Effects of Cyclic Fatigue Loading on Partially Prestressed Beams - Phase 2

这是对部分预应力混凝土梁在循环疲劳荷载下的行为和建模的两部分研究调查的第二部分。部分预应力梁在这里被定义为用预应力和非预应力钢筋组合加固的混凝土梁，其设计允许在全服务荷载（恒载加活载）下开裂。研究了构件的疲劳寿命、疲劳作用下裂纹和裂纹宽度的增加以及挠度和挠度随加载循环次数的增加而增加。第一阶段的研究处理了矩形截面在恒幅疲劳载荷下的试验。第二阶段研究变幅疲劳荷载作用下的T型截面模拟桥梁实际活载。这项研究包括一个实验程序和一个分析程序。试验变量包括三个级别的配筋，每个级别有四个级别的局部预应力，其中包括完全配筋和完全预应力两个边界。整个实验程序和测量记录的目的是提供一个全面的数据基础的开裂挠度，其增加与循环疲劳载荷。在疲劳下预测裂缝宽度和挠度的分析程序旨在生成合理的模型，这些模型在以全钢筋和全预应力混凝土为代表的边界上仍然有效。

This is the second of a two-part research investigation of the behavior and modeling of partially prestressed concrete beams subjected to cyclic fatigue loading. Partially prestressed beams are defined here as concrete beams reinforced with a combination of prestressed and non- prestressed reinforcement, designed to allow cracking under full service load (dead plus live load). The following aspects of fatigue will be investigated: the fatigue life of the members, cracking and crack width increases under fatigue, and deflection and deflection increases with the number of cycles of loading. The first phase of the research dealt with rectangular sections tested under constant amplitude fatigue loading. The second phase deals with T sections under variable amplitude fatigue loading simulating real live loads on bridges. The research comprises an experimental and an analytical program. The experimental variables include three levels of reinforcement and, for each, four levels of partial prestressing which include the two boundaries of full reinforcing and full prestressing. The total experimental program and the measurements to be recorded are designed to provide a comprehensive data base on cracking deflections, and their increases with cyclic fatigue loading. The analytical program to predict crack widths and deflections under fatigue is designed to generate rational models that remain valid at the boundaries, represented by fully reinforced and fully prestressed concrete.