Shaking Table Testing of Rocking—Isolated Bridge Pier on Sand
Shaking Table Testing of Rocking—Isolated Bridge Pier on Sand
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DOI：
10.1080/13632469.2012.705225
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发表时间：
2013-01
影响因子：
2.6
通讯作者：
I. Anastasopoulos;M. Loli;Takis Georgarakos;V. Drosos
中科院分区：
文献类型：
--
作者：
I. Anastasopoulos;M. Loli;Takis Georgarakos;V. Drosos
本文研究了砂基上的隔震桥墩的抗震性能。进行了一系列缩尺振动台试验，比较了隔震体系和传统基础桥墩的性能。这两种设计方案经受了各种震动事件，包括真实的记录和不同强度的人工运动。为了探索系统在连续地震事件中的性能，进行了三种不同的震动序列。摇摆隔离被证明是非常有效的，在减少传递到上部结构的惯性力。隔震桥墩得到有效保护，在所有地震激励下都能幸存下来，而不会造成结构损坏，但会增加基础沉降。相比之下，对于建立在常规设计基础上的相同系统，一定程度的结构损坏将是不可避免的。摇摆隔离系统被证明是显着抵抗累积循环荷载，表现出有限的强度退化，即使受到超过5.5%的循环漂移率。由于土壤致密化，沉降累积率被发现与重复的地震激励减少。当前面的地震运动是对称的（如正弦运动）时，旋转响应实际上对振动历史不敏感。与此形成鲜明对比的是，当前面的地震运动是不对称的（如本研究的方向性影响的记录），该系统往往积累旋转后，每个事件，逐步恶化其性能。然而，即使受到极不可能的、不切实际的严酷地震事件序列的影响，隔震系统也能经受住倾倒倒塌。
This article studies the seismic performance of a rocking-isolated bridge pier on surface foundation, resting on sand. A series of reduced-scale shaking table tests are conducted, comparing the performance of a rocking-isolated system to a pier founded on conventionally designed foundation. The two design alternatives are subjected to a variety of shaking events, comprising real records and artificial motions of varying intensity. In an effort to explore system performance in successive seismic events, three different shaking sequences are performed. Rocking isolation is proven quite effective in reducing the inertia forces transmitted onto the superstructure. The rocking-isolated pier is effectively protected, surviving all seismic excitations without structural damage, at the cost of increased foundation settlement. In contrast, a certain degree of structural damage would be unavoidable for the same system founded on a conventionally designed foundation. The rocking-isolated system is proven remarkably resistant to cumulative cyclic loading, exhibiting limited strength degradation even when subjected to cyclic drift ratio in excess of 5.5%. Due to soil densification, the rate of settlement accumulation is found to decrease with repeating seismic excitations. The rotational response is practically insensitive to the shaking history when the preceding seismic motions are symmetric (such as sinusoidal motions). In stark contrast, when the preceding seismic motions are non-symmetric (such as the directivity-affected records of this study), the system tends to accumulate rotation after each event, progressively worsening its performance. Nevertheless, the rocking-isolated system survives toppling collapse, even when subjected to a highly improbable, unrealistically harsh, sequence of seismic events.