Magnitude scaling factors in liquefaction triggering procedures

• Magnitude scaling factor for duration effects in liquefaction triggering analyses.
• Formulated to include dependency on soil characteristics and earthquake magnitude.
• Examination of cyclic testing results for broad range of soil types.
• Implemented in SPT and CPT based liquefaction triggering procedures for practice.

A revised magnitude scaling factor (MSF) relationship for CPT-based and SPT-based liquefaction triggering analyses is presented in this paper. The revised MSF relationship incorporates functional dependency on the soil characteristics [represented by clean sand equivalent penetration resistances in the present form] as well as on earthquake magnitude. The revisions in MSF are based on the examination of cyclic testing results for a broad range of soil types and densities, analyses of strong ground motion records to develop relationships for the equivalent number of loading cycles for different soil properties, and the synthesis of those results into an MSF relationship suitable for implementation in practice. A separate study [2] showed that use of the revised MSF relationship in CPT-based and SPT-based liquefaction triggering procedures is well-supported by the case history databases. Other factors known to fundamentally influence the MSF are discussed.