• Steel and Composite Structures
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• 제31권4호
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• pp.329-340
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• 2019

An innovated type of the flat steel plate-lightweight aggregate concrete hollow composite slab was presented in this paper. This kind of the slab is composed of flat steel plate and the lightweight aggregate concrete slab, which were interfaced with a set of perfobond shear connectors (PBL shear connectors) with circular hollow structural sections (CHSS) and the shear stud connectors. Five specimens were tested under static monotonic loading. In the test, the influence of shear span/height ratios and arrangements of CHSS on bending capacity and flexural rigidity of the composite slabs were investigated. Based on the test results, the crack patterns, failure modes, the bending moment-curvature curves as well as the strains of the flat steel plate and the concrete were focused and analyzed. The test results showed that the flat steel plate was fully connected to the lightweight aggregate concrete slab and no obvious slippage was observed between the steel plate and the concrete, and the composite slabs performed well in terms of bending capacity, flexural rigidity and ductility. It was further shown that all of the specimens failed in bending failure mode regardless of the shear span/height ratios and the arrangement of CHSS. Moreover, the plane-section assumption was proved to be valid, and the calculated formulas for predicting the bending capacity and the flexural rigidity of the composite slabs were proposed on the basis of the experimental results.

• Steel and Composite Structures
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• 제49권4호
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• pp.381-392
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• 2023

This study experimentally investigates the flexural behavior of steel-UHPC composite slabs composed of an innovative negative Poisson's ratio (NPR) steel plate and Ultra High Performance Concrete (UHPC) slab connected via demountable high-strength bolt shear connectors. Eight demountable composite slab specimens were fabricated and tested under traditional four-point bending method. The effects of loading histories (positive and negative bending moment), types of steel plate (NPR steel plate and Q355 steel plate) and spacings of high-strength bolts (150 mm, 200 mm and 250 mm) on the flexural behavior of demountable composite slab, including failure mode, load-deflection curve, interface relative slip, crack width and sectional strain distribution, were evaluated. The results revealed that under positive bending moment, the failure mode of composite slabs employing NPR steel plate was distinct from that with Q355 steel plate, which exhibited that part of high-strength bolts was cut off, part of pre-embedded padded extension nuts was pulled out, and UHPC collapsed due to instantaneous instability and etc. Besides, under the same spacing of high-strength bolts, NPR steel plate availably delayed and restrained the relative slip between steel plate and UHPC plate, thus significantly enhanced the cooperative deformation capacity, flexural stiffness and load capacity for composite slabs further. While under negative bending moment, NPR steel plate effectively improved the flexural capacity and deformation characteristics of composite slabs, but it has no obvious effect on the initial flexural stiffness of composite slabs. Meanwhile, the excellent crack-width control ability for UHPC endowed composite members with better durability. Furthermore, according to the sectional strain distribution analysis, due to the negative Poisson's ratio effect and high yield strength of NPR steel plate, the tensile strain between NPR steel plate and UHPC layer held strain compatibility during the whole loading process, and the magnitude of upward movement for sectional plastic neutral axis could be ignored with the increase of positive bending moment.

• Steel and Composite Structures
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• 제34권1호
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• pp.91-105
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• 2020

Steel-concrete composite beam with profiled steel sheet has gained its popularity in the last two decades. Due to the ageing of these structures, retrofitting in terms of flexural strength is necessary to ensure that the aged structures can carry the increased traffic load throughout their design life. The steel ribs, which presented in the profiled steel deck, limit the use of shear connectors. This leads to a poor degree of composite action between the concrete slab and steel beam compared to the solid slab situation. As a result, the shear connectors that connects the slab and beam will be subjected to higher shear stress which may also require strengthening to increase the load carrying capacity of an existing composite structure. While most of the available studies focus on the strengthening of longitudinal shear and flexural strength separately, the present work investigates the effect of both flexural and longitudinal shear strengthening of steel-concrete composite beam with composite slab in terms of failure modes, ultimate load carrying capacity, ductility, end-slip, strain profile and interface differential strain. The flexural strengthening was conducted using carbon fibre reinforced polymer (CFRP) or steel plate on the soffit of the steel I-beam, while longitudinal shear capacity was enhanced using post-installed high strength bolts. Moreover, a combination of both the longitudinal shear and flexural strengthening techniques was also implemented (hybrid strengthening). It is concluded that hybrid strengthening improved the ultimate load carrying capacity and reduce slip and interface differential strain that lead to improved composite action. However, hybrid strengthening resulted in brittle failure mode that decreased ductility of the beam.

• 한국공간구조학회논문집
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• 제5권4호
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• pp.91-100
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• 2005

데크플레이트와 콘크리트가 합성되어 있는 합성 바닥판 구조물은 데크플레이트의 골 방향과 골 직각방향에 대하여 강성이 다르므로 직교이방성판 거동을 보이고 있으며 테크플레이트와 콘크리트의 합성 거동으로 인하여 적층 바닥판 구조물로 평가할 수 있다. 이러한 합성데크 바닥판 구조물의 진동에 대한 정확한 사용성 평가를 위해서는 합성데크 바닥판 구조물의 정밀 진동해석을 수행하여야 한다. 이를 위해서는 합성데크 바닥판 구조물의 강성에 대한 직교이방성 그리고 데크플레이트와 콘크리트의 합성에 대한 정확한 거동 평가가 수반되어야 한다. 본 논문에서는 합성데크 바닥판 구조물의 골 직각 방향에 대한 강성을 계산하기 위하여 각각의 토핑 콘크리트 두께와 데크플레이트 두께를 적용하였다. 또한 골 방향에 대한 강성을 계산하기 위하여 콘크리트와 데크플레이트의 단면 강성을 구하여 등가두께를 적용하였다. 그리고 콘크리트와 데크플레이트의 합성거동을 표현하기 위하여 적층판에 대한 등가 강성식을 적용, 합성데크 바닥판 구조물의 강성을 나타내었다. 본 논문에서 제안한 합성데크 바닥판 구조물의 실용적인 모형화방법을 적용할 경우에 합성데크 바닥판 구조물의 강성에 대한 직교이방성과 콘크리트와 데크플레이트의 합성 거동을 잘 표현할 수 있었다.

• Steel and Composite Structures
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• 제11권2호
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• pp.169-181
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• 2011

The behavior of connections between open sandwich slabs and double steel skin composite walls in steel plate-concrete(SC) structure is investigated by a series of experimental programs to identify the roles of components in the transfer of forces. Such connections are supposed to transfer shear by the action of friction on the interface between the steel surface and the concrete surface, as well as the shear resistance of the bottom steel plate attached to the wall. Experimental observation showed that shear transfer in slabs subjected to shear in short spans is explained by direct force transfer via diagonal struts and indirect force transfer via truss actions. Shear resistance at the interface is enhanced by the shear capacity of the shear plate as well as friction caused by the compressive force along the wall plate. Shear friction resistance along the wall plate was deduced from experimental observation. Finally, the appropriate design strength of the connection is proposed for a practical design purpose.

• 한국강구조학회 논문집
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• 제16권3호통권70호
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• pp.325-332
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• 2004

강합성거더 교량의 단면은 강거더와 콘크리트 슬래브의 합성정도에 따라 각각 비합성, 부분합성 그리고 완전합성 단면들로 구분 할 수 있다. 국내의 경우 강합성거더 교량의 단면을 합성시키기 위하여 일반적으로 전단 연결재 중 스터드를 사용하도록 규정하고 있고, 진단 연결재가 없는 경우 즉 비합성 단면의 경우에는 바닥판 앵커를 설치하도록 경험적으로 규정하고 있다. 그러나 바닥판 앵커를 사용한 단면의 실제 거동은 비합성 거동이 아닌 부분합성의 거동을 나타낸다. 그러한 이유로 본 연구에서는 바닥판 앵커를 사용한 플레이트거더교의 부분합성에 관한 해석 및 실험연구를 수행하였다. 실험연구를 통해서 바닥판 앵커의 초기강성을 산정하였고, 해석연구를 통해서 바닥판 앵커를 사용한 단순 및 2경간 연속 플레이트거더교의 합성정도를 비교$\cdot$분석하였다. 또한, 실험에 의해 산정된 강성 값에 근거하여, 2경간 연속 플레이트거더교에 바닥판 앵커를 적용하였을 때 발생할 수 있는 내부지점부 콘크리트의 인장응력 저감 효과를 검토하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.293-298
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• 1995

The strength of shear connectors embedded in lightweight concrete slab with deck plate is influenced by various factors of deck plate, shear conncetor and concrete. Generally, it is reported that the strength of shear connector in lightweight concrete decreases in comparison with that in normal concrete. So this paper is to use compressive strength of lilghtweight concrete, width-height ratio of deck plate, and cross sectional area of shear conncetor as variables, to evaluate the strength of shear conncetors in composite beam of steel and lilghtweight concrete slabs with deck plate, and then to suggest the reasonable strength equation by comparing the push-out test results with establixhed strength formula. As the result of 24 specimens test, in case of lightweight concrete slab with deck plate, it has showed that in the same strength, the strength of shear connector decreased about 10~20% in comparison with that in normal concrete. In spite of lightweight concrete, the test results were closely approached the established strength formula of shear connector using Fisher's reduction coefficient.

• 한국강구조학회 논문집
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• 제8권3호통권28호
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• pp.67-78
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• 1996

This paper provides the results of a study on the structural behavior of the composite slabs using the metal form deck plate. Cold-formed steel deck sections are used in many composite floor slab applications wherein the steel deck serves not only as the form for the concrete during construction but also as the principal tensile reinforcement for the bottom fiber of the composite slab. A total of 16 specimens are tested to clarify the composite action between the concrete and metal deck plate and to find the method to increase the composite effect, whether or not non-slip bars are used. The test results are summarized for the shear-bond capacities, deformation capacities, and failure modes for the specimens.

• Steel and Composite Structures
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• 제37권6호
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• pp.741-759
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• 2020

Steel plate-concrete composite slabs provide attractive features, such as more effective loading transfer, and more cost-effective stay-in-place forms, thereby enabling engineers to design more high-performance light structures. Although significant studies in the literatures have been directed toward designing and implementing the steel plate-concrete composite beams, there are limited data available for understanding of the composite slabs. To fill this gap, nine the composite slabs with different variables in this study were tested to unveil the impacts of the critical factors on the ultimate strength behavior. The key information of the findings included sample failure modes, crack pattern, and ultimate strength behavior of the composite slabs under either four-point or three-point loading. Test results showed that the failure modes varied from delamination to shear failures under different design factors. Particularly, the shear stud spacing and thicknesses of the concrete slabs significantly affected their ultimate load-carrying capacities. Moreover, an analytical model of the composite slabs was derived for determining their ultimate load-carrying capacity and was well verified by the experimental data. Further extensive parametric study using the proposed analytical methods was conducted for a more comprehensive investigation of those critical factors in their performance. These findings are expected to help engineers to better understand the structural behavior of the steel plate-concrete composite slabs and to ensure reliability of design and performance throughout their service life.

• Steel and Composite Structures
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• 제26권2호
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• pp.183-196
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• 2018

The traditional prestressed concrete composite box-girders with corrugated steel webs have several drawbacks such as large deflection and potential local buckling. In this study, two methods were investigated to optimize and improve the prestressed concrete composite box-girders with corrugated steel webs. The first method was to replace the concrete bottom slab with a steel plate and the second method was to support the concrete bottom slab on the steel flanges. The behavior of the prestressed concrete composite box-girders with corrugated steel webs with either method was studied by experiments on three specimens. The test results showed that behavior of the optimized and upgraded prestressed concrete composite box-girders with corrugated steel webs, including ultimate bearing capacity, flexural stiffness, and crack resistance, is greatly improved. In addition, the influence of different shear connectors, including perfobond leisten (PBL) and stud shear connectors, on the behavior of prestressed concrete composite box-girders with corrugated steel webs was studied. The results showed that PBL shear connectors can greatly improve the ultimate bearing capacity, flexural stiffness and crack resistance property of the prestressed concrete composite box-girders with corrugated steel webs. However, for the efficiency of prestressing introduced into the girder, the PBL shear connectors do not perform as well as the stud shear connectors.