• Earthquakes and Structures
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• v.11 no.3
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• pp.407-420
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• 2016

The aim of this study is to investigate the effect of vertical ground motion (VGM) on seismic behavior of reinforced concrete (RC) regular frame with construction joints, and determine more proper modeling method for cast-in-situ RC frame. The four-story RC frames in the regions of 7, 8 and 9 earthquake intensity were analyzed with nonlinear dynamic time-history method. Two different methods of ground motion input, horizontal ground motion (HGM) input only, VGM and HGM input simultaneously were performed. Seismic responses in terms of the maximum vertex displacement, the maximum inter-story drift distribution and the plastic hinge distribution were analyzed. The results show that VGM might increase or decrease the horizontal maximum vertex displacement depending on the value of axial load ratio of column. And it will increase the maximum inter-story drift and change its distribution. Finally, proper modeling method is proposed according to the distribution of plastic hinges, which is in well agreement with the actual earthquake damage.

• Earthquakes and Structures
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• v.20 no.2
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• pp.175-185
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• 2021

This study strives to highlight the importance of considering the vertical ground motions (VGM) in the seismic evaluation of RC buildings. To this aim, IDA (Incremental Dynamic Analysis) is conducted on three code-based designed high-rise RC frame-core wall buildings using a suite of earthquake records comprising of significant VGMs. To unravel the significance of the VGM inclusion on the performance of the buildings, IDAs are conducted in two states (with and without the vertical component), and subsequently based on each analysis, fragility curves are developed. Non-simulated collapse criteria are used to determine the collapse state drift ratio and the area under the velocity spectrum (SIm) is taken into account as the intensity measure. The outcome of this study delineates that the inclusion of VGM leads to the increase in the collapse vulnerability of the structures as well as to the change in the pattern of inter-story drifts and failure mode of the buildings. The results suggested that it would be more conservative if the VGM is included in the seismic assessment and the fragility analysis of RC buildings.