• 한국방재학회 논문집
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• 제3권1호
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• pp.123-131
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• 2003

파형강관을 삽입하여 보강된 중공원형단면의 역학적 거동을 연구하기 위하여 직경 50cm, 길이 340cm의 시험체를 제작하였고, 3점 휨시험을 수행하였다. 하중재하는 파괴 또는 최대한변형이 발생할 때까지 느리게 증가시켰다. 시험하는 동안에 시험체 중앙의 휨방향 변위와 인장측과 압축측의 종방향 변위를 측정하였다. 측정데이타를 분석한 결과를 파형강관이 삽입되지 않은 등가단면에 대한 해석결과와 비교하였다. 비교결과, 중공 철근콘크리트 부재의 휨강성과 연성이 파형강관을 내부에 삽입함으로써 크게 향상시킬 수 있는 것으로 나타났다.

• Earthquakes and Structures
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• 제15권4호
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• pp.419-429
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• 2018

The seismic vulnerability analysis of multi-span bridges can be based on the response of the piers, provided that deck, bearings and foundations remain elastic. The lateral response of an RC bridge pier can be affected by different mechanisms (i.e., flexure, shear, lap-splice or buckling of the longitudinal reinforcement bars, second order effects). In the literature, simplified formulations are available for mechanisms different from the flexure. On the other hand, the flexural response is usually calculated with a numerically-based Moment-Curvature diagram of the base section and equivalent plastic hinge length. The goal of this paper is to propose a simplified analytical solution to obtain the Moment-Curvature relationship for hollow circular RC sections. This based on calibrated polynomials, fitted against a database comprising 720 numerical Moment-Curvature analyses. The section capacity curve is defined through the position of 6 characteristic points and they are based on four input parameters: void ratio of the hollow section, axial force ratio, longitudinal reinforcement ratio, transversal reinforcement ratio. A case study RC bridge pier is assessed with the proposed solution and the results are compared to a refined numerical FEM analysis, showing good match.

• Steel and Composite Structures
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• 제46권3호
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• pp.353-366
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• 2023

This paper presents a finite-element analysis (FEA) of aluminum alloy rectangular hollow sections (RHSs) and square hollow sections (SHSs) with circular through-openings under three-point and four-point bending. First, a finite-element model (FEM) was developed and validated against the corresponding test results available in the literature. Next, using the validated FE models, a parametric study comprising 180 FE models was conducted. The cross-section width-to-thickness ratio (b/t) ranged from 2 to 5, the hole size ratio (d/h) ranged from 0.2 to 0.8 and the quantity of holes (n) ranged from 2 to 6, respectively. Third, results obtained from laboratory test and FEA were compared with current design strengths calculated in accordance with the North American Specifications (NAS), the modified direct strength method (DSM) and the modified Continuous strength method (CSM). The comparison shows that the modified CSM are conservative by 15% on average for aluminum alloy RHSs and SHSs with circular through-openings subject to bending. Finally, a new design equation is proposed based on the modified CSM after being validated with results obtained from laboratory test and FEA. The proposed design equation can provide accurate predictions of flexural capacities for aluminum alloy RHSs and SHSs with circular through-openings.

• Structural Engineering and Mechanics
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• 제81권2호
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• pp.231-242
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• 2022

Numerical solutions for the linear buckling behavior of thin-walled circular hollow section members (CHS) with and without longitudinal stiffeners are presented using the semi-analytical finite strip method (SAFSM) which is developed based on Marguerre's shallow shell theory and Kirchhoff's assumption. The formulation of 3-nodal line finite strip is presented. The CHS members subjected to uniform axial compression, uniform bending, and combination of compression and bending. The buckling behavior of CHS is investigated through buckling curves which relate buckling stresses to lengths of the member. Effects of longitudinal stiffeners are studied with the change of its dimensions, position, and number.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.183-188
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• 2002

In locations where the cost or concrete is relatively high, or in situations where the weight or concrete members is to be kept to a minimum, it may be economical to use hollow reinforced concrete vertical members. Hollow reinforced concrete columns with low axial load, moderate longitudinal steel percentage, and a reasonably thick wall were found to perform in a ductile manner at the flexural strength, similar to solid columns. However, hollow reinforced concrete columns with high axial load, high longitudinal steel percentage, and a thin wall were found to behave in a brittle manner at the flexural strength, since the neutral axis is forced to occur away from the inside face of the tube towards the section centroid and, as a result, crushing of concrete occurs near the unconfined inside face of the section. If, however, a steel tube is placed near the inside face of a circular hollow column, the column can be expected not to fail in a brittle manner by disintegration of the concrete in the compression zone. Design recommendation and example by moment-curvature analysis program for curvature ductility are presented. Theoretical moment-curvature analysis for reinforced concrete columns, indicating the available flexural strength and ductility, can be conducted providing the stress-strain relation for the concrete and steel are known. In this paper, a unified stress-stain model for confined concrete by Mander is developed for members with circular sections.

• Steel and Composite Structures
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• 제4권3호
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• pp.169-188
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• 2004

A mechanics model is developed in this paper for concrete-filled steel CHS (circular hollow section) beam-columns. A unified theory is described where a confinement factor (${\xi}$) is introduced to describe the composite action between the steel tube and the filled concrete. The predicted load versus deformation relationship is in good agreement with test results. The theoretical model was used to investigate the influence of important parameters that determine the ultimate strength of concrete-filled steel CHS beam-columns. The parametric and experimental studies provide information for the development of formulas for the calculation of the ultimate strength of the composite beam-columns. Comparisons are made with predicted beam-columns strengths using the existing codes, such as LRFD-AISC-1999, AIJ-1997, BS5400-1979 and EC4-1994.

• 한국강구조학회 논문집
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• 제24권1호
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• pp.35-46
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• 2012

초고층 빌딩의 수요가 증가함에 따라 고강도 강관의 수요 또한 함께 증가하고 있다. 이에 고강도 고인성의 600MPa급 강관의 접합부 내력 연구가 필요하게 되었다. 또한 현행국내기준에는 강관의 경우 항복응력 360MPa 이하에 설계식을 적용하도록 되어 있다. 즉, 고강도강재를 이용한 600MPa 강관의 경우 현행기준을 적용할 수 없으므로 600MPa급 고강도 강관의 거셋플레이트 접합부의 내력실험 및 유한요소해석을 통하여 기존 설계식의 적용가능성을 조사하고 접합부의 거동을 연구하고자 한다. 특히, 본 논문에서는 원형강관에 길이 방향으로 거셋플레이트가 접합된 접합부에 횡력(수평력)이 작용하였을 때의 거동을 다루었다. 유한요소해석 및 실험결과를 설계식과 비교해보면, 고강도 강재에서는 기존의 설계식들이 56~79%로 과소평가되었다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 춘계학술발표대회 개요집
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• pp.178-181
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• 2002

This is a partial report of the investigation of fatigue behaviour of hollow section T-joints with circular brace members and rectangular chord members (CRHS). Hot spot stresses and the stress concentration factors (SCFs) were determined experimentally. Fatigue testing was carried out under constant amplitude loading in air. The experimental SCF values for CRHS joints were found to be below those of circular-to-circular (CCHS) and rectangular-to-rectangular (RRHS) hollow section joints. The fatigue strength referred to experimental hot spot stress was in reasonably good agreement with current fatigue design codes for tubular joints.

• Steel and Composite Structures
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• 제19권4호
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• pp.877-895
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• 2015

Connections to circular hollow steel sections (CHS) are considered one of the most complex and time consuming connections in steel construction. Such connections are usually composed of gusset plates welded to the outside of the steel tube or penetrating the steel tube. Design guides, accounting for the effect of connection configuration on the strength of the connection, are not present. This study aims to investigate, through experimental testing and a parametric study, the influence of connection configuration on the strength of one sided branch plate-to-CHS members. A notable effect was observed on the behavior of the connections due to its detailing changes with respect to capacity, failure mode, ductility, and stress distribution. A parametric study is performed using the calibrated analytical model to include a wider range of parameters. The study involves 26 numerical analyses of finite element models including parameters of the diameter-to-thickness (D/t) ratio, length of gusset plate, and connection configuration. Accordingly, a modification to the formulas provided by the current design recommendations was suggested to include connection configuration effects for the one sided branch plate-to-CHS members.

• 한국방재학회 논문집
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• 제3권2호
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• pp.127-137
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• 2003

구조적으로 콘크리트의 자중이 문제 시 되는 곳이나, 콘크리트의 재료비가 높은 경우, 수직부재로 중공 콘크리트의 사용이 경제적일 수 있다. 콘크리트의 구속효과를 발휘를 위해 외측 면을 띠철근으로 보강하고 내측 면에 강관을 삽입하여 보강한 원형 중공 콘크리트 기둥의 연성 거동에 관해 연구하였고, 압축강도와 콘크리트의 극한변형율을 증가시키는 구속력의 효과를 나타낸 Mander의 응력-변형률 관계를 사용하여, 모멘트-곡률 관계 해석을 유도하였다. 극한변형율에 영향을 주는 인자인 구속력을 발휘하는 철근의 철근비와 항복응력, 구속 콘크리트의 압축강도 등을 극한변형율과 횡철근비의 관계를 통하여, 강관 삽입된 원형 중공 철근콘크리트 기둥의 구속응력과 횡철근비의 관계식을 제안하였다. 제안된 횡철근비 관계식은 실험을 통하여 검증하였다.