• 한국강구조학회 논문집
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• 제25권2호
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• pp.153-164
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• 2013

본 연구에서는 균일휨모멘트를 받는 일축대칭단면 HSB800 고강도강 플레이트거더의 횡비틂좌굴(LTB) 강도를 비선형해석으로 평가하였다. 압축플랜지 단면이 인장플랜지에 비해 작은 경우와 큰 경우에 대해 각각 세장, 비조밀 및 조밀 복부판을 갖는 단면들을 고려하였으며, 비지지길이는 비탄성 LTB 영역을 대상으로 하였다. Eurocode 3 및 AASHTO, AISC 기준들과의 비교를 위해 단일패널모델과 3-패널모델을 각각 고려하였으며, 모델의 타당성을 평가하기 위해 SM490 강재 거더에 대해 먼저 해석을 수행하고 각 기준과 비교하였다. 이후 동일한 방법으로 HSB800 강재거더에 대해 LTB 강도 평가 해석을 수행하였으며, 압축플랜지 단면이 인장플랜지에 비해 작고 비조밀플랜지-세장/비조밀복부판 단면들은 현재 기준의 휨강도에 도달하지 못하는 결과를 얻었다.

• 한국구조물진단유지관리공학회 논문집
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• 제25권6호
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• pp.131-142
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• 2021

노후 교각은 내진설계가 적용되지 않아 소성힌지구역에 겹침이음이 대다수 존재한다. 철근부식은 철근 단면적 감소 및 겹침이음부의 거동저하를 유발하여 교각의 내진성능을 저하시킨다. 본 연구에서는 이러한 노후교각의 특성에 따라 철근부식, 겹침이음, 내진설계 및 내진 보강 여부를 고려하여 실험체를 설계 및 제작하고 실험을 통해 그 영향을 조사하였다. 실험결과, 겹침이음 또는 철근부식은 변위연성도를 감소시킨다. 내진설계 상세 또는 강판 내진보강을 적용하면 충분한 변위연성도가 확보됨을 확인하였다. 모든 비내진실험체는 소성힌지구역 내의 횡철근 겹침이음부의 풀림으로 인해 주철근 좌굴과 심부콘크리트 압축파쇄가 발생하였다. 내진설계된 실험체는 철근부식에 의한 소성힌지구역 내 횡철근의 단면감소와 갈고리 풀림에 의해 주철근 좌굴 및 심부콘크리트 압축파쇄가 발생하였다.

• Steel and Composite Structures
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• 제50권1호
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• pp.1-13
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• 2024

The objective of this research is to study experimentally and numerically the behavior of steel beam columns with openings. Although the presence of openings in the beam columns is inevitable, finding ways to maintain strength is crucial. The studied parameters are opening shape, the ratio between opening height to specimen height, the percentage of opening location from support to beam column length, and web slenderness. Experimental tests are conducted including twelve specimens to study the effect of these parameters and record failure load, load deflection curve, and stress strain curve. Two failure modes are observed: local and flexural buckling. Interaction curves plotted from finite element model analysis are also used to expand the parametric study. Changing the location of the opening can decrease failure load by up to 7% and 60% in both normal and moment ratios respectively. Increasing the opening dimension can lead to a drop in the axial ratio by up to 29% and in the moment ratio by up to 74%. The weakest beam column behavior is noticed in specimens with rectangular openings which results from uneven and concentrated stresses around the opening. The main results of this research illustrate that the best location for opening is at 40% - 50% from beam column support. Also, it is advisable to use circular openings instead of rectangular openings in specimens having slender webs because moment ratios are raised by 85% accompanied by a rise in normal ratios by 9%.

• 한국강구조학회 논문집
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• 제24권5호
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• pp.559-569
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• 2012

기존 임시교량은 대부분 거더의 횡-비틀림좌굴을 방지하고 시공의 효율성을 확보하기 위해 가로보를 설치하고 있다. 이 가로보는 볼트로 연결되며, 중력방향 하중에 대한 저항성능이 매우 작은 것으로 평가되고 있다. 그러나 최근 일체화된 가로보를 사용함으로써 가로보를 하중저항요소로 이용한 임시교량이 최근 개발된 바 있다. 이 연구는 새롭게 개발된 임시교량에 대한 구조적 거동 및 하중전달능력을 실험 및 구조해석 등을 통해 조사, 분석하였다. 일체로 연속된 가로보를 이용한 임시교량은 가로보의 휨강성을 통해 하중을 인접거더로 분산하여 거더에 발생하는 최대휨응력을 감소시키고, 거더의 휨강성을 증대시키는 것으로 확인되어 장경간 임시교량에서도 유리할 것으로 판단된다.

• Steel and Composite Structures
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• 제16권6호
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• pp.559-576
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• 2014

A new mathematical model and its finite element formulation for the non-linear stress-strain analysis of a planar beam strengthened with plates bolted or adhesively bonded to its lateral sides is presented. The connection between the layers is considered to be flexible in both the longitudinal and the transversal direction. The following assumptions are also adopted in the model: for each layer (i.e., the beam and the side plates) the geometrically linear and materially non-linear Bernoulli's beam theory is assumed, all of the layers are made of different homogeneous non-linear materials, the debonding of the beam from the side-plates due to, for example, a local buckling of the side plate, is prevented. The suitability of the theory is verified by the comparison of the present numerical results with experimental and numerical results from literature. The mechanical response arising from the theoretical model and its numerical formulation has been found realistic and the numerical model has been proven to be reliable and computationally effective. Finally, the present formulation is employed in the analysis of the effects of two different realizations of strengthening of a characteristic simply supported flexural beam (plates on the sides of the beam versus the tension-face plates). The analysis reveals that side plates efficiently enhance the bearing capacity of the flexural beam and can, in some cases, outperform the tensile-face plates in a lower loss of ductility, especially, if the connection between the beam and the side plates is sufficiently stiff.

• 한국강구조학회 논문집
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• 제8권4호통권29호
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• pp.85-94
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• 1996

This paper investigated structural behaviors of joint of concrete filled steel tube column and P.C reinforced concrete beam through a series of hysteretic behavior experiment. The results are summarised as follows: (1) The joint stiffness of concrete filled square steel tube column and P.C reinforecd beam was higher than that of concrete filled circular steel tube column and P.C reinforecd beam, and it was decreased as the increase of the number of hysteretic cycle. (2) The aspects of the hysteretic behavior in the joint was stable as the increase of the number of hysteretic cycle, and rotation resisting capacity of joint of concrete filled square steel tube column and P.C reinforced concrete beam was higher than those of the concrete filled circular steel tube column and P.C reinforced concrete beam. (3) Some restriction must be put upon the ratio of axial force in this joint model because the load carrying capacity was decreased by flexural and flexural-torsional buckling in case of the ratio of axial force 0.6. (4) The emprical formula to predict the ultimate capacity of joint model to superimpose shearing strength of steel web(H section) and bending strength of reinforced concrete beam was expected.

• 한국강구조학회 논문집
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• 제20권5호
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• pp.665-673
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• 2008

최근 장대 건설 구조물에 사용이 증가되고 있는 합성형 구조물에서 나타나고 있는 예기치 못한 일부 균열 현상의 구조적 원인을 분석하기 위하여, 강재복부의 수직보강재, stud 및 dowel bar의 유무, 전단철근의 간격과 콘크리트 강도 등을 실험변수로 하여 4점 재하 휨시험을 통해 강재와 철근콘크리트간의 구조적 합성거동 효과를 분석 하였다. 실험결과, 수직보강재는 강재의 국부좌굴 방지와 파괴시 강재와 콘크리트의 부착파괴를 방지하여 구조적 합성거동에 따른 단면내력(파괴하중)의 증진에 효과적인 것으로 나타났으나, 추가적으로 설치한 stud 및 dowel bar, 콘크리트의 강도와 전단철근량 등은 합성보의 휨거동에 큰 영향을 주지 않는 것으로 나타났다.

• Steel and Composite Structures
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• 제37권3호
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• pp.371-390
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• 2020

One of the most common strategies for retrofitting as-built reinforced concrete (RC) columns is to enlarge the existing section through the application of a new concrete layer reinforced by both steel transverse and longitudinal reinforcements. The present study was dedicated to developing a comprehensive model to predict the seismic behavior of as-built RC jacketed columns. For this purpose, a new sectional model was developed to perform moment-curvature analysis coupled by the plastic hinge method. In this analysis-oriented model, new methodologies were suggested to address the impacts of axial, flexural and shear mechanisms, variable confining pressure, eccentric loading, longitudinal bar buckling, and varying axial load. To consider the effective interaction between core and jacket, the monolithic factor approach was adopted to extent the response of the monolithic columns to that of a respective RC jacket strengthened column. Next, parametric studies were implemented to examine the effectiveness of the main parameters of the RC jacket strategy in retrofitting as-built RC columns. Ultimately, the reliability of the developed analytical model was validated against a series of experimental results of as-built and retrofitted RC columns.

• 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.

• Earthquakes and Structures
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• 제7권5호
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• pp.667-689
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• 2014

Structural walls (also known as shear walls) are one of the common lateral load resisting elements in reinforced concrete (RC) buildings in seismic regions. The performance of RC structural walls in recent earthquakes has exposed some problems with the existing design of RC structural walls. The main issues lie around the buckling of bars, out-of plane deformation of the wall (especially the zone deteriorated in compression), reinforcement getting snapped beneath a solitary thin crack etc. This study compares performance of a typical wall designed by different standards. For this purpose, a case study RC shear wall is taken from the Hotel Grand Chancellor in Christchurch which was designed according to the 1982 version of the New Zealand concrete structures standard (NZS3101:1982). The wall is redesigned in this study to comply with the detailing requirements of three standards; ACI-318-11, NZS3101:2006 and Eurocode 8 in such a way that they provide the same flexural and shear capacity. Based on section analysis and pushover analysis, nonlinear responses of the walls are compared in terms of their lateral load capacity and curvature as well as displacement ductilities, and the effect of the code limitations on nonlinear responses of the different walls are evaluated. A parametric study is also carried out to further investigate the effect of confinement length and axial load ratio on the lateral response of shear walls.