Nonlinear Analysis And Design Method Research On T-shaped Concrete-filled Steel Tubular Column-steel Beam Fream Top Side Joint

Special-shaped cross-section concrete-filled steel tubular column frame system is a new structure form in recent years, because its beam and column section havn’t extruded wall surface of the living room, it can not only save a building area, but also make the bedroom tidy and beautiful, which can satisfy requirement of person to the residence, so it has been used widly in high-rise residential building in our country.Joint is the part of framework system which is forced very complicatedly, playing a role of transforing^assigning internal force and ensuring structural integrity. A large number of data at home and abroad also show that there are many examples of the whole structure destruction caused by joint destruction when the earthquake action occurs, so joint is the key part of the framework structure, which has an important effect on the the seismic performance of whole structure.At present, studies about special-shaped cross-section concrete-filled steel tubular frame joint are still few, especially for the seismic behavior research. This paper bases on the2009National Science Fundamental Project which named" mechanical properties and design method about special-shaped cross-section CFST column-steel beam joint "(the project approval number is50978033), designes and produces four T-shaped concrete-filled steel tubular column and I-section steel beam top side joints with outer reinforcement ring, on the basis of experiments, using large general software ABAQUS to establish the corresponding finite element joint specimens model, and carry on the whole process of analysis under the low cyclic loading. According to the results from the finite element numerical simulation, this paper analyzes the failure mechanism and stress distribution of each joint at the process of loading, aiming to make clear about microscopic stress state and macroscopicdeformation form of the joint, comparing theoretical results to experimental results, it found they have a good agreement. This paper still investigate the effects of axial compression ratio、concrete strength grade、 steel yield strength and steel pipe wall on the joint hysteretic performance through parameter analysis, it provides a foundation for further comprehensive studying on the special-shaped column joint.The current standards and technical regulations have not given the design method and calculation formula of shear capacity about special-shaped cross-section concrete-filled steel tubular column and steel beam joint, so this paper simplifies T section to square section according to the principle of equivalent stiffness, preliminarily discusses the calculation formula of shear capacity of joint zone, and put forward the concrete equivalent effect coefficient and steel tube equivalent influence coefficient, revises the existing calculation formula, but it has some sideness. and still remain to do further research.