| With the rapid development of China's economy, there are more and more large-scale construction projects, and this kind of construction is complete in function and complex in structure. Safety accidents frequently happen in engineering projects which are more difficult in construction, especially when the template overall collapse has occurred one after another in recent years, so based on that situation, China released "the template construction safety technical specifications" (JGJ162-2008) in 2008. This thesis research results will provide some references for the revision of "the template construction safety technical specifications".This thesis mainly aims to analyze the forced mechanism of the single vertical rod in fastener type steel pipe formwork support system. According to the related requirements of'the template construction safety technical specifications" in laboratory, put up fastener style steel pipe formwork support, and make the single vertical rod destructive tests, testing the critical loads of the forced vertical rod instability in formwork support, vertical rod axial force along the vertical rod distribution regularities as well as the bridging stress. Then study the stress characteristics, and find out the influence of the bridging on the single vertical rod bearing capacity. According to experimental data, the author tries to analyze the single vertical rod stress regularities, destroy the bad shape, and investigate the influence of different parameter settings (different settings of vertical and horizontal spacing interval, step and bridging) on the vertical rod bearing capacity.Through the analysis, it is found that the weak link of the vertical rod in fastener type steel pipe formwork support system is in the top step, rather than the bottom. Each time in the test, the bucking of top and midspan of vertical rod happens first, and at last vertical peak buckling instability causes the loss of poling bearing capacity. Deformation of top and midspan of the vertical rod is the most obvious. Reduce lag spacing does little to enhance stud bearing capacity, while reduce step can significantly improve the bearing capacity of the stud. This paper will deeply analyze the regularities which is got in single vertical rod destructive experiment, draw the forced mechanism of the single vertical rod, and lay foundation for the overall stability of fastener style steel pipe formwork support and provide some references for the revision of'the template construction safety technical specifications".Research results of this paper will contribute to the study of the overall stability of fastener style steel pipe formwork support, at the same time, it will ensure that formwork support system can not only be used safely, but also give full play to the material performance, reduce costs, achieving the goal of safety, reliability and easy affordability. |
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