The Robustness Research Of Portal Frame Failure Under Extreme Snow Load

The portal frame structure of the light roof is one of the most common architecturalstructures under the present steel structure engineering application. With the increasingfrequency of extreme natural disasters in recent decades, the portal frame structure systemis sensitive to snow load especially on extreme snowstorm, because its stability is less thanthe masonry and concrete structure, it leads to the structure failure with extremesnowstorm. According to the different forms and the loss or damage of frame structuredamage, this paper selected a greater impact form caused by structure failure and madefurther analysis on the internal plane collapse.There are lots of internal factors influencing in portal frame structure. This paperselected five more significant affected factors. It can be obtained the unknown connectionbetween ultimate bearing capacity and many influencing factors through buliding thesignificant response surface simulation function of the established form. The test schemeof solving response surface function are obtained by central composite designs. It can beobtained ultimate bearing capacity based on MSC.MARC under the extreme snowstorm.For many factors influencing on ultimate bearing capacity, we can change the allowabledeviation of beam-column plate thickness and steel yield strength. Then we can obtain theresponse surface model of steel ultimate bearing capacity meeting significant requirementsby MATLAB.Based on the response surface simulation function of steel ultimate bearing capacity,it can be screened the significant factors by variance analysis, ignoring less influencingfactors and regained response surface simulation function. In order to making the furtheranalysis of robust distribution characteristics, the response surface simulation function isgreatly simplified based on minimizing the significant influence of simulation function.By analysing the response surface function distribution characteristics of ultimatebearing capacity of rigid frame, we can think that the design factors specified by relevantcodes have the greater influencing on ultimate bearing capacity of the steel frame in the range of allowable deviation or fluctuation. Generally sensitive factors have notnecessarily robust region near the design value.