ABSTRACT

Three inclined historical masonry towers, located in the city of Ferrara (North-East region of Italy), are analyzed under seismic loads employing advanced numerical models. This study provides a critical review on the conservation state, present vulnerabilities, influence of peculiar structural features, and future need for strengthening interventions. Three scenarios were performed, mimicking the seismic severity of earthquakes for three different return periods: 50y, 200y, and 500y. The mechanical properties adopted for the models were extracted by tuning the dynamic response of the models with ambient vibrations test results. A concrete damage plasticity material, with a simplified multilinear softening in both tension and compression, is here adopted. Three parameters are investigated for an insight into the seismic performance estimation: (i) the damage pattern, (ii) the dissipated plastic energy, and (iii) the top displacement. Nonlinear dynamics simulations show the dissemination of structural damages for relatively low magnitude of ground acceleration, where clear failure mechanisms are prone to be activated. The present case studies exhibit unsymmetrical failure mechanisms due to the geometrical features, favoring the crack propagation in in-tension sidewalls, or stability loss of compressed walls. From a preliminary estimation of their seismic vulnerability, it is deduced that a relatively high risk is still present.

摘要

使用先进的数值模型在地震荷载下分析了位于费拉拉市（意大利东北部地区）的三座倾斜的历史砌体塔。本研究对保护状态、目前的脆弱性、特殊结构特征的影响以及未来加强干预的需要进行了批判性审查。执行了三种情景，模拟了三种不同重现期的地震的地震严重程度：50 年、200 年和 500 年。通过使用环境振动测试结果调整模型的动态响应来提取模型采用的机械性能。这里采用了一种混凝土损伤塑性材料，在拉伸和压缩中都具有简化的多线性软化。为了深入了解地震性能估计，研究了三个参数：(i) 损伤模式，(ii) 耗散的塑性能，以及 (iii) 顶部位移。非线性动力学模拟显示结构损伤在相对较低幅度的地面加速度下的传播，其中明显的失效机制很容易被激活。目前的案例研究显示出由于几何特征导致的不对称失效机制，有利于受拉侧壁中的裂纹扩展或受压壁的稳定性损失。初步估计其地震易损性，推断仍存在较高的风险。明确的故障机制容易被激活。目前的案例研究显示出由于几何特征导致的不对称失效机制，有利于受拉侧壁中的裂纹扩展或受压壁的稳定性损失。初步估计其地震易损性，推断仍存在较高的风险。明确的故障机制容易被激活。目前的案例研究显示出由于几何特征导致的不对称失效机制，有利于受拉侧壁中的裂纹扩展或受压壁的稳定性损失。初步估计其地震易损性，推断仍存在较高的风险。