Study On Earthquake-resistant Behaviors Of Underpinning Joints Of Building Moving

With the development of society, the structure underpinning technology has been widely used in large numbers of projects, and underpinning is one of the key links for monolithic moving technology, which is the key to success for moving. In monolithic moving structures of our country at present, the frame structures take a large proportion. With the increasing of layers and column spacing of moving buildings, axial force of frame column is biger and biger, which is put forward higher requirements for design. In recent years, many scholars studied on force mechanism of underpinning joints, attaining a series of theoretical research achievement, but they mainly focused on underpinning joint under static vertical load, lacking of systematic research on earthquake-resistant behaviors. What is more, in recent years, due to Wenchuan, Ya’an earthquakes, causing a huge of economic losses and painful injuries, therefore the research on seismic-resistant behaviors of underpinning joints is very important.Three specimens were designed in this paper, with the height of joint surface200mm,300mm,400mm separately, in order to research the influence on force mechanism and seismic-resistant behaviors of different height of joint surface by the method of combining abaqus finite element analysis with experiment.Firstly, it was analysed including mechanical characteristics, failure mode and the maximum horizontal bearing capacity of underpinning joint under reciprocating loads. Then the test piece was designed reasonably, and the reasonable test program was chosen.MTS was selected as test loading device, obtaining horizontal displacement and horizontal forces by sensor of the MTS hydraulic servo, capturing strain of steel and concrete by strain gauge and strain acquisition instrument. They were used to get the rule of crack propagation and distribution, the percussive load displacement curve and the main strain component. According to the test result, we got the failure mechanism of the structure, the percussive skeleton curves, the yield load and ultimate load, the displacement ductility coefficient, energy dissipation performance and stiffness degradation curve. Through the analysis of these contents, the following conclusions were gotten:different heights of surfaces had little effect on the bearing capacity, but impact failure modes. Node destruction happened when surface height is small, and the cracks of connecting beam developed rapidly; bending failure of column happened when surface height was large, and the combination of surface shows good, which conforms with the requirements of the seismic "strong node and weak components". Hysteresis curve had a "pinch" phenomenon, but the smaller of combined surface height was, the more obvious of "pinch" was, resulting in a greater amount of slippage.Compared with the results of the analysis, and the test results and the analytical results were basically identical with each other, illustrated that it is feasible to simulate seismic testing by the finite element software of ABAQUS.Finally, the stress mechanism and failure modes of underpinning joint under cyclic loads was concluded, with advice for future theoretical research provided.