• Title/Summary/Keyword: Load History

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A Study on a Repair Technique for a Reinforced Concrete Frame Subjected to Seismic Damage Using Prestressing Cable Bracing

  • Lee, Jin Ho;EI-Ganzory, Hisham
    • Architectural research
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    • v.3 no.1
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    • pp.53-60
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    • 2001
  • The proposed building upgrading technique employs prestressing cables to function as bracing to improve the seismic performance during future events. A four-story reinforced concrete moment resisting frame damaged from an ultimate limit state earthquake is assessed and upgraded using the proposed technique. Both existing and upgraded buildings are evaluated in regard of seismic performance parameters performing static lateral load to collapse analysis and dynamic nonlinear time history analysis as well. To obtain realistic comparison of seismic performance between existing and upgraded frames, each frame is subjected to its critical ground motion that has strength demand exceeding the building strength supply. Furthermore, reliability of static lateral load to collapse analysis as a substitute to time history analysis is evaluated. The results reveal that the proposed upgrading technique improves the stiffness distribution compared to the ideal distribution that gives equal inter-story drift. As a result, the upgraded building retains more stories that contribute to energy dissipation. The overall behavior of upgraded building beyond yield is also enhanced due to the gradual change of building stiffness as the lateral load increases.

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Artificial neural network modeling to predict the flexural behavior of RC beams retrofitted with CFRP modified with carbon nanotubes

  • Almashaqbeh, Hashem K.;Irshidat, Mohammad R.;Najjar, Yacoub;Elmahmoud, Weam
    • Computers and Concrete
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    • v.30 no.3
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    • pp.209-224
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    • 2022
  • In this paper, the artificial neural network (ANN) is employed to predict the flexural behavior of reinforced concrete (RC) beams retrofitted with carbon fiber/epoxy composites modified by carbon nanotubes (CNTs). Multiple techniques are used to improve the accuracy of the ANN prediction, as the data represents a multivalued function. These techniques include static ANN modeling, ANN modeling with load history, and ANN modeling with double load history. The developed ANN models are used to predict the load-displacement profiles of beams retrofitted with either CFRP or CNTs modified CFRP, flexural capacity, and maximum displacement of the beams. The results demonstrate that the ANN is able to predict the flexural behavior of the retrofitted RC beams as well as the effect of each parameter including the type of the used epoxy and the presence of the CNTs.

An Experimental Study on the Inelastic Behavior of the Reinforced Concrete Column Subject to Cyclic Lateral Loads (반복수평하중을 받는 철근콘크리트 기둥의 비탄성 거동에 관한 실험적 연구)

  • 정세환;정하선;김상식
    • Proceedings of the Korea Concrete Institute Conference
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    • 1991.10a
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    • pp.45-50
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    • 1991
  • This research has been carried out experimently to verify the structural efficiency of the reinforced concrete columns subjected to cyclic lateral loadings in the inelastic range. Sixteen specimens have been used in the tests, the factors such as reinforcing bars, shear-span ratio, axial load level and loading history being taken differently. The load-carrying capacities and the stiffness degradation in the inelastic range by cycle lateral load application have been counted by observing the load-deformation relationship, the crack initiation and propagation and the energy dissipation phenomena.

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Fatigue life estimation using the multi-axial multi-point Load Counting method under Variable Amplitude Loading (가변진폭하중에서 다축-다점 하중 Counting method를 이용한 피로수명평가)

  • 이원석;이현우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.913-920
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    • 1996
  • In this study, the counting method for multi-axial and multi-point load states was proposed. Using this counting method, the load spectrum is generated from the service load history which is measured for boom structure of excavator. Loading state for loading points of boom structure is described as a multi-dimensional state space. From this load spectrum, the stress spectrum was generated by FEM analysis using the superposition of the unit load. The cumulated damage at the severe damage point of In nm structure by the failure example is calculated by Palmgren-Miner's rule. As a result of this study, the fatigue life estimation using the multi-axial and multi-point load counting method is useful.

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A new lateral load pattern for pushover analysis in structures

  • Pour, H. Gholi;Ansari, M.;Bayat, M.
    • Earthquakes and Structures
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    • v.6 no.4
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    • pp.437-455
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    • 2014
  • Some conventional lateral load patterns for pushover analysis, and proposing a new accurate pattern was investigated in present research. The new proposed load pattern has load distribution according weight and stiffness variation in height and mode shape of structure. The assessment of pushover application with mentioned pattern in X type braced steel frames and steel moment resisting frames, with stiffness and mass variation in height, was studied completely and the obtained results were compared with nonlinear dynamic analysis method (including time history analysis). The methods were compared from standpoints of some basic parameters such as displacement, drift and shape of lateral load pattern. It is concluded that proposed load pattern results are closer to nonlinear dynamic analysis (NDA) compared to other pushover load patterns especially in tall and medium-rise buildings having different stiffness and mass during the height.

A Study of the Change of Ship Speed according to the Ice Load Signal during Slow Ramming (저속 충격쇄빙 시 빙하중 신호에 따른 선속 변화 연구)

  • Ahn, Se-Jin;Lee, Tak-Kee
    • Journal of Ocean Engineering and Technology
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    • v.33 no.6
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    • pp.627-631
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    • 2019
  • Recently, researchers in Korea and abroad actively have conducted research activities using the ARAON, a Korean icebreaking research vessel. The ARAON regularly conduct research activities in the Arctic and Antarctic waters every year. The icebreaking mode, which can be either continuous breaking or ramming, is determined by the conditions of the ice and the ice-covered waters. When the icebreaker encounters thick sea ice or an ice ridge, ramming is used. At that time, the speed of the ship generally is slower than that of continuous icebreaking. In this study, the ice load signal at the time of repetitive ramming during ARAON's 2012 Antarctic research voyage was analyzed. The time history of the ice load signal and the change in the speed of the ship used in ramming were compared with these values during continuous icebreaking.

Evaluation of Risk Factors for Nasopharyngeal Carcinoma in a High-risk Area of India, the Northeastern Region

  • Lourembam, Deepak Singh;Singh, Asem Robinson;Sharma, T. Dhaneshor;Singh, Th Sudheeranjan;Singh, Thiyam Ramsing;Singh, Lisam Shanjukumar
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.12
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    • pp.4927-4935
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    • 2015
  • Northeastern India is a major nasopharyngeal carcinoma (NPC) high risk-area although the rest of the country has very low incidence. A case-control study of 105 NPC cases and 115 controls was conducted to identify the potential risk factors for NPC development in this region. Information was collected by interviewer about socio-demographic characteristics, cigarette smoking, alcohol consumption, dietary history, occupational history, and a family history of cancer. Epstein-Barr viral load was assayed from the blood DNA by real time PCR. Associations between GSTs genotypes, cytochrome P450 family including CYP1A1, CYP2E1 and CYP2A6 polymorphisms and susceptibility to relationship between the diseases were studied using PCR-RFLP assay. Results indicate that Epstein-Barr virus load was significantly higher in patients compared to controls (p<0.0001). Furthermore, concentration of blood EBV-DNA was significantly higher in advanced stage disease (Stage III and IV) than in early stage disease (Stage I and II) (p<0.05). Presence of CYP2A6 variants that reduced the enzyme activity was significantly less frequent in cases than controls. Smoked meat consumption, exposure to smoke, living in poorly ventilated house and alcohol consumption were associated with NPC development among the population of Northeastern India. Thus, overall our study revealed that EBV viral load and genetic polymorphism of CYP2A6 along with living practices which include smoked meat consumption, exposure to smoke, living in poorly ventilated houses and alcohol consumption are the potential risk factors of NPC in north eastern region of India. Understanding of the risk factors and their role in the etiology of NPC are helpful forpreventive measures and screening.

Profile Analysis on Signal Measured Local Ice Load during Icebreaking in Arctic Sea (북극해에서의 쇄빙시 국부 빙하중 계측 신호에 대한 파형 분석)

  • Jeon, Young-Ju;Rim, Chae-Whan;Lee, Tak-Kee
    • Journal of Navigation and Port Research
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    • v.37 no.2
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    • pp.143-148
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    • 2013
  • The aim of this study is to investigate the characteristics on the profile of local ice load acting on side shell of port side in bow part due to broken ice during icebreaking of ships in ice covered waters. The first Korean icebreaking research vessel 'ARAON' had a sea ice field trial in the Arctic Sea during early August, 2010, and the signals due to local ice impact measured from several strain gauges installed at bow part were gathered. It is known that these data with structural response characteristics due to local ice impact have some different characteristics with a typical hydraulic impact pressure - time history. In this study, the time history on the measured signals was analyzed and the characteristic values were presented using non-dimensional parameters.