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Modern seismic hazard analysis utilizes various ground motion prediction equations (GMPEs) to estimate intensity measures (IMs) such as spectral acceleration (Sa), Arias intensity (Ia), significant duration (D5‐95), and cumulative absolute velocity (CAV) as scalar parameters. The use of these GMPEs leads to independent estimations of IMs for the same earthquake scenario. Since the IMs belonging to the same earthquake scenario are naturally correlated, the GMPEs used for characterization of seismic hazard are expected to incorporate such correlation structure. Particularly, Sa corresponding to different periods of a single‐degree‐of‐freedom oscillator is estimated by GMPEs that do not explicitly account for internal correlations between the Sa at various periods for the same ground motion. The current approach to incorporate such a correlation for Sa spectrum is through a post‐processing technique developed by Baker and Jayaram; their method relates the spectral accelerations of different periods using functional forms describing linear correlations. However, the proposed correlation functions can be further improved and extended to more accurately estimate the spectrum of near‐fault high‐magnitude ground motions using high order dependencies among the spectral accelerations. This study proposes a generalized ground motion prediction model (GGMPM) using a hybrid recurrent neural network (RNN) framework that can be used to estimate a 29 × 1 correlated vector (denoted as IM) of RotD50 Sa at 26 periods and geometric means of Ia, D5‐95, and CAV using a set of seismic source and site parameters as inputs. This is an improvement to the current body of knowledge because the high order dependencies between the individual components of IM are incorporated. A RNN framework is developed that estimates the median vector of IM. The discrepancy between the IM estimated using the RNN framework and the IM computed from recorded motions is further minimized using the covariance matrix adaptation evolution strategy (CMA‐ES), which is a non‐convex optimization method. The residuals of the RNN framework are used to construct the inter‐event and the intra‐event covariance matrices to account for the inter‐event and intra‐event variabilities of the ground motions. Hence, given the source and site parameters, the RNN‐framework returns a median prediction of the IM, which is then combined with estimated inter‐event and intra‐event covariance matrices to obtain the probabilistic estimation of IM. Furthermore, this GGMPM framework is compared against various currently used GMPEs, and the results of these comparisons demonstrate that the proposed GGMPM leads to improved predictions while maintaining the internal dependencies of the IM components. [ABSTRACT FROM AUTHOR]

We describe the formulation and application of an integrated general regional seismic loss assessment (RSLA) method for buildings in seismic regions. An efficient method for RSLA is valuable for engineers involved in city planning, risk management, and insurance dealings. In contrast to previously reported methods, the framework presented herein is hazard-based and utilizes a regional rapid seismic hazard deaggregation tool that allows regional assessment to be conducted more efficiently. The proposed technique is implemented as an example to assess general regional seismic loss in Los Angeles County for a ground motion hazard with 10% probability of exceedance in 50 years. [ABSTRACT FROM AUTHOR]

A comprehensive risk based bridge design procedure through which the effect of abutment skew angle is considered upfront aiming at uniformity in seismic risk is presented. We demonstrate a method for conceptual design of bridges with skewed abutments aiming at uniform performance (i.e., tolerable loss) objectives. In the proposed technique, few simple design aid graphs are developed by estimating the bridge repair cost ratios (RCRs) at different levels of column drift ratios (CDRs) and abutment skew angles. The suggested graphs parameters are estimated by implementing a full Monte Carlo probabilistic simulation over Pacific Earthquake Engineering Research Center (PEER) Probabilistic Based Seismic Assessment (PBSA). To show the significance of the proposed conceptual design method, a two-span Caltrans ordinary bridge class is selected for case study while various design parameters such as column diameter, column height to depth ratio, longitudinal reinforcement ratio, and span length are included as design variables. The effect of abutment skew angle on the probability of exceeding an RCR as well as probability of bridge collapse is explored by considering various bridge design parameters. Limitations of the proposed approach are discussed. [ABSTRACT FROM AUTHOR]

SUMMARY This study utilized nonlinear response history analysis to compare the seismic demand on three variations of a 40-storey buckling-restrained braced frame designed for high seismic hazard in the Los Angeles region. The three designs were referred to as a 'code-based design', based on the 2006 International Building Code, a 'performance-based design', based on criteria published by the Los Angeles Tall Building Design Council (LATBSDC) and a 'performance-based design plus', based on newly developed criteria from The Pacific Earthquake Engineering Research Center (PEER). The response history analysis utilized spectrum-matched ground motions as well as simulated ground motions for the Puente Hills fault. The spectrum-matched motions were selected from the Next Generation Attenuation of Ground Motions (NGA) database, which is largely composed of recorded motions and scaled to five hazard levels. The simulated ground motions were broadband signals generated from a moment magnitude (Mw) 7.15 scenario rupture of the Puente Hills fault for two near fault regions and exhibit long period energy content that significantly exceeds the uniform hazard spectrum. Structural performance was assessed in terms of exceedance of a safe inter-storey drift ratio (IDR). It was seen that the simulated ground motions impose higher IDR demands on the structures than the spectrum-matched NGA ground motions. Furthermore, the number of instances of exceedance of a safe IDR, considered for this study as IDR = 0.03, is substantially higher for the simulated ground motions, pointing to the importance of considering such motions in the collapse prevention of tall buildings on a site-specific basis. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study assesses the deformation demands posed by high hazard seismic events ~o some common steel moment frame (SMF) structures in the Los Angeles region. The structures under consideration were SMF structures designed using the 1994 UBC for high seismic risk, both short and tall, similar to many SMF structures in Los Angeles. Lumped plasticity frame models are developed with the most current knowledge of nonlinear modelling techniques and component properties and are subjected to recorded and simulated ground motions. The recorded ground motions are selected and scaled to represent a high hazard seismic event. The simulated ground motions are extracted from a simulation of a magnitude 715 rupture of the Puente Hills fault. The frame models are varied to consider brittle pre-Northridge welds, ductile post-Northridge welds as well as simplified and detailed modelling techniques. Structural safety is assessed in terms of the number of structures that exceeded a safe inter-storey drift ratio for each ground motion set. Also, the relative safety of the tall and short SMF, taking into account brittle and ductile welds, is evaluated. Lastly, the differences in demands imposed by the recorded and scaled ground motions on tall SMF structures are compared. [ABSTRACT FROM AUTHOR]

This paper summarizes collapse performance measures and the probabilistic basis for their development to assist in understanding of collapse behaviour of buildings and implementation of performance objectives in design and evaluation of buildings for collapse safety. Collapse in this context is defined as the loss of lateral load-resisting capability of a building's structural system caused by ground shaking. Estimation of collapse performance requires the relation between a ground motion intensity measure (IM) and the probability of collapse, denoted as collapse fragility curve, and the relation between the same ground motion IM and the seismic hazard for the building, denoted as seismic hazard curve. Two methods for estimating the collapse fragility curve of a building are discussed: the EDP-based approach and the IM-based approach. In both approaches, collapse is associated with a scalar ground motion IM and is obtained by utilizing Incremental Dynamic Analysis. The collapse performance criteria presented in this paper are compared with the collapse performance criteria recommended in the SAC! Federal Emergency Management Agency guidelines. An eight-storey moment-resisting frame case study is used to compare the estimates of collapse performance of various approaches discussed in this paper. [ABSTRACT FROM AUTHOR]