Influence of Ground Motion Duration on the Structural Response at Multiple Seismic Intensity Levels

Abstract

This paper aims to investigate the effects of motion duration on the structural seismic demands, seeking potential correlations between motion durations and structural responses at several seismic intensity levels. Three seismic intensity levels with 100years, 475years, and 2475years earthquake return periods (RPs) are first considered for correlation computations. Spectrally matched ground motions are employed to isolate the contribution of duration from the effects of ground motion amplitudes and response spectral shape. Four single degree of freedom systems derived from four real reinforced concrete structures are studied, where both degrading and non-degrading equivalent SDOF systems are included for structural modeling. Results show a low positive correlation between motion duration and structural displacement demand, but this correlation increases with an increase in earthquake RP. It is also investigated whether or not this insignificant positive correlation has an impact on the incremental dynamic analysis curves. The spectrally matched ground motions are divided into two distinct groups in this case: short and long duration ground motions. The comparison of incremental dynamic analysis of these two groups at the collapse limit reveals that long-duration ground motions can cause up to a 20 percent decrease in the spectral acceleration demand of considered structural systems.

Fragility analysis of nonlinear soil-structure systems including foundation uplifting and soil yielding

“…There are a number of procedures for performing nonlinear dynamic structural analyses to collect the data for estimating a fragility function. One common approach is incremental dynamic analysis (IDA), where a suite of ground motions are repeatedly scaled in order to find the IM level at which each ground motion causes collapse [21,[32][33]. For fragility function fitting, an optimal strategy, as described below, must be followed in order to obtain an accurate fragility estimate with a minimal number of structural analyses.…”

Application of Endurance Time Method in Seismic Assessment of RC Frames Designed by Direct Displacement-Based Procedure

“…For the simulation of this series of ETEFs, the consistency of the ground motion duration has been included directly in the generation process. This is because structural responses could be influenced by ground motion duration significantly [71][72][73][74]. In addition, since the ETA40lc series of ETEFs follows an exponentially intensifying profile that is consistent in cumulative absolute velocity (CAV) when compared to conventional GM scaling to match desired intensity.…”

Application of endurance time method in damage assessment of concrete moment frames

“…It may be a question as to why the 10th second is used for a target time. The ET acceleration functions and ground motions should be compatible with other characteristics such as the number of vibration cycles and strong motion duration since these parameters are among the most significant parameters in the nonlinear behavior of the structures [15,27,28,29] . The target time could influence the duration and frequency content of the records.…”