变刚度梁弯曲解析解在桥面板中的应用

针对新型连续窄幅钢箱梁-混凝土组合桥梁，研究了该桥型桥梁的桥面板拉应力控制方法与措施．将该桥型组合桥梁等效为可变刚度的Euler梁，给出任意横向荷载作用下变刚度梁的静力弯曲解析通解，并得到三跨连续阶梯型变刚度梁变形及其内力分布特征．在此基础上，以三跨连续窄幅钢箱梁-混凝土组合桥梁为研究对象，考虑下部钢箱梁与上部混凝土桥面板完全剪力连接，通过改变负弯矩区钢箱梁壁厚、内部充填混凝土的强度、长度与高度等参数，分析得到可有效控制桥面板拉应力的关键因素．结果显示：在负弯矩区段内的钢箱梁内部充填混凝土对控制该区域混凝土桥面板拉应力效果明显，但混凝土强度影响较弱．混凝土桥面板开裂区域随钢箱梁中充填混凝土长度的增加而减少，但桥面板顶部拉应力会随混凝土充填高度的增加呈现先减小后增大的趋势，在充填高度为箱梁内部净高的20 %~30 %左右时效果较为显著，此时经济效益最佳．

Application of Analytical Solution of Beading Beam with Stepped Variable Stiffness in Bridge Deck

For new practical composite bridges, several methods and measures of controlling the tensile stress of bridge deck of concrete-filled narrow-width steel box continuous composite bridges were investigated. The composite bridge was equivalent to a stepped variable stiffness Euler-Bernoulli beam, and the general analytical solution of static bending of variable stiffness Euler beam subjected to arbitrary transverse load was presented. And the deformation and internal force distribution characteristics of the three-span continuous beam with stepped variable stiffness were given. On this basis, taking the three-span continuous narrow steel box girder concrete composite bridge as the research object and considering the complete shear connection between the lower steel box girder and the upper concrete bridge deck, the key factors that can effectively control the tensile stress of the bridge deck were analyzed by changing the parameters such as the wall thickness of the steel box girder in the hogging moment region and the strength, length and height of the concrete filled inside. It was revealed from the results that the tensile stress of concrete deck can be effectively reduced with filling concrete in steel box girder in the area of hogging moment, and the cracking area of the bridge deck can be reduced by increasing the concrete-filled length. Furthermore, as the concrete-filled height increases, the tensile stress at the top of the bridge deck in the hogging moment area decreases first and then increases. The tensile stress can be reduced to a great extent when the concrete fills to 20 %-30 % of the steel box girder internal height, but concrete with different strength has little effect.