余震作用下早龄期钢筋混凝土握裹力试验

Experimental study on bond force of early-age reinforced concrete under aftershock

汶川灾后重建过程中余震不断,新浇筑的混凝土结构受余震作用后钢筋产生甩动、构件出现微裂缝等现象,这些现象是否会影响钢筋与混凝土间的握裹力,是重建项目所面临的问题之一。对早龄期钢筋混凝土试件施以不同峰值加速度的振动力后即时进行拉拔试验,分析不同振动力对不同龄期的混凝土钢筋握裹力的影响。结果表明:早龄期混凝土在12h(初凝至终凝间)受振动作用,对钢筋握裹力影响最大,即时可产生13.86%的折损;而2d以上龄期的混凝土受振动作用,其钢筋握裹力折减率最大仅为4.69%。

The process of Wenchuan reconstruction suffered ongoing aftershock.Fresh reinforced concrete was influenced by the aftershock,such as reinforcing steel swung,crack appeared on components.It is one of the problems of reconstruction whether the phenomenon would influence the bond force.After subjected to different earthquake excitations at different ages,early-age reinforced concrete specimens were studied by pull-out tests.Under the different earthquake force,bond force of bars at different ages were discussed.The results show that,the bond force of early-age concrete is effected by vibration at 12 hours（between the initial and final set） mostly,reduced about 13.86%.And the bond force of concrete after 2 days is influenced little,only 4.69% damaged.