Nonlinear Finite Element Analysis On Joints Of Unequal Depth Beams To Square Steel Tubular Column To H Shaped Steel Beam With External Diaphragms

With the rapid development of economy and society,quality of people's lives has gradually improved.Environmental protection has become the theme of this era.Therefore,steel structure attracts more people's attention gradually.However,on account of the different function partition of the steel structure buildings,the span of the beam of the column on both sides is often different.Based on the function of structure and engineering economy,this paper presents a project that H-shaped beam whose height is smaller is used to the side of the little span.Unequal-depths-beam joint is that changing the original joint with same beam depths into the irregular joint with different beam depths in the unequal span steel structure.On basis of the results of the existing test of unequal-depth-beams joint,comparing the finite-element calculation of ABAQUS with the test result firstly,which proved that finite element modeling is accurate.Analyzing beam depth ratio,width to thickness of column,ratio of axial compression,width ratio of column to beam,width to thickness of beam flange,height to width of beam web,aspect ratio of entire panel of unequal-depth-beams by finite analysis.Comparing the influences that different parameters towards yield mode,shear bearing capacity,the initial stiffness of shear force-shear deformation curve(V-? curve),stress distribution sate of yield and plastic point of unequal-depth-beams,under monotonic loading.The main conclusions are as follows:(1)The V-? curve is similar to skeleton curve of test result in unequal-depth-beams joints' panel zone under monotonic loading.Thus,replacing cyclic loading with monotonic loading to analyze the effect of various parameters on the panel zone's mechanical performance in FEM.(2)When the joint types changed from equal-depth-beams joint to unequal depth beams joint,the panel's shear-bearing capacity decreased evidently,While reducing the beam depth ratio of unequal-depth-beams joint has little influence on the panel's shear-bearing capacity.The panel's initial stiffness didn't change significantly with the decrease of the beam depth ratio.When the beam depth ratio reduced,the area of high-stress zones in the panel decreased,but the width to thickness of column has great influence on the area of high-stress zones in yield point and plastic point.The width to thickness of column is higher,the area is bigger.In the meantime,the panel's shear-bearing capacity and the initial stiffness decreased obviously.(3)With the increasing of ratio of axial compression,the panel's shear-bearing capacity decreased and the initial stiffness altered little.High ratio of axial compression will make the panel yielded come earlier,but smaller width to thickness of column needs bigger ratio of axial compression.(4)With the increasing of the width ratio of column to beam,the bearing capacity of the panel is increasing.But the increasing has no obvious effect on the initial stiffness and the area of high-stress zones in the panel.With the reducing of the width to thickness of beam flange,he bearing capacity of the panel is greater,but the initial stiffness has little change.With the increasing of width to thickness of beam flange,the high-stress zones in the panel can be extended from panel 1 to panel 2 in the entire panel,and eventually cause the entire panel to yield.The changes of height to width of beam web have no effect on the mechanical performance of the panel.When the aspect ratio of entire panel increases,the shear capacity of panel decreases,but the initial stiffness and the high stress distribution are not changed.(5)Unequal-depth-beams joint will occur two kinds of yield modes at the plastic point,named global yield and local yield.The main influential factors are width to thickness of column,ratio of axial compression and width to thickness of beam flange.