铁路先简支后连续梁疲劳性能与抗裂性能试验研究

Test research of the fatigue behaviour and anticrack property on thesimply supported-to-continuous beam of the railway

研究带有湿接缝的先简支后连续梁桥结构的疲劳性能和抗裂性能,对3条模型梁的疲劳试验和抗裂试验进行了研究。介绍了铁路预应力混凝土先简支后连续梁模型梁的设计和试验方法,根据3条模型梁疲劳试验结果,分析了在正常使用状态下结构刚度、各典型截面特别是湿接缝段混凝土、普通钢筋和预应力钢筋应变随疲劳加载次数的变化规律,指出重复加载明显降低了梁体刚度,并使梁体混凝土、普通钢筋和预应力钢筋应变增大。根据开裂试验结果,分析了重复加载对各关键断面特别是湿接缝断面抗裂性的影响,得出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。给出了关于铁路预应力混凝土先简支后连续梁疲劳性能和湿接缝抗裂性的一些结论和建议。

In order to study the fatigue behaviour and anticrack property on the simply supported to-continuous beam,the fatigue test and the anticract test on three model beams are carried out.The paper concisely introduces the design and test method of the railway prestressed concrete simply supported-to-continuous model beams.Based on the fatigue test results of three model beams,the stiffness of the structure system and the strain change relation about concrete, reinforceing steel bars and prestressed steel bars especially in the wet joint zones with the variational circles of fatigue load under the normal condition are analyzed and studied.It is concluded that the fatigue load decreases the stiffness of the beams clearly and augments the strain of concrete, reinforceing steel bars and prestressed steel bars.In addition,the effect of the fatigue load on the anticrack property of the key sections especially the wet-joint sections is investgated.It is pointed that the fatigue load decreases the strength of breaking of the wet-joint sections,nevertheless it has no obvious effects on that of the sections of middle span and support.Accordingly,some conclusions and advice are given.