• Earthquakes and Structures
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• 제23권1호
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• pp.75-85
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• 2022

The megacity Istanbul was struck by an earthquake on September 26, 2019, with a moment magnitude (Mw) of 5.8. The mainshock was followed by many aftershocks. Although the peak ground acceleration (PGA) of the mainshock was as low as 0.08 g, its effect has been more than expected. The intensive reconnaissance studies were accomplished in the highly populated Zeytinburnu and Pendik districts of Istanbul. While the earthquake (EQ) was relatively smaller concerning record-specific intensity measures; the damages such as concrete spalling in reinforced concrete (RC) members, detachment and diagonal cracking of infill walls in RC frames as well as cracks in masonry structures were reported from non-engineered and some engineered buildings. Many studies in the literature state that record-specific intensity measures are not sufficient to evaluate the seismic performance of the structures. The structure-specific intensity measures, soil characteristics, as well as significant duration, energy, and frequency content of EQs should be considered for the evaluation. Dependently, the frequency and energy contents of the Istanbul Earthquake are evaluated to discuss the possible reasons for the perceived effects and the damages. It is concluded that the EQ caused resonance effects on a variety of structures because of its complex frequency content as well as rather low building quality.

• Earthquakes and Structures
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• 제16권2호
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• pp.141-148
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• 2019

In this study, a well-established model and a new simplified version of it, that help avoid collapses in reinforced concrete structures during strong earthquakes, are presented and discussed. Using this model, the initial formation of plastic hinges and the final concentration of the damages only in beams are accurately assured. The model also assures that the columns and the beam-column joints can remain intact. This model can be applied for the design of modern R/C structures, as well as for the design of strengthening schemes of old R/C structures by the use of reinforced concrete jackets. The model can also predict the form of earthquake damages in old structures but also earthquake damages in the modern structures.

• 한국농공학회지
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• 제35권2호
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• pp.43-56
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• 1993

The laboratory tests are performed on how the liquefaction potential of the sea dike structures on the saturated sand or silty sand seabed could be affected due to earthquake before and after construction results are given as follows ; 1. Earthquake damages to sea dike structures consist of lateral deformation, settlement, minor abnormality of the structures and differential settlement of embankments, etc. It is known that severe disasters due to this type of damages are not much documented. Because of its high relative cost of the preventive measures against this type of damages, the designing engineer has much freedom for the play of judgement and ingenuity in the selection of the construction methods, that is, by comparing the cost of the preventive design cost at a design stage to reconstruction cost after minor failure. 2. The factors controlling the liquefaction potential of the hydraulic fill structure are magnitude of earthquake(max. surface velocity), N-value(relative density), gradation, consistency(plastic limit), classification of soil(G & vs), ground water level, compaction method, volumetric shear stress and strain, effective confining stress, and primary consolidation. 3. The probability of liquefaction can be evaluated by the simple method based on SPT and CPT test results or the precise method based on laboratory test results. For sandy or silty sand seabed of the concerned area of this study, it is said that evaluation of liquefaction potential can be done by the one-dimensional analysis using some geotechnical parameters of soil such as Ip, Υt' gradation, N-value, OCR and classification of soils. 4. Based on above mentioned analysis, safety factor of liquefaction potential on the sea bed at the given site is Fs =0.84 when M = 5.23 or amax= 0.12g. With sea dike structures H = 42.5m and 35.5m on the same site Fs= 3.M~2.08 and Fs = 1.74~1.31 are obtained, respectively. local liquefaction can be expected at the toe of the sea dike constructed with hydraulic fill because of lack of constrained effective stress of the area.

• Earthquakes and Structures
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• 제18권2호
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• pp.201-213
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• 2020

Seismic damages that occurred by the effects of epicenter distance of the earthquake are one of the most important problems for the earthquake engineering. In this study, it is aimed to examine the nonlinear seismic behaviors of concrete gravity (CG) dams considering various epicenter distances. For this purpose, Boyabat CG dam that is one of the biggest concrete gravity dams in Turkey is selected as a numerical application. FLAC3D software based on finite difference method is used for modelling and analyzing of the dam. Drucker-Prager nonlinear material model is used for the concrete body and Mohr-Coulomb nonlinear material model is taken into account for the foundation. Special interface elements are used between dam body and foundation to represent interaction condition. Free-field and quiet non-reflecting boundary conditions are utilized for the main surfaces of 3D model. Total 5 various epicenter distances of 1989 Loma Prieta earthquake are considered in 3D earthquake analyses and these distances are 5 km, 11 km, 24 km, 85 km and 93 km, respectively. According to 3D seismic results, x-y-z displacements, principal stresses and shear strain failures of the dam are evaluated in detail. It is clearly seen from this study that the nonlinear seismic behaviors of the CG dams change depending to epicenter distance of the earthquake. Thus, it is clearly recommended in this study that when a CG dam is modelled or analyzed, distance of the earthquake fault to the dam should be strongly examined in detail. Otherwise, earthquake damages can be occurred in the concrete dam body by the effects of seismic loads.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 춘계학술대회 논문집
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• pp.478-492
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• 2006

• Earthquakes and Structures
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• 제20권3호
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• pp.325-335
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• 2021

The majority of Turkey's geography is at risk of earthquakes. Within the borders of Turkey, including the two major active faults contain the North-Eastern and Eastern Anatolia, earthquake, threatening the safety of life and property. On January 24, 2020, an earthquake of magnitude 6.8 occurred at 8:55 p.m. local time. According to the data obtained from the stations in the region, peak ground acceleration in the east-west direction was measured as 0.292 g from the 2308 coded station in Sivrice. It is thought that the earthquake with a magnitude of Mw 6.8 was developed on the Sivrice-Puturge segment of the Eastern Anatolian Fault, which is a left lateral strike slip fault, and the tear developed in an area of 50-55 km. Aftershocks ranging from 0.8 to 5.1 Mw occurred following the main shock on the Eastern Anatolian Fault. The earthquake caused severe structural damages in Elazığ and neighboring provinces. As a result of the field investigations carried out in this study, significant damage levels were observed in the buildings since it did not meet the criteria in the earthquake codes. Within the study's scope, the structural damage cases in reinforced concrete and masonry structures were investigated. Many structural deficiencies and mistakes such as non-ductile details, poor concrete quality, short columns, strong beams-weak columns mechanism, large and heavy overhangs, masonry building damages and inadequate reinforcement arrangements were observed. Requirements of seismic codes are discussed and compared with observed earthquake damage.

• 건설안전기술
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• 통권49호
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• pp.92-102
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• 2009

Earthquake is one of the hazard so hard because it is difficult predicted occurred time, scale and characters. Due to a recent Sichuan earthquake in China with a magnitude of 7.8, it is worried about having a major earthquake in Korea peninsula in near future. The earthquake in Kobe, Japan showed that the damages were concentrated on the buildings which were not considered to be protected from the earthquakes. In this study, apartment structures in Korea analyze about earthquake hazard and evaluate seismic performance. Through the this study we have notice of earthquake hazard for apartment structures which live a lot of population of Korea and suppose necessary for seismic retrofit.

• 한국안전학회지
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• 제23권6호
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• pp.100-107
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• 2008

Earthquake is one of the hazard so hard because it is difficult predicted occurred time, scale and characters. Due to a recent Sichuan earthquake in China with a magnitude of 7.8, it is worried about having a major earthquake in Korea peninsula in near future. The earthquake in Kobe, Japan showed that the damages were concentrated on the buildings which were not considered to be protected from the earthquakes. In this study, apartment structures in Korea analyze about earthquake hazard and evaluate seismic performance. Through the this study we have notice of earthquake hazard for apartment structures which live a lot of population of Korea and suppose necessary for seismic retrofit.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.281-288
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• 1999

This paper studied the efficiency of retrofitting of reinforced concrete structure which was not designed to endure an earthquake. The earthquake in Kobe Japan showed that there was a great possibility of having an earthquake even in big city and the damages were concentrated on mid or low story buildings which were not considered to be protected from an earthquake, . This experiment used reinforced concrete structure which restrained side-by-side displacement to test durability against an earthquake. This study deals with the structural performance of reinforced concrete frame structures strengthened with steel materials.

• Earthquakes and Structures
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• 제9권3호
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• pp.639-656
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• 2015

Seismic isolation devices are commonly used to mitigate damages caused by seismic responses of structures. More damages are created due to progressive collapse in structures. Therefore, evaluating the impact of the isolation systems to enhance progressive collapse-resisting capacity is very important. In this study, the effect of lead rubber bearing isolation system to increase the resistance of structures against progressive collapse was evaluated. Concrete moment resisting frames were used in both the fixed and base-isolated model structures. Then, progressive collapse-resisting capacity of frames was investigated using the push down nonlinear static analysis under gravity loads that specified in GSA guideline. Nonlinear dynamic analysis was performed to consider dynamic effects column removal under earthquake. The results of the push down analysis are highly dependent on location of removal column and floor number of buildings. Also, seismic isolation system does not play an effective role in increasing the progressive collapse-resisting capacities of structures under gravity loads. Base isolation helps to localize failures and prevented from spreading it to intact span under seismic loads.