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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. • FE models of the steel-concrete-steel sandwich beam with interlocked angle connectors (SCSSB-IACs) were established. • The accuracy of FE models of the SCSSB-IACs was validated with experimental results. • The internal force distributions, strain and stress responses and energy response of the SCSSB-IACs were discussed. • Parametric studies were conducted to further reveal the failure mechanisms of SCSSB-IACs. [ABSTRACT FROM AUTHOR]

Abstract Steel-concrete-steel (SCS) sandwich shells, which are combined with steel plates, concrete core and shear connectors, are usually applied as protective structures in the civil engineering. In this paper, nine curved SCS sandwich shells subjected to concentrated load by a hemi-spherical head were tested to obtain the failure characteristic, ultimate strength and load–displacement response. The finite element (FE) models of curved SCS sandwich shells were also established by using LS-DYNA. The accuracies of the FE models were verified by comparing the load–displacement curves, local and global deformation between the experimental results and FE predictions. The factors influencing the ultimate strength and deformation behavior of curved SCS sandwich shells were analysed, including concrete core and steel plate thickness, top to bottom steel plate thickness ratio and spacing of shear connectors. Through experiments and numerical simulations, three failure modes could be summarized. It was also found that increasing concrete core and top steel plate thickness and reducing the spacing of shear connectors could increase yield strength and ultimate strength of curved SCS sandwich shell. The increase of concrete core and steel plate thickness also led to higher energy absorption capacity; whereas, the spacing of shear connectors showed little effect on energy absorption capacity. Highlights • Nine curved SCS sandwich shells subjected to concentrated load were experimentally studied. • Failure modes of curved SCS sandwich shells were summarized. • Parameters affecting the strength of curved SCS sandwich shells were discussed. • The FE analysis was conducted to reproduce the experimental observations. [ABSTRACT FROM AUTHOR]

This study explored the impact responses of a steel–concrete–steel sandwich composite panel with novel interlocked angle connectors (SCSP-IACs). Impact tests on nine SCSP-IACs were performed via a hemispherical hammer. The failure modes of all specimens were determined as the local punching failure of the concrete core. Moreover, the impact force–time and displacement–time histories and the permanent deformation were discussed. The experiment results showed that increasing the steel faceplate thickness and concrete core height enhanced the impact performance of the SCSP-IACs. By contrast, increasing the IAC spacing weakened the impact performance. Moreover, the interlocking bolts slightly affected the impact responses of the SCSP-IACs. A finite element (FE) model was established and verified with test data. The model was used to analyze the internal forces and energy absorption of the SCSP-IACs under impact loads. The internal force diagrams of the panels at different impact stages were provided, and a significant hogging moment was observed from the bending moment distributions. The FE results also showed that the zones close to the center of the panel absorbed most of the impact energy. • A novel SCS panel with interlocked angle connectors (SCSP-IACs) was proposed. • The effects of variant parameters on impact responses of SCSP-IACs were studied. • Distributions of internal forces of SCSP-IACs under impact loads were revealed. • The variations of energy absorption in different zones of SCSP-IACs were presented. [ABSTRACT FROM AUTHOR]

• A SCS panel with energy absorption connectors (SCS-EC) was proposed for impact resisting. • Drop-weight impact tests and Finite Element simulations were conducted on the SCS-EC. • Failure modes and impact responses of the SCS-EC were obtained. • The effect of variant parameters on impact response of the SCS-EC was analyzed. This paper developed a new steel-concrete-steel sandwich panel with energy absorption connectors (SCS-EC) for resisting impact load, and the impact responses of the SCS-EC were studied by conducting impact tests and Finite Element (FE) simulations. The failure modes of the SCS-EC under impact loading could be categorized into two types based on the crushing magnitude of the energy absorption connector (EC). The EC was found to effectively dissipate impact energy via the plastic deformation of pleated steel plates and the compression of aluminum foam fillers. The steel-concrete-steel (SCS) panel showed the combination of global and local deformation under impact loading. Moreover, the influences of pleated plate thickness (t p) and angle (θ p), aluminum foam filler and initial momentum on the impact performances of the SCS-EC were studied quantitatively. The results showed that the SCS-EC exhibited enhanced impact resistance via increasing initial momentum of the impactor as well as filling aluminum foam in the EC and assuring the maximum crushing displacement of the EC being equal to its densification displacement. [ABSTRACT FROM AUTHOR]

In this study, a novel multi-cell steel–concrete–steel (MCSCS) sandwich panel was proposed for enhancing impact resistance of the traditional steel–concrete–steel​ (SCS) sandwich panel. The MCSCS sandwich panel employed stiffeners and headed studs to improve the bonding behavior between faceplates and concrete core as well as enhance its composite action and impact resistance. Impact tests were conducted on seven MCSCS panels via employing a drop weight loading system, and the influences of impact direction, spacing of headed stud and steel plate thickness on responses of MCSCS panels were investigated. Furthermore, the Finite Element (FE) model of the MCSCS panel was established, and the FE predictions were shown to be reasonable as compared to test results. Two types of failure modes of MCSCS panels under impact load were obtained via analyzing the test and FE results. In addition, based on the verified FE model, the influences of stiffeners, impact location and curvature of hammer head on impact responses of MCSCS panels were revealed via parametric studies. The results of FE simulations indicated that the impact location and curvature of hammer head had evident effect on the energy absorption and impact response of the MCSCS panel. Moreover, owing to the employment of stiffeners, the impact resistance of the MCSCS panel was evidently enhanced as compared to the traditional SCS panel. • A novel multi-cell steel–concrete–steel (MCSCS) sandwich panel was proposed. • The influences of critical parameters on impact responses of MCSCS sandwich panels were analyzed. • The energy dissipation mechanism of the MCSCS sandwich panel was revealed. • Combined with the inertial force, a clear definition of the inertial stage in the impact process was given. [ABSTRACT FROM AUTHOR]

This paper presents a new steel–concrete–steel sandwich panel with interlocked angle connectors (SCSP-IACs), and its punching performances were experimentally and analytically studied. Nine SCSP-IACs were fabricated and tested under the out-of-plane patch loads. Test results showed that SCSP-IACs exhibited two types of load–deflection (P – δ) responses with the variation of spacing of IACs (S), and increasing S also showed significantly negative influences on their punching behaviors. Two peak resistances were observed from the P – δ curves of all SCSP-IACs, and the first and second peak resistances (P u1 and P u2) corresponded to the punching shear failure of the concrete core and top steel faceplate, respectively. The punching shear resistance of SCSP-IACs was found to be evidently improved with the increase of steel faceplate thickness (t s) and concrete core thickness (d), while increasing S led to the decrease of punching shear resistance of SCSP-IACs. Moreover, the interlocking bolt in IACs exhibited little influence on the punching behaviors of SCSP-IACs. Finally, analytical models were proposed for calculating the punching shear resistance of SCSP-IACs, and their accuracies were also verified with test data. • A novel steel–concrete–steel sandwich panel with interlocked angle connectors (SCSP-IACs) was proposed. • The influences of variant parameters on punching behaviors of SCSP-IACs were studied. • The punching shear failure criterion of the SCSSP-IACs under out-of-plane patch loads was revealed. • Analytical models were developed to predict the punching shear resistance of SCSP-IACs. [ABSTRACT FROM AUTHOR]

New steel-concrete-steel sandwich beams with interlocked angle connectors (SCSSB-IACs) were first proposed, and their static behaviours were studied via conducting two-point loading tests. The failure mode, load–displacement response, resistance, and stiffness of the SCSSB-IACs were obtained. Moreover, the influences of thickness of steel faceplate, spacing of IACs, thickness of concrete core, shear-span ratio and interlocking bolts on static performances of the SCSSB-IACs were discussed. Two failure modes of the SCSSB-IACs were observed from the static tests, including flexural and shear failure. Moreover, test results indicated that the resistance and stiffness of the SCSSB-IACs were significantly affected by the thickness of steel faceplate, spacing of IACs and thickness of concrete core. In addition, the load–strain curves and deformation shapes of the SCSSB-IACs were obtained and discussed. Finally, analytical models were developed for predicting elastic stiffness and resistance of the SCSSB-IACs. The analytical models were also validated against the test data. • A steel-concrete-steel (SCS) sandwich beam with novel interlocked angle connectors (IACs) was proposed. • Two-point loading tests were conducted on the SCS sandwich beams with IACs (SCSSB-IACs). • The failure mode, load–displacement response, resistance, and stiffness of SCSSB-IACs were studied. • Analytical models were proposed to predict elastic stiffness and resistance of the SCSSB-IACs. [ABSTRACT FROM AUTHOR]

The blast response behaviors of curved Steel-Concrete-Steel (SCS) sandwich shells were investigated using nonlinear finite element method. The accuracy of the numerical model was verified against the available field blast test results. The numerical results showed that shear connectors played a vital role in bonding the face plates and concrete core and therefore improving the blast resistant capacity of curved SCS sandwich shell. In addition, different failure modes for the curved SCS sandwich shell under close- and far-field blast loading were observed, i.e., separation of rear plate from concrete core and buckling of face plates for the shell under close- and far-field blast loading, respectively. The effects of rise height (or rise to span ratio) and rear to front plate thickness ratio on the blast responses of curved SCS sandwich shells were also studied. Numerical results showed that the damage of curved SCS sandwich shell could be reduced by increasing rise height and rear to front plate thickness ratio. Moreover, the energy absorption efficiency of concrete core also showed increase with increasing rear to front plate thickness ratio. [ABSTRACT FROM AUTHOR]

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. • A novel interlocked angle connector (IAC) was developed for the steel–concrete–steel (SCS) sandwich beam. • Drop-weight impact tests on the SCS sandwich beams with IACs were performed. • Flexural and shear failure modes were observed for the SCS sandwich beams under impact load. • An analytical model was developed for obtaining dynamic responses of the SCS sandwich beam under impact load. [ABSTRACT FROM AUTHOR]

The response behavior of steel–concrete–steel (SCS) sandwich panels without shear connectors was experimentally studied under lateral pressure loading in this paper. The loading was applied by a hydraulic actuator on an inflated airbag to assert lateral pressure on the SCS panels. The failure modes and maximum resistance of the SCS panels were obtained from the test and compared with the numerical analysis results. It was found from the experimental and numerical studies that the end plates could function as shear connectors to achieve the composite action between face plates and concrete core. Based on the experimental and numerical observations, the formulae to predict the bending resistance and transverse shear resistance of SCS panel without shear connectors were developed and the accuracy of the proposed formulae was verified by comparing with the experimental and numerical results. [ABSTRACT FROM AUTHOR]

The performance of non-composite Steel–Concrete–Steel (SCS) sandwich panels under impact-induced impulsive loading was experimentally and numerically studied in this paper. Two SCS sandwich panels with different core depths were tested and the impulsive loading was applied in the laboratory by utilizing an inflated high pressure airbag to transfer the impact load from dropped projectile onto the panels. The deformation modes, applied pressures, displacement and strain responses of the panels were determined in the test. A combination of bending and shear deformation mode was observed in the SCS panel with thinner core while there was minimal visible deformation in the thicker panel. The maximum and permanent deformations of the panel with thicker panel were significantly reduced due to the increase in resistance and mass. Debonding between grout core and bottom plate was also noted in both panels during impact from the strain–time histories. Following the test, Finite Element (FE) models were constructed and verified against the test data to simulate the tests. It was shown in the FE analysis that the steel plates absorbed more energy due to its higher strength and ductility as compared to the grout core under the impact-induced impulsive pressure loading. [ABSTRACT FROM AUTHOR]

A steel-concrete-steel sandwich panel with novel hybrid connectors (SCSSP-HC) was proposed in this paper, and the flexural behaviours of the SCSSP-HC were obtained via conducting four-point bending tests. All the tested SCSSP-HCs exhibited the typical flexural failure mode with three specific failure types being categorized. The typical load–displacement response of the SCSSP-HC exhibited initial elastic stage, strength hardening stage and descending stage. In addition, the effects of faceplate thickness, spacing of headed stud, shear span and loading direction on the responses of SCSSP-HCs were quantitatively studied. The results indicated that the flexural resistance and elastic stiffness of the SCSSP-HC could be significantly improved via increasing the steel faceplate thickness and decreasing the shear span. However, the spacing of headed stud and loading direction had insignificant effect on the responses of the SCSSP-HC. Moreover, an analytical model was developed to predict the elastic stiffness, yielding moment and ultimate moment of the SCSSP-HC, and the accuracy of the analytical model was validated via comparing the analytical predictions with experimental results. [Display omitted] • A novel steel-concrete-steel sandwich panel with novel hybrid connectors (SCSSP-HC) was proposed. • Four-point bending tests were conducted on the SCSSP-HC. • The failure modes and load-displacement responses of the SCSSP-HC under flexural bending were obtained. • The effects of variant parameters on the flexural behaviour of the SCSSP-HC were quantitatively studied. • An analytical model was proposed to predict the elastic stiffness and flexural resistance of the SCSSP-HC. [ABSTRACT FROM AUTHOR]

In this paper, a novel cladding sandwich panel with aluminum foam-filled tubular cores (AFTC panel) was proposed to enhance the impact resistant performance of the traditional sandwich panel with empty tubular cores (ETC panel). The impact force and displacement responses, failure modes and energy absorption of the ETC and AFTC panels under impact loading were studied via drop-weight impact tests and numerical simulations. It was found that the impact process of the sandwich panel could be divided into three stages. In addition, the tubular cores and aluminum foam filler were found to dissipate the majority of the impact energy. The effects of impactor shape, impact position, aluminum foam filler and thickness ratio of flat steel plate to tube ( t f / t t ) on the impact behaviors of the sandwich panels were quantitatively studied. The results indicated that the impact force and energy absorption could be improved via filling aluminum foam, increasing the aluminum foam density and increasing the contact area between the impactor and sandwich panel. Filling aluminum foam could also avoid the sharp increase of the impact force after the compaction of the sandwich panel. The impact position exhibited little effect on the energy absorption of the sandwich panel when it was away from the edge of the sandwich panel. Moreover, the sandwich panel generally exhibited better energy absorption performances via specifying the flat steel plate and tubular cores to be of similar thickness. • A novel cladding sandwich panel was proposed for dissipating impact energy. • Drop-weight impact tests and FE simulations were conducted on the sandwich panel. • Failure modes and energy absorption behaviors of the sandwich panel were obtained. • The effect of variant parameters on responses of the sandwich panel was analyzed. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Off-center impact behaviors of SCS sandwich beams with bolt connectors were investigated. • Three failure modes, i.e., flexure, flexure-shear and fracture of bottom plate for the SCS beams. • The locations of impact on the SCS sandwich beams changed their failure modes. • An analytical model was proposed for predicting impact-induced displacement of the SCS beam. [ABSTRACT FROM AUTHOR]

A new stiffener-enhanced steel–concrete–steel (SESCS) sandwich beam was proposed for impact resisting, and the dynamic response of the SESCS sandwich beam under low-velocity impact loading was experimentally, numerically and analytically studied. Drop weight impact loading tests on SESCS sandwich beams were first conducted to obtain their failure modes, impact forces and displacement responses. All the tested beams exhibited flexural failure modes, and the impact resistance was found to be significantly improved for the beam enhanced with stiffeners in the tension plate. The Finite Element (FE) model of the SESCS sandwich beam under impact loading was established and validated against the test data in terms of failure mode, impact force and displacement. In addition, an analytical model was also developed for predicting displacement response of the SESCS sandwich beam under impact loading. The analytical-predicted displacement responses were found to be well matched with the FE-predictions and test results, which demonstrated the accuracy of the proposed analytical model. • A new stiffener-enhanced steel–concrete–steel (SESCS) sandwich beam was proposed. • Drop weight impact tests on the SESCS sandwich beams were conducted. • Flexural failure mode was observed for the SESCS sandwich beams under impact load. • An analytical model was proposed for predicting displacement response of the SESCS sandwich beam under impact load. [ABSTRACT FROM AUTHOR]

• Four curved SCS shells subjected to concentrated load were experimentally studied. • Failure mechanism and types of curved SCS shells were summarized. • Parameters affecting strength of curved SCS shells were numerically investigated. • Analytical models of curved SCS shells subjected to concentrated load were proposed. In this study, experimental works on four curved steel-concrete-steel (C-SCS) sandwich shells were carried out to assess their behaviors when subjected to concentrated loading with a 100-mm diameter hemispherical steel hammer through analyzing the failure mode, load–displacement relationship, strain, and deformation. The influences of the concrete and steel plate thicknesses, shear connector spacing, and rise–span ratio were numerically investigated. The results showed that the ultimate strength of C-SCS shells was improved with increasing concrete and face steel plate thicknesses and with decreasing shear connector spacing. The optimal rise-span ratio was found to be between 0.25 and 0.33. Moreover, to predict the nominal yield strength and the ultimate strength of C-SCS shells, an analytical model was developed, which matched well with the experimental and FE results. This analytical model can be used as a quick method to calculate the resistances of C-SCS shells under concentrated loading by a hemispherical steel hammer. [ABSTRACT FROM AUTHOR]

In order to improve the impact resistance of sandwich panels under low-velocity impact, the lotus leaf vein is selected as a biological prototype to design a bio-inspired honeycomb (BIH) sandwich panel. ABAQUS is used to establish and effectively verify the finite element (FE) model of the BIH sandwich panel. To systematically compare and study the mechanical properties of BIH and conventional hexagonal honeycomb sandwich panels under low-velocity impact, the maximum displacement of face-sheets, the deformation mode, the plastic energy consumption and the dynamic response curve of the impact end are presented. At the same time, the performance differences between them are revealed from the perspective of an energy absorption mechanism. Furthermore, the influence of the circumscribed circle diameter ratio of the BIH trunk to branch (γ), the thickness ratio of the trunk to branch (K) and the impact angle (θ) on impact resistance is studied. Finally, the BIH sandwich panel is further optimized by using the response surface method. It can be concluded that, compared to conventional hexagonal honeycomb sandwich panels, the addition of walls in the BIH sandwich panel reduces the maximum deformation of the rear face-sheet by 10.29% and increases plastic energy consumption by 8.02%. Properly adjusting the structural parameters can effectively enhance the impact resistance of the BIH sandwich panel. [ABSTRACT FROM AUTHOR]