基于无损检测和概率的古代石拱桥结构可靠度评估

Reliability evaluation of historic stone-arch bridge structure based on non-destructive testing and probability

中国古代石拱桥由于其年代久远、结构复杂、露天保存以及可靠度评估过程中参数不易确定等特点,导致传统结构稳定性分析评估方法难以准确评估古代石拱桥结构实际响应和可靠度。提出一种基于无损检测和概率的古代石拱桥结构可靠度评估方法。该方法首先提出利用无损检测技术或工程地质类比法获取石拱桥结构物理力学参数并建立数值模型;然后基于无损检测数据或《工程地质手册》,利用敏感性分析方法确定对石拱桥整体结构响应影响较大的关键参数,即第一类关键参数,并根据参数先验分布提出不同的抽样方法,生成随机样本实现贝叶斯更新过程;最后通过ANSYS软件对桥梁结构的响应进行有限元分析,并利用可靠度分析方法计算出石拱桥结构可靠度指标,并根据相关标准对石拱桥结构安全与可靠度进行评估。以全国重点文物保护单位隋代赵州桥(大石桥)为研究对象建立简化模型,采用本文提出的可靠度评估方法计算得到目前赵州桥的可靠度为3.42,该桥梁安全等级为二级,该评估结果与实际情况基本相符,从而验证了本文方法的可靠性和可行性。该方法可规避传统物理力学检测过程中对石拱桥古建筑的损害,筛选出的关键参数合理,且数据更新处理充分考虑模型参数的不确定性,从而可更精确地计算出古代石拱桥可靠度指标,可为古建筑文物的预防性保护提供科学依据。

Due to the characteristics of Chinese historic stone-arch bridges,such as long age,complex structure,open air protection environment and uncertain parameters,it is difficult to accurately evaluate the actual structural response of the historic stone-arch bridges by the traditional structural stability analysis methods.A novel non-destructive testing technology and probability-based structure reliability evaluation method for historic stone-arch bridges is proposed.Firstly,non-destructive testing technology and engineering geology analogy method are used to obtain physical and mechanical parameters of stone-arch bridge structure and then a numerical model is established.Then based on the non-detection data or engineering geology manual,the sensitivity analysis method is used to determine the key parameters that have a greater impact on the overall structural response of the stone-arch bridges,that is,the first type of key parameters,and different sampling methods are proposed to generate random samples according to parameter prior distribution to realize the Bayesian update process.Finally,the response of the bridge structure is analyzed by ANSYS software,and the reliability index of stone-arch bridges is calculated by the reliability method,and the relative standards are compared to evaluate the safety of the stone-arch bridge structure.Taking the simplified model of Zhaozhou Bridge of Sui Dynasty(big stone bridge),a national key cultural relic protection unit,as the research object,the reliability value calculated by this evaluation system is 3.42,and the bridge safety grade is second level.The evaluation results are basically consistent with the actual situation,thus verifying the reliability and feasibility of the proposed method.The method can avoid the damage to the cultural relics of historic stone-arch bridges caused by the traditional physical and mechanical detection process,and the selected key parameters are reasonable and the uncertainty of observation and model parameters is fully considered in the data updating processing,so as to calculate the reliability index of historic stone-arch bridges more accurately,which can provide a scientific basis for the preventive protection of cultural relics of heritage buildings.