Analysis Of The Overall And Local Buckling Behavior Of High Strength Steel Welded I-beams

High strength steel has been successfully applied in many building structures and bridge structures, and achieved good economic and social benefits. Because of the difference among the performance of materials, the processing technology, the initial defects and other aspects, there is some difference in overall stability and local stability between high strength steel and ordinary strength steel. While the related research for high strength steel welded I-beam stability performance is seldom. Therefore, there is no specific design code to guide the design calculation of the high strength steel welded I-beams. The paper studied the overall stability and local stability properties of the high strength steel welded I-beams through finite element analysis, and modified the related formulas. The main work and the conclusions include the following aspects:(1)According to the general method to process the initial geometric imperfections and the existing model of residual stress distribution which is applicable to high strength steel, the finite element model considering the initial geometrical imperfections and residual stress influence was established. Through the parameter analysis, the affection to the overall stability of high strength steel welded I-beam has been studied, caused by initial geometric imperfections, section residual stress, steel strength grade, ratio of section height to width(ratio of distance between upper and lower flange surface and the width of compression flange), load type and cross section form.(2) According to the nonlinear buckling analysis, the paper got the overall stability bearing capacity of different strength grade of high strength steel welded I-beams, proposed the overall stability coefficient calculation formula of high strength steel welded I-beams, and provided the reference for the high strength steel welded I-beams calculation. The formula of index n of overall stability coefficient is given.(3) The paper studied overall stability bearing capacity of 4 strength grades of high strength steel welded I-beams under concentrated load and distributed load. According to pattern of the bearing capacity changed as the steel strength grade, the depth to width ratio and normalized slenderness ratio, summarized the calculation formula of the overall stability of high strength steel welded I-beams under the concentrated load and distributed load.(4)By finite element analysis, the shear bearing capacity of high strength steel welded I-beams was researched. Considering the flange and web thickness ratio against the influence of shear bearing capacity, the calculation formula of shear bearing capacity of high strength steel welded I-beams is suggested on the basis of existing calculation formula of the ultimate bearing capacity.(5)Through finite element analysis of stable performance of web zone, the stability calculation formula modification suggestions are put forward.