Research On Seismic Behavior Of Joints Of Heavy-Load Steel Tubular Columns Filled With Steel-Reinforced Concrete

With the perfection day by day of the concrete-filled steel tube theory and the wide application in engineering, the joint between the column of concrete-filled steel tubes and the beams has become one of the key technology problems of studying in the structure of concrete-filled steel tubes. The new type of composite column, which is studied in this thesis, is heavy-load steel tubular column filled with steel-reinforced concrete. This type of composite column has both very high bearing capacity (especially suitable to the columns with axial force, which is greater than 30000kN) and very high ductility. The joint design of heavy-load column is very important to prevent the collapse of buildings, and will play a significant role in resisting earthquakes and reducing disaster in city. According to the project of National Natural Science Foundation named "the design methods and aseismatic performance of joints of heavy-load steel-concrete composite columns"(No.50378010), investigations are carried out as follows:1. The design method of the new type heavy-load column is studied firstly. Based on the investigationg of research and application of joints and the character of the new type heavy-load columns, six joint forms of the new type of columns are given in this paper.2. Thirty-two joints, including the joints between the heavy-load columns and steel beams,and the joints between the heavy-load columns and reinforced concrete beams,have been designed and made for researched in the experiment. The dynamic behavior of these joints under low frequency cyclic loading is investigated. In term of the data obtained from the experiment, the index of seismic behavior to the joints are achieved, such as proportional coefficient on energy consuming and the coefficient of the ductility on displacement. By means of analyzing the index, we can know the properties of these new types of joints of steel-concrete composite columns.The test results show that these beam-column joints can provide very high shear strength and excellent quake-resist property.3. The calculation of shear strength of the joints. Based on the theoretical and experiment analysis, the shear formula of the connection core area is derived.4. In order to know the service behavior and bearing capability of this new type of joints entirely, it's necessary not only to analyze the data of experiment but also to make use of software ANSYS doing the finite element analysis on the structure of joint. In this paper, the finite element analysis results will be compared with the data of experiment. And the comparison show that the finite element model could be used to analyse this type of joint because of their good results.5. Base on the result of the reseach, the design suggestion and the mode of construcions of the joints are given in the paper. Through analysing these results of the test, the conclusion drawn from this paper can be used as a reference for engineering practice.