Abstract

To improve the crack-resisting behavior of normal-strength concrete (NC) bridge deck and to reduce the deadweight of conventional steel-concrete composite girders, a new steel-ultrahigh performance concrete (UHPC) continuous composite box girder was proposed. Aiming to reveal the static behavior of the proposed structure, including the load-deflection response, the strain distribution, the crack development, the moment redistribution and the failure mode, a comparative experimental study was conducted on two types of the composite girder, namely a steel-UHPC continuous composite girder (SUCG) and a prestressed steel-concrete continuous composite girder (SCCG). The test results indicated that the ultimate loading capacity of the SUCG was 20.4% higher than that of SCCG; the nominal cracking strength of the SUCG was 22.9 MPa, and its corresponding cracking moment was 2.1 times higher than the conventional one; the crack development mode of UHPC slab were significantly different from the SCCG, the cracks appeared in UHPC slab dominated by microcracks with smaller length were numerous and intensive. It is also shown that the SUCG has smaller degree of moment redistribution. Thus, the current study verified the SUCG could be one of effective solutions for long-span continuous composite girder bridges.

摘要

为提高常强混凝土（NC）桥面的抗裂性能，降低传统钢-混凝土组合梁的自重，提出了一种新型钢-超高性能混凝土（UHPC）连续组合箱梁。为了揭示所提出结构的静态行为，包括荷载-挠度响应、应变分布、裂纹发展、弯矩重新分布和破坏模式，对两种类型的组合梁进行了对比试验研究，即钢-UHPC 连续组合梁 (SUCG) 和预应力钢-混凝土连续组合梁 (SCCG)。试验结果表明，SUCG的极限承载能力比SCCG高20.4%；SUCG的名义开裂强度为22.9 MPa，其相应的开裂力矩是常规的2.1倍；UHPC板的裂纹发展模式与SCCG有显着差异，UHPC板中出现的裂纹以长度较小的微裂纹为主，多且密集。还表明，SUCG 具有较小程度的力矩重分布。因此，目前的研究验证了SUCG可以成为大跨度连续组合梁桥的有效解决方案之一。