中文摘要：

针对受火后混凝土箱梁悬臂板的挠变与塌裂耦合灾害,利用热-力耦合方法对局部火灾模式下混凝土箱梁高温场、悬臂板变形及有效分布宽度进行了分析,研究了混凝土箱梁单侧局部火灾高温强热模式,计算了此模式下混凝土箱梁横桥向和纵桥向温度场的分布状态,分析了迎火面和背火面悬臂板变形和有效分布宽度随延火时间与荷载比的变化规律。研究结果表明：箱梁单侧腹板和翼缘板下侧受火,迎火面温度相对其他部位较高,背火区温度无变化,火温从箱形截面外侧到内侧呈明显的半渗层状梯度分布;顺桥向温度梯度线以强热区为中心沿跨径呈层流状分布,火灾的局部效应显著;迎火面悬臂板挠度随延火时间的增加逐渐增大,背火面悬臂板挠度随延火时间的增加直线下降,迎火面悬臂板挠度变化趋势明显大于背火面悬臂板挠度的变化趋势,并且挠度随荷载比的增加呈非线性增长关系;迎火面悬臂板有效分布宽度随延火时间的增加而减小,背火面悬臂板有效分布宽度随延火时间的增加而增大。研究可为桥梁的抗火设计实用方法的提出与火灾后桥梁加固提供依据。

英文摘要：

Being aimed at the destruction and deformation coupled hazard of cantilever plate for concrete box girders exposed to fire,thermo-mechanics coupled methods was applied to analyze high temperature field and the deformation of cantilever plate and effective distribution width of cantilever plate,high temperature model of part fire for concrete box girder was studied,temperature field distribution state of cross section and direction for concrete box girder was computed,and the variation law for deformation and effective distribution width of cantilever plate exposed and unexposed to fire with the changes of fire time and load ratio was analyzed.The results indicate that：temperature of concrete box girder exposed to fire is higher than other parts when its unilateral web plate and cantilever plate are in fire,and that unexposed to fire keeps unchanged,fire temperature hasagradient distribution presenting semi-seep layer from outside to inside;direct temperature gradient also presents a layer distribution at a center of high temperature zone,and part effect of fire temperature is obvious;deflection of cantilever plate exposed to fire increases gradually with increment of fire time,deflection of cantilever plate unexposed to fire decreases sharply with increment of fire time,variation tendency of cantilever exposed to fire is larger than that of cantilever unexposed to fire,and deflection shows a non-linear increment tendency with increment of load ratio;effective distribution width of cantilever plate exposed to fire decreases with increment of fire time,effective distribution width of cantilever plate unexposed to fire increases with increment of fire time.This research can provide a basis for the proposal of design method of bridge fire-resistance and the reinforcement of bridge after fire.