(1 南京水利科学研究院 210029；2 清华大学土木系 北京 100084)
［提要］为研究钢混凝土组合梁的弯扭性能，完成了6根箱形组合梁的纯扭和弯扭试验，详述了在不同扭弯比下箱形组合梁的受力性能及破坏形态，对裂缝发展和应力的变化情况进行了分析，揭示了箱形组合梁在弯扭复合作用下，极限扭矩和极限弯矩会相应提高的机理。对组合梁扭型破坏和弯型破坏进行了对比分析，指出了根据传统的弯剪扭相关方程而得到的相关公式的不合理性，并给出了在复合弯扭和弯剪扭下的相关公式，得到的结论能为组合梁计算和分析设计提供参考。
［关键词］ 闭口钢混凝土组合梁 复合弯扭 试验分析
Experimental Study on Composite Steelconcrete Beams with Box Sections Under Combined Bending and Torsion/Hu Shaowei1,Nie Jianguo2(1 Nanjing Hydraulic Research Institute，Nanjing 210029,China; 2 Dapartment of Civil Engineering,Tsinghua University,Beijing 100084,China)
Abstract:In order to investigate the behavior of composite steelconcrete beam with box sections under combined bending and torsion，six specimens are tested.Based on different  bendingtorsion ratios，the experimental results，including loading behaviors，failure modes，cracking behavior and stress development are analyzed in detail.The reasons why its ultimate torsion and ultimate bending becomes increase when composite steelconcrete beam with box sections are loaded under combined bending and torsion,are found out.Both its tensional failure and bending failure are compared and analyzed.The current bendingsheartorsion relativity equation is unreasonable.Then，the interaction equations of composite beams subjected to flexure combined with torsion and to flexure combined with shear and torsion are given respectively.Finally,many valuable conclusions are gotten and can be used in design and analysis practice of composite steelconcrete beam with box sections.
Keywords:composite steelconcrete beam;box sections；combined flexure;torsion