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Performance-based seismic design (PBSD) of wood frame structures has been only preliminarily investigated by a handful of researchers around the world and is currently under development in the United States as well as other countries worldwide. This paper presents the basic concept of applying system identification logic as one alternative for PBSD of wood frame structures. In PBSD of wood frame structures, one prescribes combinations of hazard level and corresponding performance, and 'designs' the system such that these performance metrics ate met. For wood frame buildings this procedure fits the definition of a system identification problem, i.e., the input and output are known and the nonlinear system between them is sought. In most cases the shearwall locations, i.e., geometry, are known, and only the wall design is sought. In this papel the concept is presented and a procedure to apply it within a PBSD framework is proposed. The validity of the procedure is confirmed through two illustrative examples, namely the design for a two-story wood shearwall and a two-story wood frame building. An existing ten-parameter hysteresis model commonly used for seismic analysis of wood frame structures was used in both examples to represent the nonlinear system to be identified. The 'design' is then checked by applying a suite of ordinary ground motion records and compafing the multirecord incremental dynamic analysis of the peak deformation response to the target (performance) curve. The approach was found to work well for the example structures and shows promise for extension to more complicated structures and performance measures. DOI: 10.1061/(ASCE)0733-9445(2008)134:2(240) CE Database subject headings: Seismic design; Wood structures; System analysis; Identification; Frames; Probability.

The dynamic performance of a woodframe structure is examined through the qualitative correlation between the transient interstory drift and the observed damage following a series of full-scale shake-table tests. The structure was subjected to simulated Northridge earthquake ground motions scaled to seismic hazard levels of 50, 10, 2, and 1% exceedance in 50 years. Added mass was used in an effort to examine the qualitative correlation of the observed performance with the performance tabulated in FEMA 2000. The structure was repaired to the extent possible between each test. The structure was tested at three different structural/nonstructural stages: (1) oriented strand board (OSB) only; (2) gypsum wall board (GWB) and OSB; and (3) OSB, GWB, and a nonstructural interior partition wall, in order to determine the effect of each component and to qualitatively determine its effect on overall damage to the system. It was determined that qualitative damage descriptions were not significantly different from those given in FEMA 2000. It was also found that the percent torsion increased with increasing peak ground acceleration. The effect of GWB on structural response and damage was as expected, but the partition wall behaved differently than expected. Specifically, the partition wall sustained very little damage even though it had full load transfer at the top plate. DOI: 10.1061/(ASCE)0887-3828(2007)21:1(35) CE Database subject headings: Earthquake engineering; Ground motion; Performance characteristics; Shear walls; Framed structures; Wood structures; Shake table tests.

Railway vehicles frequently have derailed during major earthquakes. Although a probabilistic approach based on fragility analysis was established in structural engineering, it has never been applied to railway vehicles. Thus, the aim of this study was to select optimal intensity measures (IMs) and develop fragility curves for the derailment of vehicles. Eight commonly seen IMs were examined to determine their suitability for use in analyzing the derailment of vehicles. The railway vehicle response was analyzed using a nonlinear vehicle-track simulation, and 22 far-field and 28 near-field ground motion records were used as input. Based on the results of the simulation, the correlations of these IMs with the responses of vehicles were evaluated in terms of commonly accepted criteria in the literature, such as efficiency, practicality and sufficiency. It was found that spectral IMs were superior to peak-type IMs. In addition, the acceleration spectral intensity (ASI) and the velocity spectral intensity (SI) were shown to be optimal IMs for the evaluation of derailments. Using the selected IM (ASI), derailment fragility curves were developed for three levels of vehicle performance, which facilitated the probabilistic assessment of vehicle derailment in a performance-based manner. [ABSTRACT FROM AUTHOR]

The running safety of high-speed trains over bridges is a great concern in bridge design. Typically, the running safety of vehicles is evaluated by vehicle–track simulations that are computationally expensive and unfamiliar to bridge designers. This study investigates simplified vehicle–track models for assessing the running safety of vehicles on deformed bridges. Four types of simplified vehicle models along with four types of simplified wheel–track models are investigated. The predicted wheel–rail forces are compared with those simulated by the detailed vehicle–track program. In these simulations, typical bridge deformations are taken as excitations to the dynamic system. It is found that omitting the rail vibration leads to large wheel–rail response errors. The wheel–rail constraint model gives similar wheel–rail responses to those obtained by the Hertz contact model. A vehicle–track model with five degrees-of-freedom is adequate for assessing wheel–rail forces. Furthermore, an analytical solution to the wheel–rail forces running over an angular rotation was obtained. These simplified vehicle–track models provide an efficient way to assess the running safety of vehicles on deformed bridges when using probabilistic or optimal analyses that require a large number of simulations. [ABSTRACT FROM AUTHOR]