• 한국안전학회지
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• 제20권3호
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• pp.143-151
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• 2005

In this study, it is demonstrated that how the effect of the Near Fault Ground Motion affects the response of the structure. Considering the general characteristic of Near Fault Ground Motion the characteristics of Near Fault Ground Motions is analysed by elastic response spectrums, and the inelastic response spectrum is evaluated with the ductility and the yield strength to consider the inelastic behavior which couldn't be simulated through the elastic response spectrum. The result of this study shows that the effect of Near Fault Ground Motion should be considered in the long period range of long span structures but the domestic seismic design code was developed based on Far Fault Ground Motions, so the effects of Near Fault Ground Motions, which is very serious especially in large structures with a long period, are not considered. Therefore, the effect of the Near Fault Ground Motion has to be examined especially in the seismic performance evaluation of long period structure.

• Structural Engineering and Mechanics
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• 제51권2호
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• pp.267-276
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• 2014

Wharfs are essential to shipping and support very large gravity loads on both a short-term and long-term basis which cause quite large seismic internal forces. Therefore, these structures are vulnerable to seismic activities. As they are supported on vertical and/or batter piles, soil-pile interaction effects under earthquake events have a great importance in seismic resistance which is not yet fully understood. Seismic design codes have become more stringent and suggest the use of new design methods, such as Performance Based Design principles. According to Turkish Code for Coastal and Port Structures (TCCS 2008), the interaction between soil and pile should somehow be considered in the nonlinear analysis in an accurate manner. This study aims to explore the lateral load carrying capacity of recently designed wharf structures considering soil-pile interaction effects for different soil conditions. For this purpose, nonlinear structure analysis according to TCCS (2008) has been performed comparing simplified and detailed modeling results.

• Geomechanics and Engineering
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• 제7권6호
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• pp.613-631
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• 2014

To complement the method of field-scale seismic ground motion simulations by buried blast techniques, the application and evaluation of the capability of a numerical modeling platform to simulate buried explosion-induced ground motion at a real soil site is presented in this paper. Upon a layout of the experimental setup at a level site wherein multiple charges that were buried over a large-diameter circle and detonated in a planned sequence, the formulation of a numerical model of the soil and the explosives using the finite element code LS-DYNA is developed for the evaluation of the resulting ground motion and surface subsidence. With a compact elastoplastic cap model calibrated for the loess soils on the basis of the site and laboratory test program, numerical solutions are obtained by explicit time integration for various dynamic aspects and their relation with the field blast experiment. Quantitative comparison of the computed ground acceleration time histories at different locations and induced spatial subsidence on the surface afterwards is given for further engineering insights in regard to the capabilities and limitations of both the numerical and experimental approaches.

• 한국안전학회지
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• 제29권3호
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• pp.72-78
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• 2014

The minimum thickness of long-span deck slab is proposed by checking the limit state according to the Korean highway bridge design code(limit state design). Both minimizing thickness and ensuring safety of deck slab are important design factors to increase a competitive price of the long span deck slabs. The required thicknesses for satisfying flexural capacity, preventing punching shear failure and limiting deflection were calculated by considering KL-510 load model which has increased total load compared to DB 24 from 432 kN to 510 kN. The results of the required thickness for various limit states were compared to propose the minimum thickness as a function of span length of deck slabs. The proposed minimum thickness is influenced by satisfying flexural capacity and limiting deflection. It turns out to be similar compared to the results of the previous study by ultimate strength design method even if the live load model was increased in total weights.

• Earthquakes and Structures
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• 제21권5호
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• pp.477-487
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• 2021

This study focuses on the influence of strong ground motion duration on the response and collapse probability of reinforced concrete walls with a predominant response in flexure. Walls with different height and mass were used to account for a broad spectrum of configurations and fundamental periods. The walls were designed following the specifications of the Chilean design code. Non-linear models of the reinforced concrete walls using a distributed plasticity approach were performed in OpenSees and calibrated with experimental data. Special attention was put on modeling strength and stiffness degradation. The effect of duration was isolated using spectrally equivalent ground motions of long and short duration. In order to assess the behavior of the RC shear walls, incremental dynamic analyses (IDA) were performed, and fragility curves were obtained using cumulative and non-cumulative engineering demand parameters. The spectral acceleration at the fundamental period of the wall was used as the intensity measure (IM) for the IDAs. The results show that the long duration ground motion set decreases the average collapse capacity in walls of medium and long periods compared to the results using the short duration set. Also, it was found that a lower median intensity is required to achieve moderate damage states in the same medium and long period wall models. Finally, strength and stiffness degradation are important modelling parameters and if they are not included, the damage in reinforced concrete walls may be greatly underestimated.

• 한국지진공학회논문집
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• 제20권4호
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• pp.245-256
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• 2016

In the companion paper (I - Database and Site Response Analyses), site-specific response analyses were performed at more than 300 domestic sites. In this study, a new site classification system and design response spectra are proposed using results of the site-specific response analyses. Depth to bedrock (H) and average shear wave velocity of soil above the bedrock ($V_{S,Soil}$) were adopted as parameters to classify the sites into sub-categories because these two factors mostly affect site amplification, especially for shallow bedrock region. The 20 m of depth to bedrock was selected as the initial parameter for site classification based on the trend of site coefficients obtained from the site-specific response analyses. The sites having less than 20 m of depth to bedrock (H1 sites) are sub-divided into two site classes using 260 m/s of $V_{S,Soil}$ while the sites having greater than 20 m of depth to bedrock (H2 sites) are sub-divided into two site classes at $V_{S,Soil}$ equal to 180 m/s. The integration interval of 0.4 ~ 1.5 sec period range was adopted to calculate the long-period site coefficients ($F_v$) for reflecting the amplification characteristics of Korean geological condition. In addition, the frequency distribution of depth to bedrock reported for Korean sites was also considered in calculating the site coefficients for H2 sites to incorporate sites having greater than 30 m of depth to bedrock. The relationships between the site coefficients and rock shaking intensity were proposed and then subsequently compared with the site coefficients of similar site classes suggested in other codes.

• 한국지반공학회논문집
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• 제28권3호
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• pp.25-34
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• 2012

최근 제안된 2-매개변수 지반분류 방법 및 지반 증폭계수가 국내 지반조건 및 지반증폭특성에 적합함을 검증하기 위하여 내진설계기준연구II, Eurocode-8, 현재 개정중인 미국 동부지역 NYC DOT 내진설계기준과 비교를 수행하였다. 유사한 조건의 지반 조건에 대하여 각 기준의 설계응답스펙트럼을 비교한 결과, 2-매개변수 지반분류, Eurocode-8, NYC DOT 내진설계기준은 일반적인 국내 지반특성인 단주기 영역의 증폭을 크게 고려하고 있는 반면, 내진설계기준 연구II는 장주기 영역의 증폭을 크게 평하는 것으로 나타났다. 추가적으로 경주시 $10km{\times}10km$ 지역내 50개 부지에 대한 지반응답해석 결과를 확보하고, 이를 내진설계기준연구II 및 2-매개변수 지반분류 방법에서 제안하는 지반 증폭계수와 2차원 공간적인 비교를 수행하였다. 단주기 및 장주기 증폭계수 모두에 대하여 내진설계기준연구II가 2-매개변수 지반분류 방법에 비하여 부지응답해석 결과와의 오차값이 월등히 큰 것으로 평가되어, 2-매개변수 지반분류 방법에서 제안하는 지반 증폭계수의 타당성을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.425-432
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• 2004

In this paper, the results of the numerical analysis for the minimum depth of soil cover have been compared with those of currently suggested codes. Based on this comparison, the minimum depth of soil cover for the structures with long spans was suggested. Results showed that the actual depth of the soil cover required against soil failure over a circular and low-profile arch structure does not vary significantly with the size of the span and for the circular structure, the minimum depth of the soil cover was about 1.5m, and for the low-profile arch structures, below about 1.6m. And the previously established code in which the minimum depth of soil cover is defined to linearly increase with the increase in the span (CHBDC, 2001) was very conservative. For the structure with the relieving slab, the maximum live load thrust was reduced by about 36 percent and the maximum moment about 81 percent. The numerical analysis gave more conservative estimation of the live-load thrusts than the other design methods.

• Earthquakes and Structures
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• 제16권6호
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• pp.743-755
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• 2019

In this paper, a new system of seismic isolation for buildings - called suspended columns - is introduced. In this method, the building columns are placed on the hinged cradle seats instead of direct connection to the foundation. In this system, each of the columns is put on a seat hung from its surrounding area by a number of cables, for which cavities are created inside the foundation around the columns. Inside these cavities, the tensile cables are hung. Because of the flexibility of the cables, the suspended seats vibrate during an earthquake and as a result, there is less acceleration in the structure than the foundation. A Matlab code was written to analyze and investigate the response of the system against the earthquake excitations. The findings showed that if this system is used in a building, it results in a significant reduction in the acceleration applied to the structure. A shear key system was used to control the structure for service and lateral weak loads. Moreover, the effect of vertical acceleration on the seismic behavior of the system was also investigated. Effect of the earthquake characteristic period on the system performance was studied and the optimum length of the suspension cables for a variety of the period ranges was suggested. In addition, measures have been taken for long-term functioning of the system and some practical feasibility features were also discussed. Finally, the advantages and limitations of the system were discussed and compared with the other common methods of seismic isolation.

• Steel and Composite Structures
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• 제51권3호
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• pp.337-349
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• 2024

The growing quantity of tires and building trash piling up in landfills poses a serious threat to the stability of the ecosystem. Researchers are exploring ways to reduce and use such byproducts of the construction industry in an effort to promote greener building practices. Thus, using recycled crumb rubber from scrap tires in concrete manufacturing is important for the industry's long-term viability. This study examines the proportion of waste rubber in fiber form, specifically at weight percentages of 5%, 10%, and 15%. Moreover, the study examines the shear behavior of reinforced concrete beams. A total of twelve RC beam specimens, each sized 100 mm by 150 mm by 1000 mm (w × d × L), were constructed and positioned to the test. Various mixtures were designed with different levels of scrap tire rubber content (0%, 5%, 10%, and 15%) and Stirrup Vol. Ratio (2.10, 2.80, and 3.53) in reinforced concrete beams. The findings indicate that the inclusion of scrap rubber in concrete leads to a decrease in both the mechanical characteristics and weight of the material. This is mostly attributed to the lower strength and stiffness of the rubberized concrete. Furthermore, estimations generated by a variety of design codes were examined alongside the obtained data. In order to make a comparison between the estimates provided by the different codes such as ACI 318-14, CEB-FIB and Iranian national building codes, a calculation was done to determine the ratio of the experimental shear strength to the anticipated shear strength for each code.