Anti-collapse Mechanism Analysis Of Frame Structure Under Considering Cast-in-situ Concrete Slab Reinforcement Effects

The cast-in-situ floor and the frame-beams have the best coordinated ability, thefloor can improve the beam bending stiffness and flexural strength significantly. Therectangular section beam is designed under the force after considering the bendingstiffness from the floor, which underestimate the bearing capacity contribution, the beamsteel bar and the slab steel bar work together even without considering the longitudinalreinforcement paralleled with the beam in the plate and enhanced the actual bendingstrength of the frame beams. Therefore, studying the impact of the steel plate inside theboard is a necessary link to solve "strong column weak beam" problem.In order to research the cast-in-situ floor leads to "strong column weak beam", theframe structure of3x2across six floors was considered as the research object, whosequality and stiffness distribution are uniform, the fortification intensity is8degrees andthe design basic earthquake acceleration is0.2g, the seismic grade is the second, Ⅱkindof site, use the PKPM software of2008version to get the frame beam-columnreinforcement and select the corner node, border node, middle node in the first layer asthe research object. Reduce part of the upper longitudinal reinforcement at the girder endsparalleled with the board bar so as to consider the influence of the cast-in-situ reinforcedslab under the horizontal load, which makes its nodes satisfy "strong column weak beam"seismic design requirements, and satisfy the requirements of the beam bending strength,and put out the most reasonable column end bending moment increase coefficient.Use the software ADINA to finish nonlinear analysis about the framework structurejoints, and comparative the stress-strain relation between the steel stress of beam, plateand column, and research cast-in-situ floor produce "super" influence about the bearingcapacity in the framework, and puts forward the effective flange width floor value, thenputs forward the “strong column weak beam" design calculation method and reasonablesuggestions with considering the longitudinal reinforcement inside the plate.