• International Journal of Concrete Structures and Materials
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• 제10권1호
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• pp.99-112
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• 2016

During earthquake, reinforced concrete walls show complicated post-yield behavior varying with shear span-to-depth ratio, re-bar detail, and loading condition. In the present study, a macro-model for the nonlinear analysis of multi-story wall structures was developed. To conveniently describe the coupled flexure-compression and shear responses, a reinforced concrete wall was idealized with longitudinal and diagonal uniaxial elements. Simplified cyclic material models were used to describe the cyclic behavior of concrete and re-bars. For verification, the proposed method was applied to various existing test specimens of isolated and coupled walls. The results showed that the predictions agreed well with the test results including the load-carrying capacity, deformation capacity, and failure mode. Further the proposed model was applied to an existing wall structure tested on a shaking table. Three-dimensional nonlinear time history analyses using the proposed model were performed for the test specimen. The time history responses of the proposed method agreed with the test results including the lateral displacements and base shear.

• Earthquakes and Structures
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• 제15권2호
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• pp.203-214
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• 2018

Deflection control in tall buildings is a challenging issue. Connecting of the towers is an interesting idea for architects as well as structural engineers. In this paper, two reinforced concrete core-wall towers are connected by a truss bridge with buckling restrained braces. The buildings are 40 and 60-story. The effect of the location of the bridge is investigated. Response spectrum analysis of the linear models is used to obtain the design demands and the systems are designed according to the reliable codes. Then, nonlinear time history analysis at maximum considered earthquake is performed to assess the seismic responses of the systems subjected to far-field and near-field record sets. Fiber elements are used for the reinforced concrete walls. On average, the inter-story drift ratio demand will be minimized when the bridge is approximately located at a height equal to 0.825 times the total height of the building. Besides, because of whipping effects, maximum roof acceleration demand is approximately two times the peak ground acceleration. Plasticity extends near the base and also in major areas of the walls subjected to the seismic loads.

• Structural Engineering and Mechanics
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• 제62권4호
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• pp.497-506
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• 2017

A low damage self-centering braced frame equipped with post-tensioning strands is capable of directing damage to replaceable butterfly-shaped fuses. This paper investigates the seismic performance of rocking braced frame under near-field pulse-like ground motions compared to far-field records. A non-linear time history analysis is performed for twelve self-centering archetypes. A sensitivity analysis is carried out to examine the influences of ground motion types and modeling parameters. Findings represent the proper efficiency of the self-centering system under both far-field and near-field pulse-like ground motions.

• International Journal of Railway
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• 제3권2호
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• pp.73-82
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• 2010

Global and local behaviors of a lightly RC shear walls are investigated in this paper. For the sake of cyclic behaviors, nominal ground accelerations of 0.15 g, 0.40 g and 0.55 g which associated with natural periods of the walls are applied as listed in French CAMUS-2000 shake table test. Modified Kent & Park model, Drucker-Prager model for concrete material and $Giufr\acute{e}$-Menegotto-Pinto model for rebar are used for time history analyses using fiber/solids elements respectively. Alternatively, Eulerian beam analysis are discussed by imposing inelastic hinges at the most possible plastic hinge location using modified Takeda's trilinear model with stiffness reduction. Relative displacements, base shears, bending moments of 5-story shear building with 36-tons of mass under bi-lateral seismic excitation are extracted and compared with EC-8, PS-92 and KBC-09 provisions. Multi-scaled degradation process; material damage, elemental fracture and structural failure in turn is discussed in the view of numerical accuracy, efficiency and limitation depending on three different model-based analyses.

• Earthquakes and Structures
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• 제20권3호
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• pp.261-278
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• 2021

In the current work, a series of seismic analyses of one-storey asymmetrical reinforced concrete (R/C) framed buildings is accomplished while the effect of soil deformability on the structural response is investigated. A comparison is performed between the simplified elastic behavior of R/C elements according to the structural regulations' instructions to the possible non-linear behavior of R/C elements under actual circumstances. The target of the time history analyses is the elucidation of the Soil-Structure Interaction (SSI) effect in the seismic behavior of common R/C structures by examining the possible elastic or elastoplastic behavior of R/C sections because of the redistribution of the internal forces by employing a realistic damage index. The conclusions acquired from the presented elastic and elastoplastic analyses supply practical guidelines towards the safer design of structures.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2007년 가을학술발표회
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• pp.317-333
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• 2007

The Round-Robin Test (RRT) for ground response analysis was performed by Division of Geotechnical Earthquake Engineering of Korean Geotechnical Society. This research analyzed the influence of analysis methods on variation of ground response by using the results of this RRT. The analysis methods include equivalent linear analysis, non-linear analysis and effective stress analysis. A total of 5 teams among 12 teams applied two kinds of analysis methods. This research compared the results of these 5 teams and analyzed the variation of the results according to analysis methods. The compared results were shear stress-shear strain relation, transfer function, time history and the response spectrum of ground surface acceleration, peak ground acceleration, peak shear strain and maximum excess pore pressure ratio.

• Structural Engineering and Mechanics
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• 제77권6호
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• pp.735-744
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• 2021

In recent years, the use of new materials and technologies with the aim of developing high-performing and cost-effective structures has greatly increased. Application of high-strength concrete (HSC) has been found effective in reducing the dimensions of frame members; nonetheless, such reduction in dimensions of structural elements in the most cases may result in the lack of accountability in the tolerable drift capacity. On this basis, strengthening of frame members using fiber reinforced polymers (FRPs) may be deemed as an appropriate remedy to address this issue, which albeit requires comprehensive and systematic investigations. In this paper, the performance of properly-designed, two-dimensional frames made of high-strength concrete and strengthened with Carbon Fiber Reinforced Polymers (CFRPs) is investigated through detailed numerical simulation. To this end, nonlinear dynamic time history analyses have been performed using the Seismosoft software through application of five scaled earthquake ground motion records. Unstrengthened (bare) and strengthened frames have been analyzed under seismic loading for performance assessment and comparison purposes. The results and findings of this study show that use of CFRP can be quite effective in seismic response improvement of high-strength-concrete structures.

• 한국지진공학회논문집
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• 제15권5호
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• pp.25-33
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• 2011

비선형 시간이력응답해석에서 입력지진동은 구조물의 탄소성 지진응답을 결정짓는 중요한 요소이다. 시간이력해석에 사용되는 기록지진동파형은 지진발생 메카니즘, 전달경로, 지반의 성질에 따른 여러 가지 인자가 복잡하게 관련되어 있기 때문에 구조물의 지진응답해석에 사용될 일반성을 갖는 입력지진동을 선정하는 것은 매우 어려운 문제이다. 본 논문은 실무에서 내진설계용 지진동으로 가장 선호하지 않는 입력지진동을 선정하여 인공지진동파형을 작성하였다. 인공지진동은 기록지진동과 동일한 위상각을 가지며, 감쇠정수 h=5%일 때의 설계용 스펙트럼과 거의 일치하도록 작성되었다. 기록지지동과 인공지진동을 입력한 1자유도계의 탄성 및 탄소성 지진 응답해석을 수행하여 탄소성 응답스펙트럼 및 입력에너지 응답 특성을 분석하였다. 본 연구에서 작성된 인공지진동은 건축구조물의 탄소성 지진응답해석용 입력지진동으로 충분히 타당성이 있다고 사료된다.

• Geomechanics and Engineering
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• 제4권1호
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• pp.1-18
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• 2012

The spatial variation of ground motion in Kolkata Metropolitan District (KMD) has been estimated by generating synthetic ground motion considering the point source model coupled with site response analysis. The most vulnerable source was identified from regional seismotectonic map for an area of about 350 km radius around Kolkata. The rock level acceleration time histories at 121 borehole locations in Kolkata for the vulnerable source, Eocene Hinge Zone, due to maximum credible earthquake (MCE) moment magnitude 6.2 were generated by synthetic ground motion model. Soil investigation data of 121 boreholes were collected from the report of Soil Data Bank Project, Jadavpur University, Kolkata. Surface level ground motion parameters were determined using SHAKE2000 software. The results are presented in the form of peak ground acceleration (PGA) at rock level and ground surface, amplification factor, and the response spectra at the ground surface for frequency 1.5 Hz, 3 Hz, 5 Hz and 10 Hz and 5% damping ratio. Site response study shows higher PGA in comparison with rock level acceleration. Maximum amplification in some portion in KMD area is found to be as high as 3.0 times compared to rock level.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.513-520
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• 2002

This study is for seismic analysis of building structures with ambiguous modal direction This case is revealed symmetrical building structure or the structure that isn't coincided building axis with physical axis. Seismic analysis-time history analysis, response spectrum analysis and lateral force procedure-is carried out. It is concluded that analysis method for the structure with ambiguous modal direction don't suitable for lateral force procedure. It is recommended to use the CQC method for combining modal responses to the individual components and the SRSS rule for combining responses to the two horizontal components are of nearly equal intensities.