圆钢管轻集料混凝土构件抗弯性能的试验研究

进行了21根钢管轻集料混凝土以及8根空钢管的纯弯试验。通过对试件在加载过程中的挠度及表面应变的测试分析,研究钢管轻集料混凝土构件在弯矩作用下的宏观变形特征、弯矩-曲率关系和破坏模式,分析了轻集料混凝土强度、含钢率、剪跨比等主要参数对构件抗弯性能的影响。试验研究结果表明,钢管轻集料混凝土构件在纯弯矩的作用下,其宏观变形特征和破坏形态与钢管普通混凝土构件相似;内填的轻集料混凝土可以大大延缓或避免钢管局部屈曲的发生,钢管轻集料混凝土的极限抗弯承载力较空钢管提高了20%～30%,抗弯刚度也有所提高;在钢管和轻集料混凝土相互作用下,钢管轻集料混凝土受弯试件具有较高的抗弯承载力和良好的延性性能;含钢率是影响钢管轻集料混凝土抗弯承载力和初始抗弯刚度的主要因素,含钢率越大,初始刚度越大和构件极限抗弯承载力也越大;而内填混凝土强度和剪跨比对构件抗弯承载力的影响较小;与钢管普通混凝土研究结果的对比分析表明,在相同条件下,钢管轻集料混凝土与钢管普通混凝土的极限抗弯承载力大致相当。

An experimental study on the behavior of lightweight aggregate concrete filled circular steel tubes under pure bending load

Twenty-one lightweight aggregate concrete filled steel tubes (LACFST) and eight steel tubes were tested under pure bending load. The macroscopic characteristics of deformation, moment-curvature curves and failure mode were studied by analyzing the deflections and surface strains of the specimens. In addition, the effects of concrete strength, steel ratio and shear-span ratio on the bending capacity of the members were discussed. The test results indicate that the macroscopic characteristics of deformation, moment-curvature curves and failure mode of LACFST are similar to those of common concrete filled steel tubes (CFST). Not only the buckling of the steel tube is suspended or even avoided due to lightweight aggregate core concrete, but also the bending capacity and rigidity are enhanced. The steel ratio has the most significant effect on the flexural capacity of the member, while the concrete strength and shear-span ratio have little effect.Comparison between the current work and the published data were carried out and it is found that the ultimate bearing capability of lightweight aggregate concrete filled steel tubes is close to that of normal concrete filled steel tube.