现浇箱梁模板支架受力性能研究及应用

发布时间：2018-03-30 02:38

本文选题：土木工程施工　切入点：模板支架　出处：《郑州大学》2014年硕士论文

【摘要】：碗扣式钢管脚手架由于其自身的优点被广泛地应用在市政桥梁工程中。由于碗扣式模架在设计及施工过程中理论依据不足及相关施工经验较少，并且其杆件多且整体受力规律复杂，稍有不慎就会造成模架坍塌，致使人员伤亡及财产损失。目前，现有的碗扣式模板支架安全技术规范只是针对箱梁正下方模架的设计，对于翼缘下模架的搭设没有提出设计标准，该部分搭设通常是根据经验搭设，无论从安全性还是经济性角度，都没有定量的依据；另外，国内外的研究也主要是针对预压期箱梁正下方模架受力性能的研究；而且纵观脚手架现场事故，大部分是在混凝土浇筑过程发生的，因此，在混凝土浇筑期杆件受力性能的研究具有重要的意义。而论文以混凝土浇筑过程为前提进行的研究。以郑州市西三环-航海路立交工程中箱梁模板支架为试验对象，通过现场内力监测，研究混凝土浇筑过程中杆件内力分布和传递规律，并通过理论分析与现场实测值对比，探索模板支架立杆、斜撑和剪刀撑内力发展过程，总结模板支架搭设的技术要求。研究得出以下主要结论：（1）混凝土浇筑过程中，，刚刚浇筑完成的断面为危险断面；施工断面前后10m范围内受混凝土浇筑影响较大，超出此起止范围，混凝土浇筑对架体影响较小。（2）一般立杆上部内力大于下部内力，建议工程实际中应减小支架立杆上部步距。（3）翼缘下方的立杆，越靠近中轴线方向内力幅度越大，建议减小靠近中轴线的立杆的横向间距。（4）当混凝土浇筑速度过快时，支架中拉压变号构件数量增多。建议工程实际中应控制混凝土的浇筑速度，且制定措施，保障均匀对称浇筑。（5）翼缘下方的剪刀撑以受拉为主，且下部拉力大于上部拉力；箱梁下方的剪刀撑，下部以受拉为主，上部以受压为主。（6）剪刀撑内力最大值达到16kN，超过双排扣件理论抗滑强度，所以剪刀撑斜杆的接长处应采用特别挑选的优质扣件，且不少于3个。（7）翼缘下方的斜撑与模板的夹角应小于90°，且应上疏下密，与满堂支架立杆的连接扣件应不少于3个。
[Abstract]:The bowl-button steel tube scaffolding has been widely used in municipal bridge engineering because of its own advantages, because of the lack of theoretical basis in the design and construction process and the lack of relevant construction experience, Moreover, it has many members and complex law of the whole force, which will cause the mould frame collapse and cause casualties and property losses. At present, the existing safety technical specifications of the bowl button-type formwork support are only for the design of the mould frame directly below the box girder, but there is no design standard for the construction of the die frame under the flange, which is usually based on the experience. There is no quantitative basis in terms of safety or economy; in addition, domestic and foreign studies are mainly aimed at the mechanical performance of the formwork under the box girder in preloading period. Most of them occur in the process of concrete pouring. Therefore, it is of great significance to study the mechanical properties of the members during the period of concrete pouring, and the research of this paper is based on the process of concrete pouring. Taking the box girder formwork support in the Xi San Huan-Haihe Road Interchange Project of Zhengzhou City as the test object, the distribution and transfer law of the internal force of the bar during the concrete pouring process are studied by monitoring the field internal force, and the theoretical analysis is compared with the field measured value. To explore the development process of internal force of formwork stand, diagonal brace and scissors brace, and summarize the technical requirements of formwork support erection. The main conclusions of the study are as follows:. 1) in the process of concrete pouring, the section that has just been poured is dangerous section, and the concrete pouring has a great influence on the frame body within 10m before and after construction, beyond which the concrete pouring has little influence on the frame body. 2) the upper internal force of the vertical rod is larger than the lower one. It is suggested that the upper step distance of the support rod should be reduced in engineering practice. The lower the flange, the greater the amplitude of internal force in the direction of the central axis. It is suggested that the transverse distance between the poles near the central axis be reduced. 4) when the pouring speed of concrete is too fast, the number of tension-compression variable number members in the support increases. It is suggested that the pouring speed of concrete should be controlled in engineering practice, and measures should be made to ensure uniform and symmetrical pouring. The lower part of the box girder is more tension than the upper one, and the lower part of the box girder is mainly under tension, and the upper part is mainly under compression. The maximum internal force of scissors braces is 16kNs, which exceeds the theoretical anti-slip strength of double-row fasteners. Therefore, special selection of high-quality fasteners should be adopted in the joint strength of shear-braces, and not less than three. The angle between inclined brace and formwork under flange should be less than 90 掳, and the upper and lower parts should be close, and the connection fastener should be not less than 3.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.57

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