基于奇异值分解的混凝土工字梁应力超声测试

Ultrasonic Stress Test of Concrete I-beam Based on Singular Value Decomposition

目的在特定荷载模式下,研究混凝土梁应力的超声测试,提出并验证一种基于超声信号奇异值分解的应力测试方法.方法在弹性范围内的若干荷载等级下,采集三点弯曲混凝土工字梁模型的超声波形并组成矩阵,构造一个由其奇异向量线性叠加的特性向量,使得该向量与超声波形的内积为应力的线性函数,由此建立超声信号与混凝土梁应力之间的线性拟合关系.结果平均意义上,由笔者方法得到的超声信号应力指标与混凝土梁应力严格满足线性关系;在文中试验条件下用该方法测试应力,相对误差小于14%.结论针对混凝土梁应力的超声测试,笔者提出的测试方法在三点弯曲工字梁模型上得到试验验证.

Based on ultrasonic signal and the SVD(singular value decomposition)method,a new approach for testing the stress of concrete beams under specific load modes is proposed and verified.The ultrasonic signal of a concrete I-beam model under the three-point bending loads with 22 load levels within the elastic range is collected and composed into a matrix.A characteristic vector is constructed by linear superposition of the singular vector of the signal matrix,so that the inner product of the vector and the ultrasonic signal turns to be a linear function of the stress,and then a linear fitting relationship between the signal and the stress can be established.The results show that,in the sense of mathematical expectation,the stress indicator obtained by this method is strictly a linear function of the stress,and,under the experimental conditions described in this paper,the relative error of stress indicator is less than 14%.It is concluded that the stress measurement method proposed in this paper is validated with experimental results from the concrete I-beam model.