钢-混凝土组合梁纯扭及复合受扭性能

为了研究钢-混凝土组合梁的扭转性能，对5根新型外包钢-混凝土组合梁进行了纯扭和复合受扭试验，研究了组合梁在纯扭和复合受扭作用下的破坏形态、工作机理以及裂缝开展分布的情况，比较分析了组合梁扭矩-扭率、荷载-应变、弯矩-挠度、荷载-裂缝开展之间的相互关系。通过对组合梁受扭性能的弹塑性理论分析，提出了在组合梁纯扭及复合受扭作用下的开裂扭矩计算公式；采用变角空间桁架模型，提出了该新型组合梁在纯扭及复合受扭作用下的极限扭矩计算公式。结果表明：理论公式计算结果与试验结果吻合良好，为评估结构的安全性及稳定性提供了依据。

Pure Torsion and Combined Torsion Behaviors of Steel-concrete Composite Beams

In order to study torsion behavior of steel concrete composite beams, pure torsion and combined torsion tests were conducted on five specimens of the new type steel-encased concrete composite beams. Authors studied this new steel encased concrete composite beam＇s destruction shape, worked mechanism and the crack development and distributed situation under pure torsion and combined torsion, and also compared and analyzed composite beam＇s relationships of torsion and torsion ratio, load and strain, bending and deflection, load and crack development. On the basis of elasto-plastic theory, the calculation formulas about cracking torsion of pure torsion and combined torsion were presented; and using spatial truss model with variable angle, formulas for ultimate torsion strength of pure torsion and combined torsion were proposed. The results are in good agreement with measured ones, and provide a basis for safty and stability evaluation of structures.