• Steel and Composite Structures
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• 제23권1호
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• pp.115-130
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• 2017

A new type of moment-resisting bolted connection was developed for use in composite steel- concrete construction to connect composite open section steel beams to concrete filled steel square tubular columns. The connection was made possible using anchored blind bolts along with two through bolts. It was designed to act compositely with the in-situ reinforced concrete slab to achieve an enhanced stiffness and strength. The developed connection was incorporated in the design of a medium rise (five storey) commercial building which was located in low to medium seismicity regions. The lateral load resisting system for the design building consisted of moment resisting frames in two directions. A major full scale test on a sub-assembly of a perimeter moment-resisting frame of the model building was conducted to study the system behaviour incorporating the proposed connection. The behaviour of the proposed connection and its interaction with the floor slab under cyclic loading representing the earthquake events with return periods of 500 years and 2500 years was investigated. The proposed connection was categorized as semi rigid for unbraced frames based on the classification method presented in Eurocode 3. Furthermore, the proposed connection, composite with the floor slab, successfully provided adequate lateral load resistance for the model building.

• Steel and Composite Structures
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• 제45권6호
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• pp.895-905
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• 2022

Composite flooring systems consisting of cold-formed steel joists and reinforced concrete slabs offer an efficient, lightweight solution. However, utilisation of composite action to achieve enhanced strength and economical design has been limited. In this study, finite element modelling was utilised to create a three-dimensional model which was then validated against experimental results for a composite flooring system consisting of cold-formed steel joists, reinforced concrete slab and steel bolt shear connectors. This validated numerical model was then utilised to perform parametric studies on the performance of the structural system. The results from the parametric study demonstrate that increased thickness of the concrete slab and increased thickness of the cold formed steel beam resulted in higher moment capacity and stiffness of the composite flooring system. In addition, reducing the spacing of bolts and spacing of the cold formed steel beams both resulted in enhanced load capacity of the composite system. Increasing the concrete grade was also found to increase the moment capacity of the composite flooring system. Overall, the results show that an efficient, lightweight composite flooring system can be achieved and optimised by selecting suitable concrete slab thickness, cold formed beam thickness, bolt spacing, cold formed beam spacing and concrete grade.

• Steel and Composite Structures
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• 제32권5호
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• pp.583-594
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• 2019

In recent years, composite concrete-filled steel tubular (CFST) members have been widely utilized in framed building structures like beams, columns, and beam-columns since they have significant advantages such as reducing construction time, improving the seismic performance, and possessing high ductility, strength, and energy absorbing capacity. This paper presents a new composite joint - the composite CFST beam-column joint in which the CFST member is used as the beam. The main components of the proposed composite joint are steel H-beams, CFST beams welded with the steel H-column, and a reinforced concrete slab. The steel H-beams and CFST beams are connected with the concrete slab using shear connectors to ensure composite action between them. The structural performance of the proposed composite joint was evaluated through an experimental investigation. A three-dimensional (3D) finite element (FE) model was developed to simulate this composite joint using the ABAQUS/Explicit software, and the accuracy of the FE model was verified with the relevant experimental results. In addition, a number of parametric studies were made to examine the effects of the steel box beam thickness, concrete compressive strength, steel yield strength, and reinforcement ratio in the concrete slab on the proposed joint performance.

• Steel and Composite Structures
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• 제3권2호
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• pp.111-122
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• 2003

The paper presents a model for analysing the shear-lag effect on the slab of twin-girder composite decks subjected to static actions, support settlements and concrete shrinkage, which are the main actions of interest in composite bridge design. The proposed model includes concrete creep behaviour and shear connection flexibility. The shear-lag in the slab is accounted for by means of a new warping function. The considered actions are then applied to a realistic bridge deck and their effects are discussed. The proposed method is utilised to determine the slab effective widths for three different width-length ratios of the deck. Finally, a comparison between the results obtained with the Eurocode EC4-2 and those obtained with the proposed model is performed.

• 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.

• 복합신소재구조학회 논문집
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• 제5권1호
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• pp.22-27
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• 2014

The flat plate slab system have many good features, which are design flexibilities, saving of story-height and economy of construction etc. But the study of flat plate slab system for H-steel column have been rare both at home and abroad. Recently high-rise residential and commercial buildings have been constructed in urban areas in Korea. The suggested dowel connection system is more likely to adoptable because it remarkably contribute to save inter story height and also to have many advantages compared with conventional steel works such as H-Steel frame + Deck plate slab system. This study aims at developing design method and program for connection between H-Steel column and flat plate slab system, which contribute to save significantly inter-story height.

• Steel and Composite Structures
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• 제21권6호
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• pp.1307-1325
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• 2016

Nonlinear behavior of two-span, continuous composite steel-concrete girders strengthened with Carbon Fiber Reinforced Polymers (CFRP) bonded to the top of concrete slab over the negative moment region was evaluated using a non-linear Finite Element (FE) model in this paper. A three-dimensional FE model of continuous composite girder using commercial software ABAQUS simulated and validated with experimental results. The interfacial regions of the composite girder components were modeled using suitable interface elements. Validation of the proposed numerical model with experimental data confirmed the applicability of this model to predict the loading history, strain level for the different components and concrete-steel relative slip. The FE model captured the different modes of failure for the continuous composite girder either in the concrete slab or at the interfacial region between CFRP sheet and concrete slab. Through a parametric study, the thickness of CFRP sheet and shear connection required to develop full capacity of the continuous composite girder at negative moment zone have been investigated. The FE results showed that the proper thickness of CFRP sheet at negative moment region is a function of the adhesive strength and the positive moment capacity of the composite section. The shear connection required at the negative moment zone depends on CFRP sheet's tensile stress level at ultimate load.

• 콘크리트학회논문집
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• 제27권4호
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• pp.387-397
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• 2015

본 연구에서는 시공성 향상을 위해 데크플레이트와 비정질강섬유 콘크리트를 적용하여 현장 무배근 슬래브 시스템을 연구하였다. 제안한 슬래브에서는 온도철근을 강섬유로 대체하였다. 본 연구는 연속슬래브에서 상부 철근이 연속되지 않는 경우 슬래브의 상부 균열 제어를 주로 고려하였다. 실험변수로 비정질강섬유 혼입량, 강섬유 종류, 데크플레이트 종류, 연속구간의 철근 이음을 고려하였으며, 수직하중을 받는 2경간 슬래브를 실험하였다. 슬래브의 균열저항성능을 평가하기 위하여 연속슬래브의 하중에 따른 균열폭을 계측하였다. 실험결과, 상부 이음철근을 사용하지 않더라도 합성슬래브의 높은 휨강성으로 인하여 균열을 억제할 수 있는 것으로 나타났다.

• Composites Research
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• 제27권1호
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• pp.7-13
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• 2014

대형구조물 설계 건설시 가장 큰 제약은 모든 건설재료에는 치수의 한계가 있다. 본 논문에서는 고전적인 보이론에 의하여 단순 지지된 비등방성 슬래브의 처짐값을 구한 후 그 값을 비교하였고, 특별 직교이방성 판이론에 의하여 콘크리트와 샌드위치 교량의 물성을 비교하여 그 결과에 따른 처짐비와 강성값을 비교하였다. 경계조건은 임의의 경계조건을 갖는 판에 대한 해석해가 없기 때문에 부득이하게 네변이 모두 단순지지 되었을 경우로 해석을 하였고 복합재료의 인장강도는 콘크리트나 강재보다 훨씬 높으므로 비교대상은 처짐으로 하였다. 즉, 철근콘크리트 슬래브보다 자중이 1/10이면서 처짐이 작은 몇 가지 형태의 샌드위치패널을 고려하였다.

• Structural Engineering and Mechanics
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• 제78권3호
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• pp.319-332
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• 2021

The wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridges, as well as in the building construction for the design of wood concrete floor systems. The authors of this paper has been working for the past few years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors, this assembling technique does ensure an almost perfect connection between wood and concrete. This paper presents a careful theoretical investigation into interfacial stresses at the level of the two interfaces in composite wooden beam- reinforced concrete slab strengthened by external bonding of prestressed composite plate under a uniformly distributed load. The model is based on equilibrium and deformations compatibility requirements in all parts of the strengthened composite beam, i.e., the wooden beam, RC slab, the CFRP plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the CFRP- wooden-concrete hybrid structures.