【摘要】 为获得混凝土重力坝实际运行下的自振特性,降低模态参数识别误差,在探究随机减量法对加速度信号适用性问题的基础上,对传统时域ITD法进行改进。用两自由度算例验证了本方法的可靠性后,将其应用于水口电站混凝土重力坝的模态参数识别。从计算结果看,随机减量与时域ITD法识别的重力坝固有频率、阻尼比略大于功率谱峰值法,与有限元结果相近;因有限元几何模型、材料和边界条件的影响,振型系数与有限元计算值偏差略大。上述分析表明,基于人工边界的有限元计算理论和模态参数识别技术具有一定的合理性,但仍有待一步研究完善。更多还原

【Abstract】 Recently,the modal parameter identification technology is applied to civil engineering and gradually developing,however it is rarely used to analyze hydraulic structures. In order to obtain the vibration characteristics of the gravity dam under actual operation,the conventional time-domain ITD method was improved based on the applicability study of the random decrement technique for the acceleration signal. After the verification of a two-freedom numerical example,the improved time-domain ITD method was applied to identify the modal parameters of the concrete gravity dam in Shuikou power station. The identified results indicate that the natural frequency and damping ratio are larger than those of the peak picking method,but similar to those of the finite element. Due to the restrictions of the model,material and boundary conditions,the deviation of identified modes is slightly larger than the results of the finite element method. The above analysis shows that the rationality of the finite element calculation theory based on artificial boundary and the modal parameter identification technology is limited and further research is needed.更多还原