• 콘크리트학회지
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• 제10권6호
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• pp.233-240
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• 1998

구조역학에 기초한 보의 종방향 휨모멘트변화율과 전단력의 관계와 본 연구자가 이전에 발표한 아취모델을 이용하여 복부보강이 안된 철근콘크리트 보의 전단강도 예측식을 제안하였다. 이론적으로 유도된 본 연구의 전단강도식은 주로 실험결과에 기초한 ACI 318 전단강도식과 비슷한 형태이다. 본 연구에서 제안한 식은 콘크리트 압축강도, 주인장철근비 및 전단지간대 유효높이의 비가 주변수이며, 보작용과 아취작용의 조합에 의한 철근콘크리트 보의 전단저항메카니즘이 합리적으로 반영되어 있다. 본 연구에서 제안한 전단강도식은 ACI 318 전단강도식 및 Zsutty의 전단강도식과 함께 기존의 실험결과와 비교되었다.

• Steel and Composite Structures
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• 제36권3호
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• pp.261-272
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• 2020

A novel precast concrete-encased steel composite beam, which can be abbreviated as PCES beam, is introduced in this paper. In order to investigate the shear behavior of this PCES beam, a test of eight full-scale PCES beam specimens was carried out, in which the specimens were subjected to positive bending moment or negative bending moment, respectively. The factors which affected the shear behavior, such as the shear span-to-depth aspect ratio and the existence of concrete flange, were taken into account. During the test, the load-deflection curves of the test specimens were recorded, while the crack propagation patterns together with the failure patterns were observed as well. From the test results, it could be concluded that the tested PCES beams could all exhibit ductile shear behavior, and the innovative shear connectors between the precast concrete and cast-in-place concrete, namely the precast concrete transverse diaphragms, were verified to be effective. Then, based on the shear deformation compatibility, a theoretical model for predicting the shear capacity of the proposed PCES beams was put forward and verified to be valid with the good agreement of the shear capacities calculated using the proposed method and those from the experiments. Finally, in order to facilitate the preliminary design in practical applications, a simplified calculation method for predicting the shear capacity of the proposed PCES beams was also put forward and validated using available test results.

• 콘크리트학회논문집
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• 제14권6호
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• pp.910-921
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• 2002

철근콘크리트 보의 전단거동을 예측하기 위하여 휨모멘트가 고려된 변환각 트러스 모델(TATM)을 제안하였다. 제안된 TATM으로 구한 전단응력-전단변형률 관계는 본 연구에서 수행된 실험결과와 잘 일치하였다. 또한, TATM으로 구한 전단강도는 다양한 전단스팬비와 지점형태 및 단면형태를 가지는 총 170개 실험결과와 비교되었다. TATM에 의한 해석결과는 평균 0.96, 변동계수 11.9 %로서 기존의 트러스 모델에 의한 해석결과보다 실험결과를 더 잘 예측하였으며, 해석결과에 대한 실험결과의 비는 a/d와 η에 관계없이 거의 일정하였다.

• Steel and Composite Structures
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• 제49권6호
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• pp.685-699
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• 2023

In recent years, Carbon Fibre Reinforced Plastic (CFRP) strengthening is found to be one of the best methods to strengthen steel structures. The fibrous bond can also influence the vibration characteristics of the strengthened element apart from its static strength enhancement property. The main objective of this study is to understand the influence of CFRP strengthening on the dynamic Behaviour of Thin-Webbed Castellated Beams (TWCBs). A detailed experimental investigation was carried out on five sets of beams with varying parameters such as domination of shear (Shear Dominant, Moment Dominant and Moment and Shear Dominant), sectional classification (Plastic and Semi-compact) and perforation geometries (h_o/d_wratio 0.65 and e/h_o ratio 0.3). Free vibration analysis was carried out by exciting the simply supported TWCBs with an impact force generated by a ball dropped from a specific height. Logarithmic decrement method was used to obtain the damping ratio and natural frequencies of vibration were found by Fast Fourier Transform (FFT). Natural frequency showed an increase in a range of 10.5 - 55% for the different sets of castellated beams. An increase of 62.30% was noted in the damping ratio of TWCBs after strengthening which is an indication of improvement in the vibration characteristics of the beam.

• 한국구조물진단유지관리공학회 논문집
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• 제3권1호
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• pp.171-178
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• 1999

Despite of decrease in shear and moment strengths, most steel structural designers use web openings in beams because of economical benefit and requirement. The purpose of this study is to suggest the method of reinforcement of H-shape steel beams with a rectangular web opening. If shear predominates over bending, it is necessary to consider all possible combinations of shear force and bending moment acting at the opening. In this paper, the ultimate strength and behavior of perforated beams have been investigated according to parameters (ratio of M/V, opening width within opening height ratio D/h, various reinforcing types A/B/C/D/M/N/W). The results of this study are as follows ; 1. Deformation of H-shape steel beams with a rectangular web opening was greatly affected by not only bending but also shear. 2. SB1-2/3 series have little difference in the reinforced efficiency, but SB1-2E/3E series have difference in the reinforced efficiency according to the reinforcement type. 3. Efficiency of SB1-2E/3E series is determined by reinforcing types, which RB1-2E-B/M/C and RB1-3E-M/D/C specimens have good efficient. Reinforcing type of perforated beams chooses efficient method according to ratio of M/V and D/h.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.989-994
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• 2000

Nine tests to failure are performed on full-scale eight composite beams with unreinforced web opening having ribbed slabs with formed deck which are perpendicular to the steel section and one steel beam. The effects of slab width, reinforcing of stud, moving of rib, moment-shear ratio are studied. At the low M/V ratio, Vierendeel action around the high moment end of the opening is occurred and the large deflection across the opening and transverse cracking are occurred with increasing of applied load. As the M/V ratio increases, the relative deflection across the opening decreases. And at failure, full tensile strain are occurred at bottom T section of steel beam, and concrete crushes at the High Moment End of the opening. With narrow slabs, diagonal tension failure at the high moment end of the opening is occurred. And with wide slabs, rib punch-through failure is occurred near the high moment end of the opening. The implications for design are discussed.

• Steel and Composite Structures
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• 제18권5호
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• pp.1177-1195
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• 2015

Six specimens are tested to investigate the cyclic behavior of beam-to-column abnormal joints in steel moment-resisting frames, which are designed according to the principle of strong-member and weak-panel zone. Key parameters include the axial compression ratio of column and the section depth ratio of beams. Experimental results indicate that four types of failure patterns occurred during the loading process. The $P-{\Delta}$ hysteretic loops are stable and plentiful, but have different changing tendency at the positive and negative direction in the later of loading process due to mechanical behaviors of specimens. The ultimate strength tends to increase with the decrease of the section depth ratio of beams, but it is not apparent relationship to the axial compression ratio of column, which is less than 0.5. The top panel zone has good deformation capacity and the shear rotation can reach to 0.04 rad. The top panel zone and the bottom panel zone don't work as a whole. Based on the experimental results, the equation for shear strength of the abnormal joint panel zone is established by considering the restriction of the bottom panel zone to the top panel zone, which is suitable for the abnormal joint of H-shaped or box column and beams with different depths.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.215-222
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• 2001

This study investigates the shear lag phenomenon existing in the shear wall of the wall-frame structure. Elastic analysis of such structures is carried out using a 3-D frame analysis program. The structural parameters governing the shear lag phenomenon are wall height and thickness. The analysis shows that the overturning moment due to external lateral load is resisted by both of the shear/core wall and the external frame. Severe unstable stresses are identified in height ratio of about 0.7 The taller or thinner wall shows the smaller shear lag phenomenon.

• Structural Engineering and Mechanics
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• 제64권1호
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• pp.135-143
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• 2017

To upgrade shear performance of reinforced concrete (RC) beams, and particularly of the segments under negative moment within continuous T-section beams, a series of original schemes has been proposed using carbon fibre-reinforced polymer (CFRP) U-shaped strips for shear-strengthening. The current work focuses on one of them, in which CFRP U-strips are wound around steel bars against the top of the flange of a T-beam and then spliced on its bottom face in addition to being bonded onto its sides. The test results showed that the proposed scheme successfully provided reliable anchorage for U-strips and prevented premature onset of shear failure due to FRP debonding. The governing shear mode of failure changed from peeling of CFRP to its fracture or crushing of concrete. The strengthened specimens displayed an average increase of about 60% in shear capacity over the unstrengthened control one. The specimen with a relatively high ratio and uniform distribution of CFRP reinforcement had a maximum increase of nearly 75% in strength as well as significantly improved ductility. The formulas by various codes or guidelines exhibited different accuracy in estimating FRP contribution to shear resistance of the segments that are subjected to negative moment and strengthened with well-anchored FRP U-strips within continuous T-beams. Further investigation is necessary to find a suitable approach to predicting load-carrying capacity of continuous beams shear strengthened in this way.

• KCI Concrete Journal
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• 제11권3호
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• pp.5-17
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• 1999

In recent years. the concept of the modified compression field theory (MCFT) was develped and applied to the analysis of reinforced concrete beams subjected to shear, moment, and axial load. Although too complex for regular use in the shear design or beams. the procedure has value in its ability to provide a rational method of anlysis and design for reinforced concrete members. The objective of this paper is to review the MCFT and apply it for the prediction of the response and shear strength of reinforced concrete beams A Parametric analysis was Performed on a reinforced T-section concrete beam to evaluate and compare the effects of concrete strength. longitudinal reinforcement ratio shear reinforcement ratio, and shear span to depth ratio in two different approaches the MCFT and the ACI code. The analytical study showed that the concrete contribution to shear strength by the MCFT was higher than the one by the ACI code in beams without stirrups, while it was lower with stirrups. On the other hand. shear reinforcement contribution predicted by the MCFT was much higher than the one by the ACI code. This is because the inclination angle of shear crack is much smaller than 45$^{\circ}$assumed in the ACI code.