In current engineering practice, the torsional effects of ground motions are only considered implicitly through “accidental eccentricity coefficients". In seismic design codes, these coefficients account for not only the unintended (or uncertain) asymmetric distributions of structural mass and stiffness in the plan but also the torsional components of ground motions. The torsional effects may develop due to wave passage effects or the incoherency of translational ground motions along the foundation systems. While it is possible to obtain torsional components of ground motions directly from seismic records with modern instruments, such sensors are uncommon. Therefore, several numerical procedures have been proposed in the literature for estimating torsional components of ground motions from translational measurements. In this study, the Single Station Procedure (SSP)—based on the deconstruction of translational ground motions into body waves and the subsequent reconstruction of rotational ground motions—is employed to obtain torsional ground motions for seven different seismic events in Turkey. Additionally, the corresponding accidental eccentricity coefficients that can cause the same response modification with torsional ground motions are determined. First, a conventional procedure is utilized to obtain the corresponding accidental eccentricity coefficients. Various drawbacks of the conventional procedure, such as negative eccentricity coefficients, are addressed. Then, a relatively obscure definition of accidental eccentricity is revived to propose a novel procedure for determining accidental eccentricity coefficients. It is observed that the proposed procedure yields higher values for the accidental eccentricity coefficients than the conventional procedure. It also observed that the torsional spectrum provided in Eurocode 8 provisions requires higher eccentricity values than those implied by the recorded ground motions from Turkey.

在当前的工程实践中，地震动的扭转效应仅通过“偶然偏心系数”隐含地考虑。在抗震设计规范中，这些系数不仅考虑了计划中结构质量和刚度的非预期（或不确定）不对称分布，而且还考虑了结构质量和刚度的非预期（或不确定）非对称分布。还有地面运动的扭转分量。由于波道效应或沿基础系统的平移地面运动的不相干性，可能会产生扭转效应。虽然可以使用现代仪器直接从地震记录中获得地面运动的扭转分量，例如传感器并不常见。因此，文献中提出了几种数值程序，用于通过平移测量来估计地面运动的扭转分量。在这项研究中，单站程序（SSP）——基于将平移地面运动解构为体波和随后重建旋转地面运动，用于获取土耳其七次不同地震事件的扭转地面运动。此外，还确定了相应的意外偏心系数，该系数可以导致与扭转地面运动相同的响应修改。首先，利用常规程序获得相应的偶然偏心率系数。解决了传统程序的各种缺点，例如负偏心率系数。然后，恢复了偶然偏心率的相对模糊的定义，提出了一种确定偶然偏心率系数的新程序。据观察，所提出的程序产生比传统程序更高的意外偏心系数值。它还观察到，欧洲规范 8 条款中提供的扭转谱需要比土耳其记录的地面运动所暗示的偏心率值更高的偏心率值。