en Structure-Earthquake Structure-Earthquake Research Paper Research Paper <p class="MsoNormal" style="margin: 0mm 0mm 0pt text-align: justify line-height: 150% -ms-text-justify: inter-ideograph mso-layout-grid-align: none"><font face="Times New Roman"><span lang="EN-US" style="line-height: 150% font-size: 10.5pt mso-fareast-language: JA">The near field ground motions have a high amplitude pulse like at the beginning of the seismogram which are </span><span lang="EN-US" style="line-height: 150% font-size: 10.5pt">significantly influenced by the rupture mechanism and direction of rupture propagation. T</span><span lang="EN-US" style="line-height: 150% font-size: 10.5pt mso-fareast-language: JA">his type of ground motion cause higher demands for engineering structures and its response spectrum is dramatically different than far field spectra.</span></font></p> <p></p> <p class="MsoNormal" style="margin: 0mm 0mm 0pt text-align: justify line-height: 150% -ms-text-justify: inter-ideograph mso-layout-grid-align: none"><font face="Times New Roman"><city w:st="on"><span lang="EN-US" style="line-height: 150% font-size: 10.5pt mso-fareast-language: JA">Tabriz</span></city><span lang="EN-US" style="line-height: 150% font-size: 10.5pt mso-fareast-language: JA"> is one of the ancient cities in </span></font></p> <p lace="" w:st="on"><font face="Times New Roman"><country-region w:st="on">Azerbaijan</country-region> province with many <span style="mso-bidi-font-style: italic"><font size="3">industrial factories, financial centers and historical monuments </font></span>in North-West of Iran. In this region, North Tabriz Fault which has a well known history of intense seismic activity is passing through in close distance of urban area. In this regard investigation of near field ground motion effect on current practice seismic design spectrum in this region is necessary.</font></p> <p></p> <p class="MsoNormal" style="margin: 0mm 0mm 0pt text-align: justify line-height: 150% -ms-text-justify: inter-ideograph mso-layout-grid-align: none"><font face="Times New Roman"><span lang="EN-US" style="line-height: 150% font-size: 10.5pt mso-fareast-language: JA">Hence, probabilistic seismic hazard analysis is carried out using appropriate </span><span lang="EN-US" style="line-height: 150% font-size: 10.5pt mso-bidi-language: FA">attenuation relationship to consider </span><span lang="EN-US" style="line-height: 150% font-size: 10.5pt mso-fareast-language: JA">near field effect. The peak ground acceleration (<stockticker w:st="on">PGA</stockticker>) and several spectral accelerations (SA) over bedrock are estimated for different return periods and maps of iso acceleration contour lines are provided to indicate the earthquake hazard in different points of </span></font></p> <p lace="" w:st="on"><font face="Times New Roman"><city w:st="on">Tabriz</city> city. </font></p> <p></p> <p><span lang="EN-US" style="font-family: font-size: 10.5pt">Afterward,</span><span lang="EN-US" style="font-family: font-size: 10.5pt"> the generated horizontal equal-hazard spectrums </span><span lang="EN-US" style="font-family: font-size: 10.5pt">considering</span><span lang="EN-US" style="font-family: font-size: 10.5pt"> near field effect are compared </span><span lang="EN-US" style="font-family: font-size: 10.5pt">with </span><span lang="EN-US" style="font-family: font-size: 10.5pt">different spectrums developed base on simple pulses model for near field motion. Both types spectrum used to verify </span><span lang="EN-US" style="font-family: font-size: 10.5pt">current practice </span><span lang="EN-US" style="font-family: font-size: 10.5pt">seismic design</span><span lang="EN-US" style="font-family: font-size: 10.5pt"> spectrum of</span><span lang="EN-US" style="font-family: font-size: 10.5pt"> Iranian code (2005) </span><span lang="EN-US" style="font-family: font-size: 10.5pt">and International Building Code (IBC 2000)</span><span lang="EN-US" style="font-family: font-size: 10.5pt">.</span><span lang="EN-US" style="font-family: font-size: 10.5pt"> The results reveal the</span><span lang="EN-US" style="font-family: font-size: 10.5pt"> long-period structures which are seismically designed based on </span><span lang="EN-US" style="font-family: font-size: 10.5pt">current practice seismic codes are in high risk to be damaged </span><span lang="EN-US" style="font-family: font-size: 10.5pt">during near</span><span lang="EN-US" style="font-family: font-size: 10.5pt"> </span><span lang="EN-US" style="font-family: font-size: 10.5pt">fault ground motion. </span></p> Equal-Hazard Spectrum, Near Field Effect, Tabriz City 49 56 http://ijce.iust.ac.ir/browse.php?a_code=A-10-160-1&slc_lang=en&sid=1 J. Vafaie jvafaie@gmail.com 1800319475328460010185 1800319475328460010185 No Amirkabir University of Technology T. Taghikhany ttaghikhany@aut.ac.ir 1800319475328460010186 1800319475328460010186 Yes Amirkabir University of Technology M. Tehranizadeh tehz@govir.ir 1800319475328460010187 1800319475328460010187 No Amirkabir University of Technology