Composite Shear Research Articles

Cyclic performance of prefabricated composite shear stud connectors for accelerated bridge construction

This study examines the cyclic shear-slip performance of a novel prefabricated composite shear stud (PCSS) connector designed for accelerated bridge construction (ABC) of composite structures. An in-depth experimental procedure is employed involving the design and fabrication of four push-out specimens with two different stud configurations. The specimens are then tested under both monotonic and cyclic-to-monotonic loading protocols. Upon completion of the testing phase, a meticulous inspection of the fractography is conducted to delineate and qualify the failure mode of the PCSS connectors. Simultaneously, a comprehensive shear-slip curve is derived from the measured data, enabling a detailed analysis over the mechanical performance. Furthermore, the study calculates a series of deformation-associated indicators from the shear-slip curve, effectively quantifying the ductility, recoverability, and capacity of the PCSS. The test results accentuate a well-deformed and ductile failure mode of the tested PCSS specimens, marked by the stud fracture and crushing of surrounding concrete. This could be attributed to the constraint of vertical plates of the PCSS on the concrete, which improves the capacity and recoverability of the PCSS. Whereas, the performance of the PCSS is also notably influenced by the group nail effect, for which the ductility and per-stud capacity degrade with the increase in the number of studs. Especially, the PCSS specimen exhibits full elastic-to-plastic hysteresis loops under cyclic loads, together with the satisfied ductility, implying an excellent potential of the PCSS to dissipate energy under impact loads. In addition, the PCSS displays a robust stiffness across different cyclic loading blocks. Hence, satisfactory post-damage ductility has still been observed in the PCSS under the monotonic loading after the cyclic loading. In conclusion, this work elucidates the superiority of the PCSS in terms of capacity, ductility, and recoverability, providing a promising basis for their application in the accelerated construction of composite bridges.

Sectional strength design of a double-skin truss-reinforced composite shear wall

The double-skin truss-reinforced composite shear wall is an innovative element which comprises two steel plates, core concrete, concrete-filled steel tubes (CFSTs), which act as boundary members, and steel truss connectors. Truss connectors decrease the out-of-plane deformation that affects the steel plates, and due to the resultant connection and constraint effects, the truss connectors enhance the bearing capacity of the wall. This paper briefly introduces the quasi-static test of five full-scale rectangular double-skin truss-reinforced composite shear wall specimens. The specimen exhibited shear compression failure with an aspect ratio of 2.0, and flexure shear failure occurred when the aspect ratio exceeded 2.0. Based on the analysis of actual stress state of the steel web and actual working performance of the infilled concrete, the shear strength and flexure strength design formulas of double-skin truss-reinforced composite shear wall were established. Comparison results with 26 specimens demonstrate that the design formulas exhibit remarkable accuracy, as most errors are within 20 % and 25 %, respectively. Which provide a preliminary sectional strength design proposal for the double-skin truss-reinforced composite shear wall.

Study on post-fire resistance of ceramsite foamed concrete sandwich composite slabs

The ceramsite foamed concrete sandwich composite slab has the characteristics of light weight and good heat insulation performance. At present, there are few research on the fire resistance of ceramsite foamed concrete sandwich composite slab at home and abroad, and the damage mechanism of ceramsite foamed concrete sandwich composite slab under fire is not clear. To fill this gap, constant load-temperature rise fire test and static loading test on five slab specimens are conducted by varying the parameters such as sandwich layer thickness, reinforcement pattern, shear span ratio and construction method. Based on the test, the results are studied, including the temperature distribution and deformation characteristics under fire, load–displacement curves, crack pattern and damage mode, residual bearing capacity of the slab after fire. The results show that ceramsite foamed concrete sandwich composite slab has good thermal insulation performance, the overall working performance, flexural bearing capacity and deformation ability of the slab is mainly affected by the slip at the composite surface. The integrity of the slab and the residual bearing capacity and ductility after fire could be significantly improved by the configuration of truss rebar. It is suggested to decrease the time difference of concrete placement at the composite surface or set shear keys and truss rebar to improve the cooperative working ability between the surface layer and the sandwich layer. Moreover, Finite Element analysis is carried out by ABAQUS software and the results show good agreement with experiment results. A new compositeness degree analysis (CDA) method for calculating the residual bearing capacity of ceramsite foamed concrete sandwich composite slab after fire considering different compositeness degree is proposed, which could be used for the practical engineering design.

Data-Driven Prediction Model for High-Strength Bolts in Composite Beams

In recent years, the application of artificial intelligence-based methods to engineering problems has received consistent praise for their high predictive accuracy. This paper utilizes a BP neural network to predict the strength of steel–concrete composite beam shear connectors with high-strength friction-grip bolts (HSFGBs). These connectors are widely used in bridge and building construction due to their superior strength and stiffness compared to traditional beams. A validated finite element model was used to predict the strength of HSFGB shear connectors. A reliable database was created by analyzing 208 models with different characteristics for machine learning modeling. Previous studies have identified issues with result variation and overestimation or underestimation of shear connection strength. Among the machine learning methods evaluated, the backpropagation neural network model performed the best. It achieved a goodness of fit of over 93% in both the training and testing sets, with a low coefficient of variation of 6.50%. Concrete strength, bolt diameter, and bolt tensile strength were found to be important variables influencing the strength of shear connectors. Other variables showed a proportional or inverse relationship with compressive strength, except for concrete strength and bolt pretension. This study presents an accurate machine learning approach for predicting the strength of HSFGB shear connectors in steel–concrete composite beams. The study offers valuable insights into the effects of various variables on the performance of shear connection strength, providing support for structural design and analysis.

To the magnetorheological properties of magnetic gels with non-spherical particles. Viscoelastic modulus relaxation after the field alternation

We present a theoretical model of magnetorheological effects in a soft magnetic gel with non spherical (disc-shaped) magnetizable particles. This model is based on micro-mechanic consideration of the particles reorientation in a soft elastic-viscous medium after step-wise alternation of an applied magnetic field. Analysis of dynamics of the composite macroscopic shear modulus change after the field alternation is in focus of our consideration. The presented results explain recently experimentally observed magnetorheological and relaxation effects in ferrogels with the discotic particles: increase of the composite modulus under the field action; relaxation of its storage and loss components as well as overshoot of the loss modulus after the field stepwise activation and deactivation.

ÇEVRİMSEL YÜKLER ALTINDA CFRP İLE GÜÇLENDİRİLMİŞ ÇELİK LEVHALI PERDELERDE ÇELİK LEVHA İLE CFRP ARASINDAKİ BİRLEŞİMİN AYRILMASININ DENEYSEL İNCELENMESİ

Steel plate shear walls, as an innovative lateral load resisting system, are widely used in the world. In this study, carbon fiber-reinforced polymer textile (CFRP) is used in order to increase load carrying capacity, ductility and energy dissipation of steel plate shear walls. A specimen of composite plate shear wall through epoxy bonding between two steel plates in a steel frame was prepared, and cyclic loading was applied. The finite element model of the steel plate shear wall without CFRP textile was prepared, and an in-plane static pushover analysis was conducted. The load-displacement curves obtained from the analysis of the model were compared with the results of the experimentally-obtained CFRP textile added specimen, and they were found to be in a good agreement. In conclusion, as a result of the addition of CFRP textile to the steel plate shear wall, it was observed that the carbon fiber reinforced polymer delaminated from the plate surface, and its contribution to the system behavior remained limited. Accordingly, it has been observed that in order to obtain the expected contribution, it is necessary to ensure that the steel plate and the textile must have full bonding and act as a composite material.

Finite element simulation and strength evaluation on innovative and traditional composite shear wall systems

SummaryComposite shear wall (CSW) system, which consists of a steel boundary frame and a steel panel with a reinforced concrete (RC) panel attached to one side of it using bolts, is commonly used in mid‐ to high‐rise buildings. In a CSW system, RC panel functions as out‐of‐plane restraint to prevent overall buckling of steel panel, thereby enhancing system behavior. However, for a traditional CSW system, the RC panel is in direct contact with the steel boundary frame. The RC panel tends to crush under seismic loading, thereby leading to a weak constraint to steel panel buckling. The innovative CSW system, where a gap remained between steel boundary frame and RC panel, demonstrated better cyclic behavior than the traditional CSW system. Current studies aimed to investigate cyclic behavior, parameter effects, and determination of RC panel stiffness of CSW systems. In this paper, detailed FE models were developed for simulating cyclic behavior of both innovative and traditional CSW systems and validated by test results. FE models accurately predicted lateral load‐drift response and failure patterns of both innovative and traditional CSW systems. System failure patterns and load‐carrying mechanism of RC panels were discussed. The effects of major parameters, including steel panel thickness, RC panel thickness, ratio of bolt spacing to steel panel thickness, and gap between frame and RC panel, were examined using the validated models. Simulation results indicated that steel panel thickness contributed to increase the lateral strength and initial stiffness of both innovative and traditional CSW systems. Although RC panel thickness, ratio of bolt spacing to steel panel thickness, and gap between frame and RC panel had negligible effects on system strength and stiffness, they should also be carefully designed to ensure local stability of the steel panel and system ductility. Formulations were proposed for predicting the lateral strength of both innovative and traditional CSW systems. The average difference between calculated and test/simulated lateral strength was less than 3%.

Experimental study on effect of assembly process on seismic performance of modular precast composite shear wall structures

Modular buildings utilize prefabricated volumetric modules to resist gravity and lateral loads and can achieve a high prefabrication level. Different from cast-on-site reinforced concrete structures, the seismic performance of precast structures is affected by the construction process. This study investigated the effect of assembly process on the seismic performance of an innovative modular precast composite shear wall structure. Contrastive shaking table tests were carried out on two 1/4-scaled modular models, one by the fully modular precast method and the other by the modular cast-on-site method. Test results showed that the bottom vertical joints were the most critical components and dominated the failure patterns for both modular models. The weakening of screw threads induced by the small model size and assembly process decreased the ultimate capacity of the modular precast model. The modular precast model showed up to a 6.7 % lower initial frequency and 17.6 % lower initial damping ratio than the modular cast-on-site model. The assembly process had no essential influence on the displacement and acceleration responses before vertical joint failure but significantly increased the displacements as the joints approached failure in the limit state. The test work highlights the importance of ensuring bolt strength and protecting bolt threads in practical engineering applications.

Research on seismic resilience evaluation index of mid-rise CFS structures

This paper focuses on the deficiencies of Chinese standard GB/T 38591–2020, and combines the mechanical characteristics, post-earthquake damage characteristics, and repair methods of mid-rise cold-formed steel (CFS) structures to define the damage grade of structural components and revise various index parameters in the “Standard”. Based on the calculation results of 120 sets of 6-story CFS composite shear wall structures, the multi-parameter seismic resilience evaluation index and grading criteria applicable to mid-rise CFS structures are fitted, and the index values (R values) for dividing the 5 resilience grades are 0.5, 1.0, 1.25, and 1.7, respectively. By considering different building usage functions and seismic effects, the 5-story CFS structure shaking table test models and the irregular eccentric CFS structure numerical model are used to jointly verify the reasonableness and universality of the seismic resilience evaluation index and grade classification criteria. The multi-parameter resilience evaluation index system lays the foundation for the study of seismic resilience of mid-rise CFS buildings and provides new ideas for establishing quantitative resilience evaluation indexes for different building systems.

Experimental investigation on the seismic behavior of composite steel plate shear wall restrained by ECC panels

The composite structures using engineered cementitious composites (ECC) and steel are promising to achieve good seismic performance due to their excellent deformability and energy dissipation. This paper proposed a novel composite steel plate shear wall restrained by ECC panels. The shear wall system consists of boundary frame, steel plate and precast ECC panels. The steel plate is sandwiched between two precast ECC panels by bolts. Then, the sandwich panel is bolted to the boundary frame by angle steels. Experimental investigation was conducted on the proposed composite shear walls to evaluate their seismic performance. Five one-story one-span specimens with ECC panels considering the effects of panel-frame connection types, reinforcement ratio in ECC panels and aspect ratio were tested, as well as a control specimen with concrete panels. Test results revealed that compared with ordinary buckling-restrained steel plate shear wall, the proposed composite shear walls displayed sufficient ductility, high initial stiffness and satisfactory energy dissipated capacity. Severe cracking and spalling of concrete panels were detected, while the ECC panels still maintained integrity and had high residual strength in the later stage of loading. ECC panels made a considerable contribution to shear resistance in addition to effectively restraining the buckling of the steel plate. In comparison with the specimen using partial four-side connection, the shear capacity, initial lateral stiffness and accumulated dissipated energy of the specimen using four-side connection were notably enhanced by 103%, 22.8% and 108%, respectively. Moreover, using two-side connection weakened the shear capacity and initial lateral stiffness of the specimen by 29.4% and 29.8%, because it could not exhibit complete shear and tension field actions as the specimen using four-side connection.

Thermal performance and reduced carbon footprint of precast concrete sandwich wall panels (PCSWPs) with composite shear connector – an experimental assessment

ABSTRACT The objective of the present work is to compare the thermal performance of precast-reinforced sandwich wall panels to that of precast-reinforced concrete wall panels. The variables used in this investigation are two different insulation materials (expanded polystyrene (EPS) and extruded polystyrene (XPS) and three different connectors (steel, glass fiber (GFRP)-wrapped steel, and aramid fiber (AFRP)-wrapped steel). A thermal analyzer setup was developed to investigate the heat transfer between the exterior and interior of the panels. The results showed that sandwich wall panels had better thermal resistance compared to the precast concrete wall panel. The temperature on the interior surface of the control specimen was 44°C after the stipulated test period. According to the experimental findings, inclusion of the insulation layer (no connectors) reduced heat transfer by 7.4°C for XPS and 6.7°C for EPS. The temperature on the interior surface was reduced only by 1.6°C and 3.6°C for sandwich panels with steel shear connectors and EPS and XPS as insulation material, respectively, indicating thermal bridging. Diminution of temperature on the interior surface of the sandwich panels with FRP-wrapped connectors varied between 5°C and 7.1°C compared to control specimen as the corrugated C-type fiber-wrapped shear connectors significantly decreased the thermal bridge between layers. In sandwich wall specimens, CO2 emissions from concrete were decreased up to 33%. Embodied carbon during the manufacturing of these panels was also compared, and it was found that the carbon emission was reduced up to 21% in the precast sandwich panels when compared to the precast reinforced wall panels.

Cyclic test evaluation of double skin composite hybrid coupled wall with frictional steel truss coupling beams

The seismic performance of double skin composite shear walls (DSCSWs) has significant superior to conventional reinforce concrete (RC) shear walls. Previous studies have neglected the changes of axial compressive forces and bending moments actting on the top of wall piers. In addition, behaviors hybrid coupled wall (HCW) under real boundary condition have not been fully investigated. Thus, in this study, a novel quasi-static test which incorporates the boundary conditions of substructures in a prototype building was preformed. And a cyclic test was carried out on a 2/3-scaled double skin composite (DSC) HCW with frictional steel truss coupling beams (FSTCBs) using the proposed method. The seismic behavior of specimen under reversed lateral cyclic loads was investigated. The failure modes of the wall piers mainly included local buckling of the steel faceplate, fracture of the side plate, and concrete crushing at the corners of walls. The force-displacement hysteresis curve of FSTCBs was obtainable from the attached instruments as the force transmission path of the steel truss could be clearly observed. DSCSW pier deformation was evaluated based on the deformative relationship between the wall pier and FSTCB. The FSTCB primarily dissipated 80% of the total energy input prior to damage occurring in the DSCSW. Strain distribution curves along the DSCSW showed that the pre-peak-resistance plane section assumption was still valid.

Seismic behavior of self-restrained grid shear wall with diagonal CFRP-steel composite strips

This paper introduces an innovative structure for a self-restrained grid shear wall with diagonal CFRP-steel composite strips. Steel and CFRP strips are interwoven to enhance the structural integrity of the shear wall. Quasi-static tests are initially conducted on two shear wall specimens with and without diagonal CFRP-steel composite strips. Subsequently, a finite element model is established to represent the self-restrained grid shear wall with diagonal CFRP-steel composite strips. This model is helpful for exploring the influence of composite strips arrangement on the performance of shear walls. Furthermore, a prediction formula is developed to estimate the load-bearing capacity of the CFRP-steel composite strips grid shear wall. The test results show that the yield bearing capacity, ultimate bearing capacity, stiffness and energy dissipation capacity of the specimens increase by 46.6%, 58.2%, 43.6%, and 16.3% respectively after the replacement of composite strips. In addition, the results of finite element simulation indicate that the diagonal arrangement exhibits the highest efficiency in the use of CFRP materials among three reinforced structural forms-diagonal, spaced, and fully arranged composite strips. This arrangement is also the most economical and has the least adverse influence on the internal forces of the frame columns.

Optimized Computational Intelligence Model for Estimating the Flexural Behavior of Composite Shear Walls

This article presents a novel approach to estimate the flexural capacity of reinforced concrete-filled composite plate shear walls using an optimized computational intelligence model. The proposed model was developed and validated based on 47 laboratory data points and the Transit Search (TS) optimization algorithm. Using 80% of the experimental dataset, the optimized model was selected by determining the unknown coefficients of the network-based computational structure. The remaining 20% of the data was used to evaluate the accuracy of the model, and the best-performing structure was selected. Furthermore, the final neural network details were subjected to statistical analysis to extract a user-friendly formula, making it easier to apply in practice. The proposed ANN model and the proposed user-friendly formula were then compared with the AISC 341-16 and experimental results and demonstrated their efficacy in predicting the flexural behavior of composite shear walls. Overall, the proposed approach provides a more reliable and efficient framework for estimating the flexural behavior of composite shear walls.

Axial compressive behavior of corroded double-steel-plate composite shear wall with binding bars

Steel structure is susceptible to corrosion, and corrosion will seriously affect its own load-bearing capacity and service life. In this paper, the axial compressive behavior of double-steel-plate composite shear wall (DSCW) with binding bars under different corrosion degrees is experimentally studied. The typical failure modes include the steel plate local buckling, binding bars fracture, concrete crushing, and steel plate weld tearing. The increase of corrosion rate has unfavorable influence on the axial compressive bearing capacity, initial stiffness, and ductility of DSCW. Finite element (FE) models are established to further investigate the axial compressive behavior of DSCW. It is concluded that the concrete and steel plate strength grade, the concrete section area, the steel plate thickness, and the binding bars diameter and spacing significantly affect the axial compressive bearing capacity of DSCW. A formula calculating the axial compressive bearing capacity of corroded DSCW with binding bars is proposed. The formula agrees well with the test results and can provide a reference for the engineering application.

Numerical investigation on seismic performance of reinforced rib-double steel plate concrete combination shear wall

Double steel plate concrete composite shear wall (SCSW) has been widely utilized in nuclear power plants and high-rise structures, and its shear connectors have a substantial impact on the seismic performance of SCSW. Therefore, in this study, the mechanical properties of SCSW with angle stiffening ribs as shear connections were parametrically examined for the reactor containment structure of nuclear power plants. The axial compression ratio of the SCSW, the spacing of the angle stiffening rib arrangement and the thickness of the angle stiffening rib steel plate were selected as the study parameters. Four finite element models were constructed by using the finite element program named ABAQUS to verify the experimental results of our team, and 13 finite element models were established to investigate the selected three parameters. Thus, the shear capacity, deformation capacity, ductility and energy dissipation capacity of SCSW were determined. The research results show that: compared with studs, using stiffened ribs as shear connectors can significantly enhance the mechanical properties of SCSW; When the axial compression ratio is 0.3–0.4, the seismic performance of SCSW can be maximized; with the lowering of stiffener gap, the shear bearing capacity is greatly enhanced, and when the gap is lowered to a specific distance, the shear bearing capacity has no major affect; in addition, increasing the thickness of stiffeners can significantly increase the shear capacity, ductility and energy dissipation capacity of SCSW. With the rise in the thickness of angle stiffening ribs, the improvement rate of each mechanical property index slows down. Finally, the shear bearing capacity calculation formula of SCSW with angle stiffening ribs as shear connectors is derived. The average error between the theoretical calculation formula and the finite element calculation results is 8% demonstrating that the theoretical formula is reliable. This study can provide reference for the design of SCSW.

Microstructure and deformation workability of Ni-based superalloy Udimet720Li fabricated by composite shear flow casting

In this study, the effect of composite shear flow casting (CSFC) on microstructure and hot deformation process of Ni-based superalloy Udimet720Li has been investigated. Udimet720Li superalloy was produced by using CSFC and conventional casting methods, followed with the same isothermal forging process. The microstructures of both CSFC and conventionally solidified (CS) samples were characterized using optical microscope, scanning electron microscope, energy dispersive X-ray spectroscopy and electron backscatter diffraction. Results show that the CSFC sample owns excellent microstructural uniformity with a reduced area fraction of segregation regions, leading to a wider processing window for subsequent deformation, compared to the CS sample. Besides, the deformation resistance and the thermal workability of CSFC sample are significantly improved because of the homogeneous microstructure, resulting in the uniform deformation during subsequent isothermal forging.

Shear performance investigation of recycled concrete load-bearing blocks for sustainable masonry

PurposeRecycled concrete is an economical and environmentally friendly green material. The shear performance of recycled concrete load-bearing masonry is studied, which is great of significance for its promotion and application and also has great significance for the sustainable development of energy materials.Design/methodology/approachIn total, 30 new load-bearing block masonry samples of self-insulating recycled concrete are subjected to pure shear tests, and 42 samples are tested subjected to shear-compression composite shear tests. According to the axial design compression ratio, the test is separated into seven working conditions (0.1–0.8).FindingsAccording to the test results, the recommended formula for the average shear strength along the joint section of recycled concrete block masonry is given, which can be used as a reference for engineering design. The measured shear-compression correlation curves of recycled concrete block masonry are drawn, and the proposed limits of three shear-compression failure characteristics are given. The recommended formula for the average shear strength of masonry under the theory of shear-friction with variable friction coefficient is given, providing a valuable reference for the formulation of relevant specifications and practical engineering design.Originality/valueSimulated elastoplastic analysis and finite element modeling on the specimens are performed to verify the test results.

Effective width evaluation for HSS-UHPC composite beams with perfobond strip connectors

This paper investigates the design criteria for predicting the effective width in high strength steel (HSS)-to-Ultra-high performance concrete (UHPC) composite beams with perfobond strip connectors (PBLs). Twenty-eight HSS-UHPC composite beams with varying parameters of shear connection degree (C), span length (S), thickness (T) and width (W) of UHPC slab were numerically simulated and evaluated. The composite beams' strain distribution and shear lag effect were presented and analyzed. Results indicate that the shear lag of the HSS-UHPC composite beam under flexural loadings was significant, and the effective width coefficient (β) of the concrete slab was enlarged by the magnification of the C, T, and S. A comparison between the results obtained from the FE model and procedures for predicting the composite beams’ effective width was performed to assess the feasibility of design approaches. It reveals that existing codes provide good predictions for the HSS-UHPC composite beams with a W/S ratio below 0.3 but underestimate the effective width for those with W/S ratio beyond 0.3. Furthermore, an empirical model for predicting the effective width of HSS-UHPC composite beams, considering the shear lag and steel-to-UHPC interfacial slip, is derived and fitted by a data regression. The outcome of this study can provide a reference for HSS-UHPC composite beams in practical applications.

Confinement mechanism of rectangular CFST components using double horizontally-corrugated steel plates

This paper presents experimental and analytical investigations on the confinement mechanism of a novel rectangular concrete-filled steel tube (CFST) component for use in composite shear walls. The CFST component consists of a steel tube made by welding double horizontally corrugated steel plates and double flat steel plates, and infilled with concrete. Tests of eight components and finite element analysis of twenty-three components under uniform compression were conducted to explore confinement mechanism of the novel tube to core concrete. The impacts of several factors such as steel plate thickness, nominal sectional aspect ratios, slenderness ratios, and the strength of the steel and concrete on the confinement mechanism were analyzed. The non-uniform confinement mechanism of horizontally corrugated steel plates was investigated based on their vertical and horizontal strain responses at the wave crests, middles, and troughs. The test results and numerical simulations demonstrate that the proposed CFST components exhibited desirable axial compressive behavior with ductile failure modes. The tested specimens with nominal sectional aspect ratios ranging from 1.2 to 2.39 had strength indexes greater than 1.17. Even with a width-thickness ratio of 325.33, the horizontally corrugated steel plates effectively confined the core concrete. Furthermore, this research proposed a design strength model that considered the confinement effects of corrugated plates. The model accurately predicted the experimental and numerical results.