约束状态下混凝土拉伸徐变模型

Tensile creep model for concrete subject to constant restraints

为准确计算混凝土收缩变形在受到内、外部约束情况下产生的拉应力,评估混凝土收缩开裂风险、提高结构物耐久性,该文基于浇筑后混凝土的约束应力及应变试验,研究了混凝土约束状态下的拉伸徐变行为。研究结果表明:约束状态下的混凝土具有较大的流动徐变变形,建立在压缩徐变试验基础上的传统徐变模型不能够精确预测约束状态下混凝土的应力发展。研究根据混凝土实测约束应力-应变数据对传统模型进行改进,建立了更能代表实际工程情况、能够用于混凝土约束应力计算的徐变及松弛模型。

Tensile stresses develop in restrained concrete slabs with shrinkage deformation.The appropriate creep or relaxation functions are crucial for assessing the stress development and the associated cracking potential.Existing creep models were found not suitable for such stress evaluations.This study investigates restrained slabs stress-strain characteristics and tensile creep behavior in axially restrained concrete specimens which represent field conditions of actual structures.A modified tensile creep compliance function is used to account for the high viscous effect with restrained conditions for accurate predictions of the stress and cracking potential in structures.