Research On The Influence Of Axial Force On Seismic Performance Of Precast Concrete Columns Connected By Grout-filled Sleeve

Precast structure is a new structure system assembled on site with important load-bearing elements. These elements are prefabricated in the factory. Precast structure has various advantages such as high construction efficiency, short construction period, energy conservation, environmental protection, recyclable and reusable of elements. Precast structure has been included in the 13 th Five-Year plan, which definitely shows that precast structure is an important direction in the architecture development process. The connection mode is the key factor that influences the seismic performance of precast structure, thus research and development of it is extremely urgent. Precast reinforced concrete frame structure is the important type of the precast structure. Grout-filled sleeve connection, grout-filled lap connection, mechanical connection are frequently used at present. It is easily found that the existing research mainly consider the compression column. In fact, the tension column is existed. For instance, verticle ground motion will induce tension bending failure. Therefore, seismic performance of grout-filled sleeve connection of precast frame columns with different compression and tension is researched in this paper.First, Six full-scale specimens are designed, including one cast-in-site column and five precast columns, and then pseudo-static test are carried out for these specimens. The tensile test includes one cast-in-site column and three precast columns, the other two precast columns are compression columns. The seismic performance of precast columns with different axial tension ratio and axial compression ratio are experimentally studied and analyzed. The test results show that grout-filled sleeve connection is reliable. There are few differences on strength, stiffness, ductility and energy dissipation between cast-in-site column and precast column with grout-filled sleeve connection. Morever, the ductility and bearing capacity of precast component increased at first and then decreased with the increase of axial tension. With the increase of axial compression ratio, the ductility decreases even more, while bearing capacity improves, yield and peak load increase significantly.Then six finite element models corresponding to test conditions and two compression cast-in-site columns models are built by ABAQUS, and then compare numerical simulation results with experimental results. Numerical simulation results are explained from the failure mode, stresses, skeleton curves, ducility and bearing capacity. The numerical simulation results are in agreement with the experimental results. The stress of sleeve is smaller than that of the steel bars all the time, and it's smaller than the ultimate stress of the material itself. It shows that sleeve will not be broken before fracture of steel bars, which meets the code of sleeve.Finally, according to results of tests and numerical simulation, design suggestions about precast concrete columns connected by grout-filled sleeve are proposed relevant measures are brought up. For instance, add steel mesh reinforcement in sleeve section and its involved fields to restrain the development of cracks, adding shear connector in the joint layer to decrease relative slip between column and foundation beam.