Lu Liang, Yin Minghao, Xia Wanqiu, Suliman Musaab, Wang Lei
State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China.
Department of Disaster Mitigation for Structures, Tongji University, Shanghai 200092, China.
Materials (Basel). 2025 Mar 15;18(6):1300. doi: 10.3390/ma18061300.
The internal force state in concrete components is a crucial factor in evaluating the safety performance of existing buildings, bridges, and other concrete structures, while theoretical and numerical analysis of an ideal model may not accurately capture the actual internal forces within concrete components. This study introduces the basic principles of stress release technology for identifying internal forces in existing reinforced concrete components and provides a detailed derivation of normal and shear strains of component sections under each internal force component. It demonstrates that the internal forces of reinforced concrete sections can be accurately identified by testing the strain on the midpoint of three surface sides. A finite element model is established to investigate the relationship between groove depth and groove side length when normal or shear stress is released to zero, as well as the impact of reinforcement ratio on the stress release level. Experimental research is conducted using the grooving method to identify internal forces in reinforced concrete components under different external loads. The test results exhibit strong agreement with numerical simulation results. Additionally, the identification errors for axial forces and bending moments are within 10%, underscoring the feasibility of measuring internal forces in existing reinforced concrete components through the stress release method.
混凝土构件的内力状态是评估现有建筑物、桥梁及其他混凝土结构安全性能的关键因素，而对理想模型进行理论和数值分析可能无法准确捕捉混凝土构件内部的实际内力。本研究介绍了用于识别现有钢筋混凝土构件内力的应力释放技术的基本原理，并详细推导了各内力分量作用下构件截面的正应变和剪应变。结果表明，通过测试构件三个表面边中点处的应变，可准确识别钢筋混凝土截面的内力。建立了有限元模型，研究了法向或剪应力释放至零时槽深与槽边长的关系，以及配筋率对应力释放水平的影响。采用开槽法对不同外部荷载作用下钢筋混凝土构件的内力进行识别的试验研究。试验结果与数值模拟结果吻合良好。此外，轴力和弯矩的识别误差在10%以内，这表明通过应力释放法测量现有钢筋混凝土构件内力是可行的。
