超载作用下曲线梁桥倾覆计算理论与设计方法研究

Lateral overturning accidents of bridge in service happened more frequently in recent years due to overloading vehicles. For straight bridge, the mechanism of overturning failure is mainly based on rigid body rotation theory which was proved with large error and can’t satisfy the calculation requirement. Furthermore, compared to the straight bridge, due to bending-torsional coupling, space stress behavior and large rotation, the overturning of curved beam bridge is more complex and remains to be solved. Therefore, focusing on curved beam bridge, this research conducts the following four aspects. Firstly, the possible failure modes and corresponding overturning criteria can be summarized based on the existing bridge overturning cases. The essence of overturning can be proposed, it include not only rotation of rigid body, but also deformation body. The vertical deflection, the radius deformation and torsion deformation will be considered in large rotation calculation theory. Secondly, through combination of statistical characteristics of resistance and reliability index, the anti-overturning design performances objects can be derived from different components, even structures. The practical design expression on anti-overturning of curved beam bridge under different design performance objectives will be studied, the practical design expression of "strong overturning and weak bending" will be established. Thirdly, new anti-overturning bearings and its layout will be studied to classified control the rotation of rigid body, deformation and the translational displacement. Finally, Experimental study of the large similarity ratio will be designed in order to verify and feedback the large rotation overturning calculation theory and the anti-overturning effect of new type bears.

近年来，超载导致的在役桥梁倾覆事故频发。即使是直线梁桥，其倾覆机理研究还主要基于刚体转动理论，误差过大，无法满足实际倾覆计算需要；而对于曲线梁桥，由于弯扭耦合、空间受力和大转动，其倾覆计算更未得到有效解决。本研究以曲线梁桥为研究对象，开展以下四个方面的研究。首先，在对现有倒塌案例进行深入研究的基础上，系统归纳总结可能的破坏模式并形成相应的倾覆判断准则，基于倾覆是箱梁变形体转动和刚体转动叠加，构建综合考虑竖向挠曲变形、径向弯曲变形及扭转变形三自由度的倾覆计算理论。其次，结合抗力统计特征及目标可靠指标，确定不同构件乃至结构的抗倾覆设计性能目标，研究曲线梁桥不同设计性能目标下抗倾覆设计计算理论，建立 “强倾覆弱弯” 实用设计表达式。第三，开展新型抗倾覆支座及布置方案研究，实现倾覆中刚体转动与变形体变形的分类控制。最后，设计曲线梁桥倾覆大比例模型试验，验证大转动倾覆计算理论和新型支座的抗倾覆效果。

近年来桥梁倾覆事故时有发生，严重威胁通行安全。随着交通基础设施的持续建设，我国桥梁数量已超100万座，其中包含数万座独柱墩梁桥。在超载等不确定荷载作用下，倾覆是量大面广的梁桥面临的共性基础问题。课题组针对梁桥缺少科学的抗倾覆计算理论、设计方法、专业化构造措施的研究现状，通过理论分析、数值模型和模型试验等手段，开展了超载作用下曲线梁桥倾覆计算理论与设计方法研究，在新理论、新方法、新构造和新技术等方面研究取得了突破，主要创新成果如下：.发现了先转动后滑动箱梁倾覆破坏模式，系统地建立了变形体和刚体耦合的梁桥抗倾覆计算理论。提出梁桥倾覆破坏模式是上部结构小转动，再横向滑动，引发最终的倾覆破坏，证明了基于支座脱空前的变形体转动可以偏安全的计算倾覆，被《公路钢筋混凝土及预应力混凝土桥涵设计规范》（JTG 3362-2018）中抗倾覆规范条文编制组参考借鉴；.提出并实现了强度与抗倾覆承载力匹配的强倾弱弯梁桥设计准则。针对事故桥梁脆性的倾覆破坏发生在延性强度破坏之前的特点，将倾覆和抗弯抽象为结构力学问题后，实现了强度与抗倾覆承载力匹配的强倾弱弯的梁桥设计准则，在设计准则层面上为建设韧性梁桥提供理论支撑；.研发了性能可靠的新型抗倾覆限位构造与抗倾覆支座。研究了限位措施对抗倾覆能力提升效果，并在此基础上研发了支座竖向抗倾覆约束，综合梁桥横向爬移平动的自复位和箱梁转动的分类控制，设计了适用于曲线梁桥抗倾覆爬移支座及布置方案并在浙江湖州南浔大桥中得到应用，案例桥长期监测数据表明上述弯桥专用支座可有效控制刚体变位和变形体变形。.项目共获得国家发明专利授权1项，申请发明专利1项，发表学术论文14篇，其中SCI 论文4篇，项目成果浙江、北京、天津、广东、安徽、河南、福建和湖南等省份桥梁工程中得到应用，系统建立了独柱墩梁桥倾覆计算理论，完成一系列独柱墩梁桥的倾覆验算和加固，并形成面向量大面广梁桥的抗倾覆设计准则，产生了良好的社会经济效益，具有广阔的市场应用前景。