超长悬臂钢-砼组合行车道梁的理论分析与试验研究

Theoretic and Experimental Research on Loading Characteristics of Cantilever Beam in Composite Structure

长沙市洪山大桥是一座竖琴式无背索斜塔斜拉桥,主跨跨径206 m,主梁为脊骨梁布置形式,两侧挑梁采用13 m超长悬臂钢-砼组合梁结构,纵向间距4 m.为了准确把握钢挑梁的受力特性,提出了采用修正的铰接梁法计算钢挑梁的荷载横向分布系数,推导了详细的计算公式,并进行了模型试验研究予以验证,试验结果与理论分析结果吻合良好;采用压重320 kN的方法解决负弯矩区域砼板的开裂问题;综合比较各种规范关于砼收缩徐变的规定;分析了砼板的裂缝宽度;为大桥设计和类似工程提供重要的参考和指导.

Hongshan Bridge which locates in Changsha City, is a harp style cable-stayed bridge with inclined pylon and without any back-stays. The main span is 206 m long. The main girder is a spine girder, and the bilateral girders are of 13-meter-long steel-concrete composite cantilever stucture, with the longitudinal space of 4 m. The theories of loading distribution along crosswise were analyzed by adopting the modified articulated beam, The calculating formulas were deduced, and a model test was performed to prove the correction of these formulas. Finally, adding ballast weight of 320 kN on the edge of cantilever beam was adviced to solve the crack problem of negative moment zone. The crack width of concrete deck was analyzed by taking creep and shrinkage of concrete into account and comparing kinds of various specification. The above-mentioned results provide strong basis for the design of bridge deck.