Elasto-plastic Seismic Response Analysis Of Flexible Connected Structures Under Rare Earthquake Excitations

Generally, the early connected form was rigid, but for large-span connected structures with rigid form, a great temperature stress could be created in the connecting truss due to the temperature changes, and the rigid connection will increase torsion coupling seismic response of the structure under earthquake excitations. In order to solve these problems, some experts have taken a new attempt on connection form and designed some new project examples with flexible connection. The flexible connection mainly refers to the elastic bearing connection between the tower building and the corridor; which can effectively reduce the temperature stress and torsion coupling seismic response of the connceted structure under earthquake excitations. But it also brings some new problems, such as, excessive displacement and pounding between the connecting body and the towers, the collapse of the corridors under strong earthquake excitations. In this paper, the same and different height Connected Structures linked with flexible bearings are taken as the research objects and the contents of the research are as follows:1) Elasto-plastic time history analysis of the Connected Structures linked with flexible bearings are analyzed under the rarely occurred earthquake of intensity7and the maximum displacement of bearings and the seismic response of connected structures are received. The results indicate that the Connected Structures linked with all flexible bearings have rational failure mode under over fortification criterion earthquake excitations when the bearings stiffness is rational. Although the rebar and concrete of shear-wall at bottom strengthened part yield, and plastic hinges based on different performance occur in coupling beams of shear-wall and frame beams, the frame columns supporting the corridor don’t yield, and the displacement of the bearings are reasonable, which show that the Connected Structures linked with flexible bearings have enough shock absorption and anti-collapse performance.2) The maximum displacement of the bearings are designed as a critical collision gap, and magnifying the peak ground acceleration1.2or1.4times, the structural dynamic response and the plastic development level of the connected structures are further studied in details. The results as follow:pounding can occur in upper and lower parts of corridors under over fortification criterion earthquake excitations. The internal forces direction of the connecting truss caused by pounding is opposite with the direction of the internal forces caused by gravity when the pounding occurred in the lower part of the corridor, which can reduce truss internal force, or even lead to the internal forces reverse in a certain extent, but the internal forces direction is consistent when the pounding occur in the upper part of the corridor, which cause the internal forces of the connecting truss larger. As the pounding force between corridor and the tower most through the floor to the core of the shear-wall, pounding has few influence on the internal force of tower frame beams and columns.3) Making a detail study of the connected structures’dynamic responses of different isolator bearings, which show that smaller the flexible bearings stiffness, the greater the displacement under earthquake excitations and the corresponding shear forces of bearings are smaller too. But the excessive displacement will cause obvious P-△effect of the structures, which may also lead to the collapse of corridors.The pin bearings can cause huge forces at the connective joints between tower and corridor under the rare earthquake excitations. Therefore, the seismic performance of connected structures with pin bearings is less than flexible bearings, and the flexible bearings are usually the first choice when the displacemet of bearings can meet the design requirements under rare earthquake excitations.