混凝土结构锈裂形态试验研究及数值模拟

Experimental study and numerical simulation of corrosion-induced crack patterns of concrete structures

混凝土结构服役后期会出现保护层剥落的情况,混凝土保护层剥落与内部锈胀裂缝的分布情况密切相关。通过对不同尺寸与配筋情况的混凝土试块进行内部锈胀裂缝开展与分布研究,采用改进通电加速锈蚀方法加速试块劣化,通过切片观测锈蚀后试块内部锈胀裂缝形态,研究箍筋、保护层厚度、钢筋间距对内部锈胀裂缝开展的影响。研究结果表明:箍筋显著改变了内部锈胀裂缝开展与分布情况;混凝土保护层厚度较小或钢筋间距较大时,钢筋锈胀裂缝表现为单根锈胀开裂形式,反之则表现为钢筋之间的水平贯通裂缝。基于黏聚力单元建立了有限元分析模型,将钢筋锈胀变形作为位移加载依据,对试块锈裂过程进行数值分析,模拟结果与试验结果吻合较好。

Concrete cover spalling,which is closely related with the concrete crack pattern induced by steel corrosion, may happen at the later service life of concrete structures.This paper investigated the crack and crack pattern induced by inner steel corrosion,considering the influence of stirrups,thickness of concrete cover and rebar spacing.The concrete specimens were first corroded by an electrochemical method,and then sliced to disclose the crack patterns. The test results show that stirrups significantly change the crack patterns induced by inner steel corrosion.With the increase of concrete cover thickness or the reduction of rebar spacing,the corrosion-induced concrete crack pattern changes from the individual cracking mode to the delamination mode.A finite element model was established using cohesive element.The expansive effect of corrosion products is considered as nodal displacements at the steel-concrete interface in the finite element model.The numerical simulation results show good agreements with the experimental results.