铁路混凝土箱梁钢筋锈蚀后其挠度和裂缝宽度取值

Deflection and Crack Width of Railway Concrete Box Girder after the Rebar Corrosion

为了研究钢筋锈蚀下混凝土箱梁挠度和裂缝宽度的变化,基于梁截面平衡和变形协调,引入锈蚀钢筋混凝土梁非线性本构关系,建立了箱梁受弯挠度和裂缝宽度解析表达式。针对铁路简支箱梁算例,研究了混凝土性能退化和钢筋锈蚀对梁挠度和裂缝宽度的影响;并和铁路桥梁规范中挠度和裂缝宽度的规范值进行了对比分析。结果表明:混凝土性能的退化对梁挠度和裂缝宽度影响很小;锈蚀钢筋力学性能的退化和锈蚀黏结滑移对挠度和裂缝宽度具有较大影响。当锈蚀率小于1.5%时,挠度和裂缝宽度均小幅减小;当锈蚀率超过1.5%后,挠度和裂缝宽度随着锈蚀率的增加开始增大。针对规范中挠度和裂缝宽度公式,提出了锈蚀黏结滑移修正系数,修正后的规范值与解析解吻合良好。

In order to research the changes of deflection and crack width of corroded reinforced concrete box girder,nonlinear constitutive relation of corroded reinforced concrete beam was introduced,and the analytical expression for flexural deflection and crack width was established based on the beam equilibrium and compatibility of deformation.For an example of simply supported box girder,the effect of concrete deterioration and corrosion were researched on the deflection and crack width,the standard values of deflection and crack width in railway bridge codes were compared and analyzed.The results showed that the concrete deterioration has less effect on the deflection and crack width of beams,while the effect that the deterioration of corroded rebar mechanical properties and corrosion bond-slip is significant.The deflection and crack width decreases slightly when the corrosion rate is less than 1.5%,while it begins to increase with the increase of corrosion rate when the corrosion rate is more than 1.5%.According to the formula of deflection and crack width in the code,developed the correction coefficient of corrosion and bond-slip,and the revised standard values were in good agreement with the analytical solution.