Mojtaba Mousavi Ourimi - M.Sc. Student of Geotechnical Engineering, Department of Civil Engineering, Qum University of Technology, Iran
Mohsen Saleh Asheghabadi - PHD Student of Department of civil Engineering, Tsinghua University, Beijing ۱۰۰۰۸۴, China
Zulfiqar Ali - School of Civil, Environmental and Mining Engineering, The University of Adelaide, Australia
Morteza Jiryaei - Assistant Professor of Geotechnical Engineering, Department of Civil Engineering, Qum University of Technology, Iran

Estimating the seismic bearing capacity of soil under shallow foundation is important for seismically active areas. A new approach is suggested for the computation of bearing capacity factor, Nγe considering logspiral failure mechanisms. This paper uses modified pseudo-dynamic method to estimate the dimensionless seismic bearing capacity factor Nγe for dry sand underlying a surface strip footing. Soil amplification is considered inherently in this method and seismic acceleration is found to have significant effect on Nγe. The present study shows that the value of Nγe considering kh=0.1, kv=0,decreases by 86% as compared to the static condition forΦ=30o.the vertical seismic acceleration coeffcient also significantly affects the seismic bearing capacity factor. It was found that Nγe decreased by 84% when kh increased from 0.1 to 0.2 for k v=0 and it decreased by 95% when kv=kh for Φ =30o. With decrease in Φ from 40o to 30o, Nγe decreased by 68% for kh= kv=0.1. The proposed method can be used for seismic design of shallow strip foundations in sand.

Bearing capacity; Earthquakes; Slopes; Foundations; Failure mechanism