Analysis Of The Influence Of Local Constraints On The Mechanical Behavior Of Portal Frames

The portal frame structure in accidental loads encountered large too large deformation or even collapse,if by directly increasing cross-section area to increase the structural safety degree is too redundant waste,can not reflect the economic performance of light steel structure.In this paper,the failure modes and mechanism of portal frame structure based on the proposed near the beam column joint of portal frame is added(rib plate,flange,outsourcing stick)idea of local constraints proposed by local constraints to improve the mechanical properties of the whole portal frame structure,improve the portal frame structure the overall safety redundancy degree,to improve the portal frame structure under extreme loads of collapse resistant capacity.In order to investigate the local constraints of portal frame structure stress performance,through the portal frame stress characteristics and failure mechanism analysis,the factors to determine the local constraints imposed and the main influence to establish three kinds of numerical models of ultimate bearing capacity analysis and hysteretic performance analysis,analysis showed that: part of the internal force of beam and column local constraints can share the constraint position,reduce the peak value of stress zone,and the stress distribution tends to be uniform,the local constraint can delay or prevent the nodes near the beam column portal frame flange or web local buckling or yield,improve the bearing capacity and energy dissipation structure the limit,obviously improve the stress performance of portal frame structure;local constraint does not affect the basic ductility of portal frame structure;local added outsourcing board,posted outside the flange than the Bureau With the rib to improve portal frame structure of ultimate bearing capacity and energy dissipation capacity,improve the hysteretic performance effect is more obvious;for local portal design outsourcing board and with flange frame,increased the scope of the arrangement than to increase its thickness onimproving the mechanical performance for more for the local portal;a floor frame,reducing floor spacing than increase floor layout on improving the mechanical performance of the larger.In this paper,the influence of local constraint on the mechanical behavior of portal frame structures is preliminarily studied,which can be used as a reference for the application of local constraints in portal frame structures.