环境激励下定州开元寺塔结构状态评估研究

Study on condition assessment of Dingzhou Kaiyuan Pagoda under ambient vibration

基于环境激励,对定州开元寺塔的动力性能进行了研究,并获得其基本动力性能信息。在平面维度上,基于动力信息推导得到模态参与率系数,对古塔各层刚度中心进行了识别;在立面维度上,基于柔度曲率幅值法,对古塔层间刚度分布进行了识别;最终基于模糊评价法,结合材料劣化、平面偏心损伤及立面维度刚度分布信息对古塔健康状态进行了科学评估。研究表明:古塔的层间刚度随着高度的增加而减小,且东北侧新砌筑塔体部分的层间刚度大于旧塔体部分;古塔的刚度中心存在偏心现象,但是偏心不明显,第2~11层中70%左右楼层的刚度中心范围在东北-西南直线方向上,30%左右的刚度中心在东南-西北直线方向上。古塔顶层的柔曲率突变系数存在明显的突变,底层的柔度曲率变化较小,塔体的10~11层的层间刚度有明显突变,古塔的顶部楼层存在局部损伤。根据模糊评价法的结果显示,古塔总体处于健康状态,但需要针对各类损伤表征指标进行长期健康监测与性能维护。

Based on the ambient vibration method, the dynamic performance of the Kaiyuan Pagoda in Dingzhou was studied, and the dynamic performance information of the pagoda was obtained. The stiffness center of each layer of the ancient pagoda in the plane dimension and the stiffness distribution in the facade dimension were identified based on the obtained model participation ratio coefficient and the flexibility curvature amplitude method, respectively. Finally, a scientific evaluation of the health status of the ancient pagoda was carried out based on the fuzzy evaluation method, which included the information of the material deterioration, the eccentric damage and the stiffness distribution. The studies show that the inter-story stiffness of the ancient pagoda decreases with the height. The inter-story stiffness of the new masonry tower on the northeast side is greater than that of the old tower. The stiffness center of the ancient pagoda is eccentric, but the eccentricity is not obvious. About 70% of the stiffness center of the 2 nd to 11 th floors is in the northeast-southwest straight-line direction, and the last 30% of the stiffness center falls in the southeast-northwest straight-line direction. There is an obvious sudden change in the flexibility curvature coefficient on the top floor while the flexibility curvature of the bottom layer has a small change. The stiffness between the 10 th and 11 th floors of the pagoda body also has an obvious sudden change. It shows that the local damage exists on the top floor of the ancient pagoda. According to the results of the fuzzy evaluation method, the ancient pagoda is in good health, but it needs long-term monitoring and performance maintenance.