DEVELOPMENT OF IRANIAN SEISMIC DESIGN PROVISIONS FOR ESTIMATING NEAR-FAULT EARTHQUAKE EFFECTS  CASE-STUDY: IMAM REZA HOLY SHRINE AND AHWAZ PETROL-FIELD

Signi cant di erences between speci cations of struc-tural damage occurrence for buildings subjected to near- eld and far- eld earthquakes have been observed inrecent years. According to recent experiences¡ therehas been extensive damage occurrence in structures sub- jected to near- eld earthquakes compared to far- eld ones. The adopted approach in existing design codes isthe consideration of coecients¡ to take into account the e ects of near- eld earthquakes in evaluating the design base shear of structures. The aim of the present paper is the development ofstructural design methods for more adequate simula- tion of near- eld earthquakes e ects in the structural design process in order to take into account an increase in the seismic demand of structural systems. In this method¡ the e ects of near- eld earthquakes are not lim- ited to only consideration of additional design base shear demands¡ but extra capacity¡ in addition to the ulti- mate strength of the structure is demanded also. In the present study¡ the proposed development of current Ira- nian seismic design provisions for estimating near-fault earthquake e ects in the structural design process ofbuildings is investigated. In this manner¡ some near- eld coecients are proposed for some of the near-faultareas of the country¡ based on the results of seismic haz- ard analysis. It should be noted that in this investi- gation¡ both deterministic and probabilistic approaches are followed in the seismic hazard assessment procedure and various attenuation relationships have been con- sidered with judgmental weighting factors and the ob- tained results have been combined in a logic tree. In addition¡ the proposed modi cations and corresponding results are compared with the current code-conforming seismic demands for two special cases; the Imam Reza holy shrine site and Ahwaz oil eld. The obtained re- sults lead to a signi cant increase in design base shear¡ especially for structures with low and medium natural periods in near-fault areas¡ when compared with corre- sponding structures located on far- eld sites.