钢筋混凝土梁桥火灾后结构剩余承载能力分析

Analysis of residual bearing capacity of the reinforced concrete beam bridge structure after a fire

采取数值模拟方法,研究某钢筋混凝土梁桥在火灾后的剩余承载能力,根据国际标准升温曲线ISO-834,利用Midas FEA建立了有限元模型进行计算,得出了构件内部温度场的变化情况,发现混凝土保护层对钢筋的强度有较好的抗火保护作用,混凝土内部温度随梁底沿梁高迅速降低;利用Midas Civil建立受损后和加固后钢筋混凝土梁桥有限元模型,计算研究了梁桥火灾作用后结构剩余承载能力变化,发现短时间的火灾对钢筋混凝土梁桥的整体强度影响不大,不会导致结构承载能力的变化;最后提出了针对钢筋混凝土梁桥抗火措施和加固设计思路。

The numerical simulation method was used to study the residual bearing capacity of a reinforced concrete beam bridge after a fire. According to the international standard temperature rise curve of ISO-834,the finite element model was established by using Midas FEA for calculation,and the changes of internal temperature field of the component were obtained. It is found that the reinforced concrete protection layer has good fire resistance protection to the reinforcing bar strength,the internal temperature of the concrete decreases rapidly with the beam bottom along beam height; By using Midas Civil to establish the finite element model of the reinforced concrete beam bridge after damage or after reinforcement for calculation,the change of residual bearing capacity of the beam bridge structure after fire was further studied,and it is found that the short time fire has little effect on the integral strength of the reinforced concrete beam bridge,and it will not lead to the change of structure bearing capacity; Finally,the fire resistance measures and reinforcement design ideas for the reinforced concrete beam bridge were put forward.