混凝土保护层锈胀开裂过程分析的细观刚体弹簧元模型

Mesoscale Rigid-Body-Spring Model for analyzing the crack propagation of concrete cover due to steel bar corrosion

建立了描述保护层锈胀开裂过程的细观刚体弹簧元模型(RBSM),获得了锈胀裂缝的扩展过程和保护层的力学响应。数值结果表明,锈胀裂缝开展过程与试验现象较为一致;混凝土采用弹性本构关系时,平均锈胀压力-径向位移曲线的斜率(模型刚度)与厚壁圆筒模型理论值接近;采用软化本构关系时,平均锈胀压力峰值与理论值接近,从而验证了本文模型的正确性。此外,探讨了保护层厚度和钢筋直径对锈胀过程力学响应的影响规律。结果表明,保护层厚度减小将导致峰值锈胀压力和径向位移降低;钢筋直径增大同样会导致峰值锈胀压力降低,对应的径向位移整体上呈现随钢筋直径增大而减小的趋势。

In order to obtain the crack propagation process and mechanical response of concrete cover induced by steel bar corrosion,a numerical model based on the mesoscale Rigid-Body-Spring Model（RBSM）was established in the present work.The results show that the crack pattern is in good agreement with the experimental observations,and the model stiffness is similar to that obtained when the theoretical model for concrete composite materials,while the peak averaged corrosion pressure calculated with a softening constitutive model for concrete is also similar to that of the theoretical model,thus the numerical model is yalidated.Then the effects of concrete cover thickness and steel bar diameter on mechanical response during the corrosion process were investigated.The results show that the peak corrosion pressure and displacement decrease with the decreasing concrete cover thickness.The increase in steel bar diameter will bring about the decrease of the peak corrosion pressure,and the corresponding displacement presents a decreasing tendency on the whole.