Study On Moment-Rotation Relationship Of End-Plates Connection Semi-Rigid Beam-to-Column Joints Of Steel Frames

Steel structure has been used widely in industrial and civil construction especially in high-build with the rapid development of city economy in our country. As the key part of the beam-column connection in the structural steel frame, the connected capacities influence the integral mechanics capability of the whole frame structure on loading. To make analysis and design procedure simple, the traditional analysis and design of steel frame assume beam-column connections are ideal Pinned connections or fully rigid connections. ideal Pinned connections means no moment could be transferred from beam to column, so rotations of beams and columns are independent each other; And, fully rigid connections means included angle between beam and column holds the line, from unchanged frame without loads to transfigured frame with loads. However, experiments prove that all connections of the steel structures are semi-rigid connections, which are between fully rigid connections and ideal pin connections. The analysis of steel frames adopting the assumption can simplify the procedure of analysis and design, but cannot precisely reflect structural practical circumstance and the errors of calculating results are large, even, get incorrect conclusions. So it is necessary to research the feature of beam-column semi-rigid connections. The research of our country in this respect is later than abroad, and the research is much more in-depth abroad, but the research results are not always suited to the situation of our country. Flush end-plate connection is a typical semi-rigid joint,the work of this paper follows the subject. The key content and study as follows:First, utilize ANSYS finite element to establish three-dimensional finite element model to simulate the flush end-plate connection semi-rigid steel frame beam-to-column joints. The analytic results compare with the test results of predecessor and they are comparatively same. So this proves that utilizing ANSYS finite element to analyze the flush end-plate connection semi-rigid steel frame beam-to-column joints is feasibility.Second, utilize ANSYS finite element to analyze the flush end-plate connection semi-rigid steel frame beam-to-column joints, and distill displacement-deformation chart of each member. We can see from the chart that the flush end-plate occurres biggish rotation distortion, and this minishes segmental bending moment and axis force which transferred to the column, so flush end-plate connection semi-rigid steel frame beam-to-column joints possesses better ductility and aseismatic capability. Distilling Von-Mises stress map of each member from ANSYS finite element software, we can see that, under symmetrical load action, bolting connection zone and column ribbed stiffener zone of flush end-plate connection semi-rigid steel frame beam-to-column joints has much biggish stress, and the stress concentration is bad. The part of flush end-plate which lies aboard the top limb flange of the column has biggish stress, and reaches yield primarily, the mid-part of the flush end-plate has much less stress correspondingly. The mid-part of the screw of the upside bolt has much biggish stress.Third,study the influencing factor of work behavior of the flush end-plate connection semi-rigid steel frame beam-to-column joints by changing parameter, and get the impact law of work behavior of flush end-plate connection semi-rigid steel frame beam-to-column joints due to changing end-plate thickness,bolt diameter,space between bolts,ribbed stiffener of the column belly board,section height of the beam. While the end-plate thickness is less, with increasing the thickness, the moment-rotation curve has evident change, and the initial rotational stiffness and the plasticity bending bearing capacity increases evidently. While the end-plate thickness is much biggish, with increasing the thickness, the moment-rotation curve does not change, and the initial rotational stiffness and the plasticity bending bearing capacity is changeless. The reason which causes this change rules is that the breakage model is not same. Increasing the bolt diameter has less impact on the joint initial rotational stiffness. On occasion that the screw has no yield and the bolt does not break, with increasing the bolt diameter, the plasticity bending bearing capacity advances a little.Space between bolts has some impact on work behavior of the flush end-plate connection semi-rigid steel frame beam-to-column joints. When doing structural design, after considering that each member is installed expediently, we can take the bolt approach the beam web at horizontal direction as far as possible, and take the bolt approach the beam up and down wing edge at vertical direction as far as possible. The column web stiffener has a little impact on initial rotational stiffness and plasticity bending bearing capacity of the flush end-plate connection semi-rigid steel frame beam-to-column joints. Increasing the section height of the beam can improve the initial rotational stiffness and plasticity bending bearing capacity of the flush end-plate connection semi-rigid steel frame beam-to-column joints effectively. Four, Summarize the predecessor research of the moment-rotation relationship mathematics equation. Improve the moment-rotation relationship mathematics equation basing on the model advised by Europe steel structure criterion to fit flush end-plate connection semi-rigid steel frame beam-to-column joints.The research of this paper tries to supply theory gist, which has some reference worth, to revise our country steel structural design criterion, and make some slender contribution to perfect the design method of our country steel structure criterion. The research of this paper is only a corner of the iceberg, and has much next work to do.