Guidelines for seismic assessment of damaged buildings (original) (raw)
Related papers
Earthquake Engineering & Structural Dynamics, 2017
A methodology is introduced to assess the post-earthquake structural safety of damaged buildings using a quantitative relationship between observable structural component damage and the change in collapse vulnerability. The proposed framework integrates component-level damage simulation, virtual inspection, and structural collapse performance assessment. Engineering demand parameters from nonlinear response history analyses are used in conjunction with component-level damage simulation to generate multiple realizations of damage to key structural elements. Triggering damage state ratios, which describe the fraction of components within a damage state that results in an unsafe placard assignment, are explicitly linked to the increased collapse vulnerability of the damaged building. A case study is presented in which the framework is applied to a 4-story reinforced concrete frame building with masonry infills. The results show that when subjected to maximum considered earthquake level ground motions, the probability of experiencing enough structural damage to trigger an unsafe placard, leading to building closure, is more than 2 orders of magnitude higher than the risk of collapse.
The value of seismic structural health monitoring for post-earthquake building evacuation
Bulletin of Earthquake Engineering, 2022
In the aftermath of a seismic event, decision-makers have to decide quickly among alternative management actions with limited knowledge on the actual health condition of buildings. Each choice entails different direct and indirect consequences. For example, if a building sustains low damage in the mainshock but people are not evacuated, casualties may occur if aftershocks lead the structure to fail. On the other hand, the evacuation of a structurally sound building could lead to unnecessary financial losses due to business and occupancy interruption. A monitoring system can provide information about the condition of the building after an earthquake that can support the choice between several competing alternatives, targeting the minimization of consequences. This paper proposes a framework for quantifying the benefit of installing a permanent seismic structural health monitoring (S2HM) system to support building evacuation operations after a seismic event. Decision-makers can use th...
Challenges in the Western Balkans: Infrastructure and Development in the Region International Conference, 2023
In recent years, catastrophic earthquakes have caused devastating collapses all over the world, thus emphasizing the importance of taking the necessary precautionary measures to evaluate existing buildings prior and/or afterward to an impending earthquake. Because detailed assessment methods are not appropriate for assessing large building stock, Rapid Visual Screening (RVS) methods have been developed to assess large building inventory quickly. These methods are classified as pre-earthquake and postearthquake building evaluation. Pre-earthquake RVS methods are used to determine expected performance of a building in an impending earthquake to take necessary precautions, whereas post-earthquake RVS methods are used to assess the level of damage afterward an earthquake. Existing pre-earthquake RVS methods, which are developed based on expert opinion, and data obtained from detailed building analysis and/or using data collected after an earthquake, are designed to determine the damage classes of structures prior to an impending earthquake. Additionally, even though all post-earthquake RVS methods were created to determine the degree of damage to a building after an earthquake, they differ in many ways, including risk assessment, usability classification, and in terms of data collection depth. Therefore, this study provides a comparative evaluation of two reinforced concrete and two unreinforced masonry structures with postearthquake RVS methods (EMS-98, ATC-20, and AeDES) in order to elaborate on the similarities and differences between these methods. The importance of data collection forms of post-earthquake RVS methods in terms of the pre-earthquake RVS method development or enhancement for classifying building vulnerability, energy, and resource waste reduction has been discussed.
Building Performance Loss After Damaging Earthquakes an Investigation Towards Reparability Decisions
In the aftermath of damaging events, agreed and transparent policies should establish acceptable levels of safety, and facilitate decisions on appropriate course of action for specific buildings. A significant indicator for repair and/or upgrade decisions is the Performance Loss (PL), that is a measure of variation of building seismic capacity from intact to damaged state. However, it is not clear how to choose significant PL thresholds with regard to damage acceptability. This study investigates, by means of a detailed case study, the expected PL for increasing seismic demand and its relationship with varied building safety level. The response of an existing non-ductile reinforced concrete building is simulated using a finite element model that properly accounts for both flexural, shear and axial failure of members and simulates joints behavior. Different definitions of building collapse are introduced, and consistent assessment of building PL are performed. The study shows interesting relations between PL and building safety level for varying return period of the damaging earthquake, demonstrating its usability as a practical indicator for reparability.
A Probabilistic Casualty Model to Include Injury Severity Levels in Seismic Risk Assessment
2020
Despite the increasing adoption of Performance-Based Earthquake Engineering (PBEE) in seismic risk assessment and design of buildings, earthquakes resulted in around 1.8 million injuries (three times the number of fatalities) over the past two decades. Several existing PBEE-based methodologies use rudimentary models that may not accurately estimate earthquake-induced casualties. Even when models are suitable for predicting the total number of fatalities and critical injuries, they may fail to adequately differentiate between different levels of injury severity. This paper draws attention to the importance of extending the seismic casualty assessment method by broadening the perspective on injury severity. To this cause, a probabilistic model is developed to predict fatalities and injuries due to earthquakes. The proposed model adopts the FEMA P-58 framework for risk assessment and considers six injury severity levels (minor, moderate, serious, severe, critical and fatal), in accordance with the Abbreviated Injury Scale (AIS). The aforementioned framework evaluates the casualty risk with five modules: seismic hazard analysis, structural analysis and response evaluation (using incremental dynamic analysis), building collapse simulation, detailed casualty assessment caused by structural, nonstructural, and content components of the building, and injury severity assessment. The injury severity assessment module assumes two modes of injury: occupants falling on the floor resulting in injury and injuries caused by unstable building contents hitting occupants as a result of sliding or overturning. The framework uses an occupant-time location model to predict the number of injuries and a set of building content fragility curves for sliding and overturning failure modes, developed by the incremental dynamic analyses. The proposed model was applied to a case study of a reinforced concrete, moment-frame office building furnished with 21 different content objects. The results show that the frequency of injuries resulting in hospitalization can be up to 30 times more than that of the fatal injuries at low shaking intensity levels and may amplify by 20 times at high intensity shaking.
Earthquake Engineering & Structural Dynamics, 2015
Current seismic design codes and damage estimation tools neglect the influence of successive events on structures. However, recent strong seismic events have demonstrated that mainshockdamaged structures are shown to be more vulnerable to severe damage and collapse during subsequent earthquakes. This increased vulnerability during aftershocks results in the likelihood of additional damage and loss-of-life and property. Thus, a reliable risk assessment tool that can evaluate the current and future damage state of structures is essential. To accomplish this objective, this paper develops a framework for aftershock fragility assessment of damaged structures that can account for their damage accumulation and associated increased vulnerability due to successive earthquakes. The proposed framework includes several activities; creation of frame models, characterization of existing damage states due to mainshocks, generation of a mainshock and an aftershock suite, mainshock-aftershock analyses, development of probabilistic aftershock demand models and aftershock fragility curves. The framework is not limited to a specific structure type if proper modifications are provided in these activities. In the current study, non-ductile reinforced concrete frames (low-, mid-, and high-rise) are selected as case studies for the application of the framework. Aftershock fragility curves quantitatively estimate the relative and increased vulnerability of the damaged frames associated with the extent of existing damage. The output of the aftershock fragility curve of RC frames will not only be a means to provide a building tagging methodology for making evacuation and re-occupancy decisions, but also a reliable analytical damage estimation tool prior to building visual inspection.
Evaluating the safe interim use of seismically deficient buildings
Structural Design of Tall and Special Buildings, 2018
How long can a seismically deficient building be used until the seismic risk becomes too high to be acceptable? A model interim use plan is developed with requirements to abandon the building if retrofit is not completed in the use period. Acceptable seismic performance is keyed to American Society of Civil Engineers (ASCE) 41 levels. The acceptable occupancy or use period is limited to that which results in the same probability of performance as stated for an ASCE 7-16-compliant building, except that the total risk in the use period is due to all possible earthquakes impacting the site, not just the maximum considered earthquake. The Thiel-Zsutty damage model is used to determine the probabilities for assigned threshold ranges where unacceptable performance can occur. Other response prediction models can be used if they provide an annual probability of a given performance level exceedance. Example applications are given for both marginally and highly deficient buildings located at 17 national sites in high and moderate seismic hazard regions and include ASCE 7 Risk Class I-IV buildings. This approach may be applied to any risk decision-making issue for which there is an annual probability of damage exceedance.
Post-earthquake building assessments
Bulletin of the New Zealand Society for Earthquake Engineering
Major seismic events occurring around urban centres often cause widespread damage to the building stock. Engineers are then required to perform safety inspections of these buildings. This process may be time-consuming and can cause residents or businesses to be displaced for a considerable duration even if the building is safe to occupy. Furthermore, other post-earthquake recovery phases, such as repair and demolition/reconstruction works, may not even initiate until the building inspection phase is complete. As such, the disruptions caused by post-earthquake inspection need to be considered when modelling building occupancy/functionality downtime. This study uses the data obtained from the 2011 Christchurch earthquake to develop a post-earthquake inspection duration quantification model. Firstly, the duration of the rapid assessment phase is estimated from the number of damaged buildings to be assessed, the total number of available engineers, and the median time needed for assessi...
E3S Web of Conferences
Earthquake loss estimation (ELE) refers to the analysis and study of the possible effects of an earthquake in a region or population and quantifies the consequences of the earthquake. The objective of this study is to provide an insight into earthquake loss estimation for the most common approaches by seeking to survey the current methodologies for quantifying the earthquakes' negative effects. Naturally, peoples search about desirable approaches to estimate of earthquakes costs and losses which are not predetermined to subsist as usual. Other issues related to those approaches are endeavor to achieve the state of art to quantify the earthquakes consequences, the aspects of a building's response to earthquake. The aspects that will be characterized in this research are: 1) Input data like building information (Structure system, location, occupation, etc.), earthquake hazard; 2) Analysis methods; 3) Output data. ELE methods are categorized in different ways depending on one o...