低高度预应力UHPC-RC组合箱梁桥设计研究

Design and research of low-height prestressed UHPC-RC composite box girder pedestrian bridge

针对福建某人行天桥的工程背景,基于UHPC的优异性能,研究开发了低高度预应力UHPC-RC组合箱梁桥。研究进行了组合箱梁的设计与计算分析,并根据模型试验获得新型结构的基本受力性能。随后,利用经试验结果验证后的有限元模型,针对新型结构的不同参数对结构受力性能,尤其是承载力的影响进行了深入分析。研究结果表明,采用UHPC-RC材料设计的桥梁,其强度、挠度以及自振频率计算均能满足现行桥梁规范的要求。同时,UHPC在人行天桥中可有效减轻自重、减小结构尺寸,提升桥梁结构的刚度和稳定性,充分发挥其材料特性。采用预制拼装施工方法,可充分利用UHPC的抗拉强度,增大预制块大小,减小预应力及普通钢筋的配置,实现优化结构设计。

Based on the excellent properties of UHPC,this paper aims to develop a low-height prestressed UHPC-RC composite box girder pedestrian bridge for a project in Fujian.The design and calculation analysis of the composite box girder were conducted,and the basic mechanical properties of the new structure were obtained through model tests.Then,using the validated finite element model based on experimental results,a thorough analysis was performed on the effect of different parameters on the mechanical properties of the new structure,especially the bearing capacity.The results show that the bridge designed with UHPC-RC material can meet the requirements of current bridge specifications in terms of strength,deflection,and natural frequency.Meanwhile,UHPC can effectively reduce the self-weight and size of the pedestrian bridge,enhance the stiffness and stability of the structure,and fully exploit its material properties.By utilizing the tensile strength of UHPC and increasing the size of prefabricated blocks while reducing the prestress and ordinary steel reinforcement,the optimized structure design was achieved through the prefabricated assembly method.