脚手架立杆套管接长下轴压稳定性研究

Study on stability of casting-extended scaffolding steel pipe under axial compression

为研究脚手架立杆套管接长下轴压稳定性能,对30根套管接长立杆进行了轴压试验,并对影响其稳定承载力的5个影响因素进行了有限元分析。研究结果表明:增加套管长度可以提高套管接长立杆承载力;当立杆长细比较大时,套管接长后具有较大初始缺陷,为此,建议长细比不宜大于135;脚手架立杆套管接长后受力性能与不接长立杆存在较大差异,其初始缺陷与GB 50018—2002《冷弯薄壁型钢结构技术规范》中规定值不同,试验稳定系数与规范最大差异达到-25.4%,为此,不建议直接引用该规范中稳定系数。有限元分析表明,接长比、间隙比和初始缺陷是影响稳定系数的主要因素,给出了不同初始缺陷下套管接长立杆稳定系数,并提出了修正的稳定设计公式,通过计算结果与试验结果比较,证明提出的稳定计算公式准确有效。

In order to study the stability of the casing-extended scaffolding steel pipe,axial compression tests of 30 casing-extended steel pipes were conducted.In addition,five factors affecting its stability capacity were examined using finite element analysis.The study shows that the bearing capacity of the casing-extended scaffolding steel pipe increases with the length of the casing.When the slenderness of the steel pipe is relatively large,the steel pipe has relatively large initial defects after the extension,therefore,the slenderness ratio should not be greater than 135.There is a big difference between the performance of the scaffold steel pipe with and without casting extension.Its initial defect is different from the specified value in the GB 50018—2002‘Technical code of cold-formed thin-wall steel structures’,and the maximum difference of stability coefficient between test and the code is-25.4%.For this reason,it is not recommended to directly quote the stability coefficient in the code.The finite element analysis shows that the extension ratio,gap ratio and initial defects are the main factors affecting the stability coefficient.The stability coefficients of casing-extended steel pipes under different initial defects were given,and a modified stability design formula was proposed.Compared with the test results,it proves that the proposed stability calculation formula is accurate and effective.