ABSTRACT

Pounding among internal structural parts of seismically isolated structures may happen because of high horizontal deformability of the isolation system. To study this poorly investigated issue, a reinforced concrete (r.c.) framed structure built in Sicily (Italy) is considered, with a hybrid isolation system combining elastomeric and sliding bearings. The building consists of four-storey, basement included, with the steel-framed structure of the elevator crossing the isolation level. Two structural configurations are considered for the elevator shaft: base-isolated, with rigid link to the surrounding building; fixed-base, with a seismic gap to prevent internal pounding. Effectiveness of the Italian and European code provisions, based on setting up adequate separation distance, is assessed. Four modelling assumptions of the highly nonlinear behavior of elastomeric bearings are examined and a mathematical model is calibrated on experimental data. Nonlinear seismic analysis of the test structure is carried out considering eight cases, which are obtained combining four position of the elevator (i.e., at the basement and upper three levels) and two load conditions (i.e., elevator empty and with maximum load). Torsional effects induced by an asymmetric position of the elevator shaft are quantified by means of polar plots, representing the critical envelope for all excitation angles of bi-directional earthquakes.

摘要

由于隔震系统的高水平变形能力，隔震结构的内部结构部件之间可能会发生撞击。为了研究这个研究不足的问题，我们考虑了在西西里岛（意大利）建造的钢筋混凝土 (rc) 框架结构，该结构具有结合了弹性体和滑动轴承的混合隔离系统。该建筑由四层组成，包括地下室，电梯的钢架结构穿过隔离层。电梯井考虑了两种结构配置：底座隔离，与周围建筑物有刚性连接；固定底座，带有防震间隙以防止内部撞击。意大利和欧洲法规规定的有效性，基于建立足够的间隔距离，进行了评估。检验了弹性轴承高度非线性行为的四个建模假设，并根据实验数据校准了数学模型。结合电梯的四个位置（即地下室和上部三层）和两种载荷条件（即电梯空载和最大载荷），对试验结构进行了八种情况的非线性地震分析。由电梯井的不对称位置引起的扭转效应通过极坐标图进行量化，表示双向地震所有激发角的临界包络线。结合电梯的四个位置（即地下室和上三层）和两种负载条件（即电梯空载和最大负载）获得。由电梯井的不对称位置引起的扭转效应通过极坐标图进行量化，表示双向地震所有激发角的临界包络线。结合电梯的四个位置（即地下室和上三层）和两种负载条件（即电梯空载和最大负载）获得。由电梯井的不对称位置引起的扭转效应通过极坐标图进行量化，表示双向地震所有激发角的临界包络线。