Portal Frame Structure With Overall State Of The Elastic-plastic Stability Analysis

Portal frame structure system is well supported by the plane frame, tie bars, purlins space consisting of longitudinal members such as the overall structure of system. The current designed specification will convert it into a flat structure elastic force analysis, and in accordance with each member of the force characteristics limit state design, but according to the structure of the elastic state calculation of the internal forces of each component in the structure of the component is not reached the limits of the actual state of internal forces. The results obtained through this method can not accurately measure the capacity of the security architecture. A more comprehensive measure of portal frame structure system security door frame capacity should consider each component of the actual space mutual restraint, the overall space limit state stress analysis.Based on this, through the ANSYS finite element software, considering the span, cross-height ratio, lateral stiffness of the support for the door frame structure in the space of ultimate bearing capacity of the overall state of the whole process of analysis in the different working case, obtained in each span and cross bracing under high lateral stiffness ratio and spatial relationship between the overall bearing capacity, as well as supporting the overall force in the spatial distribution of the limit state.Analysis shows that different conditions and different spans and heights door frame structure, when it reaches its limit state instability patterns are different. Despite the support of the lateral stiffness can not decide on structural instability mode, but can be improved to some extent the structure instability occurs when the ultimate bearing capacity, improve the overall force structure condition. Based on the overall portal frame structure with flexible working conditions, the model obtained through an example of the support forces are generally higher than the norm algorithm supporting forces. In the vertical load and lateral horizontal loads reached the limits of the state structure, the support member generated forces, and contrast in the elastic sessions supported by the longitudinal loads generated by wind forces, in this case brace force can not be ignored, and with the structure of the span increase the support force increases.