节段预制PC箱梁弯剪变形和开裂规律试验研究

Experimental investigation of deformation and crack variation rules of segmental pre-stressed concrete box beams under bending and shearing

为探讨节段预制PC梁桥实际中存在的弯剪复合作用下梁体变形、破坏裂缝开展规律等问题,依据某实桥箱梁模型,按1∶10缩尺浇筑试件,进行破坏性试验研究。研究表明,节段PC箱梁在弯剪复合作用下,胶接缝张开破坏模式明显区别于整体浇筑混凝土梁体破坏模式。破坏主要发生在弯矩、剪力突变的节段接缝处,而两侧弯剪段完好。不同配束比梁体破坏模式差别也较大,配束较多梁体破坏出现节段间错动现象和顶板翼缘处斜裂缝,是裂缝张开后以剪切为主的弯剪破坏;而配束较少梁体顶板仅出现少量斜裂缝,但无明显错动,是以受弯曲为主的弯剪破坏。但两者弯剪破坏类型同属延性破坏。

In order to investigate the deformation and crack variation rules of segmental prestressed concrete bridge （SPCB） under shearing and bending, the specimens which were poured on the size of a real bridge with an 1 ： 10 scale, were prepared for destructive testing. Our study shows that the failure mode of SPCB for bonded joints split is obviously different from integral type con- crete beams under shearing and bending. The failure happens mostly in mutation of bending moment and shear, while the rest part of the beam is in normal operating condition. Beams with different tendon ratios result in different failure modes. The failure mode of beam with a higher tendon ratio is the failure caused mainly by shearing after joints split while dislocation appeares between segments and some diagonal cracks come out in the top slab. The beam with lower ratios is destroyed mainly by coupling effect of bending, but dislocation and diagonal cracks are not obvious. However, both of the failure modes belong to ductile fracture.