（中国矿业大学建筑工程学院，徐州  221008）
［摘要］荷载比率、轴向支撑刚度对约束钢梁的性能影响很大，各国学者对其研究主要还集中在升温阶段。对约束钢梁进行了升降温全过程的承载性能试验，给出了钢梁跨中挠度、轴向支撑应变和柱底水平推力在整个升-降温过程中的变化情况。试验结果表明：钢梁跨中挠度和轴向支撑应变都有不同程度的恢复。泼水冷却过程中也会引起结构或构件的破坏。无支撑或弱支撑情况下，失稳类别为梁端局部失稳；强支撑情况下，失稳类别为梁的整体失稳。同时冷却阶段钢材的强度得到恢复，这对梁的承载能力是有利的；但由于梁的收缩，梁内将产生收缩拉力，加之柱对梁端转动的约束引起的附加弯矩，这些对梁两端的节点是很不利的。基于此，最后从框架节点和钢框架整体两个方面提出了相应的钢框架抗火概念设计建议。
［关键词］约束钢梁；升-降温全过程；支撑刚度；失稳类别；抗火概念设计；试验研究
Experimental investigation of behavior of steel beams with axial restraint in cooling phase at elevated temperature
Sun Dongming, Xia Junwu, Long Moushi(School of Architecture and Civil Engineering, China University of Mining and Technology, Xuzhou 221008, China)
Abstract:Load ratio and stiffness of axial restraint have a great influence on the behavior of steel beams with axial restraint. Scholars home and abroad mainly concentrated on it in heating phase. So the whole-process experiment from heating to cooling phase was conducted, the development of mid-span deflection, strain of axial bracing and horizontal force at column base were presented in the whole-process. It shows that mid-span deflection and strain of axial bracing have different degrees of reversal. Breakage of members or structure occurred in splashing cooling phase. Beam with weak axial bracing results in local buckling at beam end, strong overall instability. Due to the strength reversal, it is advantage to loading capacity of beam. On the contrary, it may be disadvantage to the joints owing to shrinkage tension resulting from temperature decreasing. Based on these phenomena, advice in conducting anti-fire conceptual design is put forward on both joints and steel frame.
Keywords:steel beam with axial restraint; the whole-process in heating and cooling phase; stiffness of axial bracing; buckling mode; anti-fire conceptual design; experimental investigation
作者简介：孙冬明(1980-)，男，江苏靖江人，博士，一级注册结构工程师，主要研究钢结构防火，采动区建筑保护。
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