钢-混凝土组合连续弯箱梁耐火性能研究

火灾一直是困扰钢结构桥梁建设的世界性难题，与我国日益增长的钢结构桥梁建设重大需求相比，钢结构桥梁火灾防控研究严重滞后，因此，钢结构桥梁抗火是工程结构抗火防灾研究领域的前沿课题之一。项目拟通过开展理论分析、实桥采样、模型试验和建立极限平衡状态增量非线性迭代法相结合的研究方法，研究钢-混凝土组合连续弯箱梁薄壁空腔内部具有复杂截面配置的传热机制，建立钢-混凝土组合连续弯箱梁薄壁空腔截面升温理论；深入探索碳氢火灾下钢-混凝土组合连续弯箱梁支承的损伤机理，建立复杂高温状态下结构多维传热时的支承条件衰变计算模型；分析火灾参数（受火长度和受火位置）与支承条件、结构参数（跨径布置、平弯曲率、负弯矩区混凝土顶板预应力钢束配束率和截面配置）、荷载参数（荷载水平和荷载位置）对钢-混凝土组合连续弯箱梁破坏模式的耦合影响规律，研究高温和弯-扭-剪荷载耦合作用下钢-混凝土组合连续弯箱梁的力学行为演化过程，深入揭示其破坏机理；建立碳氢火灾下以多损伤极限（支承条件、梁端位移、钢板屈曲、挠度、挠变率和承载能力）为综合控制目标的钢-混凝土组合连续弯箱梁的破坏准则，获悉耐火性能变化规律，提出钢-混凝土组合连续弯箱梁的耐火极限计算方法和抗火设计方法。研究结果可提升我国钢结构桥梁抗火防灾的理论水平，有效解决钢结构桥梁遭遇复杂火灾环境时的“急、棘、险、难”的工程技术难题。

Fire has always been a worldwide problem that has plagued the construction of steel structural bridge girders. Compared with the growing demand of steel structural bridge girders in China, the research on fire prevention and control of steel structural bridge girders has lagged behind. Therefore, research on fire resistance of steel structural bridge girders is one of the frontier topics in the field of fire resistance and disaster prevention of engineering structures. Heat transfer mechanism inside steel-concrete continuous curved box bridge girders with complex sectional configuration is to be studied based on theory analysis, data collection in actual bridge, model test and limit equilibrium state incremental nonlinear iterative method. Subsequently, the temperature-rise theory in thin-walled cave section of steel-concrete continuous curved box bridge girders is to be presented. The damage mechanism of bearing under hydrocarbon fire exposure conditions is to be explored, and also the decay calculation model of bearing conditions, under complex high temperature status and structural multi-dimensional heat transfer, is to be proposed. The destruction model of steel-concrete continuous curved box bridge girders is to be analyzed taking into consideration fire parameters (fire exposure length and fire exposure position), bearing conditions, structural parameters (span distribution, ratio of curvature, ratio of prestressing strands in concrete slab in negative moment zone, sectional configuration) and load parameters (load level and load position). The mechanical behavior evolution procedure of steel-concrete continuous curved box bridge girders under coupled effect of high temperature and bending-torsional-shear is to be studied, and also the destruction mechanism is to be revealed. The failure criterion of steel-concrete continuous curved box bridge girders is to be established taking into consideration multi-damage limit namely; bearing, displacement at end of girder, steel buckling, deflection, ratio of deflection and bearing capacity in bridge girders. The law of change in fire resistance is to be obtained. Calculating methods of fire resistance and fire-resistant design methods of steel-concrete continuous curved box bridge girders are to be proposed. The researches can highly improve the theory level of fire resistance and hazard prevention in steel structural bridge girders, and effectively solve the “urgent, thorny, dangerous and difficult” engineering technical problems when steel structural bridge girders encounter complex fire environment.