Study On Plane Stability Of Semi-rigid Protal Frame In Mining Subsidence Area

With the continuous exploitation of underground resources, a large area of mining subsidence area was formed, which has an effect on the upper building. At present in our country, there is much protal frame built in mining subsidence area and new protal frame in goaf. The surface deformation in mining subsidence has effects on plane stability of protal frame. At the same time, for the actual portal frame,different pillar connective stiffness will affect on the overall stiffness of structure, so that the surface deformation in mining subsidence has more effects on plane stability of semi-rigid protal frame. Therefore, there is great practical significance on the analysis of plane stability of semi-rigid protal frame influenced by surface deformation.This article mainly focuses on the research of plane stability and mechanismof semi-rigid protal frame influenced by surface deformation. Through full size simulative experiment, the reasonability of the result of finite element model is verified, which is semi-rigid protal frame under three kinds of surface deformation,including differential settlement surface deformation, stretch surface deformation and compression surface deformation. According to the change of the measured stress and lateral capitals, the result is that lateral surface deformation has more effects on plane stability of semi-rigid protal frame. The stretch surface deformation has the most effects on plane stability of semi-rigid protal frame. The differential settlement surface deformation has the least effects on plane stability of semi-rigid protal frame.Establishing finite model which has the same size and restraint with experiment by ANSYS. And then we can research our issue deeply.(1) The plane stability of semi-rigid protal frame with plinth rigid will be researched, which is impacted by differential settlement surface deformation, stretch surface deformation and compression surface deformation.(2) By two parameters, beam span deflection and lateral capitals, it studies that three rules have effects on plane stability of protal frame under above three kinds of surface deformation, including plinth restraint,beam-column joint stiffness and beam-column linear stiffness ratio.(3) Program by matlab. We can do a theoretical research on plane stability of semi-rigid protal frame under surface deformation deeply and comprehensively. And compare the theoretical result with the result by ANSYS finite element simulation. According to comparison,there is less difference. The main difference is that in finite element simulativecalculation, when the protal frame enter into plastic, the overall stiffness will decline,but the overall stiffness by theoretical calculation remain unchanged, lateral capitals will be smaller.Through series of research, it indicates that semi-rigid protal frame occurs antisymmetric instability under differential settlement surface deformation, but it occurs symmetric instability under lateral surface deformation. The semi-rigid protal frame occurs P- effects by coaction of vertical load and differential settlement surface deformation under differential settlement surface deformation. The semi-rigid protal frame occurs P-! effects by coaction of vertical load and dstretch surface deformation under stretch surface deformation. To some extent, the vertical load can protect plane stability of semi-rigid protal frame under compression surface deformation. The semi-rigid protal frame with plinth hinged has less ability to resist surface deformation than semi-rigid protal frame with plinth rigid. The semi-rigid protal frame has better ductility than rigid portal frame, so it has better plane stability.In the economic and useful conditions permitted, we should choose semi-rigid protal frame with smaller beam-column linear stiffness ratio.