• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.47-57
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• 2000

Experimental and numerical studies were done to investigate seismic performance of slender shear walls with no boundary confinement that are principal structural members of high0rise bearing wall buildings. 1/3 scale specimens that model the plastic region of long slender shear walls subjected to combined axial load and bending moment were tested to investigate strength, ductility, capacity of energy dissipation, and strain distribution, The experimental results show that the slender shear walls fail due to early crushing in the compressive boundary, and then have very low ductility. The measured maximum compressive strain is 0.0021, much less than 0.004 being commonly used for estimation of ductility. This result indicates that the maximum compressive strain is not a fixed value but is affected by moment gradient along the shear wall height and distance from the neutral axis to the extreme compressive fiber.

• Earthquakes and Structures
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• v.1 no.3
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• pp.253-267
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• 2010

A novel simple approach is presented for the seismic analysis of continuous buried pipelines subject to fault ruptures. The method is based on the minimization of the total dissipated energy during faulting, taking into account the basic factors that affect the problem, namely: a) the pipe yielding under axial and bending load, through the formation of plastic hinges and axial slip; b) the longitudinal friction across the pipe-soil interface; c) the lateral resistance of soil. The advantages and drawbacks of the proposed method are highlighted through a comparison with previous approaches, as well as with finite element calculations accounting for the 3D kinematics of the pipe-soil-fault systems under large deformations. Parametric analyses are also provided to assess the relative influence of the various parameters affecting the problem.

• International Journal of Railway
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• v.3 no.2
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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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.533-541
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• 2021

Retaining walls have been used to prevent slope failure through resistance of earth pressure in railway, road, nuclear power plant, dam, and river infrastructure. To calculate dynamic earth pressure and determine the characteristics for seismic behavior, many researchers have analyzed the nonlinear response of ground and structure based on various numerical analyses (FLAC, PLAXIS, ABAQUS etc). In addition, seismic fragility evaluation is performed to ensure safety against earthquakes for structures. In this study, we used the FLAC2D program to understand the seismic response of the inverted T-type wall with a backfill slope, and evaluated seismic fragility based on relative horizontal displacements of the wall. Nonlinear site response analysis was performed for each site (S2 and S4) using the seven ground motions to calculate various seismic loadings reflecting site characteristics. The numerical model was validated based on other numerical models, experiment results, and generalized formula for dynamic active earth pressure. We also determined the damage state and damage index based on the height of retaining wall, and developed the seismic fragility curves. The damage probabilities of the retaining wall for the S4 site were computed to be larger than those for the S2 site.

• Land and Housing Review
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• v.13 no.1
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• pp.141-150
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• 2022

Responding to the increasing demand for research on seismic resistance of structures triggered by a large-scale earthquake in Korea, the Ministry of the Interior and Safety revised the typical application of the existing seismic design standards with the national seismic performance target enhanced. Therefore, in this paper, the dam body of the aged Test-Bed and the penstock with fluid were modeled by the three-dimensional finite element method by introducing several variables. The current seismic design standard law confirmed the safety of the dam structure and penstock against seismic waves. As a result of the 3D finite element analysis, the stress change due to the water impact of the penstock was minimal, and it was confirmed that the effect of the hydraulic pressure was more significant than the water impact in the earthquake situation. When the hydrostatic pressure is in the form of SPH, it was analyzed that the motion of the fluid and the location of stress caused by the earthquake can be effectively represented, and it will be easier to analyze the weak part. As a result of the analysis, which considers penstock's corrosion, the degree of stress dispersion gets smaller because the penstock is embedded in the body. The stress result is minimal, less than 1% of the yield stress of the steel. In addition, although there is a possibility of micro-tensile cracks occurring in the inlet of the dam, it has not been shown to have a significant effect on the stress increa.

• Earthquakes and Structures
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• v.19 no.1
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• pp.59-77
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• 2020

The code static eccentricity model for elastic torsional design of structures has two critical shortcomings: (1) the negation of the inertial torsional moment at the center of mass (CM), particularly for torsionally-unbalanced (TU) building structures, and (2) the confusion caused by the discrepancy in the definition of the design eccentricity in codes and the resistance eccentricity commonly used by engineers such as in FEMA454. To overcome these shortcomings, using the resistance eccentricity model that can accommodate the inertial torsional moment at the CM, interactive relations between shear and torsion are proposed as follows: (1) elastic responses of structures at instants of peak edge-frame drifts are given as functions of resistance eccentricity, and (2) elastic hysteretic relationships between shear and torsion in forces and deformations are bounded by ellipsoids constructed using two adjacent dominant modes. Comparison of demands estimated using these two interactive relations with those from shake-table tests of two TU building structures (a 1:5-scale five-story reinforced concrete (RC) building model and a 1:12-scale 17-story RC building model) under the service level earthquake (SLE) show that these relations match experimental results of models reasonably well. Concepts proposed in this study enable engineers to not only visualize the overall picture of torsional behavior including the relationship between shear and torsion with the range of forces and deformations, but also pinpoint easily the information about critical responses of structures such as the maximum edge-frame drifts and the corresponding shear force and torsion moment with the eccentricity.

• Structural Engineering and Mechanics
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• v.49 no.6
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• pp.775-792
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• 2014

Static loading tests were carried out in this study to investigate the effect of bar cutoff on the resistance of RC beam-column sub-assemblages under column loss. Two specimens were designed with continuous main reinforcement. Four others were designed with different types of bar cutoff in the mid-span and/or the beam-end regions. Compressive arch and tensile catenary responses of the specimens under gravitational loading were compared. Test results indicated that those specimens with approximately equal moment strength at the beam ends had similar peak loading resistance in the compressive arch phase but varied resistance degradation in the transition phase because of bar cutoff. The compressive bars terminated at one-third span could help to mitigate the degradation although they had minor contribution to the catenary action. Among those cutoff patterns, the K-type cutoff presented the best strength enhancement. It revealed that it is better to extend the steel bars beyond the mid-span before cutoff for the two-span beams bridging over a column vulnerable to sudden failure. For general cutoff patterns dominated by gravitational and seismic designs, they may be appropriately modified to minimize the influence of bar cutoff on the progressive collapse resistance.

• International journal of steel structures
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• v.18 no.5
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• pp.1631-1638
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• 2018

In the periodic repainting of steel bridges, often the steel surface has to be prepared by using power tools to remove surface contaminants, such as deteriorated paint film and rust, and to increase the adhesive strengths of the paint films to be applied newly. Surface preparation by bristle roll-brush grinding, which is a type of power tool, may additionally introduce compressive residual stress and increase the fatigue resistance of welded joints owing to the impact of rotating bristle tips. In this study, fatigue tests were conducted for longitudinally out-of-plane gusset fillet welded joints and transversely butt-welded joints to evaluate the effect of bristle roll-brush grinding prior to repainting on the fatigue resistance of the welded joints. The test results showed that bristle roll-brush grinding introduced compressive residual stress and significantly increased fatigue limits by over 50%.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.500-511
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• 2017

Recently, as earthquakes have occurred in Gyeongju, interest in the stability of structures against vibration from earthquakes has increased. In Korea, the capacity of load resistance is mainly considered in the design of anchors. However, the vibration resistance characteristics of anchors have not been fully elucidated. The traditional type of anchor, which is a frictional resistance anchor, is often reported to fail due to vibration in construction procedures, such as blasting. The expansion type of anchor, on the other hand, could have more resistance to vibration but its capability of demonstrating vibratory resistance has to be investigated. In order to verify the vibratory resistance characteristics of expansion anchors against blasting and earthquake vibration, field tests and numerical analyses for seismic wave were performed. Field blasting test results show that the expansion anchor has better capability against vibratory load than does the frictional type anchor. Numerical analysis to earthquake also show that the expansion type anchor provides more resistance than does the frictional type anchor.

• Steel and Composite Structures
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• v.21 no.2
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• pp.343-356
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• 2016

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-in-place joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.