• Structural Engineering and Mechanics
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• v.48 no.5
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• pp.681-695
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• 2013

Performance-based seismic design allows a structure to develop inelastic response during earthquakes. This modern seismic design requires more clearly defined levels of inelastic response. The ultimate deformation of a structure without total collapse (target displacement) is used to obtain the inelastic deformation capacity (inelastic performance). The inelastic performance of a structure indicates its performance under excitation. In this study, a new energy-based method to obtain the target displacement for reinforced concrete frames under cyclic loading is proposed. Concrete structures were analyzed using nonlinear static (pushover) analysis and cyclic loading. Failure of structures under cyclic loading was controlled and the new method was tested to obtain target displacement. In this method, the capacity energy absorption of the structures for both pushover and cyclic analyses were considered to be equal. The results were compared with FEMA-356, which confirmed the accuracy of the proposed method.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.591-600
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• 2019

Steel tubular buckling controlled braces are well known as being simple, practical and cost-effective lateral force resisting systems. Although these system features have gained the attention of the researchers over the last decade, steel tubular buckling controlled braces currently have limited application. Indeed, only a few steel tubes tightly encased within each other exist in the steel industry. In this paper, a new and practical design method is proposed in order to better promote the widespeared application for current steel tubular buckling controlled brace applications. In order to reach this goal, a holed-adapter made with polyoxymethylene adaptable to all round and square steel sections, was developed to use as infiller. The research program presents designing, producing and displacement controlled cyclic loading tests of a conventional tubular brace and a buckling controlled composite brace. In addition, numerical analysis was carried out to compare the experimental results. As a result of the experimental studies, buckling was controlled up to 0.88 % drift ratio and the energy dissipation capacity of the conventional tubular brace increased 1.46 times due to the proposed design. The main conclusion of this research is that polyoxymethylene is a highly suitable material for the production of steel tubular buckling controlled braces.

• Journal of the Society of Disaster Information
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• v.4 no.2
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• pp.10-27
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• 2008

When the ground is excavated adjacent to the existing tunnel, which is loaded by the surcharge on the ground surface, the tunnel stability would be very sensitive to the deformation of the ground induced by the horizontal displacement of braced wall. The stability of the existing surcharged tunnel could be controlled by pre-loading on the braced wall. In this paper, it was investigated, if it would be possible to keep the existing surcharged tunnel stable by preventing the horizontal displacement of a braced wall by imposing the pre-loading during the ground excavation. For this purpose, large scale model tests were performed in a scale 1/10 at the test pit which was 2.0m in width and 6.0m in height and 4.0m in length. Isotropic test ground was constructed homogeneously by wet sand. Model tunnel was constructed in the test ground. Surcharge was loaded on the ground surface above the tunnel. During the tests, the behavior of model tunnel and model braced wall was measured. Numerical analyses were also performed in the same condition as the tests. And their results were compared to that of the model tests. Consequently, the effect of a surcharge could be compensated by imposing the pre-loading on the braced wall. The existing tunnel and the braced wall could be kept stable by preventing the horizontal displacement of the braced wall through pre-loading, although the tunnel is surcharged.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.733-739
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• 1999

A theoretical model for flexural behavior of strengthened reinforced concrete beam is developed based on displacement controlled nonlinear finite element method in this study. The developed model is shown to reasonably reproducing the experimental results of variously strengthened reinforced concrete beam. Parametric studies for the strengthened reinforced concrete beam at different loading stages are then performed using this model in order to assess the effect of loading stages at the time of strengthening on characteristic values of strengthened beam under flexure. It was found that depending on loading stages of a beam, deflections at yielding and at ultimate loads are more influenced than corresponding load capacities.

• Structural Engineering and Mechanics
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• v.64 no.3
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• pp.287-292
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• 2017

In the present research, an available flexural stiffness degradation model was modified and a new comprehensive model called "X-NFSD" was developed. The X-NFSD model is capable of predicting the flexural stiffness degradation of composite specimen at different states of stresses and at room temperature. The model was verified by means of different experimental data for chopped strand mat/epoxy composites under displacement controlled bending loading condition at different displacements and states of stresses. The obtained results provided by the present model are impressively in very good agreement with the experimental data and the mean value of error of 5.4% was achieved.

• Earthquakes and Structures
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• v.13 no.4
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• pp.409-419
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• 2017

In order to analyze the vibration control effect of viscous damper in the concrete archaized buildings with lintel-column joints under seismic action, 3 specimens were tested under dynamic excitation. Two specimens with viscous damper were defined as the controlled component and one specimen without viscous damper was specified as the non-controlled component. The loading process and failure patterns were obtained from the test results. The failure characteristics, skeleton curves and mechanical behavior such as the load-displacement hysteretic loops, load carrying capacity, degradation of strength and rigidity, ductility and energy dissipation of the joints were analyzed. The results indicate that the load-bearing capacity of the controlled component is significantly higher than that of the non-controlled component. The former component has an average increase of 27.4% in yield load and 22.4% in ultimate load, respectively. Meanwhile, the performance of displacement ductility and the ability of energy dissipation for the controlled component are superior to those of the non-controlled component as well. Compared with non-controlled component, equivalent viscous damping coefficients are improved by 27.3%-30.8%, the average increase is 29.0% at ultimate load for controlled component. All these results reflect that the seismic performance of the controlled component is significantly better than that of the non-controlled component. These researches are helpful for practical application of viscous damper in the concrete archaizing buildings with lintel-column joints.

• Ocean Systems Engineering
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• v.2 no.3
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• pp.205-215
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• 2012

Recently, interest of offshore structure construction in South Korea is growing as the land space becomes limited for further development and the renewable energy grows to be more attractive for the replacement of the fossil energy. In order for the optimal construction of optimum offshore floating structures, development of safe and economical offshore foundation technologies is a priority. In this study, the large-deformation behavior of a suction pile, which markets are rapidly growing nowadays, is analyzed for three different loading locations (top, middle, and bottom of the suction pile) with three different displacement inclinations (displacement controlled with displacement inclinations of 0, 10, and 20 degrees from the horizontal). The behavior analysis includes quantifications of maximum resistances, translations, and rotation angles of the suction pile. The suction pile with its diameter of 10 m and height of 25 m is assumed to be embedded in clay, sand, and multi layers of subsea foundation. The soil properties of the clay, sand, and multi layers were determined based on the results of the site investigations performed in the West sea of South Korea. As analyses results, the maximum resistance was observed at the middle of the suction pile with the displacement inclination of 20 degrees, while the translations and rotations resulting from the horizontal and inclined pullouts were not significant until the horizontal components of movements at the loading points reach 1.0 m.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.4
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• pp.211-222
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• 2016

Reinforced concrete shear walls with deficient reinforcement details are tested under cyclic loading. The deficiency of reinforcement details includes insufficient splice length in U-stirrups at the ends of horizontal reinforcement and boundary column dowel bars found in existing low- to mid-rise Korean buildings designed non-seismically. Three test specimens have rectangular, babel and flanged sections, respectively. Flexure- and shear-controlled models for reinforced concrete shear walls specified in ASCE/SEI 41-13 are compared with the flexural and shear components of force-displacement relation extracted separately from the top displacement of the specimen based on the displacement data measured at diverse locations. Modification of the shear wall models in ASCE/SEI 41-13 is proposed in order to account for the effect of bar slip, cracking loads in flexure and shear. The proposed modification shows better approximation of the test results compared to the original models.

• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.633-645
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• 2015

In order to analyze the mechanical properties of two-way different configurations of prestressed concrete members subjected to axial loading, a finite element model based on the nuclear power plant containments is demonstrated. This model takes into account the influences of different principal stress directions, the uniaxial or biaxial loading, and biaxial loading ratio. The displacement-controlled load is applied to obtain the stress estrain response. The simulated results indicate that the differences of principal stress axes have great effects on the stress-strain response under uniaxial loading. When the specimens are subjected to biaxial loading, the change trend of stress with the increase of loading ratio is obviously different along different layout directions. In addition, correlation experiments and finite element analyses were conducted to verify the validity and reliability of the analysis in this study.

• Computers and Concrete
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• v.13 no.3
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• pp.343-359
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• 2014

In this work a numerical method to simulate the response of reinforced concrete structures subject to cyclically imposed displacements is proposed. The method consists of a combination of a displacement and load controlled version of the Newton-Raphson iterative technique, used for the loading and the unloading part of the cycles respectively. The whole procedure is combined with a relatively simple concrete model whose only material parameter is its uniaxial compressive strength. The proposed methodology may realistically simulate, in an easy way, the physical process of any experimentally tested RC structure under imposed displacements cycles. The efficiency of the approach is demonstrated through a series of analyses of experimentally tested specimens reported in the literature.