预应力叠合梁受弯性能的试验研究

针对二次受力部分预应力混凝土叠合梁的受弯性能与普通整浇梁相比具有明显的优点的问题,为了促进叠合结构的进一步推广和应用,通过对十根叠合试验梁的试验,探讨了正常使用阶段二次受力对叠合断面应力应变状态、裂缝的形成和发展、断面的短期刚度、挠度的影响,研究表明:当h1/h较小且M1/Mcr较大时,由于"扁梁弯曲效果"和"粘结增强效果"的双重作用,叠合梁的裂缝间距明显小于整浇对比梁;预制断面上残留的"荷载预应力"有助于提高叠合梁的初期抗弯刚度,在进行裂缝和刚度计算时建议考虑上述有利影响;通过合理选择h1/h、M1/ M和预应力大小可以化解应力超前现象,从而使构件的初期刚度和挠度符合规范和使用要求,充分体现此类构件的经济合理的优势.

Experimental study on flexural behavior of partially pre-stressed concrete composite beams subjected to service load

Compared with conventional cast-in-place beams, flexural behaviour of partially pre-stressed concrete composite beams have obvious advantages. For the wider popularization and application of composite structures, by the experiment of 10 composite beams, a comprehensive discussion is given on how secondary loading affects the section strain distribution, initial stiffness of section, the formation of cracks and their propagation etc.. The test results show that, if h1/h is small and M1/Mcr is big, at first load state, the crack interval of composite beams became smaller than conventional cast-in-place beams because of flexural effects and bond strengthening effects. And the residual stress also facilitates greater initial stiffness than full cast-in-place beam in service stage. The above factors are recommended to be considered in both crack width calculation and stiffness calculation. Another result of test shows that we can not only ensure the functionality of such type of member, but also benefit from its economic advantages.