• Steel and Composite Structures
• /
• 제29권4호
• /
• pp.509-526
• /
• 2018

The direct strength method adopted by the AISI Standard and AS/NZS 4600 is an advanced design method meant to substitute the effective width method for the design of cold-formed steel structural members accounting for local instability of thin plate elements. It was proven that the design strength formula for the direct strength method could predict the ultimate strength of medium strength steel welded section compressive and flexural members with local buckling reasonably. This paper focuses on the modification of the direct strength formula for the application to high strength and high performance steel welded section columns which have the nominal yield stress higher than 460 MPa and undergo local buckling, overall buckling or their interaction. The resistance of high strength steel welded H and Box section columns calculated by the proposed direct strength formulae were validated by comparison with various compression test results, FE results, and predictions by existing specifications.

• Structural Engineering and Mechanics
• /
• 제20권6호
• /
• pp.727-745
• /
• 2005

The present study is an experimental investigation into the behaviour of high strength concrete square short columns subjected to biaxial bending moments and strengthened by GFRP laminates. The main objectives of the study are: to evaluate the improvement in the structural performance of HSC short square columns subjected to small biaxial eccentricity when strengthened by externally applied FRP laminates, and to investigate the optimum arrangement and amount of FRP laminates to achieve potential enhancement in structural performance especially ductility. The parameters considered in this study are: number of FRP layers and arrangement of wraps. The load eccentricity is kept corresponding to e/t = 0.125 in two perpendicular directions to the columns principal axes, and the wraps are applied in single or double layers (partial or full wrapping). In the present work, test results of five full scale concrete columns are presented and discussed. The study has shown that FRP wraps can be used successfully to enhance the ductility of HSC columns subjected to biaxial bending by 300%.

• Structural Engineering and Mechanics
• /
• 제65권3호
• /
• pp.223-231
• /
• 2018

A numerical investigation of the impact of steel ductility on the strength and ductility of two-way corner and edge-supported concrete slabs containing low ductility welded wire fabric is presented. A finite element model was developed for the investigation and the results of a series of concurrent laboratory experiments were used to validate the numerical solution. A parametric investigation was conducted using the numerical model to investigate the various factors that influence the structural behavior at the strength limit state. Different values of steel uniform elongation and ultimate to yield strength ratios were considered. The results are presented and evaluated, with emphasis on the strength, ductility, and failure mode of the slabs. It was found that the ductility of the flexural reinforcement has a significant impact on the ultimate load behavior of two-way corner-supported slabs, particularly when the reinforcement was in the form of cold drawn welded wire fabric. However, the impact of the low ductility WWF has showed to be less prominent in structural slabs with higher levels of structural indeterminacy. The load-deflection curves of corner-supported slabs containing low ductility WWF are brittle, and the slabs have little ability to undergo plastic deformation at peak load.

• 한국화재소방학회논문지
• /
• 제27권3호
• /
• pp.72-79
• /
• 2013

최근 건축물은 재료의 고강도화 및 단면형상 최적화를 바탕으로 초고층화, 장대화 및 복합화 추세로 발달하고 있으나, 화재 위험성에 의한 구조적 거동에 관한 연구는 매우 미진한 실정이다. 특히 고강도 구조용 강재로 구성된 강구조 건축물의 구조부재에 대한 화재 노출 시 거동평가를 위한 기초적인 자료조차 거의 없는 실정이다. 따라서 본 연구에서는 고층 강구조 건축물에 활용되고 있는 고강도 구조용 강재의 고온 시 구조적 내력 평가를 위한 기계적 특성과 열적 특성 자료 도출을 목적으로 항복강도, 탄성계수 그리고 열전도율 등을 측정하고, 이를 일반 구조용 강재의 특성과 비교분석을 통하여 상대적 안전성을 평가한다.

• 풍력에너지저널
• /
• 제14권4호
• /
• pp.5-12
• /
• 2023

In this study, a structural and fatigue strength evaluation of the Fairlead Chain Stopper (FCS) was performed as a part of the development of a disconnectable mooring system to be applied to 10MW floating offshore wind power generation systems. To estimate the load acting on the FCS, a 10 MW semi-submersible floater was designed using the 10 MW wind turbine developed by Technical University of Denmark(DTU). The minimum breaking load (MBL) of the grade R5 and 147mm mooring chain was applied for the FCS strength analysis. The fatigue load was obtained from the coupled analysis results conducted by a collaborating research institute. The structural and fatigue safety of FCS were evaluated in accordance with DNV codes. From the evaluation results, it was confirmed that the FCS satisfies the structural and fatigue safety requirements.

• 토지주택연구
• /
• 제15권3호
• /
• pp.153-164
• /
• 2024

이 연구는 임팩트해머 실험을 통해 얻은 FRF 데이터를 분석하여 유효질량을 설정하고 부재의 물성치를 추정하는 방법을 제시하였다. 또한 콘크리트 구조물에 대한 콘크리트강도를 추정하는 방법을 제안하였다. 이 연구에서 측정된 FRF 데이터로부터 파라미터를 보정하고 유효질량을 추출하여 강성 및 감쇠치를 실증적으로 추정하였다. 연속계를 단자유도계로 모델링 시에 유효질량은 부재의 유연성 혹은 강성의 영향과 세장정도 및 경계조건에 영향을 받는다. 이 연구에서 실시한 실험에서 유연하고 휨이 지배하는 양단고정보와 캔틸레버보의 참여계수는 각각 0.330과 0.261으로 나타났으며, 유사한 부재에 대한 기준데이터로 적용할 수 있다. 콘크리트부재는 강성이 크며, 낮은 세장비와 기둥 상부에서 작용하는 자중을 고려하여 참여계수를 1.0으로 보정하여 콘크리트강도를 추정하였으며, 실제 콘크리트강도와 근사한 값을 나타내어 실무에 적용할 수 있는 기법으로 판단된다.

• 한국안전학회지
• /
• 제31권3호
• /
• pp.89-95
• /
• 2016

Lately, the high-strength concrete is often used to increase the lifespan of bridges. The benefits of using the high-strength concrete are that it increases the durability and strength. On the contrary, it reduces the cross-section of the bridges. This study conducted structural performance tests of the bridge deck slabs applying high-strength concrete. As result of the tests, specimens of bridge deck slabs were destroyed through punching shear. Moreover, the tests exposed that the high-strength concrete bridge deck slabs satisfy the flexural strength and the punching shear strength at ultimate limit state(ULS). Also, limiting deflection of the concrete fulfilled serviceability limit state(SLS) criteria. These results indicated that the bridge deck slabs designed by high-strength concrete were enough to secure the safety factor despite of its low thickness.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2003년도 추계학술발표대회 논문집
• /
• pp.119-122
• /
• 2003

This report describes the procedure of detailed design and structural test for the composite flexure which is a part of the hingeless hub system. First, stacking sequence design for composite flexure was done, and structural analysis by using NASTRAN was made to verify structural stability and safety. Using FPS installed at KIMM, composite flexure was laid up and cured using a autoclave. Before rotor ground test, the basic structural tests such as a bench test, tensile strength test and shear strength test, for flexure, were accomplished. Through replacing existing metal hub part with new fabricated composite flexure, improvement of aeroelastic stability and weight reduction were achieved. This result will be applied to composite rotor system design fur helicopter.

• 전산구조공학
• /
• 제17권3호
• /
• pp.57-64
• /
• 2004

• Computers and Concrete
• /
• 제14권3호
• /
• pp.233-245
• /
• 2014

In this paper, a rule based Mamdani type fuzzy logic model for prediction of slippage at maximum tensile strength and slippage at rupture of structural lightweight concretes were discussed. In the model steel rebar diameters and development lengths were used as inputs. The FL model and experimental results, the coefficient of determination R2, the Root Mean Square Error were used as evaluation criteria for comparison. It was concluded that FL was practical method for predicting slippage at maximum tensile strength and slippage at rupture of structural lightweight concretes.