【摘要】 加卸载响应比方法为非均匀脆性介质的灾变评估提供了新的思路,即用加载与卸载响应的差别来定量刻画介质的损伤程度。为了验证加卸载响应比方法应用于结构失效分析的有效性,首先运用加卸载响应比方法对意大利那不勒斯大学完成的1个2层楼房的加卸载实验进行分析,结果表明:在临近结构破坏之前加卸载响应比时间序列确实出现了异常明显的升高及回落;进而引入岩石破裂声发射实验进行研究,发现采用轴向应变做响应量计算得到的加卸载响应比时间序列与楼房结构的响应比曲线在演化趋势上非常一致。进一步比较声发射能量率和宏观应做为响应得到的加卸载响应比时间序列,发现两者有着较为同步的稳定、异常、升高至峰值、急剧回落的演化过程。为了明确加卸载响应比与结构内部损伤的联系,基于损伤力学方法从理论上对此进行了分析,很明显加卸载响应比值在一定程度上可以反推结构的损伤程度,其演化可以为大型结构健康评估和工程灾变分析提供有益的参考及借鉴。更多还原

【Abstract】 The Load/Unload Response Ratio(LURR) method is a new approach to predict the failure of heterogeneous brittle media,i.e.using the ratio between response rates during periods of loading and unloading to describe the damage state of the media.To show the effectiveness of the approach,this paper firstly evaluated the LURR time series associated with a loading and unloading experiment on a two-layer structure carried out in University of Naples in Italy.The result shows that the LURR time series climb to an anomalously high peak and then decrease rapidly prior to the final failure.Moreover,the rock failure acoustic emission(AE) experiment is conducted,and the experiment data is evaluated by the LURR method with macro-axial-strain as response.Results indicate that the LURR curve is very consistent with that of the two-layer structure experiment.Then the LURR curves are compared with AE energy rate and macro-axial-strain as response respectively.It is found both LURR values show identical evolution:initial stability,abmormity,peak value,and decrease charply prior to thefinal fracture.In order to determine the relation between LURR evolution and the damage of the structure,the LURR values are combined with damage variable(D) to provide the damage estimation of the structure.The results shown in the paper may suggest that the LURR method provides a new approach for the health assessment of large scale structures or ancient buildings and the prediction of engineering catastrophic failure.更多还原