水化热和徐变收缩对V形墩系梁应力的影响

Thelnfluence of Hydration Heat and Creep-shrinkage on Tie Beam Stress of V-Shape Pier

针对一种带系梁的混凝土V形墩施工前期温度应力可能导致系梁开裂的的问题,采用空间有限元的分析方法,分别建立系梁分次浇筑及一次浇筑数值模型,根据施工步骤及主要工况分析V形墩系梁温度场及应力场的变化规律,研究徐变收缩与温度耦合作用的效应。研究表明,两种施工方案中,温度及应力仅在合龙段区域差异较大,分次浇筑时,两侧已浇筑的混凝土限制了合龙段的变形,合龙段的拉应力明显增长;徐变收缩与水化热的温度效应是相互影响的,浇筑早期的徐变收缩作用在可以降低水化热产生的拉应力,且温度越高其作用越明显;分次浇筑可减少后期收缩作用在系梁中产生的拉应力。

Focusing on tie beam crack of concrete V-shape which caused by temperature stress at early construction period, numerical models of graded pouring and one-time pouring tie beams are established with space finite element method. The variation of temperature field and stress field of tie beam is analyzed according to construction procedure and main condition and the coupling effect of creep-shrinkage and temperature is studied.The results show that there is great difference in temperature and stress of closure segment only between the two construction schemes. Due to the limitation of closure segment deformation caused by previous concrete, the tensile stress of closure segment increased obviously with graded pouring scheme. The creep-shrinkage and the temperature effect of hydration heat interact on each other. The sensile stress caused by hydration heat at early construction period can be reduced by creep and shrinkage, especially when temperature is high. Graded pouring scheme can reduce the tensile stress caused by shrinkage at later period.