Analysis On Elastic-plastic Seismic Response Of The Arch Truss Of Rectangular Section

The arch truss is widely used in such great public buildings as gymnasiums, Convention and Exhibition Centers, etc, due to its greaceful sculpt, reasonable mechanical properties .As a kind of long-span spatial syructure,the study on its anti-seismic performence is concerned by many scholar. Nowadays, the study on failure mechanism of arch truss under earthquake is not yet fully understood.The elasto-plasyic seismic response of steel tube arch trusses with rectangular cross-section are studied using FE program ANSYS, considering the effect of material and geometric non-lineariti in the course of analysis. The detailed work is as followed:1. Analysis of dynamic response on the structure under earthquake action The FE model is builded about 90m-span steel tube arch truss .The dynamic response index of structure is recorded under different peak value of acceleration and then comparition and analysis are made between these response index . By some vary laws of these index, the course of vary in dynamic performance of the structure up to failure is understood. Preliminary discuss are made about failure pattern and machanisim on the basis of above conclusion. The detail response index are as followed: (1) the response of displacement, (2) the response of number of plastic member, (3) the response of axial force, (4) response of Maximum displacement-to-yield displacement, The results indicate that node displacement increase with the increase of the seismic wave peak value. When the buckling of the structure occurs with nodal displacement sudden increase; Plastic development is processed before the failure appears. Infact, the failure of structure is caused by the incessant interactive actions of the plastic development and deformation; the severe yield elements got together, changed the capability of structure and reduced the rigid. In conclusion, the instability collapse took place due to losing the capability subjected to earthquake and keeping the initial shape.2. Analysis of parameters effect on the structure response under earthquake actionThe comparision of displacement and plastic member ratio were made about various parameters. The results indicates that : The critical load is the biggist under X-direction seismic wave; The critical load increases with the increase of the cross-section height; The critical load gradually increases with the increase of height-soan ratio.