The seismic response of curved concrete bridges is complex because of the geometric irregularity and induced planar rotation of the deck, which can magnify the displacement of the deck and deformation of the bearings. To control the planar rotation and thus the seismic response of the curved bridge, an orthogonally separated isolation system (OSIS) is proposed, which consists of the upper and lower isolation parts. With this, the planar relative displacement of the common isolation system is decomposed into the relative displacement of the upper part in one direction and the relative displacement of the lower isolation part in the orthogonal direction. Therefore, the planar rotation can be restrained and the seismic demand of the isolation bearing is decoupled. The analytical models of a curved bridge and the OSIS are established in OpenSees. A suite of 118 ground motions, of which 80 are ordinary and 38 are pulse-like, is selected as input with 24 different angles of incidence so as to consider the seismic variation. Nonlinear dynamic time-history analyses of the two models are conducted to evaluate the effectiveness of the OSIS. The results show that the OSIS can effectively decrease the deck displacement, the bearing deformation and the pier column shear force, especially under the ground motions with higher intensities, while the shear force increases slightly on the abutment.

中文翻译：

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一种新型正交隔震系统及其在弯曲混凝土桥上的抗震性能

弯曲混凝土桥梁的地震响应是复杂的，因为桥面的几何不规则性和诱发的平面旋转会放大桥面的位移和支座的变形。为了控制平面旋转从而控制曲线桥的地震响应，提出了一种正交分离隔震系统（OSIS），它由上隔震部分和下隔震部分组成。这样，普通隔振系统的平面相对位移分解为上隔振部分在一个方向上的相对位移和下隔振部分在正交方向上的相对位移。因此，可以抑制平面旋转，解耦隔震支座的抗震需求。在 OpenSees 中建立了曲线桥和 OSIS 的分析模型。选择一组 118 种地震动，其中 80 种是普通的，38 种是脉冲状的，以 24 个不同的入射角作为输入，以考虑地震变化。对这两个模型进行非线性动态时程分析，以评估 OSIS 的有效性。结果表明，OSIS能有效降低桥面位移、支座变形和墩柱剪力，尤其是在较高强度的地震动下，而桥台剪力略有增加。