Study On The In-Plane Stability Of Residual Stresses Portal Frame On Rotationally Restricted Simple Column Feet

When testing the in-plane stability of portal frame according to Technical specification for steel structure of light-weighted buildings with gabled frames (CECS102: 2002) enacted by the Standardization Institute of Chinese Construction in 2002, it usually takes the two staple simplified column feet as hinged column feet, which makes the designing work rather easily. However, it has been proved that the two kinds of column feet (especially the foot with four anchor bolts) actually have remarkable ability of rotational restrict with the deduction of theory and experiments. In referenced essay [55], the improved the stability of the frame is carefully studied, but the was not concerned. How much can the initialized objections affect increase of the stability? And how to take account of the affection in design?Aiming at the above-mentioned issues, considering partial residual stress in this paper, compared with the researches on the rotational restricted stiffness of column feet made before, with experimental information and relational analysis, two partial sealed residual stress modeling are introduced. Codes are modified which were made in referenced essay [55] based on second-order non-linear finite element methods and for analyzing overall stability of portal frame. Two typical modeling of partial residual stresses are introduced to compute stability of one-bay portal frame loaded by typical loads with computer. After that, it is compared with the results without the affection of partial residual stresses, studies the affection due to sealed residual stresses act on one-bay portal frame based on column feet by rotational restriction. It is concluded that sealed residual stresses has a faint impact on the anti-rotational ability of column feet with 4 anchor bolts, and the overall influences slightly decrease the in-plane stability of portal frame based on column foot by rotational restriction without the residual stresses. It is proved that this advantage could be used in design, saving lots of materials and simple measures are introduced as well. On the other hand, the infection on anti-rotational ability of column base with 2 anchor bolts is un-negligible. Moreover, the actual stability is less than Specification's when the diameter of anchor bolts and the thickness of column base plate are too small. So it is suggested that no improving the overall stable capacity could be introduced when column base is consisted of 2 anchor bolts. Only when the structure of column base is ensured, could the Specification's stable capacity be used safely.