• Wind and Structures
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• v.2 no.1
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• pp.1-23
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• 1999

Wind effects are critical considerations in the design of topside structures, overall structural systems, or both, depending on the water depth and type of offshore platform. The reliable design of these facilities for oil fields in regions of hostile environment can only be assured through better understanding of the environmental load effects and enhanced response prediction capabilities. This paper summarizes the analysis and performance of offshore platforms under extreme wind loads, including the quantification of wind load effects with focus on wind field characteristics, steady and unsteady loads, gust loading factors, application of wind tunnel tests, and the provisions of the American Petroleum Institute Recommended Practice 2A - Working Stress Design (API RP 2A-WSD) for the construction of offshore structures under the action of wind. A survey of the performance of platforms and satellite structures is provided, and failure mechanisms concerning different damage scenarios during Hurricane Andrew are examined. Guidelines and provisions for improving analysis and design of structures are addressed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.247-248
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• 2022

3D printer-based self-healing capsules have been proposed to heal cracks by enabling various structural designs, repeatable fabrication, and strength analysis of the capsules. The Fusion Deposition Modeling (FDM) method was used to design, analyze, and produce new self-healing capsules that are widely used at low cost. However, PLA extruded from FDM has low interlayer adhesion energy, and thus strength varies depending on the angle of load applied to the laminated layer and the concrete structure, thereby degrading the performance of the self-healing capsule. Therefore, in this paper, the structure of the capsule manufactured by the FDM PLA method has isotropic strength was designed. In addition, the fracture strength in the x, y, and z directions of the load applied through the compression test was analyzed. As a result, it was confirmed that the newly proposed capsule design has an isotropic fracture strength of 1400% in all directions compared to the existing spherical thin-film capsule.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.599-606
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• 2014

Since progressive collapse of tall buildings can cause enormous damage, it should be considered during the design phase of tall buildings. The progressive collapse analysis of tall buildings using finite element methods is almost impossible due to the vast amount of computing time. In this paper, applied element method was evaluated as an alternative to the finite element method. Reduced DOFs modeling technique was proposed to enable the progressive collapse analysis of tall buildings. The reduced DOFs model include only the part which is subjected to direct damage from blast load and the structural properties such as mass, transferred load and stiffness of excluded parts are accumulated into the top story of the reduced DOFs model. The proposed modeling technique was applied to the progressive collapse analysis of 20-story RC building using three collapse scenarios. The reduced DOFs model showed similar collapse behavior to the whole model while the computing time was reduced by 30%. The proposed modeling technique can be utilized in the progressive collapse analysis of tall buildings due to abnormal loads.

• Wind and Structures
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• v.6 no.1
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• pp.71-90
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• 2003

In recent years, high-strength, light-weight materials have been widely used in the construction of high-rise buildings. Such structures generally have flexible, low-damping characteristics. Consequently, wind-induced oscillation greatly affects the structural safety and the comfort of the building's occupants. In this research, wind tunnel experiments were carried out to study the wind-induced vibration of a building with a tuned liquid column damper (TLCD). Then, a model for predicting the aerodynamic response in the across-wind direction was generated. Finally, a computing procedure was developed for the analytical modeling of the structural oscillation in a building with a TLCD under the wind load. The model agrees substantially with the experimental results. Therefore, it may be used to accurately calculate the structural response. Results from this investigation show that the TLCD is more advantageous for reducing the across-wind vibration than the along-wind oscillation. When the across-wind aerodynamic effects are considered, the TLCD more effectively controls the aerodynamic response. Moreover, it is also more useful in suppressing the acceleration than the displacement in biaxial directions. As s result, TLCDs are effective devices for reducing the wind-induced vibration in buildings. Parametric studies have also been conducted to evaluate the effectiveness of the TLCD in suppressing the structural oscillation. This study may help engineers to more correctly predict the aerodynamic response of high-rise buildings as well as select the most appropriate TLCDs for reducing the structural vibration under the wind load. It may also improve the understanding of wind-structure interactions and wind resistant designs for high-rise buildings.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.145-152
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• 2015

In the study, the effects of damping devices on damping ratio increase and wind-load reduction were investigated based on the computational platform, which is one of the parametric modeling methods. The computational platform helps the designers or engineers to evaluate the efficacy of the numerous alternative structural systems for irregular Super-Tall building, which is crucial in determining the capacity and the number of the supplemental damping devices for adding the required damping ratios to the building. The inherent damping ratio was estimated based on the related domestic and foreign researches conducted by using real wind-load records. Two types of damping devices were considered: One is inter-story installation type passive control devices and the other is mass type active control devices. The supplemental damping ratio due to the damping devices was calculated by means of equivalent static analysis using an equation suggested by FEMA. The optimal design of the damping devices was conducted by using the computational platform. The structural element quantity reduction effect resulting from the installation of the damping devices could be simply assessed by proposing a wind-load reduction factor, and the effectiveness of the proposed method was verified by a numerical example of a 455m high-rise building. The comparison between roof displacement and the story shear forces by the nonlinear time history analysis and the proposed method indicated that the proposed method could simply but approximately estimate the effects of the supplemental damping devices on the roof displacement and the member force reduction.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.509-512
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• 2009

본 논문에서는 KBC(Korean Building Code)와 IBC(International Building Code)의 풍하중 기준의 비교 분석을 통하여, BIM 프로세스 기반의 구조해석 및 설계 프로그램에서 풍하중 산정 시 국내 건축구조설계기준(KBC)을 적용하기 위한 방안을 제시하는 것을 목적으로 한다. 현재 BIM 기반 구조해석 및 설계 프로그램 중에는 한국구조설계기준(KBC)에 부합하는 풍하중 산정이 가능한 프로그램이 존재하지 않는다. 구조설계 기준에서 특히 풍하중 산정 방법은 기준 및 지역에 따른 산정 방법에 차이가 있기 때문에, 구조설계의 안전성을 높이고 한국 실정에 맞는 건축물의 설계를 위해서 KBC 기준의 적용이 필요하다. 본 연구에서는 IBC와 KBC 내의 풍하중 산정 방법의 차이점을 비교 분석하고, 실제 사례연구를 통하여 풍하중 산정의 차이를 확인한다. KBC 기준 풍하중 산정 결과를 구조해석 및 설계 프로그램에 적용하기 위한 방법으로써 외부 프로그램을 활용하며 외부 프로그램에서 산정한 풍하중을 다시 구조해석 및 설계 프로그램 상에 입력하여 구조해석을 수행함으로써 KBC 기준 풍하중의 적용을 통한 한국형 BIM 구조해석 및 설계의 방안을 제시한다.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.222-227
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• 2008

This study is focused on an integrated numerical modeling enabling one to investigate the dynamic behavior and failure of 2-D textile composite and 3-D orthogonal woven composite structures weakened by micro-cracks and subjected to an impact load. The integrated numerical modeling is based on: I) determination of governing equations via a three-level hierarchy: micro-mechanical unit cell analysis, layer-wise analysis accounting for transverse strains and stresses, and structural analysis based on anisotropic plate layers, II) development of an efficient computational approach enabling one to perform transient response analyses of 2-D plain woven and 3-D orthogonal woven composite structures featuring the matrix cracking and exposed to time-dependent loads, III) determination of the structural characteristics of the textile-layered composites and their degraded features under various geometrical yarn shapes, and finally, IV) assessment of the implications of stiffness degradation on dynamic response to impact loads.

• Computers and Concrete
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• v.16 no.5
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• pp.759-774
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• 2015

This study simulates the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) beams reinforced with steel and glass fiber-reinforced polymer (GFRP) rebars. For this, micromechanics-based modeling was first carried out on the basis of single fiber pullout models considering inclination angle. Two different tension-softening curves (TSCs) with the assumptions of 2-dimensional (2-D) and 3-dimensional (3-D) random fiber orientations were obtained from the micromechanics-based modeling, and linear elastic compressive and tensile models before the occurrence of cracks were obtained from the mechanical tests and rule of mixture. Finite element analysis incorporating smeared crack model was used due to the multiple cracking behaviors of structural UHPFRC beams, and the characteristic length of two times the element width (or two times the average crack spacing at the peak load) was suggested as a result of parametric study. Analytical results showed that the assumption of 2-D random fiber orientation is appropriate to a non-reinforced UHPFRC beam, whereas the assumption of 3-D random fiber orientation is suitable for UHPFRC beams reinforced with steel and GFRP rebars due to disorder of fiber alignment from the internal reinforcements. The micromechanics-based finite element analysis also well predicted the serviceability deflections of UHPFRC beams with GFRP rebars and hybrid reinforcements.

• Smart Structures and Systems
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• v.13 no.6
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• pp.1015-1039
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• 2014

The widening project on Freeway No.1 in Taiwan has a total length of roughly 14 kilometers, and includes three special bridges, namely a 216 m long-span bridge crossing the original freeway, an F-bent double decked bridge in a co-constructed section, and a steel and prestressed concrete composite bridge. This study employed in-situ monitoring in conjunction with numerical modeling to establish a real-time monitoring system for the three bridges. In order to determine the initial static and dynamic behavior of the real bridges, forced vibration experiments, in-situ static load experiments, and dynamic load experiments were first carried out on the newly-constructed bridges before they went into use. Structural models of the bridges were then established using the finite element method, and in-situ vehicle load weight, arrangement, and speed were taken into consideration when performing comparisons employing data obtained from experimental measurements. The results showed consistency between the analytical simulations and experimental data. After determining a bridge's initial state, the proposed in-situ monitoring system, which is employed in conjunction with the established finite element model, can be utilized to assess the safety of a bridge's members, providing useful reference information to bridge management agencies.

• Biomaterials and Biomechanics in Bioengineering
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• v.4 no.1
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• pp.9-20
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• 2019

Living beings are formed of advanced biological and mechanical systems which exist for millions of years. It is known that various animals and insects right from small ants to huge whales have different weight carrying capacities, which is generally expressed as a ratio of their own bodyweights i.e., Strength to Bodyweight Ratio (SBR). The puzzle is that when a rhinoceros beetle (scientific name: Dynastinae) can carry 850 times its own bodyweight, why a man cannot accomplish the same feat. There are intrinsic biological and mechanical reasons related to their capacities, as per biomechanics. Yet, there are underlining principles of engineering and structural mechanics which tend to solve this puzzle. The paper attempts to give a plausible answer for this puzzle through structural mechanics and experimental modeling techniques. It is based on the fact that smaller an animal or creature, it has larger value of weight lifting by self-weight ratio. The simple example of steel prism model discussed in this paper, show that smaller the physical model size, larger is its SBR value. To normalize this, the basic length of the model need to be considered and when multiplied with SBR, a constant is arrived. Hence, the aim of the research presented is to derive this constant on a pan-living being spectrum through size/scaling effect.