基于超短栓钉的钢-超薄UHPC组合桥面性能

为了满足对自重敏感的大跨桥梁钢桥面的翻修与加固需求，提出采用超短栓钉作为连接件的钢-超薄UHPC轻型组合桥面结构（简称“新超薄体系”）. 通过钢-超薄UHPC组合板负弯矩试验，研究关键设计参数对超薄UHPC层抗裂性能的影响. 试验结果表明：当UHPC最大裂缝宽度小于0.15 mm时，裂缝宽度的增长近似呈线性，在钢筋屈服以后，裂缝宽度迅速增大；配筋率和钢筋直径对名义开裂应力的影响较大. 基于试验结果，分析已有的裂缝宽度计算公式，确定钢-超薄UHPC组合板裂缝宽度的建议计算公式. 以某特大跨径悬索桥为工程背景，进行整体和局部有限元分析，论证了方案应用于实际工程的可行性. 计算结果表明：钢-超薄UHPC组合桥面的自重与常规60 mm厚的钢桥面铺装基本持平，主缆和吊索内力变化小于3.0%；钢桥面（OSD）各典型疲劳细节的应力幅值降低了10.1%~52.0%，且均小于200万次疲劳强度；UHPC层中最大拉应力为8.4 MPa，远小于试验得到的名义开裂应力.

Performance of steel-ultrathin UHPC composite bridge deck based on ultra-short headed studs

A new steel-ultrathin UHPC lightweight composite deck (named as new LWCD for short) was proposed by using ultra-short headed studs in order to meet the demanding requirements in retrofitting and strengthening steel deck systems for long-span flexible bridges. The experimental tests were performed for the new LWCD via steel-ultrathin UHPC composite slab specimens, and the influence of key design parameters on the anti-cracking behavior of the specimens was analyzed. The test results show that the cracks widened approximately linearly with the increasing load when the maximum crack width was less than 0.15 mm. The maximum crack width in UHPC rapidly increased when the steel reinforcement yielded. The nominal cracking stress of UHPC was significantly affected by the reinforcement ratio and rebar diameter. Different methods of predicting the crack width in UHPC were compared based on the test results, and the proposed formula for calculating the crack width of steel-ultrathin UHPC composite slab was determined. Global and local finite element (FE) analyses were performed based on a long-span suspension bridge to validate the feasibility of the proposed new LWCD. The analysis results show that the self-weight of the new LWCD is comparable to that of the original 60 mm asphalt overlay. The internal forces in main cables and suspenders are increased less than 3.0%. The stress ranges in typical fatigue-prone details of the orthotropic steel deck (OSD) are reduced by 10.1%-52.0%, and the stress ranges in the OSD are all below the corresponding fatigue strengths (under 2 million cycles). The maximum tensile stress in UHPC caused by design loads was 8.4 MPa, much less than the nominal cracking strength obtained in the experimental test.