斜拉桥混凝土索塔开裂机理及生命周期抗裂性能研究

China has the largest amount of cable-stayed bridges in the world. Bridge pylon is the most important component of cable-stayed bridges. Investigations show that a majority of pylons are confronted with cracking problems during construction and operation stage, which not only reduce the service life but also increase the structural failure risk. In this project the types and patterns of common cracks are summarized and analyzed through investigating the concrete bridges on service. Nonlinear finite element method is utilized to simulate the cracking process and then reveal the mechanism of pylon cracking and the mode of the crack propagation. Study on crack resisting reliability is carried out to be served as a rational theoretical tool to quantify and estimate the cracking resisting performance. Parametric study is performed to clarify the main contributors to the cracking and, accordingly, countermeasures are promoted. The lifecycle performance of pylon is optimized by an overall consideration of the structural and economical efficiency. The outcomes can be served as theoretical reference for bridge specification formulation and management decision. Research findings of this project are of significant meanings both theoretically and practically.

我国斜拉桥数量已居世界之首，索塔是斜拉桥中重要的受力构件，调查表明，现役斜拉桥中大部分混凝土索塔在施工和运营期间发生开裂，不仅影响结构使用寿命，还埋下了严重的安全隐患。本项目拟通过现役混凝土桥梁的裂缝调查，统计分析常见裂缝的类型和形式；通过非线性有限元方法仿真分析模拟开裂过程，揭示开裂机理和裂缝扩展规律；通过抗裂可靠度研究，为结构抗裂性能的度量和预测提供合理的理论依据；通过参数分析，探明影响开裂的主要参数，提出防止开裂的应对措施；通过综合考虑抗裂应对措施的效用和经济指标，对索塔生命周期性能进行优化，为修订相关规范条文及斜拉桥设计、管养决策提供理论依据。研究成果具有重要的理论意义和工程应用价值。

我国斜拉桥数量已居世界之首，索塔是斜拉桥中重要的受力构件，调查表明，现役斜拉桥中大部分混凝土索塔在施工和运营期间发生开裂，不仅影响结构使用寿命，还埋下了严重的安全隐患。项目通过对斜拉桥混凝土索塔的裂缝调研，分析了各类型索塔裂缝的产生原因，建立了斜拉桥混凝土索塔裂缝层次模型，初步建立了斜拉桥混凝土索塔典型开裂的病害资料库；针对可能导致斜拉桥混凝土桥塔开裂的各种因素，分别建立了相应的精细化有限元分析方法，包括施工期水化热、温度、预应力、收缩徐变等，探明了典型索塔开裂机理和各因素影响规律；通过将裂缝控制等正常使用性能纳入结构可靠性及生命周期性能分析框架，提出了混凝土索塔开裂可靠度分析方法、生命期性能退化分析方法及性能退化分析修正理论，建立了适用于斜拉桥混凝土索塔生命期开裂的可靠度分析方法；通过引入生命周期性能优化理念，对控制混凝土索塔开裂的措施进行优化，提出了斜拉桥混凝土索塔生命周期检测优化理论及维护优化理论，建立了提高索塔生命期抗裂性能的方法与措施。上述研究对在役斜拉桥的设计与管养，及制定相关的规范条文，指导桥塔设计，减少工程事故，提高结构使用寿命，具有深远的理论意义和工程价值，还将产生很大的经济和社会效益。