Elastoplastic Time History Analysis Of Unidirectional Prestressed Concrete Space Frame

Prestressed concrete structure has the advantages at crack resistance, durability, spatiality, etc. but on its seismic performance, there is always controversy in the academic and engineering field, which directly affect its promotion in high intensity areas. To determine and optimize the seismic performance of prestressed concrete structures, many research institutions at home and abroad have come to a lot of value significant results, but existing studies mostly only for the member or plane frame, and it’s more meaningful in theory and engineering to carry out seismic research for space prestressed structure directly.In this paper, correct the "strong column-weak beam" adjustment strategy when seismic grade at level.1,then design some unidirectional prestressed concrete frames with 7(0.1g) or 8(0.2g) degree fortification intensity,which are in critical height(24m) and the critical span(18m), but choose different seismic level. Based on Open Sees software, establish the space elastoplastic time history finite element analysis model, enter two-way seismic waves, study the seismic capacity, plastic hinge mechanism and earthquake response laws of the space model examples under rare earthquake. Additional,in order to compare the differences in spatial model and plane model, establish a plane prestressed concrete frame finite element model. In this paper, the main conclusions are as follows:① In critical height and the critical span, no matter chose higher or lower seismic grade, the designed prestressed frame structure with 7 and 8 degree fortification intensity in this paper, could avoid global and local failure, without any collapse under rare earthquake. But in the first floor of structure with 8 degree fortification intensity, it’s possible to form a detrimental pattern,which all the upper and lower ends of columns appear plastic hinges.② Under rare earthquake, the space prestressed frame structures with 7 and 8 degree fortification intensity, could form “column hinge mechanism” along PC beams direction, form“beam hinge mechanism” along RC beams direction, but form “mixed energy dissipation mechanism” with beam hinge mainly in the structure of the overall level. It’s not easy to yield for PC beam ends, Even if yield, the rotations and ductility of PC beams are Less than the RC beams and columns in the same structure.③ When seismic grade at level.1, The proposed "strong column-weak beam" adjustment strategy in this paper, could cause the side columns in prestressed frame structure no yield, but the middle columns yield, and ensure the ductility demand of yield columns does not exceed its capabilities at the same time.④ Even for the regular prestressed frame structure, the intermediate Pin framework couldn’t reflect its seismic performance under two-way earthquake. Although the global reaction between space model and planar model is analogous, the local reactions, especially the plastic hinges reactions is significant different. It’s more reliable to do spatial analysis.