Research On Mechanical Behavior Of Pre-stressed Concrete Girder Transfer Floor Structure

In modern tall buildings, in order to satisfy the large-space function requirements of the construction building large-scale shopping malls, garages, halls at the bottom of buildings or across the road, fire access, underground pipe network and so on, transfer layer is setup at the bottom of buildings necessarily. The requirement of 15 meters service space without columns at the bottom of multi-storey and tall buildings is increased. This means the transfer beams should have good carrying capacity with lager vertical load because of supporting more floors. And Pre-stressed concrete with the advantages of high carrying capacity, good crack resistance and light weight will solve engineering problems well. So in recent years more and more transfer members and cantilever members use the pre-stressed technology in our Country. And its mechanical behavior is one pot of the hot domains because of complexity.First, two transfer floor structure is established in this paper, one is used reinforced concrete transfer beam (called model1)and the other used pre-stressed concrete transfer beam(called model2).The two transfer beams have the same deflection under vertical load ,but have different height. Then studied and analyzed the design method of large-span pre-stressed concrete transfer beam using finite element software SAP2000 and ANSYS10.0, mainly focused on the structure analysis under vertical load, model analysis, response spectrum analysis, pushover analysis and stress analysis of transfer beam. At last compare with the analysis of cracks and stress of the two transfer beams. By using SAP2000 and ANSYS program, the conclusion we can get:1. The use of pre-stressed structural members caused by redistribution of internal forces. In model 2 under vertical load the internal forces of pre-stressed concrete transfer beam is much less than that of reinforced concrete transfer beam in model 1.pillrs directly support pre-stressed transfer beam internal forces declined also. Other internal forces of frame-supporting column is get up or get down.2. Modal analysis showed that the pre-stressed have no effect on dynamic characteristics. In horizontal seismic action, the pre-stress main affect the internal force of transfer floor. Internal force of frame-supporting column in model 2 of decreases more than half, and it become more uniformed.3 Pushover Analysis results shows that the model 2 compared to model 1 under the horizontal load effect the transfer pre-stressed reduce the stress of transfer beam, achieve the target displacement the base shear of model 2 is slightly higher than that of model1.4. Pre-stress reduces the tensile stress in the middle section of the tensile area, but has little effect on the stress in other parts of the transfer beam, the crack developing in tendons part have limited effect with larger vertical deflection.