基于转角的简支梁初始抗弯刚度识别方法

Rotation Angle-Based Identification Method of Initial Bending Stiffness of Simply Supported Beams

为寻求较优方法识别简支梁初始抗弯刚度,根据“虚拟分割”的思想,首先将梁体分段,直接测试或间接得到预制梁在已知静力荷载作用下的分段截面处转角,通过建立转角与分段梁体抗弯刚度之间的关系式,反向求解各段梁体抗弯刚度值。利用有限元数值方法和试验数据验证了所提方法的正确性及有效性。采用矩阵条件数分别分析了梁体分段数量、作用力大小、类型、个数及作用位置5个因素对识别方程组稳定性的影响规律,并考察了转角测量误差对识别精度的影响。分析结果表明:梁体分段数量、作用力个数和作用位置是影响识别方程组稳定性的关键因素;梁的分段数量越少,测试传感器精度越高,能接受的转角测量噪声程度越高;在加载和测试方法得当的前提下,所提方法具有良好的鲁棒性,可用于简支梁的初始抗弯刚度识别;所提方法不需要复杂反演算法、有限元数值模型的配合,也无须已知梁截面尺寸、配筋和材料特性等,具有简便实用的特性。

In order to develop an optimal method to identify the initial bending stiffness of a simply supported beam,the beam was segmented to directly measure or indirectly calculate the rotation angles at the segmentation cross-sections under a known static load based on the idea of virtual segmentation.The bending stiffness of various girder segments was inversely obtained by establishing a relationship between the rotation angle and bending stiffness of each girder segment.The correctness and validity of the proposed method was proved by a finite element analysis and the experiment data.The condition number of a matrix was applied to analyze the influence of the number of girder segments and the magnitudes,types,numbers,and positions of the acting forces on the stability of the identification equation set,and the influence of rotation angle measurement error on identification accuracy.The results show that the number of girder segments,number of forces,and positions of the forces were the key factors influencing the stability of the identification equation set;the acceptable rotation angle measurement noise increased with the decrease of the number of girder segments and the increase of sensor accuracy;under proper loading and test conditions,the proposed method shows high robustness in identification of initial bending stiffness of beams.The proposed method is simple and practical because it requires no complex inversion algorithm,support of a finite element model,or pre-measurement of parameters such as girder cross-section dimension,reinforcement,or mate-rial properties.