Magnetic damped links to reduce internal seismic pounding in base-isolated buildings
Magnetic damped links to reduce internal seismic pounding in base-isolated buildings
复制标题
磁阻尼连杆可减少基础隔震建筑物的内部地震冲击
DOI：
10.1007/s10518-020-00961-6
复制
发表时间：
2020
影响因子：
4.6
通讯作者：
R. Labernarda
中科院分区：
文献类型：
--
作者：
F. Mazza;R. Labernarda
在隔震结构中，由于隔震系统在强烈地震作用下会产生显著的位移，因此，紧密间隔的结构部件之间的有限间隙可能会引起内部碰撞。在这里，我们以位于西西里岛奥古斯塔镇的一座钢筋混凝土建筑为例，介绍了一个固定基座电梯井与周围建筑之间的间隙。该建筑物包括一个地下室和地面以上三层，在地下室的刚性柱顶部采用包括弹性和滑动轴承的混合隔震系统进行隔震，而钢框架电梯井穿过隔震层。尽管存在差距，但当最大负载的电梯停在上层时，上层建筑的所有楼层都可能发生内部撞击。为了减少结构碰撞效应，磁阻尼链接（MDL）之间的相邻角落的电梯和周围的建筑物提出。这是作为涡流阻尼连杆（ECDL）和弹性螺旋弹簧的并联组合而获得的，并且与传统被动阻尼器相比占据更少的空间，并且与刚性连杆配置相比传递显著更少的力。具体地，ECDL由作为导体的外圆柱形铜管和作为动子的内管组成，内管配备有由铁极片分离的轴向磁化的环形永磁体阵列。在地震荷载作用下，导体和磁体之间的相对运动会产生涡流，从而产生电磁阻尼。鉴于粘弹性线性行为可以假设为MDL，提出了一种简化的迭代设计过程的ECDL，优化的厚度和半径的磁铁，从而提高磁通量和能量耗散。通过非线性地震分析研究了近断层地震动的方向性，比较了无连接和四种互连配置：柔性和刚性弹性连杆、粘性和磁阻尼连杆。
A limited gap between closely spaced structural parts may induce internal pounding in seismically isolated structures, because of notable displacement at the level of the isolation system under severe earthquakes. A gap between a fixed-base elevator shaft and the surrounding building is presented here with reference to a reinforced concrete building located in the Sicilian town of Augusta. The building, comprising a basement and three storeys above the ground level, is seismically isolated at the top of rigid columns in the basement with a hybrid isolation system including elastomeric and sliding bearings, while a steel framed elevator shaft crosses the isolation level. Despite the gap, internal pounding may occur at all levels of the superstructure when the elevator with maximum load stops at the upper floors. To reduce structural pounding effects, a magnetic damped link (MDL) between adjacent corners of the elevator and the surrounding building is proposed. This is obtained as an in parallel combination of an eddy current damped link (ECDL) and an elastic helicoidal spring, and occupies less space than traditional passive dampers and transmits considerably less forces compared to a rigid link configuration. Specifically, an ECDL consists of an outer cylindrical copper tube, as conductor, and an inner tube, equipped with an array of axially magnetized and ring-shaped permanent magnets separated by iron pole pieces, as mover. The relative motion between conductor and magnets, during seismic loading, induces an eddy current producing electromagnetic damping. Given that viscoelastic linear behaviour can be hypothesized for the MDL, a simplified iterative design procedure of the ECDL is proposed, with optimization of the thickness and radius of the magnets, thereby enhancing magnetic flux and energy dissipation. The directionality of the near-fault ground motions is investigated through nonlinear seismic analysis, comparing no connection with four configurations of the interconnection: i.e., flexible and rigid elastic links, viscous and magnetic damped links.