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研究混凝土浇筑初期内部温度应力不均匀分布特征和预防温度裂缝的有效措施,以西安至铜川高速公路渭河特大桥某0#箱梁为研究对象,以MIDAS/FEA(multitier distributed applications services/finite element analysis)有限元分析软件为计算平台,采用有限单元法对施工期混凝土水化热温度场进行了数值模拟计算,分析了3种不同防裂工程措施的理论效果,并结合温度监测进行了工程措施的优化。结果表明:混凝土浇筑52 h左右内部温升达到高峰,有无冷却水管的箱梁内部最高温度温差在10℃左右,在内外温差20℃左右时拆除模板时机较为恰当;箱梁腹板与横隔板交界处温度应力集中,设置冷却水管改善温度应力分布效果明显。与其他研究结果相比,采取温度监测与有限元计算全过程动态分析方法优化防裂工程措施效果较好。
In order to study the characteristics of unequal distribution of internal temperature stress in early stage of concrete pouring and the effective measures to prevent temperature cracks, a 0 # box girder of Weihe Super Bridge from Xi’an to Tongchuan Freeway was taken as the research object. With MIDAS / FEA (multitier distributed applications services / finite element analysis ) Finite element analysis software is used as the calculation platform. The finite element method is used to simulate the temperature field of concrete hydration heat during construction. The theoretical results of three different crack prevention engineering measures are analyzed. Combined with the temperature monitoring, the engineering measures optimization. The results show that the internal temperature rise reached about 52 h after concrete pouring. The maximum temperature difference inside and outside of the box girder with or without cooling water pipe is about 10 ℃, and it is more appropriate to remove the template when the internal and external temperature difference is about 20 ℃. Plate junction temperature stress concentration, setting cooling water pipe to improve the temperature stress distribution effect is obvious. Compared with other research results, it is better to adopt the whole process dynamic analysis method of temperature monitoring and finite element calculation to optimize anti-cracking engineering measures.