土木工程外文文献翻译------施工与建筑材料.doc

Abstract
The combined effects of creep and shrinkage of concrete and relaxation of prestressing tendons cause gradual changes in the stresses in both concrete and prestressing tendons. A simple method is presented to calculate the long-term prestress loss and the long-term change in concrete stresses in continuous prestressed concrete members with either carbon fiber reinforced polymer (CFRP) or aramid fiber reinforced polymer (AFRP) tendons. The method satisfies the requirements of equilibrium and compatibility and avoids the use of any empirical multipliers. A simple graph is proposed to eva luate the reduced relaxation in AFRP tendons. It is shown that the prestress loss in FRP tendons is significantly less than that when using prestressing steel, mainly because of the lower moduli of elasticity of FRP tendons. The long-term changes in concrete stresses and deflection can be either smaller or greater than those of comparable girders prestressed with steel tendons, depending on the type of FRP tendons and the initial stress profile of the cross-section under consideration.
在过去的十年，纤维增强聚合体筋作为预应力钢筋的使用已经被提议，并且已经用FRP筋建造了一些混凝土桥。与传统的预应力钢筋相比，FRP筋有许多优点，其中包括它们有无腐蚀性和绝缘性的良好性能，质轻，还有较高的抗拉强度。大多数关于用FRP筋的预应力混凝土梁的研究工作都集中在预应力构件的短期行为；在文献里面关于配有FRP筋的混凝土构件的长期行为的研究成果是缺乏的。最近ACI委员会在关于用FRP筋的预应力混凝土结构的报告中指出“关于预应力的长期损失和随时间变化的弯曲度和变形的研究是必要的…。”混凝土结构中大多数的FRP筋的研究和应用要么是碳纤维增强聚合体或者是芳族聚酸胺纤维增强的聚合体。玻璃纤维增强聚合体的应用大多数都局限在传统的配筋中，因为它的抗拉强度相对较低，而且抵抗徐变的能力差。因此，这篇论文集中在CFRP 和AFRP筋的预应力构件的研究上。