Displacement/velocity‐based control of a liquid spring—MR damper for vertical isolation
Displacement/velocity‐based control of a liquid spring—MR damper for vertical isolation
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DOI：
10.1002/stc.2363
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发表时间：
2019-05
影响因子：
5.4
通讯作者：
W. Eltahawy;K. Ryan;S. Cesmeci;F. Gordaninejad
中科院分区：
文献类型：
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作者：
W. Eltahawy;K. Ryan;S. Cesmeci;F. Gordaninejad
隔震是一种用于减轻震动影响的有效技术，有助于实现更高的抗震性能。最近的研究表明，垂直激励对地震期间结构的行为有显着影响。在这项研究中，提出了三维（3D）隔离，它将弹性轴承与双线性液体弹簧（BLS）-可控磁流变流体阻尼器（CMRD）串联起来，以抵抗水平地面震动，以抵抗垂直震动。开发了简化的刚性二维块的数值模型来预测地震载荷下的 BLS-CMRD 响应。 BLS-CMRD 的响应通过非线性刚度以及粘性和迟滞（半主动）阻尼的组合进行模拟。提出了一种基于 Disp/Vel 的控制策略，根据阻尼器反馈位移和速度的瞬时矢量组合来调整输入电流。探索了控制策略的两种变体。首先，对于线性电流变化，当达到阈值下限矢量幅度时激活电流，并且当超过阈值上限幅度时施加最大电流。其次，简化的开关策略使用单阈值矢量幅度，当瞬时矢量幅度超过阈值时触发最大电流开启，否则关闭。结果表明，对于超过设计水平的地面运动，基于 Disp/Vel 的控制可以有效地调节能量耗散水平，将设备垂直位移保持在设计行程限制内，并将垂直加速度衰减到 PGA 以下。此外，基于 Disp/Vel 的控制相对于用于结构控制的众所周知的裁剪最优策略减少了所有响应。
Seismic isolation is an effective technique used to mitigate effects of shaking and helps to achieve higher seismic performance. Recent researches have suggested that vertical excitation has significant effects on structures behavior during earthquake. In this study, three‐dimensional (3D) isolation is proposed that combines an elastomeric bearing to resist horizontal ground shaking in series with a bilinear liquid spring (BLS)–controllable magnetorheological fluid damper (CMRD) to resist vertical shaking. A numerical model of a simplified rigid 2D block was developed to predict BLS‐CMRD response under earthquake loading. The response of the BLS‐CMRDs was simulated through a combination of nonlinear stiffness and viscous and hysteretic (semi‐active) damping. A Disp/Vel‐based control strategy was proposed that adjusts the input current according to the instantaneous vector combination of feedback displacement and velocity of the damper. Two variations of the control strategy were explored. First, with linear current variation, the current is activated when a threshold lower bound vector magnitude is reached, and maximum current is applied when threshold upper bound magnitude is exceeded. Second, the simplified ON–OFF strategy uses single threshold vector magnitude that triggers the maximum current to turn on when the instantaneous vector magnitude exceeds the threshold, and turn off otherwise. Results show that for ground motions that exceed the design level, Disp/Vel‐based Control is effective to moderate the level of energy dissipation, keep the device vertical displacement within the design stroke limit, and attenuate vertical acceleration below PGA. In addition, Disp/Vel‐based control reduces all responses relative to the well‐known clipped optimal strategy used for structural control.