圆截面钢管混凝土受弯构件试验研究

通过4个圆截面钢管混凝土受弯构件的试验研究，对其基本静力性能进行分析。结果表明，在本文试验参数范围内，圆截面钢管混凝土受弯构件的荷载一跨中挠度曲线可以划分为以下3个阶段：弹性阶段、弹塑性阶段和增强阶段；所有试件均在跨中挠度达到大约1／200跨度时结束弹性阶段。环向应变沿截面圆周分布不均匀：纵向受拉最大点环向压应变最大，纵向受压最大点环向拉应变最大。从加载之初直到大约0．7倍极限承载力，纵向应变沿截面高度分布基本符合平截面假定。试件的屈服与钢管的纵向受拉屈服几乎同步发生。对于同一点，纵向受压则环向受拉，反之，纵向受拉则环向受压；纵向受拉点的钢管对混凝土没有约束作用。

Experimental study on concrete filled circular steel tubular flexural members

Several basic static performances about the concrete filled circular steel tubular flexural members were analyzed based on 4 pieces of specimens test.It was found that,within the factors scope of this test,load-middle span deflection curve of concrete filled circular steel tubular flexural members could be defined as following stages: elastic,elasto-plastic and strengthening stage;all members finished their plastic period when middle span deflection reach about 1/200 times the span.The circumferential strain does not distribute uniformly: circumferential compression strain is the biggest at the point that longitudinal tension strain is the biggest,circumferential tension strain is the biggest at the point that longitudinal compression tension strain is the biggest.Longitudinal strain distribution along the depth of the cross-section obeys the plane cross-section assumption from 0 load till about 0.7 times the ultimate load bearing capacity.Specimens yield and the steel tube longitudinal tension yield happen approximately at the same time.For one same point,if it is compressed longitudinally,then must be tensioned circumferentially;if it is tensioned longitudinally,then must be compressed circumferentially;steel tube around the point longitudinally compressed point has no confinement on concrete.