波形钢腹板工字钢-UHPC组合梁抗弯性能试验研究

EXPERIMENTAL RESEARCH ON FLEXURAL PERFORMANCE OF I-BEAM-UHPC COMPOSITE BEAM WITH CORRUGATED STEEL WEBS

  • 摘要: 为研究桥面板采用叠合板形式(上层及槽孔处采用超高性能混凝土UHPC,下层采用普通混凝土NC)的波形钢腹板工字钢组合梁的弯曲性能,开展波形钢腹板工字钢-UHPC组合梁(简称CSRCU)和波形钢腹板工字钢-NC组合梁(简称CSRC)的抗弯试验,探究了试验梁的破坏特征、承载能力和应变发展规律。基于试验开展了参数敏感性分析,研究了剪力连接度、NC板厚和UHPC板厚比和叠层板等效厚度对组合梁力学性能的影响,并给出了合理取值建议。结果表明:两组试验梁破坏特征类似,UHPC高强度的特点使得CSRCU试验梁桥面板破坏范围较小,且槽孔处采用UHPC保证钢混之间不分层,抗弯承载力较CSRC试验梁更高,延性更好;在极限状态下,两组试验梁桥面板与钢梁上下翼缘板应变呈线性分布符合平截面假定,CSRCU试验梁波形钢腹板沿截面高度范围内均达到屈服强度,CSRC试验梁腹板一半高度范围内均达到屈服强度,波形钢腹板的抗弯贡献不可忽略不计;CSRCU组合梁和CSRC组合梁剪力连接度分别达到0.75和0.85即可满足受力要求;建议CSRCU组合梁NC层与UHPC层合理厚度比在1.50~2.75范围内;相比于全NC桥面板,UHPC叠合板厚度可以减薄20%左右。

     

    Abstract: To investigate the bending performance of I-steel composite beams with corrugated steel webs in the form of laminated slabs (using ultra-high-performance concrete, UHPC, for the upper layer and slots, and normal concrete, NC, for the lower layer), bending tests were conducted on I-beam-UHPC composite beam with corrugated steel webs (referred to as CSRCU) and I-beam-NC composite beam with corrugated steel webs (referred to as CSRC). The failure characteristics, bearing capacity and strain development patterns of the test beams were explored. A parameter sensitivity analysis was conducted based on the experiments to investigate the effects of shear connection degree, the ratio of NC layer thickness to UHPC layer thickness and the equivalent thickness of the laminated layer on the mechanical properties of composite beams. Practical recommendations for reasonable parameter values were also provided. The results show that the damage characteristics of the two groups of test beams are similar. The high strength of UHPC reduces the damage range in the bridge deck of the CSRCU test beam, and the application of UHPC in slot prevents the delamination between steel and concrete. The CSRCU test beam exhibits higher bearing capacity and superior ductility compared with the CSRC test beam. At the limit state, the strain distributions in the bridge decks of the two test beams and the upper and lower flange plates of the steel beams are linear, consistent with the assumption of plane section. The corrugated steel web of the CSRCU test beam reaches the yield strength across the entire section height, and the web of CSRC test beam reaches the yield strength within half the height range. The bending contribution of corrugated steel webs cannot be ignored. CSRCU composite beams and CSRC composite beams can meet the stress requirements when the shear connection degree reaches 0.75 and 0.85, respectively. It is suggested that the reasonable thickness ratio of the NC layer to the UHPC layer in CSRCU composite beams be in the range of 1.5 to 2.75. Compared with the NC bridge deck, the thickness of the UHPC laminate can be reduced by about 20%.

     

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