现浇箱梁施工过程模板支撑内力实测研究

Load Measurement of Shores in the High-Scaffold Formwork System for the Construction of Cast-in-Place Box Girder

本文探讨现浇箱梁模板支撑体系的承载机理，建立现浇箱梁模板支撑体系的设计方法和施工程序，对控制其施工垮塌事故具有重要意义。采用钢弦式应力传感器，对施工中的箱梁模板支撑的内力时程进行两轮实测。箱梁浇筑采取两次工艺，第一次浇筑箱梁底板和腹板，第二次浇筑箱梁顶板和翼缘板，两次浇筑时间差3～5d不等。分析监测结果表明：模板支撑的内力在第一次浇筑过程中显著增大且分布不均匀，而第二次浇筑过程中支撑内力增长不显著，且各支撑的内力增量呈均匀特征。建议在进行现浇箱梁模板支撑系统设计时，适当考虑两次浇筑对模板支撑系统的有利特性，改进设计方案，并强化第一次浇筑期间的施工管理，从而提高模板支撑系统施工的安全性和经济性。

The paper studies the loading-carrying mechanism of high-scaffold formwork system for cast-in-place box girder, and its load-carrying. The construction is more risk than other work, therefore studying, and proposes a set of design method and construction process which help to control the collapse accidents. The inter- nal forces in high-scaffold formwork system for cast-in-place box girder are recorded with the steel-string stress sensors during construction. The construction of concrete casting is planed two stages, as first bottom plate and web, then face plate and flange plate, and its interval is about three to five days. The results show that the internal force in the shores of high-scaffold formwork system in the first time pouring was increased largely and of the difference obviously in the every shore, while in the second time pouring it＇s not obvious and of uniform characteristics. Therefore, some suggestions are given for improving the safety and economy of high-scaffold formwork system, including the considering the favorable characteristics of two stages pouring for box girder and improving the design, and reinforcing construction management of the first time concrete pouring work.