• 한국전산구조공학회논문집
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• 제23권2호
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• pp.209-215
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• 2010

본 논문에서는 CFD와 FEM에 기초한 진보된 전산해석 기법을 적용하였고 지진에 의한 수평 및 수직방향 기반가진 및 풍하중 효과를 동시에 고려하여 MW급 풍력발전기의 지진응답 해석을 수행하였다. 본 연구에서는 실용적인 응답특성 파악을 위해 시간영역 수치해석기법을 적용하였으며, 지진기반하중 및 풍하중에 의한 영향을 상호 비교하였다. 본 연구의 결과를 통해 관성 특성이 매우 큰 초대형 풍력발전기가 정상작동 조건 중 지진이 유발되는 경우가 타워에 유발되는 응력특성에 큰 영향을 미칠 수 있기 때문에 중요하게 고려될 필요성이 있음을 알 수 있었다.

• Geomechanics and Engineering
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• 제23권1호
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• pp.71-83
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• 2020

Cantilever sheet pile walls are subjected to surcharge loading located on the backfill soil and at different distances from the top of the wall. The response of cantilever sheet pile walls to surcharge loadings at varying distances under seismic conditions is scarce in literature. In the present study, the influence of uniform surcharge load on cantilever sheet pile wall at varying distances from the top of the wall under seismic conditions are analyzed using finite difference based computer program. The results of the numerical analysis are presented in non-dimensional form like variation of bending moment and horizontal earth pressure along the depth of the sheet pile walls. The numerical analysis has been conducted at different magnitudes of horizontal seismic acceleration coefficient and vertical seismic acceleration coefficients by varying the magnitude and position of uniform surcharge from the top of the wall for different embedded depths and types of soil. The parametric study is conducted with different embedded depth of sheet pile walls, magnitude of surcharge on the top of the wall and at a distance from the top of the wall for different angles of internal friction. It is observed that the maximum bending moment increases and more mobilization of earth pressure takes place with increase in horizontal seismic acceleration coefficients, magnitude of uniform surcharge, embedded depth and decrease in the distance of surcharge from the top of the wall in loose sand.

• Earthquakes and Structures
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• 제19권4호
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• pp.261-272
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• 2020

Recent severe earthquakes in and around the vital public places worldwide indicate the severe vulnerability of ground excitation to be assailed. Reducing the effect of seismic lateral load in structural design is an important conception. Essentially, seismic isolation is required to shield the superstructure in such a way that the building superstructure would not move when the ground is shaking. This study explores the effectiveness, design, and practical feasibility of base isolation systems to reduce seismic demands on buildings of varying elevations. Thus, static and dynamic analyses were conducted based on site-specific bi-directional earthquakes for base-isolated as well as fixed-based buildings. Remarkably, it was discovered that isolators used in low-rise to high-rise structures tend to significantly decrease the structural responses of seismic prone buildings. The higher allowable horizontal displacement induces structural flexibility and ensure good structural health of the building stories. Reinforcement from vertical and horizontal members can be reduced in significant amounts for BI buildings. Thus, although incorporating base isolators increases the initial outlay, it considerably diminishes the total structural cost.

• 한국공간구조학회논문집
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• 제23권4호
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• pp.27-34
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• 2023

In this study, the seismic response characteristics of the three analysis model with or without TMD were investigated to find out the effective dome shape. The three analysis models are rib type, lattice type and geodesic type dome structure composed of space frame. The maximum vertical and horizontal displacements were evaluated at 1/4 point of the span by applying the resonance harmonic load and historical earthquake loads (El Centro, Kobe, Northridge earthquakes). The study of the effective TMD installation position for the dome structure shows that seismic response control was effective when eight TMDs were installed in all types of analysis model. The investigation of the efficiency of TMD according to dome shape presents that lattice dome and geodesic dome show excellent control performance, while rib dome shows different control performance depending on the historical seismic loads. Therefore, lattice and geodesic types are desirable for seismic response reduction using TMD compared to rib type.

• Computers and Concrete
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• 제33권6호
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• pp.689-706
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• 2024

This study is aimed at identifying structural element stiffness influence on vertical earthquake response of mid-rise R/C frame buildings. To this aim, a mid-rise RC building structure is designed as per the new Turkish Seismic Code for Buildings-2018, and 3D FE model of the building is established. Based on the established FE model, a total number of six buildings are considered depending on certain percentage increase in beam, slab, and column. The time-history response analyses (THA) are performed separately for only horizontal (H) and horizontal +vertical (H+V) earthquake motions to make a comparison between the load cases. The analysis results are presented comparatively in terms of the monitoring parameters of the base overturning moment (M_o), the top-story lateral displacement (d_L) and the top-story vertical displacement (d_V). The obtained results reveal that the base overturning moment and the top-story vertical displacement are affected by vertical earthquake motion regardless of the increase in the dimension of beam, slab, and column. However, vertical earthquake motion is not effective on the top-story lateral displacement due to no change between H and H+V load. The dimensional increase in either slab or beam leads to a considerable increase in the base overturning moment and the top-story vertical displacement while causing decrease in the top-story lateral displacement. In addition, the dimensional increase in column has a positive effect on the decrease in the monitoring parameters of the base overturning moment (M_o), the top-story lateral displacement (d_L) and the top-story vertical displacement (d_V).

• Steel and Composite Structures
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• 제24권1호
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• pp.1-13
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• 2017

In order to improve the deformation capacity of the high-strength concrete shear wall, five high-strength concrete shear wall specimens confined with high-strength rectangular spiral reinforcement (HRSR) possessing different parameters, were designed in this paper. One specimen was only adopted high-strength rectangular spiral hoops in embedded columns, the rest of the four specimens were used high-strength rectangular spiral hoops in embedded columns, and high-strength spiral horizontal distribution reinforcement were used in the wall body. Pseudo-static test were carried out on high-strength concrete shear wall specimens confined with HRSR, to study the influence of the factors of longitudinal reinforcement ratio, hoop reinforcement form and the spiral stirrups outer the wall on the failure modes, failure mechanism, ductility, hysteresis characteristics, stiffness degradation and energy dissipation capacity of the shear wall. Results showed that using HRSR as hoops and transverse reinforcements could restrain concrete, slow load carrying capacity degeneration, improve the load carrying capacity and ductility of shear walls; under the vertical force, seismic performance of the RC shear wall with high axial compression ratio can be significantly improved through plastic hinge area or the whole body of the shear wall equipped with outer HRSR.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.139-147
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• 1999

Six reinforced concrete shear wall, constructured with fully rigid, slit, and infilled types, were tested under both vertical and cyclic loadings. Experimental programs were carried out to evaluate the seismic performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility, under load reversals. All the specimens were modeled in one-third scale size. Based on the test results, the following conclusions can be made. For the diagonal reinforced slit and infilled shear wall specimens, it was found that the failure mode shows very effective crack control and crushing due to slippage prevention of boundary region and reduction of diagonal tension rathar than the brittle shear and diagonal tension failure. The ductility of specimens designed by the diagonal reinforcement for the slit and infilled shear wall was increased 1.72~1.81 times in comparison with the fully rigid shear wall frame. Maximum horizontal load-carrying capacity of specimens designed by the diagonal reinforcement ratio the slit and infilled shear wall was increased respectively by l.14 times and l.49 times in comparison with the standard fully rigid shear wall frame.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.261-268
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• 1999

The seismic performance of precast concrete panel structures tested previously has been evaluated in this paper. Hysteretic curves of test specimens are idealized to elasto-plastic curves to get reliable yielding and ultimate displacements. For the idealized curves, ductility and energy dissipation capacity of specimens have been evaluated using a few guide lines. In addition, the strength capacity of specimens is checked for the strength demand caused by the design earthquake load including overturning moment effects. The result shows while the strength of specimen with joint box for vertical continuity is little bit lower than that of specimen connected by welding, the ductility of the former is higher than that of the latter. The energy dissipation ratios of PC specimens are ranged from 83% to 96% of that of Re specimen and the average of those are shown 90%.

• 한국지진공학회논문집
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• 제23권3호
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• pp.191-199
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• 2019

To calculate proper seismic design load and seismic design category, the exact site class for construction site is required. At present, the average shear-wave velocity for multi-layer soil deposits is calculated by the sum of shear-wave velocities without considering of vertical relationship of the strata. In this study, the transfer function for the multi-layered soil deposits was reviewed on the basis of the wave propagation theory. Also, the transfer function was accurately verified by the finite element model and the eigenvalue analysis. Three methods for site period estimation were evaluated. The sum of shear-wave velocities underestimated the average shear-wave velocities of 526 strata with large deviations. The equation of Mexican code overestimated the average shear-wave velocities. The equation of Japanese code well estimated the average shear-wave velocities with small deviation.

• Earthquakes and Structures
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• 제24권6호
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• pp.439-453
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• 2023

Older brick masonry structures generally suffer from low strength defects. Using a cement mortar layer (CML) or steel-meshed cement mortar layer (S-CML) to reinforce existing low-strength brick masonry structures (LBMs) is still an effective means of increasing seismic performance. However, performance indices such as lateral displacement ratios and skeleton curves for LBMs reinforced with CML or S-CML need to be clarified in performance-based seismic design and evaluation. Therefore, research into the failure mechanisms and seismic performance of LBMs reinforced with CML or S-CML is imperative. In this study, thirty low-strength brick walls (LBWs) with different cross-sectional areas, bonding mortar types, vertical loads, and CML/S-CML thicknesses were constructed. The failure modes, load-carrying capacities, energy dissipation capacity and lateral drift ratio limits in different limits states were acquired via quasi-static tests. The results show that 1) the primary failure modes of UBWs and RBWs are "diagonal shear failure" and "sliding failure through joints." 2) The acceptable drift ratios of Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP) for UBWs can be 0.04%, 0.08%, and 0.3%, respectively. For 20-RBWs, the acceptable drift ratios of IO, LS, and CP for 20-RBWs can be 0.037%, 0.09%, and 0.41%, respectively. Moreover, the acceptable drift ratios of IO, LS, and CP for 40-RBWs can be 0.048%, 0.09%, and 0.53%, respectively. 3) Reinforcing low-strength brick walls with CML/S-CML can improve brick walls' bearing capacity, deformation, and energy dissipation capacity. Using CML/S-CML reinforcement to improve the seismic performance of old masonry houses is a feasible and practical choice.