Thickness Of Steel Faceplate Research Articles

Numerical and analytical studies of multi-cell steel-concrete-steel sandwich panels under blast load

The steel-concrete-steel (SCS) sandwich panel possesses exceptional resistance and good integrity, making it successfully applied in protective engineering. Aiming at improving the blast resistance of the structure, a novel multi-cell steel-concrete-steel (MCSCS) sandwich panel was proposed as an alternative to the traditional SCS panel. In this paper, the finite element (FE) model of the MCSCS panel under blast load was first constructed, and the modeling method was verified to be reasonable against field blast tests. Then, an analytical model for predicting the blast response of the MCSCS panel was established based on the equivalent single-degree-of-freedom (SDOF) system, and the strain rate effect was incorporated into the analytical model via employing the material models with strain rate dependence. Finally, three damage criteria for the MCSCS panel under blast load were proposed, and Pressure-Impulse (P-I) diagrams corresponding to different damage levels were constructed via the validated analytical model. Additionally, based on the established analytical model, the accuracy of simplifying the blast pressure history into the triangle form was verified. Numerical and analytical results indicate that the blast resistance of the MCSCS panel is significantly enhanced with the increase of the steel faceplate thickness, and the MCSCS panel exhibits superior blast resistance with the load acting on the top plate rather than bottom plate. In addition, owing to the arrangement of the L-shaped and side stiffeners, the MCSCS panel possesses preferable integrity, and its blast resistance is nearly unaffected by the spacing of headed stud.

Axial compressive behavior of low steel–concrete composite walls with multi-partition steel tubes and concrete

Herein an innovative steel–concrete composite walls (SCW) with multi-partition steel tubes and concrete was proposed, and the axial compressive behavior for eliminating the overall stability was firstly investigated based on three axial compression tests. The test parameters included overall height and width-to-thickness ratio of single cavity. The test results validated that low SCW component obtained considerably large axial compressive strength and axial stiffness. Experimental observations demonstrated that under the axial compression, SCW specimens did not occur apparent overall stability, and developed the step-like multi-wave local buckling in the free-weld region of steel faceplate and core-filled concrete crush at the buckling location. Based on the test results, a refined finite element model (FEM) of SCW component was built and validated, and the influences of span-to-height ratio, faceplate thickness, concrete strength, and steel strength were evaluated according to the parametric analysis. The axial compressive strength and axial stiffness of the SCW component were enhanced significantly with increasing span-to-height ratio, steel faceplate thickness, concrete strength, and steel strength. Theoretical equations were proposed based on the SCW component mechanism and parametric simulated results, and the proposed equations offer accurate predictions on the peak axial compressive resistance.

The behavior of steel-concrete-steel sandwich composite beams with box-profile shear connectors: Experimental and numerical

This study investigated the flexural behavior of new box-profile (BP) shear connectors in composite steel–concrete-steel (SCS) structures. To this end, nine beam specimens were fabricated and tested to evaluate the flexural and shear behaviors of BP shear connectors. The effects of geometric parameters, including the concrete core thickness, steel faceplate thickness, and shear connector thickness and width, on the flexural strength of BP shear connectors were then analyzed and reported. According to the results, increasing the shear connector width increased the rigidity of the beam, leading to a stress concentration in the slot welds. Therefore, the slot welds failed, leading to the detachment of the faceplate from the core. Increasing the strength of the concrete core above 40 MPa not only did not improve structural behavior but also led to BP shear connectors failing earlier than the concrete core, with the beam experiencing shear failure. Beams with 25≤hcontc≤30 and 3.33≤hconbc≤5 showed higher composite behavior. Finally, the beams were numerically modeled and validated using the nonlinear finite element method (FEM). A sensitivity analysis was conducted, and the concrete core strength and shear connector arrangement contributions were discussed.

Impact responses of steel–concrete–steel sandwich panels with interlocked angle connectors: Experimental and numerical studies

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.

Punching behaviors of steel–concrete–steel sandwich panels with interlocked angle connectors: Experimental and analytical studies

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 (Pu1 and Pu2) 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 (ts) 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.

Static behaviours of steel-concrete-steel sandwich beams with novel interlocked angle connectors: Test and analysis

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.

Double skin composite beams at Arctic low temperatures: Numerical and analytical studies

This paper focused on the developments of numerical and analytical models for double skin composite beams (DSCBs) subjected to low-temperature loadings. Firstly, ten two-point loading tests on DSCBs at varying low temperatures (T) were reported. Followed, a detailed 3D finite element model (FEM) based on ABAQUS was built for simulating ultimate strength behaviours of DSCBs at low temperatures. This FEM fully considered low-temperature influences on material properties, built detailed connector-concrete interactions, and material/geometry nonlinearities. Validations of FEM simulations by ten-test results confirmed the capabilities of the proposed FEM on simulating low-temperature structural behaviours of DSCBs. Parametric studies with 64 cases were performed with the validated FEM to make in-depth investigations on influences of T, steel-faceplate thickness (t), shear span ratio (λ), spacing of headed studs (S), and grade of concrete core (fc). The parametric studies showed that decreasing T from 20 to −80 has significantly improved the ultimate strength of DSCBs; varying shear span ratio (λ = 2.8–5.7) did not change the flexural failure mode of DSCBs; increasing fc marginally changed the ultimate strength behaviour of DSCBs. Corresponding discussions and considerations of these influencing parameters were also given. Analytical models were proposed for estimations of strength and stiffness of DSCBs under low-temperature loadings. Followed validations proved their successful predictions on the strength and stiffness of DSCBs under low-temperature loadings.

Flexural behaviours of one-way steel-concrete-steel sandwich panels with novel hybrid connectors: Tests and analysis

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.

Behaviors of novel sandwich composite beams with normal weight concrete

The ultimate strength behaviour of sandwich composite beams with J-hooks and normal weight concrete (SCSSBJNs) are studied through two-point loading tests on ten full-scale SCSSBJNs. The test results show that the SCSSBJN with different parameters under two-point loads exhibits three types of failure modes, i.e., flexure, shear, and combined shear and flexure mode. SCSSBJN failed in different failure modes exhibits different load-deflection behaviours, and the main difference of these three types of behaviours exist in their last working stages. The influences of thickness of steel faceplate, shear span ratio, concrete core strength, and spacing of J-hooks on structural behaviours of SCSSBJN are discussed and analysed. These test results show that the failure mode of SCSSBJN was sensitive to the thickness of steel faceplate, shear span ratio, and concrete core strength. Theoretical models are developed to estimate the cracking, yielding, and ultimate bending resistance of SCSSBJN as well as its transverse cross-sectional shear resistance. The validations of predictions by these theoretical models proved that they are capable of estimating strengths of novel SCSSBJNs.

Flexural performance of double skin composite beams at the Arctic low temperature

This paper presents the flexural performance of double skin composite beams (DSCBs) at different Arctic low temperatures. 12 DSCBs were prepared and tested under two-point loading at different Arctic low temperatures of 20, -30, -50, and -70C. The studied parameters include low-temperature level (T), steel-faceplate thickness (t), shear span ratio (), and spacing of headed studs (S). The experimental investigations under two-point loading tests showed that flexural failure occurred to all DSCBs, even including the specimen designed with the small ratio of 2.9. The ultimate strength behaviours of DSCBs were improved due to the improved mechanical properties of constructional materials and the confinement on shear connectors. The DSCB subjected to two-point loading and low temperatures exhibits a five-stage working mechanism. The stiffness and strength indexes of DSCBs increase linearly with temperature and t value increasing, while decreasing as shear span ratio boosts. In the contrast, the change of S value from 150 to 200 mm has little effect on the ultimate strength behavior of DSCB.

Compressive behaviours of steel-UHPC-steel sandwich composite walls using novel EC connectors

This paper reports the developments of steel-UHPC-steel sandwich composite walls with novel EC connectors (SUSSCW-ECs). The ECs in SUSSCW-ECs directly linked the two faceplates that enhance the composite action of the composite wall. Axial compression tests on 11 SUSSCW-ECs to investigate their compressive behaviours, and the selected key influencing parameters in the testing program included layout of C-channels, steel faceplate thickness, horizontal and vertical spacing of ECs, and strength of core. Under compression, the SUSSCW-ECs exhibited an elastic-plastic-recession three-stage working mechanism. Tests results show that major local buckling of faceplates ended the elastic stage, and UHPC crushing occurred at the peak compression resistance of SUSSCW-ECs. Installing the ECs with horizontal webs exhibited larger axial compression resistance of SUSSCW-ECs than those with V-web ECs. Increasing the steel faceplate thickness improved compressive behaviours of SUSSCW-ECs. Increasing horizontal and vertical spacing of EC connectors resulted in reduced ultimate compressive resistance of SUSSCW-ECs. Using UHPC improves both peak resistance and elastic stiffness of sandwich composite walls. Finally, this paper developed theoretical models to predict ultimate compressive resistance of SUSSCW-ECs, and validations against 11 test results showed their reasonable estimations.

Structural behavior of sandwich composite wall with truss connectors under compression

Sandwich composite wall consists of concrete core attached by two external steel faceplates. It combines the advantage of steel and concrete. The appropriate composite action between steel faceplate and concrete core is achieved by using adequate mechanical connectors. This research studied the compressive behavior of the sandwich composite walls using steel trusses to bond the steel faceplates to concrete infill. Four short specimens with different wall width and thickness of steel faceplate were designed and tested under axial compression. The test results were comprehensively evaluated in terms of failure modes, load versus axial and lateral deformation responses, resistance, stiffness, ductility, strength index, and strain distribution. The test results showed that all specimens exhibited high resistance and good ductility. Truss connectors offer better restraint to walls with thinner faceplates and smaller wall width. In addition, increasing faceplate thickness is more effective in improving the ultimate resistance and axial stiffness of the wall.

Steel-UHPC-steel sandwich composite beams with novel enhanced C-channel connectors: Tests and analysis

New steel-concrete-steel sandwich composite structure using novel enhanced C-channels (ECs) and ultra-high performance concrete (UHPC) was firstly proposed. The ECs offered strong tension separation resistance of faceplates from UHPC core as well as faceplate-UHPC interfacial shear resistance. Then, two-point loading tests on nine steel-UHPC-steel sandwich beams with ECs (SUSSB-ECs) were performed to study their ultimate strength behaviour. The studied parameters are thickness of steel faceplate, spacing of ECs, shear span, and strength of core. From the tests, though the shear span had quite significant influences on the ultimate strength of SUSSB-ECs, but all SUSSB-ECs failed in flexure mode even for the SUSSB-EC with short shear span ratio of 2.41, which confirms the bonding efficiency of ECs and high performance of this novel sandwich composite structures. The faceplate thickness exhibited significant, but the spacing of ECs has marginal influences on ultimate strength behaviour of SUSSB-ECs. Besides the tests, theoretical models were also developed to predict the initial stiffness, elastic stiffness, cracking load, yielding load, and ultimate load of the SUSSB-ECs. The validations of the predictions on stiffness and strength show that the developed theoretical models offer reasonable estimations on the stiffness and strength of SUSSB-ECs with limited errors.

PERFORMANCE STUDY OF SC WALL BASED ON EXPERIMENT AND PARAMETRIC ANALYSIS

Reverse cyclic lateral testing was undertaken to investigate the seismic behavior of 1/4 scale steel-plate concrete (SC) composite walls. The experimental program involved seven SC wall pier specimens. A new chamber structure is proposed, using steel diaphragms to connect the two steel faceplates to each other and to divide the SC wall pier into two parts. Conventional wall specimens failed mainly by tensile fracture of the concrete at the junction of the wall side and wall base, crushing of the concrete at the toe of the wall, or buckling of the steel faceplate. Tearing of the welded joints at the steel faceplates and steel diaphragm, buckling of steel, steel diaphragms being pulled out, tensile fracture and crushing of the concrete were the main failure modes of the chamber structure walls. A parametric numerical analysis in ABAQUS was developed to investigate the effects of the stiffening rib, steel web amount, material strength, shear-span ratio, and axial compression ratio on the seismic response of SC walls. The chamber structure of the SC wall piers can improve the peak load, ductility, and energy-dissipating capacity. The steel faceplate thickness and stiffening ribs can improve the behavior of SC wall piers.

Design and behaviour of double skin composite beams with novel enhanced C-channels

This paper firstly developed a new type of Double Skin Composite (DSC) beams using novel enhanced C-channels (ECs). The shear behaviour of novel ECs was firstly studied through two push-out tests. Eleven full-scale DSC beams with ECs (DSCB-ECs) were tested under four-point loading to study their ultimate strength behaviours, and the studied parameters were thickness of steel faceplate, spacing of ECs, shear span, and strength of concrete core. Test results showed that all the DSCB-ECs failed in flexure-governed mode, which confirmed the effective bonding of ECs. The working mechanisms of DSCB-ECs with different parameters were reported, analysed and discussed. The load-deflection (or strain) behaviour of DSCB-ECs were also detailed reported. The effects of studied parameters on ultimate strength behaviour of DSCB-ECs have been discussed and analysed. Including the experimental studies, this paper also developed theoretical models to predict the initial stiffness, elastic stiffness, cracking, yielding, and ultimate loads of DSCB-ECs. Validations of predictions against 11 test results proved the reasonable estimations of the developed theoretical models on those stiffness and strength indexes. Finally, conclusions were given based on these tests and analysis.

Seismic behaviours of SCS sandwich shear walls using J-hook connectors

This paper firstly proposed steel-concretes-steel sandwich walls with J-hook connectors (SCSWJs) as protective structures in the Arctic offshore platforms. Followed, six large scale SCSWJs were tested under lateral cyclic loading to investigate their lateral seismic behaviours. The investigated parameters in the testing program included spacing of J-hook, concrete core strength, thickness of steel faceplate, and aspect ratio. Seismic behaviours of SCSWJs were reported in details, and the effects of these parameters on their seismic behaviours were reported and discussed. The test results showed that the SCSWJ failed in flexure mode with characteristics of tensile yielding of side plate and steel faceplate, concrete crushing at the bottom toe, and outward local buckling of steel faceplates. Pinching effect was observed in the load versus lateral drift curves after the peak load due to premature local buckling of side plates and faceplates locating between the first and second row of J-hook from the bottom. This paper developed analytical models to predict the peak lateral resistance of SCSWJ. The validations against 12 results from six cyclic tests confirmed that the developed models offered reasonable but conservative predictions on the peak lateral resistance of SCSWJ. This study promotes the applications of the SCSWJ in the earthquake-prone Arctic regions.

Compressive behaviours of novel SCS sandwich composite walls with normal weight concrete

Novel steel-concrete-steel (SCS) sandwich composite walls with normal weight concrete (NWC) and J-hook connectors have been proposed for shear walls in buildings and protective walls in Arctic offshore platforms. Eight SCS sandwich walls with J-hook connectors and NWC were tested under monotonic compression. Investigated parameters in this testing programme included thickness of steel faceplate, spacing of J-hook connectors, strength of NWC core, and different types of connectors. Based on the reported test results, the influences of these parameters were analysed and discussed. Theoretical models were developed to predict compressive resistance of SCS sandwich walls with different types of connectors. The developed analytical models considered the confinement of steel faceplate on compressive strength of concrete core and proposed new buckling length coefficient for steel faceplate in SCS sandwich wall. The accuracies of the proposed analytical models were checked through validations against 50 test results reported by authors and other researchers. Finally, step-by-step design procedures were proposed to determine compressive resistance of SCS sandwich walls with different types of shear connectors.

Compressive behaviours of double skin composite walls at low temperatures relevant to the arctic environment

Double skin composite (DSC) ice-resistant walls have been proposed for the Arctic oil platforms. This paper makes efforts to study the compressive behaviours of DSC walls at low temperatures of −80 °C–20 °C. Seven DSC walls were tested at low temperatures to investigate the influences of different parameters on their compressive behaviours that included low temperature levels, thickness of steel faceplate, and spacing of connectors. The compressive behaviours of the DSC wall at low temperatures were reported and discussed in terms of failure mode, compressive force versus shortening behaviours, and load-strain behaviours. The influences of different parameters on compressive behaviours of DSC walls at low temperatures were reported and analysed. Theoretical models were developed to predict the ultimate compressive resistance of DSC walls at low temperatures. The accuracy of the developed theoretical models were checked through validations against reported seven test results.

Compressive behaviours of steel-concrete-steel sandwich walls with J-hooks at low temperatures

Abstract Recently, gravity base offshore platforms consisting of novel steel-concrete-steel (SCS) sandwich ice-resistant walls with J-hook connectors have been developed for the Arctic oil & gas production. This paper made pioneer studies on compressive behaviours of SCS sandwich composite walls with J-hook connectors (SCSSWJ) at the Arctic low temperatures through a nine-specimen testing program. The low temperatures ranging from 20 to −80 °C, thickness of steel faceplate, spacing of connectors, and concrete strength were selected as key parameters in this experimental study. The test results revealed the failure modes and load versus shortening/strain behaviours of the SCSSWJ at low temperatures. These studied parameters were found to have significant influences on the compressive behaviours of this novel SCSSWJ. Including experimental studies, this paper also developed theoretical models to predict the ultimate compressive resistance of SCSSWJ at the low temperature environment. The validations of predictions against results of nine reported tests confirmed that the theoretical models were capable of provide reasonable but conservative estimations on the compressive resistance of such novel SCSSWJ.

Developments of double skin composite walls using novel enhanced C-channel connectors

The developments of double skin composite (DSC) walls with novel enhanced C-channel connectors (DSCW-EC) were reported. Followed axial compression tests on prototype walls were carried to evaluate structural performances of this novel DSC composite structures. The testing program consists of five specimens and focused on the layout of the novel enhanced C-channel (EC) connectors, which include the web direction of C-channels, steel-faceplate thickness, vertical and horizontal spacing of Cchannels. Crushing in concrete core and buckling of steel faceplate were two main observed failed modes from the compression tests. However, elastic or plastic buckling of the steel faceplate varies with designed parameters in different specimens. The influences of those investigated parameters on axial compressive behaviors of DSCW-ECs were analyzed and discussed. Recommendations on the layout of novel EC connectors were then given based on these test results and discussions. This paper also developed analytical models for predictions on ultimate compressive resistance of DSCW-ECs. Validation against the reported test results show that the developed theoretical models predict well the ultimate compressive resistance of DSCW-ECs.