钢-UHPC轻型组合梁桥面板受弯性能有限元分析

Finite Element Analysis of Flexural Performance of Steel-UHPC Lightweight Composite Girder Deck

为降低常规钢-混凝土组合主梁结构的自重,解决其混凝土桥面板易开裂的问题,提出了钢-UHPC轻型组合梁结构方案,该结构方案能明显降低结构自重。为得到新型钢-UHPC轻型组合梁结构桥面板的受力状况,以在建实桥应用工程胜天大桥为工程背景,分别采用应力叠加法、全桥精细有限元法和混合有限元法,对其桥面板受力最不利位置的纵桥向拉、压应力进行了计算分析。结果表明：混合有限元法与全桥精细有限元法计算结果相差在4%以内,二者结果较接近;应力叠加法相比全桥精细有限元法计算结果差值为1.58～3.80 MPa,相差在12%以上,结果偏保守。计算结果与试验结果对比表明,UHPC桥面板纵桥向最大设计拉应力小于UHPC最大裂缝宽度为0.05 mm时的实测名义拉应力,纵桥向压应力远小于UHPC抗压强度,能够满足在最不利加载工况下的设计要求。

In order to deal with the problems that conventional steel-concrete composite girders have heavy self-weight and are susceptible to develop cracks in the concrete deck,we proposed a scheme of steel-UHPC lightweight composite girder which could significantly reduce the self-weight of the girder. To obtain the stress state of the deck of the new steel-UHPC lightweight composite girder,based on an example bridge under construction—the Shengtian Bridge,the longitudinal tensile and compressive stresses in the most unfavorable place of deck are calculated by the stress superposition method,the precise overall bridge FE method and mixed FE method respectively. The FE analysis was focused on the tensile stress and compressive stress in the concrete deck at the most unfavorable load positions. The analysis shows that（ 1） the calculation results obtained from the mixed FE method are quite close to the result derived from the precise overall bridge FE method,and the relative differences are within 4%;（ 2） the stresses calculated by the stress superposition method is higher than that of the precise overall bridge FE method,with a difference of 1. 58 MPa to3. 80 MPa,and a relative difference of above 12%,which indicates that the result is conservative. In addition,by comparing the calculation result with the experimental result,it reveals that the maximum designed longitudinal tensile stress of UHPC deck is lower than the measured nominal tensile stress of UHPCthat have a maximum crack width of 0. 05 mm,and the longitudinal compressive stress is much less than the compressive strength of UHPC. Thus,the proposed steel-UHPC composite girder can meet the design requirements under the design loads.