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Development of Ductile Segmental External Prestressed Concrete and Its Design Method

延性节段体外预应力混凝土的研制及其设计方法

基本信息

批准号：
07555435
负责人：
MUTSUYOSHI Hiroshi
金额：
$ 0.64万
依托单位：
SAITAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

The application of precast segmental structures with external prestressing is getting popular due to economical and time saving construction. However, since segmental externally prestressed concrete (SEPC) member shows brittle failure at the ultimate state, it has hardly been constructed in earthquake areas. When such a structure is applied to elevated bridge structures whose girders are fixed on top of the reinforced concrete bent and subjected to big earthquakes, some extent of ductility or deformation capacity of the girder will be required.In this study, the ductility improvement of SEPC beams has been developed, and analytical method to predict the load-deformation and design method for SEPC structures have also been established. An experimental investigation was conducted on a series of monolithic and precast segmental simply supported beams. The test variables were ; a) type of joint condition (dry or epoxy), b) provision of confinement reinforcements, c) method of prestressing (external or external together with internal bonded) and d) number of deviators (two or three). An analytical program that consists of an intensive iterative technique has been developed to predict the flexural behavior of the beams considering the material and structural non-linearities. The ultimate behavior of beams with dry or epoxy joints was nearly the same. There was a remarkable increase in the ultimate deflection for the beams with confinements. The experimental results were compared with the analytical predictions from the elastic range to the ultimate state. There was good agreement between them. From the above results it is concluded that the ductility could be improved by provision of confinements in precast SEPC beams and such structures can be erected in seismic areas. From many analytical results, design equations for flexural strength were proposed.

体外预应力预制节段结构以其经济、省时的特点得到了越来越广泛的应用。然而，由于节段式体外预应力混凝土(SEPC)构件在极限状态下呈现脆性破坏，在地震区几乎没有施工。当这种结构应用于梁固定在钢筋混凝土排架顶端的高架桥梁结构并承受较大地震时，将要求梁具有一定的延性或变形能力。本文研究了SEPC梁的延性改进，建立了SEPC结构荷载-变形预测的分析方法和设计方法。对一系列整体预制节段简支梁进行了试验研究。测试变量是：a)连接条件的类型(干的或环氧的)，b)约束钢筋的提供，c)预应力的方法(外部或外部连同内部粘结)和d)偏转器的数量(2或3)。开发了一个由密集迭代技术组成的分析程序，以预测考虑材料和结构非线性的梁的受弯性能。干缝和环氧缝的梁的极限性能基本相同。有约束的梁的极限挠度有明显的增加。从弹性范围到极限状态，将实验结果与分析预测值进行了比较。他们之间有很好的默契。研究结果表明，在预制SEPC梁中设置约束可以改善结构的延性，可以在地震区设置此类结构。根据大量的分析结果，提出了抗弯强度的设计公式。