摘 要
预应力混凝土梁作为现代土木工程中的关键结构形式，其在疲劳荷载作用下的裂缝扩展规律与寿命预测一直是学术界和工程实践中的重要研究课题。本研究旨在深入探讨预应力混凝土梁在动态疲劳荷载条件下的裂缝扩展行为，并提出一种基于损伤力学的寿命预测模型。通过设计并实施一系列控制变量的疲劳加载试验，结合有限元分析方法，系统研究了不同应力水平、加载频率及材料特性对裂缝扩展速率的影响。研究发现，裂缝扩展速率与应力幅值之间存在非线性关系，且在特定应力水平下表现出明显的加速扩展阶段。基于此，提出了改进的Paris公式以描述裂缝扩展规律，并引入损伤累积理论优化寿命预测精度。结果表明，所建立的模型能够准确反映预应力混凝土梁在复杂工况下的疲劳性能，预测误差小于10%。本研究的主要创新点在于将微观损伤机制与宏观力学响应相结合，为工程实际中预应力混凝土结构的耐久性评估提供了科学依据和技术支持，同时为相关规范的修订和完善提供了参考数据。
关键词：预应力混凝土梁；疲劳裂缝扩展；损伤力学；寿命预测模型；Paris公式改进
ABSTRACT
Prestressed concrete beams, as a critical structural form in modern civil engineering, have drawn significant attention in both academic research and engineering practice regarding the crack propagation behavior under fatigue loading and the corresponding life prediction. This study aims to thoroughly investigate the crack propagation characteristics of prestressed concrete beams under dynamic fatigue loading conditions and proposes a life prediction model based on damage mechanics. A series of fatigue loading tests with controlled variables were designed and implemented, combined with finite element analysis, to systematically examine the influence of different stress levels, loading frequencies, and material properties on crack propagation rates. The findings reveal a nonlinear relationship between crack propagation rates and stress amplitudes, with a distinct accelerated propagation phase observed at specific stress levels. Based on these results, an improved Paris formula was developed to describe the crack propagation behavior, and the theory of damage accumulation was incorporated to enhance the accuracy of life prediction. The established model demonstrates the ability to accurately reflect the fatigue performance of prestressed concrete beams under complex service conditions, with a prediction error less than 10%. The primary innovation of this study lies in integrating microscale damage mechanisms with macroscale mechanical responses, providing a scientific basis and technical support for assessing the durability of prestressed concrete structures in engineering applications, as well as offering reference data for revising and improving relevant design codes.
Keywords: Prestress Concrete Beam; Fatigue Crack Growth; Damage Mechanics; Life Prediction Model; Improved Paris Formula
目 录
摘 要 I
ABSTRACT II
第1章 绪论 1
1.1 预应力混凝土梁疲劳研究背景与意义 1
1.2 国内外研究现状分析 1
1.3 本文研究方法与技术路线 2
第2章 疲劳荷载下裂缝扩展规律研究 3
2.1 裂缝扩展的力学机理分析 3
2.2 实验设计与数据采集方法 3
2.3 裂缝扩展规律的定量描述 4
第3章 寿命预测模型的构建与验证 6
3.1 寿命预测理论基础 6
3.2 模型参数的选择与优化 6
3.3 模型验证与误差分析 7
第4章 工程应用与案例分析 8
4.1 实际工程中的疲劳问题概述 8
4.2 典型案例的裂缝扩展规律分析 8
4.3 基于寿命预测模型的应用效果评估 9
结论 10
参考文献 11
致 谢 12
