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将板厚为0.48、0.75、1.00 mm的LQ550钢板及板厚为1.20、1.50、1.80、2.00、2.50、3.00 mm的S350钢板,与不同直径自攻螺钉组合,进行了111个抗拉脱性能和105个抗拔性能试验。基于试验结果,考察了各国规范的相关计算方法,对自攻螺钉连接抗拉不同破坏模式的影响因素进行了探讨。研究结果表明:抗拉脱承载力随着板厚和自攻螺钉的钉头(垫圈)直径的增大而增大;自攻螺钉连接的抗拔承载力与板厚成正比,且比例系数和板厚与螺纹间距之比有关。对于普通薄钢板S350的受拉承载力,钢板板厚大于1.5 mm时,《冷弯型钢结构技术规范》征求意见稿建议的公式仍然适用。对于高强超薄板LQ550的钢材受拉承载力,征求意见稿中的设计值相对偏于不安全,需考虑折减。为防止自攻螺钉钉杆拉断,由试验确定的螺钉杆的抗拉承载力设计值不应小于自攻螺钉连接抗拉承载力设计值的1.25倍。
The LQ550 steel plate with the plate thickness of 0.48, 0.75 and 1.00 mm and the S350 steel plate with the plate thickness of 1.20, 1.50, 1.80, 2.00, 2.50 and 3.00 mm were combined with self-tapping screws of different diameters to carry out 111 pull- 105 anti-pull performance test. Based on the test results, the relevant calculation methods of different countries were investigated, and the influencing factors of different failure modes of self-tapping screw connection were discussed. The results show that the bearing capacity of anti-pull-off increases with the increase of the plate thickness and the diameter of the nail head (washer) of the self-tapping screw. The pull-out bearing capacity of self-tapping screw is proportional to the plate thickness, Thickness and thread spacing ratio. For the ordinary thin steel plate S350 tensile load capacity, plate thickness greater than 1.5 mm, “cold-formed steel structure Technical Specifications” formula proposed in the draft still applies. For the high-strength thin-plate LQ550 steel bearing capacity, the draft value of the design proposal is relatively insecure, need to consider reduction. In order to prevent the tapping screw rod from breaking off, the designed value of the tensile strength of the screw rod determined by the test should not be less than 1.25 times the design value of the self-tapping screw connection tensile load capacity.