A novel built-up column (BUC) under axial compression was experimentally investigated. The BUC consisted of four cold-formed thin-walled rectangular tubes assembled with several V-type or I-type connectors by self-tapping screws. Based on the axial loading tests of ten novel BUCs, the compressive stability of BUCs was studied, including the ultimate bearing capacity and failure mode. The relationships between load and axial shortening, lateral displacement and strain of the tubes were measured in tests. The test results were compared with predictions of codes (AISI S100-07 and GB 50018-2002) and a modified design method was developed. The results showed that the BUCs composed of four rectangular tubes assembled with V-type connectors and I-type connectors are different from classic latticed columns and battened columns in the calculation model of the transverse displacement produced by shear force. The predicted values calculated according to the suggested design method were found to be in good agreement with the experimental values of the novel BUC.

中文翻译：

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由四个冷弯管组成的新型组合柱的性能

实验研究了一种新型的轴向压缩组合柱（BUC）。BUC由四个冷成型薄壁矩形管组成，这些矩形管通过自攻螺钉组装有多个V型或I型连接器。基于十种新型BUC的轴向载荷试验，研究了BUC的压缩稳定性，包括极限承载力和破坏模式。在测试中测量了载荷与管的轴向缩短，横向位移和应变之间的关系。将测试结果与代码预测（AISI S100-07和GB 50018-2002）进行了比较，并开发了一种改进的设计方法。结果表明，在由剪切力产生的横向位移的计算模型中，由四个矩形管组成的BUC与V型连接器和I型连接器组合而成，不同于经典的格子柱和板式柱。发现根据建议的设计方法计算的预测值与新型BUC的实验值非常吻合。