• Steel and Composite Structures
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• v.34 no.1
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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.

• Steel and Composite Structures
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• v.39 no.3
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• pp.337-352
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• 2021

The study presented experimental and numerical investigation on the seismic performance of steel reinforced concrete (SRC) L-shaped column- reinforced concrete (RC) beam joints. Various parameters described as steel configuration form, axial compressive ratio, loading angle, and the existence of slab were examined through 4 planar joints and 7 spatial joints. The characteristics of the load-displacement response included the bearing capacity, ductility, story drift ratio, energy-dissipating capacity, and stiffness degradation were analyzed. The results showed that shear failure and flexural failure in the beam tip were observed for planar joints and spatial joint, respectively. And RC joint with slab failed with the plastic hinge in the slab and bottom of the beam. The results indicated that hysteretic curves of spatial joints with solid-web steel were plumper than those with hollow-web specimens. The capacity of planar joints was higher than that of space joints, while the opposite was true for energy-dissipation capacity and ductility. The high compression ratio contributed to the increase in capacity and initial stiffness of the joint. The elastic and elastic-plastic story deformation capacity of L-shaped column frame joints satisfied the code requirement. A design formula of joint shear resistance based on the superposition theory and equilibrium plasticity truss model was proposed for engineering application.

• Computers and Concrete
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• v.23 no.5
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• pp.329-334
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• 2019

Traffic flow capacity of some old road bridges is insufficient due to limited deck width. In such cases bridge deck widening is a common solution. For multi-girder reinforced concrete (RC) bridges it is possible to add steel-concrete composite girders as the new outermost girders. The deck widening may be combined with bridge strengthening thanks to thickening of the existing deck slab. Joint action of the existing and the added parts of such bridge span must be ensured. It refers especially to the horizontal plane at the interface of the existing slab and the added concrete layer as well as to the vertical planes at the external surfaces of the initially outermost girders where the added girders are connected to the existing bridge span. Since the distribution of the added concrete is non-uniform in the span cross-section the structure is particularly sensitive to the added concrete shrinkage. The shrinkage induces shear forces in the aforementioned planes. Widening of a 12 m long RC multi-girder bridge span is numerically analysed to assess the influence of the added concrete shrinkage. The analysis results show that: a) in the vertical plane of the connection of the added and the existing deck slab the longitudinal shear due to the shrinkage of the added concrete is comparable with the effect of live load, b) it is necessary to provide appropriate longitudinal reinforcement in the deck slab over the added girders due to tension induced by the shrinkage of the added concrete.

• Steel and Composite Structures
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• v.44 no.5
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• pp.677-684
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• 2022

This paper reports experimental investigation on shear behavior of steel reinforced concrete (SRC) shallow floor beam, where the steel shape is embedded in concrete and the high strength bolts are used to transfer the shear force along the interface between the steel shape and concrete. Six specimens were conducted aiming to provide information on shear performance and explore the shear bearing capacity of SRC shallow floor beams. The effects of the height of concrete slab, the size and the type of the steel section on shear performance of beams were also analyzed in the test. Based on the strut-and-tie model, the shear strength of the SRC shallow floor beam was proposed. Experimental results showed that composite shallow floor beam exhibited satisfactory composite behavior and all of the specimen failed in shear failure. The shear bearing capacity increased with the increasing of height of concrete slab and the size of steel shape, and the bearing capacities of beam specimens with castellated steel shape was slightly lower than those of specimens with H-shaped steel section. Furthermore, the calculations for evaluating the shear bearing capacity of SRC shallow floor beam were verified to be reasonable.

• Composites Research
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• v.22 no.5
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• pp.24-29
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• 2009

In this paper, a post-tensioned reinforced concrete slab was analyzed by the specially orthotropic laminates theory. Both the geometrical and material property of the cross section of the slab was considered symmetrically with respect to the neutral surface so that the bending extension coupling stiffness, $B_{ij}=0$, and $D_{16}=D_{26}=0$. Reinforced concrete slab behave as specially orthotropic plates. In general, the analytical solution for such complex systems is very difficult to obtain. Thus, finite difference method was used for analysis of the problem. In this paper, the finite difference method and the beam theory were used for analysis. The result of beam analysis was modified to obtain the solution of the plate analysis.

• Steel and Composite Structures
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• v.15 no.3
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• pp.323-342
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• 2013

In the case of seismic-resistant composite dual moment resisting and eccentrically braced frames, the current design practice is to avoid the disposition of shear connectors in the expected plastic zones, and consequently to consider a symmetric moment or shear plastic hinges, which occur only in the steel beam or link. Even without connectors, the real behavior of the hinge may be different from the symmetric assumption since the reinforced concrete slab is connected to the steel element close to the hinge locations, and also due to contact friction between the concrete slab and the steel element. At a larger level, the structural response in the case of important seismic motions depends directly on the elasto-plastic behavior of elements and hinges. The numerical investigation presented in this study summarizes the results of elasto-plastic analyses of several steel frames, considering the interaction of the steel beam with the concrete slab. Several parameters, such as the inter-story drift, plastic rotation requirements and behavior factors q were monitored. In order to obtain accurate results, adequate models of plastic hinges are proposed for both the composite short link and composite reduced beam sections.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.13-17
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• 2004

In recent years, the deterioration of reinforced concrete structures has become a serious problem in civil engineering fields. This situation is mainly due to corrosion of steel reinforcing bars embedded in concrete. Recently, there has been a greatly increased demand for the use of FRP (fiber reinforced plastic) in civil engineering field due to their superior mechanical and physical properties. This paper presents an experimental study on the behavior of concrete bridge deck reinforced with FRP Box, FRP Plate, and FRP Re-bar. In tlIe study, mechanical properties of FRP Box, FRP Plate, GFRP Re-bar, and CFRP Grid have been investigated. Full scale one-way deck slab was tested under four point lateral load (equivalent to actual wheel load of DB-24 including impact). Load-deflection and load-strain data were collected through LVDT's and strain gages attached to the specimen.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.64-71
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• 2018

This paper provides the results for experimental study on longitudinal shear performance for new-concept composite slabs embedded with silence insulator. Longitudinal shear capacity tests are used to predict characteristics of composite action between the concrete block, silence insulator and deckplate. A total set of 7 Push-Down specimens are tested to clarify the composite action between the concrete block, silence insulator and deckplate. Parameters in this study are the width of T-type bar, the depth of reinforced bar and the thickness of silence insulator. The results from experimental study on longitudinal shear capacity for new-concept composite slabs applied T-type bar, Reinforced bar and Silence insulator are summarized as follows. In test result, the Longitudinal Shear Capacity of the new concept specimen is 2 times excellent than basic specimen with safety. It is expected that applying the proposed composite slab detail at the actual site will provide a significant safety factor in structural aspect of the existing composite slab, and greatly contribute to the improvement capacities of resisting vibration and sound.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.165-170
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• 2009

In this study, the flexural experiment was conducted to propose the one-way composite slab system composed of concrete and GFRP-Deckplate by comparing with the composite deck slab system with bar-mesh As a result of experiment, the specimens of the proposed GFRP-Deck composite slab were better than the specimens for comparison in the flexural performance. It is effective for the building structures exposed to air pollution or salt.

• Computers and Concrete
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• v.14 no.5
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• pp.563-575
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• 2014

Concrete which is a composite material is frequently used in construction works. Properties and behavior of concrete are significant under the effect of different loading cases. Impact loading which is a sudden dynamic one may have destructive effects on structures. Testing apparatuses are designed to investigate the impact effect on test members. Artificial Neural Network (ANN) is a computational model that is inspired by the structure or functional aspects of biological neural networks. It can be defined as an emulation of biological neural system. In this study, impact parameters as acceleration and impact force values of a reinforced concrete slab are obtained by using a testing apparatus and essential test devices. Afterwards, ANN analysis which is used to model different physical dynamic processes depending on several variables is performed in the numerical part of the study. Finally, test and predicted results are compared and it's seen that ANN analysis is an alternative way to predict the results successfully.