Application Of Modified And Improved Component Method In The Constitutive Relation Research For Steel Connections

In traditional design of spatial steel frames, beam-to-column connections are idealized as rigid or pinned. As the research of steel joints continues, there is a wide recognition that the beam-to-column joints must be considered as semi-rigid which means that they have the capacity of bending and rotation. There are three main research methods in performance investigation of steel joins: Experimental study, Finite element analysis, Component method. So far, the application of component method was performed on the regular components of regular joints. There is little performance investigation on special components, and normative clause explanation has not been promoted.With the rapid development of steel structure in construction industry, steel joints with different kinds of connection form have been widely used in multi-story and high-rise steel frame structures. Rapid performance evaluation of steel joints has become more and more important, and it is necessary to modify and improve the component method.The main content of this thesis is depicted as follows:(1) Ten groups of different sizes of T-stub are designed for monotonic loading test. The influences of scale effect for the initial tensile stiffness and bearing capacity are discussed, the stress distribution, deformation characteristics, plastic development and failure modes are determined.(2) The accurate element models are established for comparable study with the experimental result. A theoretic formula of tensile stiffness for T-stub is derived.(3)Two internal extended end-plate connections with end-plate stiffeners are designed for monotonic loading test. The accurate element models are established for investigating the initial tensile stiffness influence of the stiffeners. The in-plane principal stress of stiffeners has been confirmed, a theoretic formula of tensile stiffness for stiffener is derived.(4)Three internal joints loaded along the major-axis including the two joints mentioned in section(3) and two internal joints loaded along the minor-axis are designed for monotonic loading. The mechanical characteristics of these joints are determined.(5)Combined with the experimental results of these five internal joints, the mechanical component models of each joint are extracted. The theoretic formula of each mechanical component model is derived. An accurate spring combination method is presented for each joint.(6) The finite element model, based on SPRING element, is established by Abaqus software. The spring stiffness of mechanical component model and the spring combination method are verified by this finite element model.(7) The calculation methods of initial rotation stiffness for different joints are promoted based on the SPRING element method. The calculation process of component method, the extracting of accurate component model, the setting of the boundary conditions and the accurate spring combination method are promoted through normative analysis. The difference between theoretical results and experimental results is also investigated.