连续结合梁桥负弯矩区处理方法的参数分析

目的通过综合施加强迫位移、预加静荷载和张拉高强钢筋等方法对大跨度钢一混凝土连续结合梁桥负弯矩区混凝土施加预压应力，研究各参数对负弯矩区混凝土内施加预压应力值的影响．方法结合实际工程，采用ANSYS进行施工全过程模拟，以强迫位移、预加静荷载、张拉高强钢筋面积值为参数进行分析．结果得到了预压应力随各参数变化规律．对比了各方法的优缺点，确定了施工方案．结论预压应力随各参数独立线性变化；3种方法综合使用可有效解决负弯矩区混凝土开裂问题，其中预加静荷载和张拉高强钢筋方法更为有效：提出了可用于类似结合梁桥负弯矩区处理的预压应力估算公式，

Parameter Analysis on Treating Method for Negative Moment Regions of Continuous Composite Beam Bridge

The 2nd segment of Lishuiqiao to north of Lishuiqiao station in Subway Line 5 in Beijing is a large-span continuous steel-concrete composite beam bridge.In order to control concrete crack in the composite beams subjected to negative moment,jacking up mediate supports and preloading heavy static load as well as pretension of high-strength bars methods were combined into a new treating method,which made construction process more complex.Based on numerical analysis by FEA Software ANSYS,real construction process is simulated to obtain the stress in deck concrete near mediate supports.Parameters considered included lifting displacement of mediate supports,preloaded weight and pretension bars' area.Optimal parameter combination is presented and practical construction scheme is also proposed for the bridge.It is shown that the relationship between each parameter and pre-stress in deck concrete is linear and independent.Concrete in negative moment regions of this bridge has been imposed sufficient compressive stress by the new method.Moreover,preloading static and tension high strength reinforcement methods are more efficient.At last,compressive estimating calculation formula is suggested and can be applied to similar continuous composite beam bridges.