考虑面力效应的端约束轻骨料混凝土梁受弯性能试验研究

Flexural tests on lightweight aggregate concrete reinforced beams with boundary constraints induced membrane actions

防护工程中的梁板构件受边界约束会在结构内部产生“面力效应”,导致结构承载力提高和破坏模式改变。根据结构的受力特点,设计了一套特殊的边界约束装置,研究竖向荷载作用下轻骨料混凝土梁的受弯性能及面力效应。对3个简支、7个两端约束的轻骨料混凝土梁试件进行了四点弯曲试验,得到了各试件的荷载-挠度曲线、裂缝分布及拉杆拉力-挠度曲线,同时对轻骨料混凝土梁的边界约束、配筋率以及是否掺加纤维对抗弯性能的影响进行分析。结果表明：边界约束越强,面力效应越明显,梁的承载力提高幅度越大;面力效应有效控制了裂缝的产生和发展,提高了构件的极限荷载。

In protective engineering, the capacities and failure modes of beam-slab structures are changed due to the membrane actions raised from boundary constraints. A special experimental setup, according to the mechanical characteristics of beam-slab members, was designed to investigate the bending resistance and membrane actions of lightweight aggregate concrete reinforced beams under lateral loads. Four-point bending tests were conducted on a total of ten lightweight aggregate concrete reinforced beams, including three simply supported beams and seven restrained beams. The load-deflection curves and crack patterns of the beams, the tension-deflection curves of tie rods were obtained. Furthermore, the effect of boundary constraints, reinforcement ratio and fiber volume on the bending resistance are analyzed. It is indicated that stronger the boundary constraints, lead to a more obvious effect of membrane action, and consequently a higher capacity of the beam. The results presented in the paper can provide a reference for future studies on the capacities of lightweight aggregate concrete reinforced beams under combined membrane action and lateral loading.