先简支后连续梁桥结构的疲劳性能与抗裂性能

采用等幅重复加载和按比例分级加载法,对3根铁路先简支后连续模型梁的疲劳性能和抗裂性能进行研究.根据3根模型梁疲劳试验和开裂试验结果,分析在正常应力状态下结构刚度,各典型截面混凝土、普通钢筋和预应力钢筋的应变随疲劳加载次数的变化规律以及重复加载对各关键断面特别是湿接缝断面抗裂性能的影响.研究结果表明:重复加载能明显降低梁体刚度,并使梁体混凝土、普通钢筋和预应力钢筋的应变增大;重复荷载降低了湿接缝的抗裂强度,而对跨中截面和中支点截面抗裂强度无明显影响.

Fatigue behaviour and anticrack property of simply supported-to-continuous beam

The fatigue test and the anticrack test on three simply supported-to-continuous model beams were carried out by the method of uniform cyclic loading and scaling increased load. Based on the fatigue and anticrack test results of the three model beams, the stiffness of the structure system and the change relation between strain of concrete, reinforcing steel bars and prestressed steel bars and the circles of fatigue load in the normal condition were studied. The effect of the fatigue load on the anticrack property of the key sections, especially the wet-joint sections, was investigated. The results show that the fatigue load can decrease the stiffness of the beams obviously and augment the strain of concrete, reinforce steel bars and prestressed steel bars, and it can decrease the strength of breaking of the wet-joint sections. Nevertheless the fatigue load has little effect on that of the sections of middle span and support.