变截面波形钢腹板组合箱梁桥剪力滞效应研究

The composite box girder bridge with corrugated steel webs is a new type of composite bridge which is energy-saving, low-carbon and sustainable. However, one of the most important problems to impede the further development of this type of bridge to a longer span and a wider deck is the lack of study on the shear lag effect taking into account the variations of both cross-section and flange thickness . So in this project, 1) a method to use three different displacement difference functions to describe the longitudinal distribution of the warping displacement amplitudes of the cantilever slab, inner top slab and bottom slab, respectively, is put forward instead of using only one for all slabs in a whole cross-section. And then the shear lag effect of this type of bridge is studied based on minimum total potential energy principle and variational principle; 2) in view of the unsuitability of the existing methods to calculate the effective widths of thickness-varying flanges, a method to use the rectangular area as the stress integral region to calculate the effective flange width is proposed and its reasonability is studied; 3) as for the problem of the applicability of the existing specifications on the effective flange width calculation in the current design codes to the composite bridge with corrugated steel webs and varying cross-sections being unverified, a practical method to calculate the effective flange width for this type of bridge will be developed. The shear lag effect of the composite bridge with corrugated steel webs and varying sections is studied through theoretical analyses, numerical simulation and experimental verification. The influence of key factors on the shear lag effect of this type bridge is also investigated by parametric analyses. The study in this project benefits the design and further development of such bridges.

波形钢腹板组合箱梁桥是一种节能、低碳、可持续性良好的新型组合结构桥梁，兼顾纵桥向截面变化和横桥向翼缘板厚度变化的剪力滞效应研究的缺乏是制约其向更大跨度和宽度发展的重要问题之一。为解决此问题本项目：1）针对用一个纵向位移差函数表征不精确的问题，提出采用三个不同的位移差函数分别表征悬臂板、箱内顶板、底板翘曲位移幅值沿组合箱梁的纵向分布，基于最小势能原理和变分法分析变截面波形钢腹板组合箱梁桥剪力滞效应；2）针对现有有效翼缘宽度计算方法不适用于变厚度翼缘板的问题，提出以矩形为应力积分面域的有效翼缘宽度计算方法；3）针对现有国内外主流规范在变截面波形钢腹板组合箱梁桥有效翼缘宽度计算方面的适用性问题，提出该类桥梁的有效翼缘宽度实用计算方法。通过理论分析、数值模拟和试验验证系统研究变截面波形钢腹板组合箱梁桥剪力滞效应，由参数分析掌握关键因素影响规律，为该类桥梁的设计提供有益参考，促进其推广和应用。

波形钢腹板组合箱梁是一种力学性能优越、节能低碳、可持续性好的新型组合桥梁结构。剪力滞效应是制约该类结构更大跨度和宽度发展的重要力学问题之一。本项目有机结合理论分析、数值模拟和试验研究，对波形钢腹板组合箱梁和双管弦杆波形钢腹板组合箱梁的剪力滞效应进行了深入研究。研究对象主要为纵向变截面结构，兼顾纵向等截面结构。所进行的主要研究工作和所得的主要结论如下。.（1）针对传统翼缘有效宽度不适用于横向变厚度翼缘板、未考虑截面应力不均匀分布的缺点，提出了翼缘有效宽度的新定义和计算方法，并得到了可作为剪力滞效应有效指标的翼缘有效宽度系数。对比研究表明，在设计计算中应用新定义的翼缘有效宽度能够更准确地估计截面最大应力，可以同时保证结构安全性和经济性。.（2）基于能量变分法推导了变截面波形钢腹板组合箱梁剪力滞效应的控制方程，提出了方程的有限差分求解方法，并开发了相关计算程序，建立了基于能量变分法理论分析和有限差分求解的半解析分析方法。根据试验和有限元分析结果对该半解析分析方法进行了验证，证明基于该半解析分析方法可以准确地得到波形钢腹板组合箱梁翼缘有效宽度系数和剪力滞系数。.（3）对波形钢腹板组合箱梁和双管弦杆波形钢腹板组合箱梁两类结构开展荷载试验，通过实测截面应力和应变分布，对剪力滞效应进行试验研究，验证了本项目半解析方法和有限元建模分析方法的准确性。.（4）基于半解析方法、有限元数值模拟和试验研究，分析了简支和连续波形钢腹板组合箱梁剪力滞效应的特征。简支波形钢腹板组合箱梁跨中呈现正剪力滞效应，沿纵向剪力滞效应强度变化不大。连续波形钢腹板组合箱梁在各跨正弯矩区呈现正剪力滞效应，而在反弯点附近可能出现负剪力滞。.（5）基于半解析方法和有限元模拟法，研究了结构体系、宽跨比、宽高比、截面顶板厚度等、腹板剪切变形、横隔板设置、汽车荷载作用等因素对波形钢腹板组合箱梁和双管弦杆波形钢腹板组合箱梁剪力滞效应的影响，并总结了相关规律。.（6）研究了国内外技术规范中有效翼缘宽度规定对变截面波形钢腹板组合箱梁桥的适用性，然后基于参数分析的结果，初步提出实际工程设计中波形钢腹板组合箱梁翼缘有效宽度取值建议，作为在实际工程设计中考虑剪力滞效应的方法。