A ground motion intensity measure based on different spectral-shape types to predict nonlinear structural response in steel buildings

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The selection of an appropriate intensity measure to assess the seismic performance in steel buildings is an important step to reduce uncertainty in the structural response. Hence, in this study, a scalar ground motion intensity measure able to increase the efficiency in the prediction of nonlinear behavior effects of steel structures subjected to earthquake ground motions named the generalized intensity measure INpg is analyzed. The intensity measure is based on a proxy of the spectral shape Npg, where it can be defined by using different types of spectral shapes, such as those obtained with pseudo-acceleration, velocity, displacement, input energy, inelastic parameters and so on. This work shows the efficiency of the generalized intensity measure named INpg when the spectral parameters of pseudo-acceleration and velocity are used. Therefore, to improve the performance of the analyzed intensity measure, two engineering demand parameters, maximum inter-story drift and horizontal peak floor acceleration, of steel frames with 5, 10, 15 and 20 stories subjected to several narrow-band ground motions are estimated as a function of the spectral acceleration at first mode of vibration of the structure Sa(T1), which is commonly used in earthquake engineering and seismology, and with the two particular cases under study of the recently developed parameter related to the structural response known as INpg. In general, the intensity measure here studied is able to efficiently predict nonlinear structural demands on steel buildings under earthquake ground motions. Further, the analyzed intensity measure must be considered to estimate maximum inter-story drift and horizontal peak floor acceleration demand of multi-story buildings.