双重环筋约束下超短混凝土试件的局部受压试验研究

Local compression experiment on super short concrete member with confinement of double layer circular steel bars

针对27个配置了双重环筋的圆柱形构件进行了局部受压试验,试件高度低于试件直径.研究了非局压区宽度b、试件高度h和约束钢筋配筋率ρ对试件的破坏形态、极限承载力、等效应力-应变曲线、开裂荷载、正常使用状态下的荷载及内外环筋屈服荷载的影响.在环筋的约束下,试件局压区核心混凝土体出现较高的强度和较好的延性.试件发生了三类破坏形态:侧面只有竖向裂缝、竖向裂缝加不全贯通环向裂缝和竖向裂缝加全贯通环向裂缝.高度系数β对于试件承载力的影响是最大的,随着β的减小,承载力呈非线性增大趋势.随配筋率增大,承载力增大,其增大量有变缓的趋势.宽度系数对试件承载力有一定影响,但不太明显.

Local compression experiments on 27 cylinder specimens strengthened by double layer ring steel bars were carried out. The height of the specimens is lower than the diameter of the specimens. The experimental parameters include the non-local compression width b, the height of the specimens h, and the steel ratio p. The failure modes, ultimate capacity, equivalent stress-strain curves, corresponding load of crack and normal service status, and the yield load of the inner and outer steel ring bars were studied. Under the confinement of the ring bars, the concrete in the local compression zone shows higher strength and well ductility. Three failure modes may occur at the side faces, namely, vertical cracks, vertical cracks with non-through horizontal cracks, as well as vertical crack with through horizontal crack. The height factor β is the main influencing factor of the beating capacity, its influence is nonlinear, and the beating capacity increases more quickly with the decrease of β The beating capacity increases with the increasing of p, but the increment slows down when ρ increases. The width factor α has some effect on the beating capacity, but its influence is not so obvious.