings that still exist in the region of Algarve (Portugal). This work was carried out in the context of the PERSISTAH project.

Seismic vulnerability assessment methodology for historic masonry buildings in the near-field areas

Timisoara is the biggest city located in the Banat seismic area, the second most important seismic zone of Romania. The specificity of the area is represented by shallow earthquakes of crustal type, with small focal depths and a PGA = 0.20 g.Because Timisoara was declared the European Capital of Culture 2021, it is mandatory to assess the seismic vulnerability of its most sensitive areas and to design potential losses scenario. This study also provides useful data for the local authorities, helping them develop/improve the prevention and intervention plans.The paper focusses on the analysis of two historical urban districts, likely to be among the most attractive tourist areas. The study aims to assess the seismic vulnerability of the districts in a quick and simplified way, seeks to identify the exposure of the city, and also to provide losses statistics for a specific seismic scenario. The empirical seismic vulnerability assessment methodology is based on European studies and is applied for more than 100 historic buildings.Our assessment analysis aims to adapt the existing seismic assessment methodologies to the near-field earthquake’s effects. That is why a new formula is proposed to correlate the empirical vulnerability curves with the actual damage level. The real damage state was observed on similar historical masonry buildings during the site inspection and after the past earthquakes in nearby areas. Besides, a new failure mechanism is highlighted based on the investigation of the effects of previous near-field earthquakes in the Banat seismic region. The new methodology proposes original vulnerability curves, particularly for the near-field earthquakes specific to Banat seismic area.

RESILIENCY OF A FOUR-STOREY STANDARD SCHOOL BUILDING USING THE REDI FRAMEWORK

Public school buildings in the Philippines are built with a code-based design philosophy, wherein the life safety of the occupants is the sole performance objective. While the loss of life is the primary consideration for design, other losses such as cost of repair or replacement and service losses are to be expected after an earthquake. The 2017 Surigao Earthquake damaged 47 schools and caused a 10-day suspension of classes. Three years after the 2013 Bohol Earthquake, 279 classrooms from 696 schools are still under construction. A resilience-based design philosophy takes into consideration safety and other losses including recovery. To assess the resilience of a structure, a resilience-based seismic assessment methodology was adopted after the REDi Framework. Other tools utilized for the seismic assessment were the FEMA P-58, their accompanying software PACT, as well as SeismoStruct. It consists of the identification of losses in terms of cost and time, as well as the evaluation of proper building management and design practices. As a pilot study, a four-storey twelve-classroom template was assessed for seismic resilience. Numerical simulations and analysis showed that the structure was not resilient in ambient and building resilience.

Recent Findings and Open Issues concerning the Seismic Behaviour of Masonry Infill Walls in RC Buildings

The extension of the damages observed after the last major earthquakes shows that the seismic risk mitigation of infilled reinforced concrete structures is a paramount topic in seismic prone regions. In the assessment of existing structures and the design of new ones, the infill walls are considered as nonstructural elements by most of the seismic codes and, generally, comprehensive provisions for practitioners are missing. However, nowadays, it is well recognized by the community the importance of the infills in the seismic behaviour of the reinforced concrete structures. Accurate modelling strategies and appropriate seismic assessment methodologies are crucial to understand the behaviour of existing buildings and to develop efficient and appropriate mitigation measures to prevent high level of damages, casualties, and economic losses. The development of effective strengthening solutions to improve the infill seismic behaviour and proper analytical formulations that could help design engineers are still open issues, among others, on this topic. The main aim of this paper is to provide a state‐of‐the‐art review concerning the typologies of damages observed in the last earthquakes where the causes and possible solutions are discussed. After that, a review of in‐plane and out‐of‐plane testing campaigns from the literature on infilled reinforced concrete frames are presented as well as their relevant findings. The most common strengthening solutions to improve the seismic behaviour are presented, and some examples are discussed. Finally, a brief summary of the modelling strategies available in the literature is presented.

Integration of reverse engineering and non-linear numerical analysis for the seismic assessment of historical adobe buildings

Abstract This paper aims at presenting a methodology that integrates reverse engineering tools with a combination of advanced and simplified analytical methods to perform predictive analysis of the structural behavior of historical adobe buildings under seismic loads. This methodology proposes the joint use of terrestrial laser scanner and photogrammetry to obtain accurate geometrical models. The methodology also proposes the in-situ measurement of structural system properties through experimental modal tests. All the collected information is used to create representative Finite Element models which are then considered for performing predictive non-linear analyses and identifying the most probable collapse mechanisms. Limit analysis method is finally used to complement the analysis and to assess the structural performance of the adobe building under study considering different seismic scenarios. The methodology proposed in this paper is validated in the church of San Juan Bautista de Huaro, located in Cusco, Peru. This church was built in the 16th century and is known for its impressive mural paintings covering the entire indoor surface of the church. The results of the seismic assessment methodology proposed in this paper allowed to estimate the global behavior and possible damage patterns in the church during seismic events, showing that the most probable failure mechanisms would be the global rocking of the facade and the partial collapse of tympanum of the facade. The application of this methodology also allowed defining the performance levels of this church when facing different seismic scenarios. The results showed that the church should stay in a safe state until occasional earthquakes with a return period of 72 years. However, the results also indicate that rare earthquakes (return period of 475 years) will produce an unsafe structural condition with partial collapses of structural elements.

Probabilistic seismic assessment of seismically isolated electrical transformers considering vertical isolation and vertical ground motion

This study presents a probabilistic response analysis of seismically isolated electrical transformers with emphasis on comparing the performance of equipment that are non-isolated to equipment that are isolated only in the horizontal direction or are isolated by a three-dimensional isolation system. The performance is assessed by calculating the probability of failure as function of the seismic intensity with due consideration of: (a) horizontal and vertical ground seismic motions, (b) displacement capacity of the seismic isolation system, (c) limit states of electrical bushings, (d) details of construction of the isolation system, (e) weight of the isolated transformer, and (f) bushing geometry and configuration. Calculations of the probability of failure within the lifetime of isolated and non-isolated transformers at selected locations are also performed. The results of this study demonstrate that seismic isolation systems can improve the seismic performance for a wide range of parameters and that systems which isolate in both the horizontal and vertical directions can be further effective. The seismic assessment methodology presented can be used for: (a) deciding on the need to use seismic isolation and selecting the properties of the isolation system for transformers depending on the design limits, location, and configuration of transformer and (b) calculating the mean annual frequency of functional failure and the corresponding probability of failure over the lifetime of the equipment. The results may also be used to assess the seismic performance of electric transmission networks under scenarios of component failures.

Performance-Based Seismic Assessment of Superelastic Shape Memory Alloy-Reinforced Bridge Piers Considering Residual Deformations

The application of superelastic Shape Memory Alloy (SMA) reinforcement in plastic hinge regions of bridge piers has been proven to reduce the residual displacement after a strong shaking owing to its unique shape recovery characteristics; however, the maximum deformation of the piers could increase due to the relatively lower modulus of elasticity of SMA bars and lower hysteretic energy dissipation capacity. In this context, this article applies a recently formulated probabilistic performance-based seismic assessment methodology that considers both the maximum and the residual deformation simultaneously to evaluate the performance of SMA reinforced bridge piers.

Modified three‐dimensional seismic assessment method for buildings based on ambient vibration tests: extrapolation to higher shaking levels and measuring the dynamic amplification portion of natural torsion

SummaryThis paper presents applications of the modified 3D‐SAM approach, a three‐dimensional seismic assessment methodology for buildings directly based on in situ experimental modal tests to calculate global seismic demands and the dynamic amplification portion of natural torsion. Considering that the building modal properties change from weak to strong motion levels, appropriate modification factors are proposed to extend the application of the method to stronger earthquakes. The proposed approach is consistent with the performance‐based seismic assessment approach, which entails the prediction of seismic displacements and drift ratios that are related to the damage condition and therefore the functionality of the building. The modified 3D‐SAM is especially practical for structures that are expected to experience slight to moderate damage levels and in particular for post‐disaster buildings that are expected to remain functional after an earthquake. In the last section of this paper, 16 low to mid‐rise irregular buildings located in Montreal, Canada, and that have been tested under ambient vibrations are analyzed with the method, and the dynamic amplification portion of natural torsion of the dataset is reported and discussed. The proposed methodology is appropriate for large‐scale assessments of existing buildings and is applicable to any seismic region of the world. Copyright © 2016 John Wiley & Sons, Ltd.

Vulnerability assessment and retrofit solutions of precast industrial structures

The seismic sequence which hit the Northern Italian territory in 2012 produced extensive damage to reinforced concrete (RC) precast buildings typically adopted as industrial facilities. The considered damaged buildings are constituted by one-storey precast structures with RC columns connected to the ground by means of isolated socket foundations. The roof structural layout is composed of pre-stressed RC beams supporting pre-stressed RC floor elements, both designed as simply supported beams. The observed damage pattern, already highlighted in previous earthquakes, is mainly related to insufficient connection strength and ductility or to the absence of mechanical devices, being the connections designed neglecting seismic loads or neglecting displacement and rotation compatibility between adjacent elements. Following the vulnerabilities emerged in past seismic events, the paper investigates the seismic performance of industrial facilities typical of the Italian territory. The European building code seismic assessment methodologies are presented and discussed, as well as the retrofit interventions required to achieve an appropriate level of seismic capacity. The assessment procedure and retrofit solutions are applied to a selected case study.

Assessment of the Seismic Resistance and Structural Safety of Existing Multistory Residential Buildings

A new methodology for approximate assessment of the seismic resistance or capacity of existing residential buildings incorporating conventional cast in situ reinforced concrete structural systems is presented. It forms a part (Stage 2) of a multistage methodology for seismic assessment and retrofitting of existing buildings, which is being developed by the authors. The methodology is based on concepts of performance-based assessment (PBA) of existing buildings. The expected seismic capacity, as well as the nominal yield and ultimate displacements of the buildings under consideration, are evaluated taking into account the characteristics of the various structural sub-systems (frames, shear walls/shafts) forming together the combined structural system of the buildings under consideration. On the basis of these evaluations, and taking into account the corresponding seismic demand relevant for the buildings under consideration, the expected behavior and structural safety of existing multistory residential buildings in various earthquake scenarios can be assessed. The results of the approximate evaluations compare very well with results of “exact” push-over analyses of the buildings under consideration, performed with the aid of a non-linear computer code.

Assessment of low-rise building with transfer beam under seismic forces

An overview of the structural performance of a transfer structure in Hong Kong under potential seismic actions is presented. A hypothetical but realistic low-rise building model has been developed comprising a seven-storey reinforced concrete frame structure with reinforced concrete transfer beams at first floor level. Structural design has been based on the British Standard BS8110 and local practices. Parametric analyses of the moment–curvature relationship of each component have been conducted. By adopting the displacement-based (DB) approach, various seismic assessment methodologies, including response spectrum analysis (RSA), manual calculation, pushover analysis (POA) and equivalent static analysis (ESA) have been implemented. The deformations induced by the predicted seismic actions in Hong Kong are compared with those arising from POA in terms of average lateral drift ratios and maximum interstorey drift ratios arising in the building. Factors influencing the performance of this form of transfer structure are highlighted and discussed. This paper also provides a general indication of seismic vulnerability of common low-rise transfer structures in regions of low to moderate seismicity.

Seismic assessment of transfer plate high rise buildings

The assessment of structural performance of transfer structures under potential seismic actions is presented. Various seismic assessment methodologies are used, with particular emphasis on the accurate modelling of the higher mode effects and the potential development of a soft storey effect in the mega-columns below the transfer plate (TP) level. Those methods include response spectrum analysis (RSA), manual calculation, pushover analysis (POA) and equivalent static load analysis (ESA). The capabilities and limitations of each method are highlighted. The paper aims, firstly, to determine the appropriate seismic assessment methodology for transfer structures using these different approaches, all of which can be undertaken with the resources generally available in a design office. Secondly, the paper highlights and discusses factors influencing the response behaviour of transfer structures, and finally provides a general indication of their seismic vulnerability. The representative Hong Kong building considered in this paper utilises a structural system with coupled shear walls and moment resisting portal-frames, above and below the TP, respectively. By adopting the wind load profile stipulated in the Code of Practice on Wind Effects: Hong Kong-1983, all the structural members are sized and detailed according to the British Standards BS8110 and the current local practices. The seismic displacement demand for the structure, when built on either rock or deep soil sites, was determined in a companion paper. The lateral load-displacement characteristic of the building, determined herein from manual calculation, has indicated that the poor ductility (brittle nature) of the mega-columns, due mainly to the high level of axial pre-compression as found from the analysis, cannot be effectively alleviated solely by increasing the quantity of confinement stirrups. The interstorey drift demands at lower and upper zones caused by seismic actions are found to be substantially higher than those arising from wind loads. The mega-columns supporting the TP and the coupling beams at higher zones are identified to be the most vulnerable components under seismic actions.