Steel-concrete-steel Sandwich Beams Research Articles

Flexural performance of steel-concrete-steel sandwich beams with lightweight fiber-reinforced concrete and corrugated-strip connectors: Experimental tests and numerical modeling

The present paper experimentally investigates the flexural behavior of steel-concrete-steel (SCS) composite beams with lightweight polypropylene fiber-reinforced concrete core and corrugated-strip shear connectors. For this purpose, the four-point bending tests have been performed on 11 specimens. This aims to investigate the influence of lightweight concrete core on the performance of the beams, and therefore all the parameters in the tested beams are kept constant except the type of concrete core. Based on the results of the performed quasi-static loading tests, the observed failure modes and force-displacement curves are reported and analyzed to achieve a deeper understanding of the influence of lightweight fiber-reinforced concrete on the flexural behavior of SCS beams. It was found that the utilization of polypropylene fiber has an improving influence on the performance of SCS beams, and especially enhances their toughness and ultimate deflection. A positive linear relationship between the fiber content (up to 2 %) with the specimen’s toughness was detected. It was also found that the addition of micro-silica to the lightweight fiber-reinforced concrete core results in considerable improvement in the flexural load capacity of the tested SCS beams. In addition, numerical finite element models including detailed material and geometric modeling of SCS beams are developed using the general software package ABAQUS. The accuracy of the developed models is validated using the attained experimental results. The numerical models can be used to simulate the load-deflection behavior and ultimate strength of SCS sandwich beams.

Finite element analysis of steel-concrete-steel sandwich beams with novel interlocked angle connectors subjected to impact loading

The steel–concrete–steel (SCS) sandwich structures are increasingly adopted to improve the impact resistance of the buildings or infrastructures owing to their good structural performances. Recently, the SCS sandwich beams with interlocked angle connectors (SCSSB-IACs) have been developed, and their performances under impact loading have been experimentally studied. This paper presents detailed numerical analyses of the SCSSB-IACs subjected to impact loading and reveals its response mechanisms. The Finite Element (FE) models of the SCSSB-IACs were established using LS-DYNA, and the FE predictions showed a good agreement with the impact test data. The impact process as well as distribution and evolution of bending moment and shear force, stress and strain were discussed. Furthermore, the internal energy histories of the SCSSB-IACs were revealed by FE analyses. Numerical results indicated that the majority of impact energy was absorbed by the concrete and bottom faceplate, and the deformation of the SCSSB-IACs was dominated by a flexural manner. Finally, parametric studies were performed to reveal the effects of impact momentum, energy and location on the response of the SCSSB-IACs.

Experimental and analytical studies on impact behaviours of a steel–concrete–steel sandwich beam with novel interlocked angle connectors

The dynamic responses of steel–concrete–steel (SCS) sandwich beams with novel interlocked angle connectors (IACs) under low-velocity impact were studied and presented in this paper. The impact tests on the SCS sandwich beams were first implemented using a drop-weight impact test machine, and the failure modes, displacement, and impact responses were obtained from the tests. The varying parameters considered in the tests included the thicknesses of the concrete and steel faceplates, as well as the spacing and type of IACs. The test results indicated that nine specimens experienced flexural failure, and one specimen exhibited shear failure. Moreover, local buckling of the top steel faceplate occurred in four specimens with a relatively larger spacing of IACs. A two-degree-of-freedom (TDOF) analytical model considering the strain rate effect was proposed for the SCS sandwich beam to obtain their impact forces and mid-span displacements. The analytically-predicted responses of the SCS sandwich beam with IACs agreed well with the test data.

The behavior of steel-concrete-steel sandwich beams with different depths effect

This research studies the effect of beam depth on the behavior of steel-concrete-steel (SCS) sandwich beams. Four SCS sandwich beams measuring 100 mm wide and 1200 mm length were cast and tested up to failure under three-point flexural loading. The depths in the tested beams ranged from 150 to 300 mm in regular increments of 50 mm. All beams had top and bottom steel skin plates with thickness 4 mm. The shear connector configuration of the Truss using 10 mm diameter steel bars was used to directly connect the two external steel skin plates. The test results confirmed that increasing the depth of the SCS beams from 150 to 300 mm led to an increase in the first cracking load and the ultimate load by 33.5 to 66.5% and 59.2 to 64.2%, respectively. In addition to improving the mechanical properties, when the SCS beams depth was raised to 50%, the service stiffness and secant stiffness both improved by 226.9 and 190.4%, respectively. Moreover, the flexural toughness increased by 101.1% with the SCS sandwich beams depth rising by 25%.

Behavior of steel-concrete-steel sandwich beams with blot connectors under off-center impact load

The structural performance of the Steel-Concrete-Steel (SCS) sandwich beams with bolt connectors subjected to off-center impact load was investigated in this paper. Nine SCS sandwich beams were tested under impact loading by employing a drop hammer impact test system. The influences of concrete core depth, steel plate thickenss, top to bottom steel plate thickness ratio, and impact location on the responses of SCS sandwich beams were experimentally studied. The experiments revealed three failure modes of the SCS sandwich beams, i.e., flexure, flexure-shear, and fracture of the bottom steel plate. The separation of steel plates was prevented, and the structural integrity of the SCS sandwich beams was maintained despite the impact near the support, owing to the presence of bolt connectors. An analytical model was developed to predict the displacement–time histories of the SCS sandwich beams subjected to impact load. The predicted displacement responses showed a good match with the experimental results. Moreover, the force–displacement curves obtained from the analytical model and impact tests were compared, and good agreement between them could be observed.

Developments of steel-concrete-steel sandwich composite structures with novel EC connectors: Members

This paper developed new steel-concrete-steel (SCS) sandwich composite structures using novel enhanced C-channels (ECs) for civil engineering infrastructures as shear walls, bridge decks, and protective structures. Their structural behaviours have been studied through a series of tests from the component to structural member level. Push-out tests on ECs, two-point loading tests on SCS sandwich beams with ECs (SCSSB-ECs), axial compression tests on SCS sandwich walls with ECs (SCSSW-ECs), in-plane cyclic shear tests and out-of-plane punching shear tests on SCSSW-ECs were carried out to investigate the shear behaviour of ECs, flexural and shear behaviour of SCSSB-ECs, compression behaviour, in-plane seismic behaviour, and out-of-plane punching shear behaviour of SCSSW-ECs, respectively. These studies offered comprehensive information of structural behaviours of SCS sandwich structural members with ECs. Including these experimental studies, corresponding prediction equations were also proposed for ultimate shear resistance and shear-slip behaviour of ECs, flexural and shear resistances of SCSSB-ECs, axial compression resistance, in-plane lateral shear resistance, and out-of-plane punching shear resistance of SCSSW-ECs. Through validations against reported test results, accuracies of these developed prediction equations were confirmed.

Behavior of Steel-Coconut Shell Concrete-Steel Composite Beam without and with Shear Studs under Flexural Load.

In this study, we investigated using coconut shell concrete (CSC) in double-skin steel plate sandwich beams, i.e., steel–concrete–steel (SCS) under flexure. Two cases—without and with shear studs to interconnect the bottom tension and top compression plates—were considered. Conventional concrete (CC) was used for comparison purposes. The effect of quarry dust (QD) in place of river sand (RS) was considered. Therefore, four mixes named as CC, conventional concrete produced using QD (CCQ), CSC and coconut shell concrete produced using QD (CSCQ) were used. Three different steel plate thicknesses were considered (4 mm, 6 mm and 8 mm). In total, twelve SCS specimens were tested to evaluate the flexural performance under two-point static loads. Study parameters include: partial and fully composite, ultimate moment and failures, deflection characteristics, ductility property, cracking behavior and strains in both tension and compression plates. It was found that the moment carrying capacity of the SCS sandwich beams increased when the thickness of the steel plate increased. Our results provided evidence that using QD in place of RS augmented the strength of beams. Theoretical deflections were underestimated the experimental deflection, except in one case. The SCS beams showed good ductility behavior. The SCS beams exhibited crack widths at yielding well below guideline values.

Shear resistance behavior of partially composite Steel-Concrete-Steel sandwich beams considering bond-slip effect

This study develops a new steel-concrete-steel (SCS) sandwich beam with hybrid shear connectors comprising both J-hooks and overlapped headed studs. For partially composite SCS sandwich beams, bond-slip is a critical factor influencing the transverse shear resistance of the beam. Thus, this study examines the effect of the degree of composite action and the mechanism of such sandwich beams by testing eight SCS sandwich beams with different shear span-to-depth ratios, steel contribution ratios, types of shear connectors, and spacing of shear connectors. The parametric study thoroughly discusses the effects of these variables on the beam failure modes and beam shear resistance. Based on existing design models, this paper proposes a new analytical model that considers the bond-slip effect to predict the ultimate resistance of SCS sandwich beams. The new model includes contributions from the concrete, shear connectors, and steel plates. Available test data from 57 specimens successfully validated the proposed model.

Cyclic Performance of Steel–Concrete–Steel Sandwich Beams with Rubcrete and LECA Concrete Core

Due to the structural and economic features of steel–concrete–steel (SCS) structural systems compared with conventional reinforced concrete ones, they are now used for a range of structural applications. Rubcrete, in which crumbed rubber from scrap tires partially replaces mineral aggregates in concrete, can be used instead of conventional concrete. Utilizing rubber waste in concrete potentially results in a more ductile lightweight concrete that can introduce additional features to the SCS structural members. This study aimed to explore different concrete core materials in SCS beams and the appropriate shear connectors required. In this study, four SCS sandwich beams were tested experimentally under incrementally increasing flexure cyclic loading. Each beam had a length of 1000 mm, and upper and lower steel plates with 3 mm thickness sandwiched the concrete core, which had a cross-section of 150 mm × 150 mm. Two of the beams were constructed out of Rubcrete core with welded and bolted shear connectors, while the other two beams were constructed with welded shear connectors and either conventional concrete or lightweight expanded clay aggregate (LECA) concrete cores. The performance of the SCS sandwich beams including damage pattern, failure mode, load-displacement response, and energy dissipation behavior was compared. The results showed that, while Rubcrete was able to provide similar concrete cracking behavior and strength to that of conventional concrete, LECA concrete degraded the strength properties of SCS. Using bolted shear connectors instead of welded ones caused a high number of cracks that resulted in a reduced ductility and deflection capacity of the beam before failure. The rubberized concrete specimen presented an improved ductility and deflection capacity compared with its conventional concrete counterpart.

Shear failure mechanisms of SCS sandwich beams considering bond-slip between steel plates and concrete

The steel-concrete-steel (SCS) sandwich structure has been proposed for containment buildings in third-generation nuclear power plants. In this paper, 27 static tests on SCS sandwich beams (by the authors and others) are adopted serially to summarize the failure modes and explore the failure mechanisms of SCS sandwich beams with different bond-slip conditions between the steel plate and concrete. Further, a three-dimensional finite element (FE) model is developed to simulate the ultimate strength of SCS sandwich beams under different failure modes. The accuracy of the developed FE model in predicting ultimate strength, cracking behaviours and bond-slip behaviours is verified by static tests. Based on the validated FE model, 65 numerical cases are calculated to investigate the effects of analytical parameters on the failure mechanism and ultimate strength of SCS sandwich beams under different bond-slip conditions. The analytical parameters include the steel plate ratio, shear span to depth ratio, spacing of shear studs and shear reinforcement ratio. In addition, theoretical models are proposed to predict the ultimate strength of SCS sandwich beams under different bond-slip conditions. The accuracy of the theoretical model is verified by comparison with current design codes for SCS sandwich beams.

Ultimate strength behaviour of S-UHPC-S and SCS sandwich beams under shear loads

The application of steel-concrete-steel (SCS) sandwich structures as containment buildings is proposed for the third-generation nuclear power plant AP1000. In this paper, ultra high-performance concrete (UHPC) is developed as the core material to improve structural behaviour. Static tests on two groups of SCS sandwich beams and two groups of steel-ultra high- performance concrete-steel (S-UHPC-S) sandwich beams were carried out to investigate the structural behaviours under three-point loading, with the research parameters consisting of the shear reinforcement ratio and core materials. Three failure modes are defined and the structural behaviours are analysed, considering the effects of the shear reinforcement ratio, shear studs and core materials on the specimens. Based on the test results, mechanical models are established to predict the shear bearing capacity of SCS sandwich beams, taking into consideration the effect of the contribution of the steel plates and the bond-slip action between the steel plates and concrete. Furthermore, a calculation method for predicting the ultimate strength of S-UHPC-S sandwich beams is presented, which takes into account the effects of steel fibres on specimens. The prediction accuracy is verified by means of comparison with the test data.

Flexural Performance of SCS Sandwich Beam with Foamed Concrete

This paper presents the investigation on the flexural performance of steel concrete steel (SCS) sandwich beam comprising of fibre reinforced foamed concrete (FRFC) as a core concrete, sandwiched between the two steel plates. The steel plates were connected by a J-hook shear connector in order to develop a composite action between the plates and core concrete. The light weight foamed concrete having a density ranged from 1400 to 1450 kg/m3. The SCS sandwich beams were tested under a static gradual loading up to failure to examine its flexural behaviour. The test results revealed that the proposed SCS sandwich beam with FRFC increased the load carrying capacity and ductility performance. The finite element based modelling has also been conducted for the corroboration of test results. A reasonably close agreement has been obtained between the experimental results and predicted values.

Numerical and parametric study of curved steel-concrete-steel sandwich composite beams under concentrated loading

The curved steel-concrete-steel (SCS) sandwich structure has been developed as the ice-resistant wall for Arctic oil and gas drilling platform. This developed curved SCS sandwich structure adopts ultra-lightweight cement composite and overlapped headed shear studs as the core material and bonding measures at the steel-concrete interface, respectively. This paper develops a three-dimensional finite element (FE) model by general commercial FE program ABAQUS to simulate the ultimate strength behaviour of the curved SCS sandwich beam. The developed FE model considers the geometric and material nonlinearities of the concrete, steel plates and connectors. The reasonable agreement between FE analysis and the quasi-static tests on nine SCS sandwich beams confirms the accuracy of the FEM in predicting the ultimate shear resistance and cracks in the concrete core of the curved SCS sandwich beam. Based on this validated FE model, a subsequence parametric study comprising 54 cases investigates the influences of the curvature, thickness of the steel face plate and core material, and horizontal movements of the supports on the shear resistance of the curved SCS sandwich beams. Finally, the paper validates accuracy of an analytical model on the shear resistance of the curved SCS sandwich beam via a comparison against a total of 41 results (32 FEA and 9 tests).

Ultimate strength behavior of curved steel–concrete–steel sandwich composite beams

A concept of using curved steel–concrete–steel (SCS) sandwich structure as the ice-resistant wall has been proposed for Arctic oil and gas drilling platform. In the developed curved SCS sandwich structure, ultra-lightweight cement composite (ULCC) and overlapped headed studs were used as the core material and bonding measures at the steel-concrete interface, respectively. In this paper, quasi-static tests on ten curved SCS sandwich beams have been carried out to investigate their ultimate strength behaviors under patch loading that considers the critical local ice-contact pressure. The test results reported the failure mode and shear resistances of structures, studied the influences of thickness of the steel skin shell, curvature, spacing of the connectors, depth of the cross section, strength of core materials, and boundary conditions on the ultimate strength behavior of the curved SCS sandwich beam. Extensive discussions and analysis were also carried out to provide information for the development of the analytical models. Analytical models were developed through modifying design code provisions. These innovative modifications in the analytical models included redefining the inclination angle of shear failure surface, redefining the effective depth of the section, considering the influence of the thickness of steel skin, and developing analytical models on tensile resistance of the overlapped headed studs. The accuracy of the predictions by the analytical models was checked by the test data. All these efforts were made to provide better predictions on the shear resistance of the curved SCS sandwich beam.

Numerical modelling of lightweight Steel‐Concrete‐Steel sandwich composite beams subjected to impact

This paper presents the numerical and analytical models to predict the response behaviour of Steel–Concrete–Steel (SCS) sandwich composite beams subjected to drop-weight impact loading. The sandwich composite beam has an ultra-lightweight concrete core of density 1440kg/m3 sandwiched between two thin steel face plates which are interconnected by J-hook connectors. Explicit nonlinear finite element analysis was carried out and the results obtained are verified against the impact test data to establish its accuracy in predicting the permanent deformation, vertical displacement–time history and impact force–time history of the sandwich beams. The numerical analysis also shows that the J-hook connectors are subjected to tension force during impact in addition to shear force due to flexural action in the beam. This signifies the important role of J-hook connectors in preventing tensile separation of the steel face plates when subjected to impact load. An analytical approach based on energy balance model was also developed to predict the impact response of SCS sandwich beams. A good agreement was observed between the analytical solution and the experimental data indicating that the approach provides a reasonable and conservative estimation of the impact resistance of the sandwich beams.

Ultimate strength behavior of steel-concrete-steel sandwich beams with ultra-lightweight cement composite, Part 2: Finite element analysis

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of 1,450 kg/m3 has been developed and used in the steel-concrete-steel (SCS) sandwich structures. This paper investigates the structural performances of SCS sandwich composite beams with ULCC as filled material. Overlapped headed shear studs were used to provide shear and tensile bond between the face plate and the lightweight core. Three-dimensional nonlinear finite element (FE) model was developed for the ultimate strength analysis of such SCS sandwich composite beams. The accuracy of the FE analysis was established by comparing the predicted results with the quasi-static tests on the SCS sandwich beams. The FE model was also applied to the nonlinear analysis on curved SCS sandwich beam and shells and the SCS sandwich beams with J-hook connectors and different concrete core including ULCC, lightweight concrete (LWC) and normal weight concrete (NWC). Validations were also carried out to check the accuracy of the FE analysis on the SCS sandwich beams with J-hook connectors and curved SCS sandwich structure. Finally, recommended FE analysis procedures were given.

Finite element analysis on steel–concrete–steel sandwich beams

Steel–concrete–steel (SCS) sandwich composite structure with J-hook connectors has been developed and exhibited versatile potential applications in the building and offshore constructions. In this structure, J-hook connectors were used to bond the steel face plates and concrete as integrity. In this paper, finite element model (FEM) by general finite element program ABAQUS was developed to analyze the nonlinear structural behavior of the developed SCS sandwich beam structures with J-hook connectors under quasi-static loading. In this FEM, the novel J-hook connectors were simplified and simulated by cylindrical studs linked by the nonlinear spring element. The validations of the FEM cover from the component to structure level. Firstly, the simulations of the FEM on the longitudinal shear-slip and axial tension–elongation behaviors of the J-hook connectors were firstly validated against the push- and pull- out tests. Then, the FE analysis (FEA) on the structural behaviors of the SCS sandwich beams was validated against those from the beam in the references. Through these verifications, the accuracy of the FEA on the nonlinear structural behaviors of the SCS sandwich beam with J-hook connectors was confirmed.

Behavior of Steel–Concrete–Steel sandwich structures with lightweight cement composite and novel shear connectors

In Steel–Concrete–Steel (SCS) sandwich structure, mechanical shear connectors are commonly used to transfer longitudinal shear forces across the steel–concrete interface. In this paper, novel shear connectors such as J-hook and cable shear connectors are proposed and their performance to achieve composite strength of SCS sandwich structures is investigated. The use of these connectors together with ultra-lightweight cement composite core reduces the overall weight of SCS sandwich system making it suitable for the construction of marine and offshore structures. Static tests were carried out on SCS sandwich beams with J-hook, cable shear connectors and headed studs. Their ultimate strengths were reported and their respective failure modes were discussed. An analytical method to predict the ultimate strength of the Steel–Concrete–Steel sandwich beams with various types of shear connectors was developed and its accuracy was ascertained by comparing with the test results. Deign recommendations are made on minimum connector spacing to prevent shear cracking of concrete core and local buckling of face plates.

Structural Performance of Steel-Concrete-Steel Sandwich Composite Structures

This paper investigates the structural performance of steel-concrete-steel (SCS) sandwich structures comprising a lightweight concrete core sandwiched in between two steel plates. Different types of mechanical shear connectors such as stud shear connectors and Bi-Steel bar connectors are reviewed and their uses in SCS sandwich construction are discussed. Special J-hook connectors are developed and their uses are not restricted by the concrete core thickness. Direct shear (push-out test) and tension tests have been carried out on J-hook connectors to investigate their performance in transferring shear and tension forces between steel and concrete. The structural performance of SCS sandwich beams and slabs with J-hook connectors subjected to static and dynamic loads is also investigated and test results show that SCS sandwich structures with the J-hook connectors are capable of resisting impact with less degree of damage in comparison with the sandwich structures with overlapping stud shear connectors. The plastic capacity of the sandwich beams and slabs can be predicted with reasonable accuracy using the plastic analysis described in this paper.