| Earthquakes occur frequently in recent years,from the Chi Chi earthquake,Kobe earthquake,Northridge earthquake to the Wenchuan earthquake.The engineering structure will be damaged by the near field earthquake due to its special effect,and most property losses and casualties concentrated in the vicinity of earthquake center.Therefore,it is necessary to analyze the failure mode and mechanism of the frame structure to the near field earthquake.It provides the foundation for the seismic design and corresponding mitigation measures of construct this type of structure in the near field.The comparative studies of the frame structure responses on the near fault earthquake with and without velocity pulse not only have the theoretical significance,but also have the engineering value for the seismic design.The analysis model of a three span reinforced concrete frame structure in the depth direction of the five layers corridor teaching building was established.Five groups seismic records of RSN1148,RSN879,RSN764,RSN1165 and RSN802 were selected in the PEER database.Each group of seismic record contains two seismic waves,which contain velocity pulses in one direction and the other without velocity pulse.The amplitude of the five groups seismic records were modulated according to the "Code for seismic design of buildings".The ABAQUS software is used to analyze the response of the frame structure on the near fault earthquake with and without velocity pulse.The relative lateral displacement of each column and the average value in the first story,the permanent displacement of each column and the average value in the first story,the reaction force of each column and the total value in the first story,the shear force of the column and beam in the first story,the bending moment of the column and beam in the first story,the relative lateral displacement of each layer were compared on the near field earthquake with or without the velocity pulse.The results of the study are as follows:To the five groups seismic records of RSN1148,RSN879,RSN764,RSN1165 and RSN802,compared with the response on the earthquake without velocity pulse,the relative lateral displacement of each column in the first story on the earthquake with velocity pulse is more obvious,the average value increased by 109.2%,11.0%,13.9%,32.7%,94.5%respectively;the permanent displacement of each column in the first story on the earthquake with velocity pulse is more obvious,the average value increased by 266.7%,42.9%,91.2%,80.2%,472.7%respectively;the reaction force of each column in the first story on the earthquake with velocity pulse is more obvious,the total value of the reaction force of the column in the first story increased by 94.3%,9.9%,10.0%,4.4%,55.9%.To the seismic records of RSN1148,compared with the response on the earthquake without velocity pulse,the shear force of each bottom column in the first story on the earthquake with velocity pulse increased by 118.4%,94.0%,77.4%,92.5%respectively;the shear force of each beam in the first story increased by 100.4%,68.3%,95.2%respectively;the bending moment of each bottom column in the first story increased by 99.1%,90.4%,63.6%,84.2%;the bending moment of each top column in the first story increased by 122.1%,95.8%,79.9%,105.1%;the bending moment of the left end of each beam in the first story increased by 151.0%,105.3%,146.4%;the bending moment of the right end of each beam in the first story increased by 76.5%,105.8%,35.1%.To the seismic records of RSN879,compared with the response on the earthquake without velocity pulse,the shear force of each bottom column in the first story on the earthquake waves with velocity pulse increased by 12.3%,6.6%,7.4%,12.7%respectively;the shear force of each beam in the first story increased by 13.8%,13.1%,15.3%respectively;the bending moment of each bottom column in the first story increased by 19.6%,16.8%,14.4%,17.4%;the bending moment of each top column in the first story increased by 64.8%,25.7%,22.4%,54.2%;the bending moment of the left end of each beam in the first story increased by 17.1%,12.0%,45.9%;the bending moment of the right end of each beam in the first story increased by 40.1%,11.8%,23.3%.Compared with the response on the earthquake without velocity pulse,the relative lateral displacement of the first to five layers of the structural on the earthquake with velocity pulse of RSN1148 increased by 109.2%,132.7%,121.9%,91.0%,91.8%;compared with the response on the earthquake without velocity pulse,the relative lateral displacement of the first to five layers of the structural on the earthquake with velocity pulse of RSN879 increased by 11.0%,11.7%,11.0%,20.3%,17.0%.Compared with the response on the earthquake without velocity pulse,the response of RC plane frame structure on the earthquake with velocity pulse was more significant. |
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