فهرست مطالب

  • Volume:20 Issue:3, 2019
  • تاریخ انتشار: 1398/08/04
  • تعداد عناوین: 8
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  • Behrokh Hosseini Hashemi*, Morteza Abasnejadfard, Babak Keykhosro Kiany Pages 1-17

    Sarpol-e Zahab - Ezgeleh earthquake (MW 7.3) occurred in Kermanshah province of Iran near the Iraq - Iran border on November 12, 2017 at 18:18 UTC (21:48 local time). The epicenter was located about 5 km from Ezgeleh town. Sarpol-e Zahab - Ezgeleh earthquake is the most destructive seismic event in Iran in recent decade in terms of financial and human losses. Based on field observations, carried out by the authors between November 25 and 30, 2017, extensive non-structural and structural damages were inflicted to all types of masonry buildings. Post-earthquake observations showed that the use of URM buildings in the area with high relative hazard of seismicity lead to significant damages. Moreover, defects in design and construction of buildings, which was the result of the lack of enough supervision by responsible organizations, can be considered as other causes of damages. In this paper, observed damages in masonry buildings are presented and investigated in detail.

    Keywords: Sarpol-e Zahab - Ezgeleh Earthquake, Masonry structures, Failure types, Seismic code
  • Behrokh Hosseini Hashemi*, Babak Keykhosro Kiany, Hamidreza Farshchi Pages 19-32

    Sarpol-e Zahab - Ezgeleh earthquake (MW 7.3) occurred in Iran and Iraq border region on November 12, 2017 at 21:48 local time. This earthquake is the most devastating event in Iran after the 2003 Bam earthquake (MW 6.6) in terms of damages. According to findings arising from the visit to the earthquake affected area between November 25 and 30, 2017, heavy structural and non-structural damages were occurred in all types of RC buildings, including structures built in national Iranian mass housing project, called Mehr housing scheme. In many cases, new structures, experienced severe damages or collapse during the earthquake, even in regions with lowrecorded PGAlike Sharafabad town in Eslamabad-e Gharb city. Post-earthquake studies showed that damages in RC structures were mostly due to the poor construction quality including low concrete strength and nonseismic detailing as well as false structural design and local site effects. According to Iran construction laws, the "Iran Construction Engineering Organization" (IRCEO) is the prime responsible for the effective supervision in structural design and construction process in urban areas. Considerable number of damaged buildings that are constructed in recent years, is probably because of the lack of enough supervision by IRCEO and other responsible organizations. In this paper, observed damages to RC structures were examined and explained in detail.

    Keywords: Sarpol-e Zahab - Ezgeleh Earthquake, RC structures, Failure types, Seismic code
  • Behrokh Hosseini Hashemi*, Babak Keykhosro Kiany Pages 33-46

    Sarpol-e Zahab - Ezgeleh earthquake (MW 7.3) occurred in Kermanshah province of Iran near the Iraq and Iran border region on November 12, 2017 at 18:18 UTC (21:48 local time). The epicenter was located about 5 m from Ezgeleh town with a focal depth of about 23 km. Sarpol-e Zahab - Ezgeleh earthquake is the most destructive seismic event in Iran in recent decade in terms of financial and human losses. Based on field observations, carried out by the authors between 25 and 30 November 2017, heavy non-structural and structural damages were occurred to all types of steel lateral load resisting systems, including concentrically and eccentrically braced frames and moment resisting frames. Early buckling of built-up brace members, excessive out-of-plane deformation in gusset plates, formation of plastic hinges at the column ends and lateral-torsional buckling of link beams were dominant failure modes in damaged steel buildings. Post-earthquake observations showed that damages in steel structures were mostly due to poor construction quality including lack of proper welding in connections, extent of irregularities of the structural system, false structural design, local site effects, and finally lack of enough supervision by "Iran Construction Engineering Organization" (IRCEO) and other responsible organizations. In this paper, observed damages to steel structures were examined and explaneed in detail.

    Keywords: Sarpol-e Zahab - Ezgeleh Earthquake, Steel structures, Failure types, Seismic code
  • Mohammad Mahdi Maddah, Sassan Eshghi* Pages 47-59

    The collapse evaluation of the seismically vulnerable structures is very important in any earthquake risk reduction program. There are several analytical methods currently available to assess the collapse capacity of structures under earthquake ground motions. Severe earthquakes in cities provides a unique opportunity to evaluate the effectiveness of the seismic collapse assessment methods. On November 21, 2017, an earthquake with the moment magnitude of 7.3 and the PGA of 0.69 g occurred in about 37 kilometers northwest of Sarpol-e Zahab region (Kermanshah, Iran). This earthquake caused the collapse of significant numbers of low and mid-rise steel structures. In this paper, an attempt is made to examine the efficiency of an approximate incremental dynamic analysis (IDA) method to estimate the collapse capacity of conventional steel structures. To this purpose, two partially collapsed steel structures are selected. Both two structures are comprised of an ordinary moment resisting frame system in one direction, and a braced frame system in other perpendicular direction. The dimensions and permanent displacements of these structures have been measured on-site. These buildings are modeled in a finite element program and analyzed by modal pushover analysis in two major directions, and the SDOF models are extracted. In the next step, the SDOF models are analyzed by the IDA method under the selected earthquake records. The median and dispersion of collapse capacity of the structures are calculated from the approximate IDA results. Finally, the collapse probability of these structures is calculated under the maximum considered earthquake (MCE), determining the uncertainties based on FEMA P695 relation and engineering judgments. The results show the development of simplified and inexpensive methods for collapse assessment is crucial to be implemented to identify existing killer buildings in cities prone to major earthquakes.

    Keywords: Sarpol-e-Zahab (Kermanshah) Earthquake, Collapse Assessment, Steel Buildings, Pushover Analysis, Collapse Capacity, Collapse Probability
  • Mazdak Zahedi, Sassan Eshghi* Pages 61-71

    Detecting the buildings experiencing collapse against future earthquakes is the most vital for seismic urban areas in Iran because of its irreparable consequences. Once again, the occurrence of Sarpol-e Zahab Earthquake (Mw=7.3) reminded us of this necessity where structural collapses resulted in a large number of casualties. A simplified methodology is developed to assess the collapse of mid-rise concrete buildings during earthquakes in Iran. Besides, an attempt is made to verify this method through analyzing the recorded data of the collapsed buildings suffered from Sarpol-e Zahab earthquake of November 12, 2017, and considers whether the occurrence of the collapse could be anticipated or not. Three severely damaged buildings were selected, located in Sarpol-e Zahab, to verify this proposed methodology. They are 2 or 3 story buildings having moment resisting frames. The buildings are analyzed through nonlinear analysis. The well-calibrated nonlinear model is adopted for the nonlinear analysis. The intensity of damages are observed and recorded by the authors. The pushover analysis is conducted for them. Drifts evaluated by pushover analysis are compared to those recorded in the buildings. One of the buildings was a bare frame that its partitions and infill walls are not still constructed. This building had much better performance than two others and experienced less loss. Moreover, the results of the analysis show that the collapse criteria related to the seismic evaluation codes are non-conservative. The results of this survey imply that the proposed method can precisely forecast the collapse or non-collapse of the studied buildings. Therefore, it would be recognized as a reliable method for collapse assessment.

    Keywords: Seismic assessment, Reinforced-concrete buildings, Pushover analysis, Sarpol-e Zahab, Iran earthquake
  • Mohammad Ghasem Vetr*, Mahdi Saeidian, Aran Naserpour Pages 73-92

    Reinforced concrete multistory buildings in Kermanshah Province, Iran, have been subjected to a strong ground motion during Sarpol-e Zahab earthquake of November 12, 2017. A wide number of Reinforced concrete buildings have been damaged in this earthquake. It has been observed that the principal reasons for the failure are the poor quality of construction materials and defects in the implementation of structural components. Some common imperfections were short columns in the stair-boxes, insufficient reinforcements at the concrete joints, inappropriate bends and splice of rebar, wide spacing of transverse reinforcements, inaccuracy in concrete mixing plans, and lack of conjunction between structural and nonstructural members. This investigation is based on the observations of IIEES reconnaissance team. The main objective of this research is to evaluate the seismic performance of reinforced concrete multistory buildings during the Sarpol-e Zahab earthquake and vulnerability assessments of important multistory reinforced concrete structures such as Mehr buildings of Sarpol-e Zahab, Eslamabad-e Gharb, and Imam Khomeini hospital in Eslamabad-e Gharb, Kermanshah Province.

    Keywords: Sarpol-e Zahab Earthquake, Reinforced concrete buildings, Seismic performance, Vulnerability assessment
  • Fereshteh Izanlu*, Aliakbar Yahyaabadi Pages 93-107

    Seismic vulnerability assessment helps to estimate the extent and the probability of damage to buildings due to the potential earthquake hazard. Determination of structural fragility curves of buildings is one of the most important steps in seismic vulnerability assessment. The fragility curve predicts the probability of exceeding specific damage states for a seismic intensity parameter. This paper is focused on the development of structural fragility curves for different building types in the Sarpol-e Zahab city. For this purpose, a reconnaissance survey was conducted after the Sarpol-e Zahab earthquake of November 12, 2017 to identify the damage state of various buildings based on the HAZUS Methodology. Then, the improved displacement coefficient method implemented in the SELENA software was used for expressing building loss probabilities. In order to find out which level of the seismic design can be used in defining the fragility curves, different weights were considered to apply to the HAZUS fragility curves of high, moderate, low and pre-code to be used in the logic tree method. Finally, the mean and standard deviation values were introduced for the construction of fragility curves with the lognormal distribution
    for the seven Iranian building types.

    Keywords: Structural fragility curves, Seismic vulnerability assessment, Damage state, Building types, Sarpol-e Zahab 2017 earthquake
  • Arash Taghinia, Akbar Vasseghi*, Mohammad Javad Jabbarzadeh Pages 109-119

    A strong earthquake with moment magnitude of 7.3 occurred near the city of Sarpol-e Zahab in western Iran on November 12, 2017. The earthquake epicenter was located 10 km from Ezgeleh and 37 km from Sarpol-e Zahab. In this paper, damages to bridges located within 100 km from the epicenter are evaluated based on the field survey conducted one month after the earthquake. Bridges in the seismically affected cities and on primary roads leading to the city of Sarpol-e Zahab were inspected during the field survey. None of the inspected bridges were severely damaged, and they were all in service immediately after the earthquake. The observed damages were mostly minor in form of minor cracking across the decks, detachment of soil and abutments, and cracking of abutments. Some bridges were moderately damaged due to settlement and rotation of abutments which resulted in significant cracking of the deck. Damages occurred mainly in the abutments and to a lesser degree in the decks. Bridge bents in multi-span bridges did not experience any visible damage. This study indicates that concrete superstructures were more vulnerable than superstructures with steel girder. It also indicates that bridges with masonry abutments were more vulnerable than those with concrete abutments. Compared to single span bridges, the state of damage in multi-span bridges were more severe.

    Keywords: Sarpol-e Zahab earthquake, Bridges, Damages, Abutment, Cracks