Response Analysis Of Frame Structures Under Velocity Impulse Earthquake

Near fault earthquake can caused serious damage or even collapse of the building structure,which brought huge economic losses and heavy casualties.Some useful results and conclusions about earthquake responses of building structures to the near fault earthquake have been obtained.However,the studies are mainly focused on the comparison between the near fault and far field earthquake responses.The comparison studies of the frame structure response to the earthquakes with and without velocity pulse are less.Therefore the comparative studies of the frame structure responses to the near fault earthquake with and without velocity pulse have not only the theoretical significance but also the engineering value for the seismic design.The research objects of this dissertation are the RC plane frame structures of 4-span three stories,2-span five stories and 3-span five stories respectively.Twelve near fault earthquake records are selected from the PEER database.There are three groups of the 6.53 magnitude Imperial Valley earthquake and three groups of the 7.62 magnitude Taiwan Chi-Chi earthquake.Each group includes one near-fault seismic record with velocity pulse and one near-fault seismic record without velocity pulse.The amplitude of the earthquake records was modulated according to the "Code for seismic design of buildings".The ABAQUS software is used in the comparative analysis of three RC plane frame structure responses to the near fault earthquake with and without velocity pulse respectively.The maximum lateral displacements of bottom columns between the column cap and the foundation as well as their average values are studied.The permanent displacements of bottom columns between the column cap and the foundation as well as their average values are also studied.The research results are as follows:For the RC plane frame structure of 4-span three stories,the average values of the maximum lateral displacements of all the bottom columns under the action of three near fault seismic waves of the 6.53 magnitude Imperial Valley with velocity pulse are respectively 20%.27%and 3.2 times bigger than the three near fault seismic waves of the 6.53 magnitude Imperial Valley without velocity pulse.The corresponding average values of three near fault seismic waves of the 7.62 magnitude Chi-Chi earthquake with velocity pulse are respectively 57%.2.3 times and 2.1 times bigger than the three near fault seismic waves of the 7.62 magnitude Chi-Chi earthquake without velocity pulse.For the RC plane frame structure of 4-span three stories,the average values of the permanent displacements of all the bottom columns between the column cap and the foundation under the action of three near fault seismic waves of the 6.53 magnitude Imperial Valley earthquake with velocity pulse are respectively 0.9mm?0.9mm and 3.3mm,which are respectively bigger than the three near fault seismic waves of the 6.53 magnitude Imperial Valley earthquake without velocity pulse.The corresponding average values of three near fault seismic waves of the 7.62 magnitude Chi-Chi earthquake with velocity pulse are respectively 1.2mm?2.5mm and 3.6mm,which are respectively bigger than the three near fault seismic waves of the 7.62 magnitude Chi-Chi earthquake without velocity pulse.For the RC plane frame structure of 2-span five stories,the average value of the maximum lateral displacements of bottom columns between the column cap and the foundation under the action of near fault seismic waves of one 6.53 magnitude Imperial Valley earthquake and one 7.62 magnitude Chi-Chi earthquake with velocity pulse are respectively 66%and 60%bigger than the results under the action of near field seismic wave without velocity pulse in the same group.The corresponding average values of permanent displacements of the two magnitudes near fault seismic waves with velocity pulse are both 3.0mm,which are bigger than the results under the action of near fault seismic waves without velocity pulse.For the RC plane frame structure of 3-span five stories,the average values of the maximum lateral displacements of bottom columns between the column cap and the foundation under the action of near fault seismic waves of one 6.53 magnitude Imperial Valley earthquake and one 7.62 magnitude Chi-Chi earthquake with velocity pulse are respectively 17%and 63%bigger than the results under the action of near field seismic wave without velocity pulse in the same group.The corresponding average values of permanent displacements of the two magnitudes near fault seismic waves with velocity pulse are respectively 0.8mm and 2.3mm,which are bigger than the results under the action of near fault seismic waves without velocity pulse.