Abstract: The internal force of bracing structure in foundation pit was an important part of observation.The calculation formulas for axial force presented in current code for design of concrete structure were not proper when using measured stress of steel bar.Based on compatibility of deformation and force equilibrium principal, some scholars’ achievements referenced, considering nonlinearity of the stress strain of concrete structure as well as foundation monitoring data, axial force calculation formulas for concrete strut were derived.Tested by foundation pit observation, the axial force of concrete strut in foundation pit was reflected properly by those formulas．

摘要： 基坑混凝土支撑轴力测试是基坑监测中非常重要的内容。使用实测钢筋应力计算时，现有混凝土结构规范给出的轴力计算公式显得不适用。结合基坑监测情况，并考虑混凝土结构应力应变非线性特性，在参考多位学者研究成果的基础上，根据变形协调原理和力的平衡原理，推导了采用钢筋应力计算支撑轴力计算公式。通过基坑监测实例验证，推导的公式能反映基坑混凝土支撑轴力的实际情况，在实际工程应用中效果良好。