| In steel frame beam-to-column connections play a vital role in transferring bending of moments and shearing force, and their behavior affects steel frames overall performance under loads. Making a thorough research on the mechanic performance of beam-to-column connections possesses important theoretic and engineering reference value. High strength bolted connections and dog-bone connection are those of connections that were researched in some countries. There are not correlative clauses about these in steel structures Design Specification (GBJ17-88). The experimental research for beam-to-column connections of steel frame and the research influence on the steel frame is one subject of 2001'Key Research Subject of Ministry of construction of china, grant No. 01-2-085. Researching for of beam-to-column connections under cyclic loading, for the factors effecting on the connections, for the deformation and failure character of connections, the arising order of plastic hinges and load-deformation hysteretic behavior of three pane frame under cyclic loading, the effect of semi-rigid connections on the frames, is the major purpose of this study. So this paper includes some titles, such as:l.On the base of comparatively analysis about various design method to beam-to-column connections, some modified computing equations about the initial stiffness and ultimate moment capacities are presented, and the main factors influencing upon the behavior of connections are summed up.2.Pseudo-static force testing of twelve full-scale connections, including top-seat angle connections, two web flange and top-seat connections, extended-end-plate connections, slit-T steel connections and dog-bone connections are carried out for the first time in our country. The relations of M- θr, initial stiffness, the yield strength, failure models, ultimate strength, seismic behaviors and characteristic of dissipation of energy were gained in this test. The experimental results accorded with the analysis results very well.3. The stiffness matrixes equations, which can be applicable to perform second-order elastic-plastic analysis for semi-rigid connection steel frame, are derived. A two-dimensional nonlinear finite element program for semi-rigid connection steel frame is compiled successfully. It can calculate the internal forces and displacements of steel frame considering connections nonlinear, geometrical nonlinear and material nonlinear, therefore, it has strong suitability.4. Pseudo-static force testing of 1:2 scale models including two steel frame with semi-rigid connections is first carried out in china in order to obtain elastic-plastic behavior of semi-rigid connections steel frames under cyclic loading as well as to analyze collapse characteristic after structural ultimate strength has lost and thecoming order of plastic hinges. The internal force and the horizontal displacement of a steel frame are computed with the program in this paper. After the analysis results are checked against the experimental results and, it is founded that a satisfactory agreement is obtained in elastic phase and a discontented agreement is gained in plastic phase since the influence of residual stress, degradation of cross-sectional stiffness and the spread of plastic zone length cannot be taken into account in plastic hinges theory.5. Pseudo-static force testing of 1:2 scale models of a steel frame with dog-bone connections is first carried out in china in order to obtain elastic-plastic behavior of dog-bone connections steel frames under cyclic loading as well as to analyze collapse characteristic after structural ultimate strength has lost. The influence of dog-bone connection on the coming order of plastic hinges and failure characteristic of steel frame, and the influence of dog-bone's shape and position on the behavior of structure is obtained.6. Nonlinear analysis about three steel frames is carried out with ANSYS finite element software, and some beneficial conclusions are received against the experimenta...
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