锈蚀损伤混凝土管桩水平承载性状时变分析

Time-dependant behavior analysis of laterally loaded corrosion damaged RC pipe piles

摘要:

为研究锈蚀损伤混凝土管桩的水平承载性状,依据Fick第二定律,建立了氯离子在混凝土管桩中的扩散方程,并结合初始和边界条件,得到扩散方程的解析解．依据厚壁圆筒模型,推导了钢筋混凝土管桩保护层锈胀开裂时的钢筋临界锈蚀深度．基于Faraday定律,对钢筋混凝土管桩保护层锈胀开裂时间进行了预测．并在此基础上,通过引入桩身抗弯刚度折减系数对海洋环境下锈蚀损伤钢筋混凝土管桩的桩身抗弯刚度的衰减规律进行了探讨,进而对海洋环境下锈蚀损伤钢筋混凝土管桩的水平承载性状的时变特性进行了分析．结果表明:海洋环境中氯离子侵蚀引起的钢筋锈蚀对钢筋混凝土管桩的水平承载性状有明显影响．随着暴露时间的延长,桩身抗弯刚度呈非线性衰减,桩身水平位移和桩身负剪力最大值逐渐增大,桩身弯矩逐渐减小．

Abstract:

To investigate the behavior of laterally loaded corrosion damaged reinforced concrete (RC) pipe pile, the governing equation of chloride diffusion into RC pipe pile was established based on Fick’s second law. Considering initial and boundary conditions, the analytical solution of chloride diffusion equation was presented. The critical corrosion penetration of reinforcing steel corresponding to cracking of concrete cover occurs was presented based on thick-walled cylinder model. Based on Faraday’s law, the time for corrosion-induced cover cracking in RC pipe pile was estimated. Then the attenuation law of flexural stiffness of corrosion damaged RC pipe pile exposed to marine environments was investigated by introducing the reduction factor of flexural stiffness. The time-dependent behavior of laterally loaded corrosion damaged RC pipe piles exposed to marine environments was further analyzed. The analysis results show that the chloride-induced reinforcement corrosion had a significant effect on the behavior of laterally loaded RC pipe piles exposed to marine environments. The flexural stiffness of RC pipe pile decreased nonlinearly with the increase of exposure time. The maximum negative shear force and the lateral deflection increased with the increase of exposure time, while the bending moment decreased.