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A methodology was recently proposed for the development of hazard-compatible building fragility models using parameters of capacity curves and damage state thresholds from HAZUS (Karaca and Luco, 2008). In the methodology, HAZUS curvilinear capacity curves were used to define nonlinear dynamic SDOF models that were subjected to the nonlinear time h...
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... that in our application of the equal area rule we maintain the initial stiffness of the structure. Figure 5 shows trilinear capacity curves with both yield points and the corresponding HAZUS curvilinear curve for the example S1L building. An advantage of using the HAZUS yield point (denoted ( , ) in Figure 5) is that it is based on a combination of seismic design codes and expert judgment, as described in the Section 2. However, using results in an effective ductility and strain hardening ratio (e.g., 18 and 0.12 respectively for the example S1L building) that are unreasonably large for general buildings. ...
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... 5 shows trilinear capacity curves with both yield points and the corresponding HAZUS curvilinear curve for the example S1L building. An advantage of using the HAZUS yield point (denoted ( , ) in Figure 5) is that it is based on a combination of seismic design codes and expert judgment, as described in the Section 2. However, using results in an effective ductility and strain hardening ratio (e.g., 18 and 0.12 respectively for the example S1L building) that are unreasonably large for general buildings. Using the equal area rule shifts the yield displacement (denoted ( , ) in Figure 5) in a way that makes the ductility and strain hardening ratio more appropriate for general buildings. ...
Context 3
... advantage of using the HAZUS yield point (denoted ( , ) in Figure 5) is that it is based on a combination of seismic design codes and expert judgment, as described in the Section 2. However, using results in an effective ductility and strain hardening ratio (e.g., 18 and 0.12 respectively for the example S1L building) that are unreasonably large for general buildings. Using the equal area rule shifts the yield displacement (denoted ( , ) in Figure 5) in a way that makes the ductility and strain hardening ratio more appropriate for general buildings. Table 1 summarizes the median spectral acceleration capacity from the fragility function for each damage state (i.e., corresponding to a damage state exceedance probability of 50%) that is computed for the two trilinear capacity curves and the curvilinear one. ...
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Citations
... It should be noted that D y = T s ∕2 2 A y . In addition, the ultimate point D u , A u is determined as [36] follows: ...
... Recall that the original capacity curve in HAZUS does not have strength and stiffness degradation after the ultimate point [31], which might be unrealistic and should be modified. Following [36], the spectral displacement and the spectral acceleration of the residual point ( D r , A r ) are, respectively, as follows: where D com and D ex are the spectral displacements for the structure to reach complete damage and extensive damage, respectively, which are defined according to FEMA [31]. ...
Current post-earthquake assessment relies on manual inspections to assess the safety conditions of existing buildings. Such field inspection in a building-to-building manner remains challenging as it is labor-intensive and relatively inefficient, which may affect the associated post-earthquake management plan and the economic loss. A simulation-based rapid performance evaluation of buildings is, therefore, needed. This study proposes a seismic performance evaluation framework for the frame structures with the aid of local ground-motion measurements, prior-event field testing, and time-history analysis. The linear behavior of the SDOF model is calibrated by the dynamic properties determined from dynamic tests under ambient vibration. When an earthquake happens, the peak spectral displacement of the building is estimated using the calibrated SDOF model via a time-history analysis. The feasibility and accuracy of the proposed method are validated using the data and inspection results collected from the Van Nuys hotel under Whitter, Landers, BigBear, and Northridge earthquakes. Results reveal that the proposed method can estimate the peak displacement with a favorable agreement. The proposed method is further applied to assess the conditions of thirty-five frame structures under earthquakes those happened from January 2019 to April 2022, in Gongxian city, Sichuan province.
... In this work, we used vulnerability functions (Figure 6), suited for the HAZUS-MH typologies, developed by GEM in collaboration with the USGS (Rao A, November 2019, personal communication). The functions were derived using an analytical approach mostly based on Ryu et al. (2008), involving nonlinear time-history analyses of single-degree-of-freedom (SDOF) models representative of all building classes. The characteristics of the nonlinear SDOFs were obtained from the capacity points, damage state thresholds, and consequence ratios provided by HAZUS-MH for the various building types and occupancy classes. ...
In the past decade, Oklahoma has experienced unprecedented seismicity rates, following an increase in the volumes of wastewater that are being disposed underground. In this paper, we perform a probabilistic assessment of the time-dependent seismic hazard in Oklahoma and incorporate these results into an integrated seismic risk model to assess the evolution of the statewide economic losses, including a conservative forecast through 2030. Our risk model employs an injection-driven earthquake rate model, a region-specific ground motion model, a recent Vs30 map, HAZUS exposure data and updated vulnerability curves for both structural and non-structural elements, and contents. The calculations are performed using a stochastic Monte Carlo based approach implemented in the OpenQuake engine. The resulting seismic hazard maps illustrate the incompatibility of the regional seismic provisions with the current seismicity. In 2015 in particular, the induced seismic hazard in several places in Oklahoma was higher than along the San Andreas fault. During the peak of seismicity in 2015, the seismic risk was 275 times higher than the background level, with the vast majority of losses originating from damages to non-structural elements and contents. Our direct economic loss estimates are in reasonable agreement with the paid insurance claims, but show significant sensitivity to the ground motion model selection. The proposed risk model, with possible regular updates on the seismicity rate forecast, can help stakeholders define acceptable production levels.
... As many of the HAZUS building types have similar international counterparts (Jaiswal and Wald 2008), HAZUS fragility functions may be transferred across contexts, making for seamless adoption. However, Ryu et al. (2008) note that HAZUS fragility functions are not in a format that can be coupled with hazard curves (e.g., USGS hazard curves) for a fully-probabilistic risk assessment, as they are based on building response and not spectral acceleration. They propose a method for extending HAZUS functionality by developing hazard-compatible building fragility models using parameters of capacity curves and damage state thresholds from HAZUS. ...
Building damage probabilities are invaluable for assessing short-term losses from natural hazards. In many countries however, the individual building level data required for assessing reliable damage are usually unavailable. This paper shows how the post-processing of aggregate HAZUS earthquake damage assessments can yield building-level damage probabilities. On the basis of three plausible scenarios for Northern Israel, we generate and visualize a building-level combined damage probability index. We use the tools of exploratory spatial data analysis to purge any causal influences in the spatial pattern of these calculated damage probabilities. The costs and benefits of our approach are discussed.
... We acknowledge that HAZUS fragility curves face criticism (e.g., they consider only 36 generic building classes and hence lack resolution) and improvements are possible (e.g., [50,51]). Our study, however, is not dependent on these particular fragility curves; alternate fragility curves can easily be incorporated into our framework when they become available. ...
The decisions that individuals make when recovering from and adapting to repeated hazards affect a region’s vulnerability in future hazards. As such, community vulnerability is not a static property but rather a dynamic property dependent on behavioral responses to repeated hazards and damage. This paper is the first of its kind to build a framework that addresses the complex interactions between repeated hazards, regional damage, mitigation decisions, and community vulnerability. The framework enables researchers and regional planners to visualize and quantify how a community could evolve over time in response to repeated hazards under various behavioral scenarios. An illustrative example using parcel-level data from Anne Arundel County, Maryland—a county that experiences fairly frequent hurricanes—is presented to illustrate the methodology and to demonstrate how the interplay between individual choices and regional vulnerability is affected by the region’s hurricane experience.
... Many analyses of archetype buildings provide additional data. Furthermore, while the capacity curves developed for Hazus-MH are not directly compatible with IDA, methods have been developed to translate those curves into deteriorating SDOF backbone curves (by Ryu et al. 2008), which are then compatible. Capacity curves were developed for Hazus-MH for a variety of structural systems, and are described by design level (i.e., conformance to building codes of different eras), and by construction quality. ...
... A methodology for simulating earthquake response using deteriorating nonlinear single-degree-of-freedom (SDOF) oscillators subjected to recorded ground motions is currently being investigated. SDOF backbone curves translated from Hazus-MH capacity curves, using a methodology developed by Karaca and Luco (2008), and Ryu et al. (2008), show promise in producing acceptably accurate results while maintaining low computational expense. Preliminary analyses are being conducted to identify potential simple, equivalent models for building exposure to the wind, surge, wave, and scour aspects of hurricane loading. ...
Resilient and sustainable multi-hazard building design can significantly benefit from a holistic approach that considers hazards in the context of the full building life-cycle. Sustainability of a building is dependent not only on well-defined impacts from initial design, construction and operation, but also those associated with uncertain future hazards. Currently available methods are adequate in addressing individual issues related to resilient and sustainable building design but fail in addressing the complexities and interconnectedness in a multi-hazard environment where these dependencies exist at multiple levels. There is a significant knowledge gap in terms of integrated decision support methodologies to reconcile these types of design considerations in a systematic framework. A decision framework under development provides robust estimates of resiliency and sustainability over a broad set of soil, foundation, structural and envelope (SFSE) systems and multi-hazard considerations. Assessment occurs in three modules that perform the following tasks: (M1) generation of site-appropriate SFSE systems; (M2) probabilistic assessment of multi-hazard performance and operation; and (M3) multi-objective and multi-attribute optimization of performance metrics to prioritize and refine the design of candidate systems. The three modules are adaptable and generalizable to multiple building types, hazards, and performance metrics. Building on previous research in performance-based assessment, the decision framework offers a comprehensive and holistic approach to the selection of SFSE systems during conceptual design. Initial development of the decision framework focuses on mid-rise commercial buildings exposed to hurricane, earthquake, and tsunami hazards.
... For the numerical model, we chose a SDOF model that represents the typical mid-rise concrete moment resisting frame structure in New Zealand. The derivation of a multilinear capacity curve for the model is explained in detail in Ryu et al. (2008) and Uma et al. (2011). Figure 1 shows the capacity curve of the model along with the median damage state threshold for five damage states (Slight, Moderate, Extensive, Complete and Collapse). ...
We present a methodology for developing fragilities for mainshock-damaged structures, "aftershock fragility", by performing incremental dynamic analysis (IDA) with a sequence of mainshock-aftershock ground motions. The aftershock fragility herein is distinguished from a conventional fragility for an intact structure. We estimate seismic response of a mainshock-damaged building by performing nonlinear time history analysis with a sequence of mainshock and aftershock ground motions (so-called "back-to-back" dynamic analysis). We perform the back-to-back dynamic analyses for a number of levels of mainshock response/damage, and a number of sequences of mainshock and aftershock ground motions. With estimated seismic responses from the back-to-back dynamic analyses, we compute various damage state transition probabilities, the probability of exceeding a higher damage state from an aftershock given a damage state due to a mainshock. For an illustration of the methodology, we develop an aftershock fragility for a typical New Zealand 5-storey reinforced concrete moment frame building. The building is modeled using a single-degree-of-freedom (SDOF) damped nonlinear oscillator with force-deformation behavior represented by a multi-linear capacity/pushover curve with moderate pinching hysteresis and medium cyclic deterioration.
This poster presents the creation, improvement, and application of a web-based seismic risk map tool developed at the USGS in Golden, CO (http://earthquake.usgs.gov/research/hazmaps/risk). Reinforced concrete buildings built prior to implementation of modern seismic code standards in 1976 behave in a non-ductile manner under seismic loading, potentially leading to catastrophic failure. The high degree of seismic activity in the western United States makes retrofitting such non-ductile concrete buildings a necessity. Due to the associated cost and time, it is virtually impossible to use a brute force approach to mitigate the seismic risk created by these older concrete buildings. This has motivated the development and improvement of a web-based seismic risk map tool as a way to quantify seismic risk. This tool provides a means to quickly identify the regions of the US where non-ductile concrete buildings are at a high risk of failure. Furthermore, with an inventory of non-ductile concrete buildings for a particular area, the buildings at the highest risk in that area can be pinpointed for seismic retrofit.
