Mechanical Properties Of The Beam-Ccolumn Connections For Considering The Effect Of Stiffeners In RBS Steel Beam

The study is about dog-bone connection which has good seismic performance, and the three schemes in weaken area of RBS steel beam setting stiffeners are considered. The same size specimens are made for the pseudo-static experiment under cyclic loading, and the corresponding finite element analysis is done, to make sure the reasonable scheme which can improve the bearing capacity and energy dissipation capacity. In order to analysis and research clearly, there named common dog-bone connection STF-0, dog-bone connection with a pair of stiffeners in the center of the weaken part is named STF-1, common connection with two pairs of stiffeners, arranged at the boundaries dividing weaken portion into three equal named STF-2-1, with two pairs of stiffeners, arranged at the end of the weaken portion is named STF-2-2.In this thesis, the nonlinear program and analysis method are firstly made sure, ABAQUS software is used to have numerical simulation. Through the finite element analysis, the stress contours and the last damage states of the four connections in the cycle load are gained, and the load-displacement hysteretic curve, skeleton curve and main performance parameters in the loading point are analyzed. From the stress contours, compared with STF-0, the bearing capacity of STF-2-2 is improved, the local buckling is delayed, plastic hinge is formed in the weaken part. This is in accord with plastic hinge off shoring intentions and improving the connection bearing performance. STF-1 and STF-2-1 have good mechanical properties, but their plastic hinges lateral migration to column.Secondly, the pseudo-static experiment with low cycle load is done with the same size specimen, there get hysteretic curve of load and displacement in the loading point on the beam end and strain analysis data in the key position. Through the analysis of hysteretic curve,the four models skeleton curve and the main performance parameters are shown. The analysis results are generally consistent to the test results through comparing them, and a conclusion is draw, that is, the specimens with stiffeners may delay the local buckling and damage, STF-2-2 is the best choice through considering the above factors and plastic hinge position comprehensively.Finally, in order to define the stress distribution and development rules of the key parts, the four kinds of connection models are established by ABAQUS, and the 3-D nonlinear finite element analysis under monotonic load is accomplished. Then, the stress distributions of model at the elastic and elastic-plastic stages are obtained, and the stress paths in the key parts of beam-column connections are analyzed through the finite element software functions at the elastic and elastic-plastic stages. The results show that STF-2-2 can slow the stress increasing speed and delay the local buckling occurs.To sum up, STF-2-2 is an improved scheme in the bearing capacity and energy dissipation capacity compared with STF-0, and also conforms to the basic idea of plastic hinge off shoring. When the dog bone type connection is applied, the scheme STF-2-2 of setting stiffener can be used, so as to better safeguard anti-seismic performance of connections.