For seismic soil liquefaction triggering and performance assessments, durational effects in field-based evaluations are mostly represented by the magnitude of the seismic event. However, in the laboratory, the equivalent number of uniform shear stress cycle concept is used. Benefitting from the findings of both case history- and laboratory-based research streams requires the conversion of earthquake-induced transient shear stresses to equivalent uniform (harmonic) stress cycles, or vice versa. A critical review of currently existing studies has revealed that; i) significantly extended earthquake catalogs are now available, which enable improved assessment of the conversion scheme, ii) based on the findings of Cetin and Bilge, weighting factors (m values) of stress conversions are now known to be stress, strain and density state dependent, and iii) these weighting factors extend to ranges that exceed the limits of earlier studies. Inspired by these, a semi-empirical probability-based model for the estimation of equivalent number of uniform stress cycles as functions of earthquake, site and performance (either strain or pore pressure-based) parameters is proposed. The proposed predictive relationship is shown to be more accurate and precise, evident by higher R² and smaller model error standard deviations. However, despite significant improvement to an R² value of 0.30, it is concluded to be still low, which addresses the uncertainties involved in duration assessments of earthquake shaking, and the need for further research. The probabilistic use of the proposed model is illustrated for a sandy soil layer at a soil site, which is expected to be shaken by a scenario earthquake event.

对于地震土液化触发和性能评估，现场评估中的持续影响主要由地震事件的幅度表示。但是，在实验室中，使用了等效数量的均匀剪切应力循环概念。得益于案例研究和实验室研究的成果，需要将地震引起的瞬时切应力转换为等效的均匀（谐波）应力周期，反之亦然。对现有研究的严格审查表明：i）现在可以提供大量扩展的地震目录，从而可以更好地评估转换方案； ii）根据Cetin和Bilge的发现，加权因子（m现在已知应力转换的最大应力值取决于应力，应变和密度状态，并且iii）这些加权因子的范围超出了早期研究的范围。受这些启发，提出了一种基于半经验概率的模型，用于估计等效应力周期的等效数量，这些等效应力作为地震，场地和性能（基于应变或孔隙压力）参数的函数。通过较高的R ²和较小的模型误差标准偏差，可以证明所提出的预测关系更为准确和精确。但是，尽管对R ²进行了重大改进值0.30仍然很低，这解决了地震震荡持续时间评估中涉及的不确定性以及进一步研究的需要。所说明的模型的概率用法说明了土壤位点的沙质土壤层，预计会因情景地震事件而震动。