Study Of Vertical Earthquake Action Of Long-span Structure And The Effect Of Its Support Structure

There is a few kind of structures are considering the effect of vertical seismic in Chinese current seismic code. For the long span roof truss, there is only a simplified calculation method to calculate the vertical seismic action, not considering the effect to its support structure. In this paper, vertical earthquake action of long-span structure has been deeply studied, and considering the effect to its support structure. The main works of this paper are as follows:(1)The dynamic internal force of long span roof truss was calculated with response spectrum method and time history analysis method. Then study the dynamic internal force distribution of top chords and bottom chord bars and web members of six trapezoid steel roof trusses with different spans. The maximum dynamical value of top chords of truss appeared on the middle span. As for bottom chord bars, the peak point of dynamical value appeared both in middle span and two terminal of roof truss. And the dynamic internal force distribution of web members are different with different span.(2)Compared with current seismic code, the distribution and value of equivalent vertical seismic force are studied. The calculation date show that triangle distribution and parabola distribution are better than uniform distribution. So triangle distribution and parabola distribution are suggested. According to calculation date, the magnitude of vertical seismic force coefficient at IIIkind of subsoil zone is introduced.(3)In this paper, the vertical seismic effort of the long span roof truss has been introduced in the seismic design of the bent frame structure. The method is calculating the vertical seismic effort of truss using both response spectrum method and seismic design standard method in the regions of 8 and 9 intensity, and then the support reaction force of roof truss under vertical seismic effort could be calculated, applying the support force on the top of the frame column and calculating the earthquake-resistance of the column . The corresponding conclusions on the basis of the data analysis is that it should take vertical seismic influence into account when bent frame structure seismic design.