| The research object of this thesis is the beam-column connections in steel structure without weld access hole, which is studied lessly in China. Firstly, the possibility of brittle fracture, the distribution on temperature and residual stress of the connections with or without weld access hole is definited by finite element thermal analysis. Secondly, through finite element analysis and experiment to compare and analyze the seismic behavior of the connection with or without weld access hole under cyclic load. This is to provide a new type beam-column connections in steel structure, and they can be for reference of engineering design of steel structure. Therefor, the study has certain scientific influence.The main contents and results of the study is as follows:(1) For using"Element Birth and Death"in the ANSYS software , the connections with or without weld access hole are analyzed by finite element thermal anaylsis. The layered model of welding is simulated by thermo-structure coupled direct method, whoes initial temperature is 1500℃and final temperature is 20℃. The results of calculation and analysis indicate that the welding residual stress of the connection without weld access hole is more outstanding in infall of the beam flange and web. And the welding residual stress of the connection with weld access hole is more outstanding in infall of the beam flange and web and the end of fillet welds namely the end of weld access hole. However, because that the weld access hole has certain heat dissipating capability, the welding residual stress of the connection with weld access hole is relatively small in the infall of the beam flange and web.(2) Considering that the welding residual stress has little effect on the results of nonlinear analysis, it is ignored in structure loading analysis. Through the ANSYS soft to compare and analyze the seismic performance of the connection with or without weld access hole under cyclic load. The results indicate that the bearing capacity and plastic deformation capacity both somewhat increased, and the increase of bearing capacity is more obvious.(3) The seismic performance experiment of the connectons with or without weld access hole is done by MTS hydraulic servo-machine. The results indicate that there is brittle fracture in the connection with weld access hole more early, which starts from the end of weld access hole namely the infall of the beam flange and web. And which hysteretic curve pinchs. But the connection without weld access hole has no brittle fracture .Which hysteretic curve is plump and exhibits better dissipation capacity. Which ultimate load and plastic deflection both higher obviously than the connection with weld access hole. By comparing the experiment results and finite element results of the two connections, ANSYS finite element analysis could well analyze the seismic behavior of the two connections, which accords well with the experiment results.The above research indicate that although the connection without weld access hole has certain difficult in processing technology, but its application in practical is not impossible. The research has proved the performance advantage of the connection without weld access hole. However, as a new type connection, it is going to be researched in depth. |
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