节段预制拼装超高性能混凝土梁弯曲试验

Bending Test of Segmental Precast Ultra-high Performance Concrete Beam

针对传统节段普通混凝土(NC)桥梁自重大、耐久性差的问题,提出用超高性能混凝土(UHPC)代替NC的方案,并配置体外预应力束,以进一步提高施工效率。为研究此类桥梁的抗弯性能,设计制作了3根T形截面体外预应力UHPC梁,包括1根整体梁和2根节段梁,并进行四点弯曲试验。结果表明:UHPC节段梁在接缝张开前,其力学性能和整体梁相似;在接缝张开时主要表现为环氧树脂胶层破坏,仅接缝附近出现局部裂缝;在接缝张开后结构抗弯刚度迅速下降;在极限状态下梁底体外预应力筋的应力增量显著。UHPC节段梁在四点弯曲试验中的力学性能与UHPC整体梁不同。

In view of the self weight and poor durability of traditional segmental ordinary concrete(NC)bridges,a scheme of using ultra-high performance concrete(UHPC)to replace NC and configuring external prestressed tendons was proposed to further improve the construction efficiency. In order to study the bending performance of this kind of bridge,three T-shaped externally prestressed UHPC beams,including one integral beam and two segmental beams,were designed and manufactured,and four point bending tests were carried out. The results show that the mechanical properties of UHPC segmental beam are similar to that of integral beam before the joint is opened. When the joint is opened,the epoxy resin adhesive layer is mainly damaged,and only local cracks appear near the joint. After the joint is opened,the bending stiffness of the structure decreases rapidly. In the limit state,the stress increment of the external prestressed reinforcement at the bottom of the beam is significant. The mechanical properties of UHPC segmental beam in four point bending test are different from that of UHPC integral beam.