Abstract：In this work, the time-dependent reliability for crack width of China Railway Track System II (CRTS Ⅱ) foundation plate on bridge was investigated under different environmental temperature. This research mainly includes: the calculation model for effective cross-sectional area of tensile reinforcement in foundation plate considering corrosion of reinforcement shall be determined through comparison and selection, the limit state function of longitudinal crack width of foundation plate shall be established under the actions of train load, temperature and bridge deformation; based on the formula of thermal conductivity, the probabilistic models for axial temperature and temperature gradient actions are developed based on meteorological information, with the correlation coefficient of the two temperature actions being calculated; the time-dependent reliability analysis on crack width of CRTS Ⅱ foundation plate on a bridge in Beijing during its 60-year service life cycle was carried out under different temperature conditions. It is found that: with the increase of service time, the reliability of longitudinal crack width of the foundation plate tends to decrease; compared to the negative temperature gradient, the positive temperature gradient shall be more unfavorable to the structure; the reliability of the crack width of the foundation plate may be reduced due to reinforcement corrosion degradation, and the decline rate of the reliability index may obviously accelerate with the increase of corrosion degree; for low environmental temperature, the crack width reliability of the foundation plate is at a relatively low level, and more attention shall be paid to such cracks.
