Dynamic Elasto-plastic Analysis On180M-span Three-center-Arc Steel Saptial Arch Truss Under Strong Earthquake

Large-span steel pipe arch truss is flexible and elegant, reasonable force and the less amount of steel and so on, so it has been widely used in train stations, airports, stadiums, exhibition centers and other large public buildings, as well as to provide a safe refuge after strong earthquake. However, there is the less dynamic response research results on large-span steel arch truss under strong earthquake. In this paper, the dynamic elasto-plastic analysis on steel arch truss under strong earthquake is investigated, and the law of plastic development and collapse mechanism of the structure are given, which provide research theory about structural seismic performance.In this paper, the180m-span and0.2-rise to span ratio steel arch truss is studied. Based on the existing dynamic response research results on steel arch truss, the paper launched the following work:Firstly, the dynamic elasto-plastic analysis was taken by inputing NH wave, LOMA wave and Shanghai RG wave with finite element analysis software SAP2000. Maximum displacement of nodes, the plastic element ratio of structure, the plastic deformation of element in pace with the increasing seismic input are investigated to gain failure critical acceleration, Maximum yield-displacement ratio, failure mechanism and failure modes of structure.Secondly, the dynamic elasto-plastic analysis was taken with three different strength steel of the Q345, Q390and Q420. The data such as amount of steel designed in the same fortification intensity, the elastic-plastic critical peak acceleration, failure critical peak acceleration and displacement ductility index are compared, and the trend of these data with the increased strength of steel are summed up.By calculation and analysis, it takes the following conclusions:1. The Maximum displacement of nodes increases slowly with earthquake peak acceleration increasing, and the steel arch truss under the earthquake occurs strength failure finally.2. The dynamic elasto-plastic analysis was taken under three different seismic waves. The elastic-plastic critical peak acceleration is different from9.68%to98%under X direction seismic waves,12.5%to47.54%under Z direction seismic waves and14.81%to93.75%under X+Z direction seismic waves. The failure critical peak acceleration is different from20%～65.52%under X direction seismic waves,1.56%～30%under Z direction seismic waves and10%～35.80%under X+Z direction seismic waves. The displacement ductility index is different from1.53%～14.50%under X direction seismic waves,9.92%～16.41%under Z direction seismic waves and5.78%～44.91%under X+Z direction seismic waves.3. The dynamic elasto-plastic analysis was taken with three different strength steel. The amount of Q390and Q420steel is reduced respectively by6.74%and11.75%compared with Q345. The elastic-plastic critical peak acceleration of Q390and Q420steel is increased respectively by about20%and30%compared with Q345. The failure critical peak acceleration of Q390and Q420steel is increased respectively by about15%and25%compared with Q345. It is indicated that the amount of steel is reduced gradually, but the elastic-plastic critical peak acceleration and failure critical peak acceleration increases greatly with the improvement of the strength of steel. Therefore, the seismic level of steel pipe arch truss is improved by high-strength steels.