Development And Research Of Bolted End-plate Steel Beams And Reinforced Concrete Columns Composite Structures

The welded moment steel connections are apt to brittle fractures, and a type of composite moment frame consisting of steel-encased reinforced concrete column and steel beam need welding in place, which results in poor constructability. However, some research has indicated that innovative details using post-tensioning and bolting can provide adequate strength and ductility for steel or concrete filled tubular moment resisting frames structures. In order to avoid the problems lying in the recent frame systems, and utilize various merits in types of frame systems, an innovative composite moment steel-concrete structure named as bolted end-plate dog-bone RCS frame structure is conceived by Professor Xiao Y.The new type of composite RCS frame structure not only possesses the common advantages of all the other types of composite RCS frame structures but also has special behaviors. It is expected to improve the constructability greatly. As we know, composite moment steel-concrete structures will become one of the main structural systems of mid-rise to high-rise buildings in the future. Therefore, bolted end-plate composite RCS structures have very high applicable values in engineering. Thus it is very necessary to research the seismic performance of the new type of structural system. Because the research of RCS joint as major force-transferring component is the key problem on the research of RCS frames, the seismic behavior of the new connection is discussed mainly in this thesis.In the thesis, bolted end-plate connection and dog-bone connection are reviewed and researched. In addition, three full-scale exterior beam-column model connections have been tested under cyclic loads. Furthermore, the seismic performance of the new type of joint and the parameters affecting the seismic performance as well as stress-transferring mechanism are analyzed in detail.The new type of joint shows stable and very high strength. Its initial stiffness can be estimated based on the assumption of rigid connection using the elastic stiffness of steel beam and reinforced concrete column. The dog-bone steel flange can protect the welds, meanwhile it will be able to result in a longer plastic zone formed in the flange, thus providing greater ductile deformation and more excellent energy dissipation capacity.