Reinforcement Size Research Articles

Mechanical performance of stud connection in steel-concrete composite beam under reversed stress

During earthquakes, concrete slabs in composite beams are subjected to cyclic compressive and tensile stresses. Previous experimental tests indicated that the strength in the cyclically loaded stud connections degraded faster than in ordinary monotonic push-out tests. To assess the mechanical performance of the local composite connection, this research first calibrates a finite element analysis (FEA) model of subassembly specimens. Using the experimentally validated FEA model, a parametric study was conducted with various stud and reinforcement sizes and configurations, material properties, slab widths, and loading protocols. A comprehensive analysis quantified the effects of influential factors on mechanical behaviour and performance. The results were compared with the previously constructed equations to assess the ultimate stud connection strength. As a novel approach from a previous study, the stud connection stiffness is newly evaluated, using classical theory and empirical formulae and a new mathematical model was proposed.

Analysis of influencing factors on shear behavior of the reinforced concrete deep beams

A database including 833 specimens on reinforced concrete (RC) deep beams with shear failure is presented in this paper. Comprehensive influences of web reinforcement ratio, shear span-to-depth ratio, depth-to-width ratio, and compressive strength of concrete on the shear behavior of deep beams are discussed. It is found that the normalized shear strength of deep beams decreases with an increase of the shear span-to-depth ratio and this trend is affected significantly by the concrete strength, depth-to-width ratio, and web reinforcement ratio. Besides, the restrictions on minimum web reinforcement and minimum sectional size are investigated. It is found that the restrictions on minimum web reinforcement and the minimum sectional size are significantly affected by the web reinforcement ratio and are closely related to the reinforcement strength and concrete strength. However, the effect of the strength ratio of concrete to shear reinforcements on the limit of the amount of web reinforcements has been ignored in current codes. The characteristic value of web reinforcement, considering the web reinforcement ratio and the strength ratio of concrete to shear reinforcements, is proposed. For the horizontal and vertical reinforcements, the minimum characteristic values of 0.54 and 0.25 are suggested as the restrictions on the minimum amount of web reinforcement, respectively. The maximum characteristic values of 1.5 and 1.7 are proposed as the restriction on the minimum sectional size. Moreover, an equation for the ultimate shear strength of deep beams corresponding to the minimum sectional size is also suggested. Compared with the relevant provisions of the current codes, the suggestions on minimum web reinforcement requirements and minimum sectional restrictions are better.

Effect of Content and Size of Reinforcements on the Grain Evolution of Graphene-Reinforced Aluminum Matrix Composites.

Graphene-reinforced aluminum matrix composites (GRAMCs) attract great interest in industries due to their high performance potential. High-temperature processes such as sintering and aging are usually applied during the preparation of GRAMCs, leading to grain coarsening that significantly influences its properties. In this work, a modified 3D Monte Carlo Potts model was proposed to investigate the effect of content and size of graphene on the grain evolution during the heat treatment of GRAMCs. Grain growth with graphene contents from 0.5 wt.% to 4.5 wt.% and sizes from 5 μm to 15 μm were simulated. The grain growth process, final grain size and morphology of the microstructure were predicted. The results indicated that both the content and size of the reinforcements had an impact on the grain evolution. The pinning effect of grain size can be enhanced by increasing the content and decreasing the size of graphene. Agglomeration and self-contacting phenomena of the graphene arose obviously when the contents and sizes were relatively high. The average grain size decreased by 48.77% when the content increased from 0.5 wt.% to 4.5 wt.%. The proposed method and predicted regulations can provide a reference for the design and fabrication of GRAMCs.

Quantitative analysis of microstructure and mechanical properties of Nb–V microalloyed high-strength seismic reinforcement with different Nb additions

Abstract HRB500E seismic steel bars are mainly used in high-rise buildings near the seismic zone. The influence of different niobium contents (0–0.023%) on the microstructure and mechanical properties of HRB500E seismic reinforcement was studied. Results showed that the grain size of ferrite was between 3.6 and 8.3 μm when only V was added. Meanwhile, as the niobium content increases, the ferrite particles are further refined. After adding niobium, the grain contribution increased by 9%. The addition of niobium significantly refined the grain size of HRB500E seismic reinforcement. The second-phase nano-elliptic precipitate is NbC. The precipitated phase is dispersed on the grain boundary and the matrix, and the dislocation density on the matrix promotes the precipitation of NbC particles along the dislocation line. The second-phase precipitation of niobium can form an effective pinning effect and then refine the pearlite spacing. The microhardness and the tensile strength also significantly improved. The yield strength increased from 509 to 570 MPa.

Investigating the Mechanical Behavior of 3D Printed PLA-Coco Coir Composites

It is quite amazing that the use of 3D printing techniques, especially the Fused Deposition Modelling (FDM) has delivered such significance in terms of cost reduction, time saver features where a different variety of thermoplastic and composite materials (Biodegradable and Non-biodegradable) are well developed. Different sectors have continually developed natural organic materials that are also both structurally composite in nature. Similarly, the use of different fibers that are abundantly accessible and considered as renewable resources which can be optionally combined with other biodegradable materials is a great challenge through the use of the FDM printing method. The study aims to determine the effect of different particle size and raster angle at a certain fiber concentration which could affect the mechanical properties of the composite by developing a printable composite filament made of Polylactic Acid (PLA) and Coco Coir materials using a filament maker and FDM printer. The composite filament was fabricated and optimized using a twin-screw extruder and 3D Devo Filament maker. 3D printing of samples for mechanical testing was conducted using three (3) raster angles (45o, 60o, and 75o) and various particle sizes of coco coir fiber reinforcement in the PLA matrix. Results showed that the < 74μm particle size of the coco-coir exhibited a 24% and 175% increase in tensile strength and izod impact strength compared to the pure PLA at 60o and 75o raster angles, respectively. Likewise, the reinforcement of <149μm particle size coco coir at 45o raster angle contributes to an increase of 4.8% flexural and 176% compressive strength compared to pure PLA. The study concludes that there is an improvement in the mechanical properties of the PLA-Coco Coir composite at a certain particle size and raster angle in 3D printing.

Predicting the self-centering behavior of hybrid FRP-steel reinforced concrete beams under blast loading

An inelastic single-degree-of-freedom (SDOF) dynamic analysis model is developed to predict the entire displacement time-history of concrete beams reinforced with hybrid mixtures of fiber reinforced polymer (FRP) and steel reinforcing bars subjected to blast loads. Hybrid FRP-steel reinforced concrete members exhibit strong self-centering tendencies which promote blast resilience through reductions in residual damage, repair cost, and facility downtime after a terrorist bomb attack or accidental explosion. FRP bars provide an internal restoring force that activates self-centering behavior after the inertial loads are removed, while the conventional steel reinforcement and concrete dissipate energy by their inelastic response. The SDOF model is equally applicable to all-steel, all-FRP, and hybrid FRP-steel reinforced concrete flexural members, incorporating all the relevant parameters of flexural response, nonlinearity, and self-centering that have been observed to play an important role in blast tests. These parameters include the type, size, spacing, arrangement, and material properties of longitudinal and transverse reinforcement, as well as concrete properties and section geometry. The effect of these parameters is described in terms of nonlinear resistance functions capturing the inbound and rebound flexural response, plastic hinge formulations to account for crack bridging provided by FRP bars, and a hysteretic model for the combined effects of self-centering behavior and stiffness degradation due to accumulated damage from progressively increasing repeated blast tests. A new response parameter, known as the Blast Self-Centering Index (BSI), is proposed to evaluate and assess the residual displacements of all-steel, all-FRP, and hybrid FRP-steel reinforced concrete beams predicted by SDOF analysis. The model has been verified extensively against data obtained from explosively driven shock tube blast experiments.

Experimental study on bamboo grid reinforced copper slag overlying soft subgrade

Design and construction of pavements and structural foundations on soft ground are risky and costly projects for civil engineers because of the low bearing capacity of soil and the massive amount of granular fill required for replacing it. Improvement of the soft ground using natural materials is a sustainable, efficient, and cost-effective technique for providing a stable and supportive base for various civil engineering structures. This paper focuses on the use of bamboo grids to effectively improve the performance of soft subgrade underlying copper slag. Two types of bamboo grids in different aperture shapes were used to compare their effectiveness. The performance of the bamboo grids was evaluated on the basis of placement depths and their sizes. Model tests were carried out to analyse the effect of thickness of copper slag layer on footing pressure and settlement response of the base-subgrade system. A substantial improvement in footing pressure and footing settlement was observed at different levels of settlement. The tridirectional bamboo grid (hexagonal aperture) reinforced foundation base exhibited better performance than the bidirectional bamboo grid (square aperture). The footing pressure improvement ratio in the foundation bed using the tridirectional and bidirectional bamboo grid was found to be 2.28 and 1.89, respectively, while footing settlement reductions were obtained as 87% and 78%, respectively, for the same size of reinforcement. From the present study, it has been suggested that the bamboo grid and copper slag can be used for improving the soft subgrade, especially considering their availability and cost.

Compressive behavior of RC members with rectangular continuous transverse reinforcement

AbstractRectangular Continuous Transverse Reinforcement (RCTR), as a replacement for conventional ties, is a relatively new form of reinforcement that can accelerate and facilitate the construction of reinforcement for RC members. In this study, the compressive behavior of concrete members with this kind of reinforcement is experimentally and theoretically investigated. Twenty‐eight RC short column specimens with multiple arrangements for bar size and spacing of transverse reinforcement; including RCTR and conventional ties are examined under monotonic and half‐cyclic loadings. The results imply that RCTR is a valid substitute for traditional ties and to a certain extent can improve the compressive strength of RC members. Based on Elasto‐Plastic and Fracture (EPF) concrete model, a theoretical method is proposed in order to predict the behavior of such members, which conforms well with the experimental results. Furthermore, the validity of existing design provisions in the compressive design of these members is investigated.

Tinjauan Kekuatan Aksial dan Persyaratan Detailing Elemen Kolom Struktur Beton Bertulang Konvensional Berpengikat Sengkang Dengan Pembatasan Rasio Penulangan Berdasarkan SNI 2847:2019 Dengan Mempertimbangkan Aspek Kemudahan Praktik Di Lapangan dan Studio

The The main parameters that determine the axial capacity of a reinforce concrete column include the dimensions of the column, the the quality of the concrete, the quality of steel reinforcement, the size of steel reinforcement, the amount of steel used. In practice, these parameters generally have a certain value so that for certain spans also the details of a reinforced concrete column can be estimated by taking parameters that exist in the field as constraints. The process of drawing and estimating detailed columns in a studio of architecture usually also refers to practical needs in the field. So by providing limits on span, concrete quality, and steel quality we can estimate the details of the column under review. The process of calculating beam dimensions is done by estimating the cross section height of the column (h) and the width of the column (b) according to the limitation of low-rise building. Calculation of dimensions of main tensile reinforcement is done by taking into account the distance of reinforcement in one line and the reinforcement ratio ductility.

Mechanical and Tribological Properties of Co-Electrodeposited Particulate-Reinforced Metal Matrix Composites: A Critical Review with Interfacial Aspects.

Particulate-reinforced metal matrix composites (PRMMCs) with excellent tribo-mechanical properties are important engineering materials and have attracted constant scientific interest over the years. Among the various fabrication methods used, co-electrodeposition (CED) is valued due to its efficiency, accuracy, and affordability. However, the way this easy-to-perform process is carried out is inconsistent, with researchers using different methods for volume fraction measurement and tribo-mechanical testing, as well as failing to carry out proper interface characterization. The main contribution of this work lies in its determination of the gaps in the tribo-mechanical research of CED PRMMCs. For mechanical properties, hardness is described with respect to measurement methods, models, and experiments concerning CED PRMMCs. The tribology of such composites is described, taking into account the reinforcement volume fraction, size, and composite fabrication route (direct/pulsed current). Interfacial aspects are discussed using experimental direct strength measurements. Each part includes a critical overview, and future prospects are anticipated. This review paper provides an overview of the tribo-mechanical parameters of Ni-based co-electrodeposited particulate-reinforced metal matrix composite coatings with an interfacial viewpoint and a focus on hardness, wear, and friction behavior.

Finite element modelling of aluminum alloy plated reinforced concrete beams

This study presents a nonlinear finite element (FE) model development of reinforced concrete (RC) beams externally strengthened with aluminum alloy (AA) plates. The aim of this numerical study was to elucidate the effects of different anchorage schemes on the capacity, ductility, and failure mode of AA plate strengthened beams reported in a published test. Three FE models were developed; namely, a reference RC beam, a beam externally bonded (EB) with an AA plate, and a beam EB with an AA plate with carbon fiber reinforced polymers (CFRP) U-wraps at the plate's end. Validation of the developed FE models was carried out by comparing their load-deflection plots, maximum attained loads, deflections at failure, and failure modes with those reported during the test. The results of each FE model yielded an absolute percentage error less than 5%. Moreover, premature failure modes like end-plate and intermediate crack debonding were simulated and closely agreed with those observed during the test. Finally, the validated models were used to employ a parametric study comprising of twelve beams varying in size of steel reinforcement, presence of AA plates, and end-anchorage. It was concluded that the developed FE models could serve as a design platform for assisting structural engineers during flexural retrofit applications using AA plates.

Effect of eutectic silicon and silicon carbide particles on high stress scratching wear of aluminium composite for various testing parameters

In the present investigation, the mechanism of material removal with the help of mechanically mixed layer has been evaluated. The effect of different experimental parameters has been evaluated on aluminium matrix alloy (ADC12) and it's composite (ADC12 + 10%SiC). For the investigation of material removal, the reinforcement size is taken as 45 to 80 μm, applied load as 2 N, 6 N, 10 N, abrasive size as 30 μm, 50 μm, 70 μm and sliding distance of 40 m, 60 m, 80 m, 100 m with 500 rpm. In the present observation, the hardness of composite is found to be better than the alloy. In addition, wear resistance of composite has been found better than the alloy. Mechanically mixed layer was formed for low load. For high load, mechanically mixed layer was not found. Maximum wear resistance of material was found for fine abrasive and low load and transition of material removal was found for high abrasive size.

Behavior of Reinforced Concrete Plates under Pure Torsion

The behavior of reinforced concrete members under torsional loading has interested many researchers during the last decades. These researches focused mainly on the response of reinforced concrete beams at different reinforcement conditions and the size effects. On the other hand, the behavior of concrete plates or slabs has not been investigated clearly under pure and/or combined torsional loading. In the present study, nine reinforced concrete plates were prepared and tested under pure torsion. Effect of steel reinforcement ratio and size change was studied and they have a great effect on the plated strength, capacity, stiffness and ductility. As stated by torsion theories of reinforced concrete beams, the torsional strength of slabs was upgraded also with increasing in cross section and transverse reinforcement ratio.

Predictive study on Mechanical strength of Lightweight concrete using MRA and ANN

The lightweight concrete is preferred over regular density concrete as it which reduces the dead load of the structure due to its lower density. The reduction in dead load of the structure, resulting in a considerable decrease in the size of structural elements and reinforcements; thereby, the building's cost can be reduced. The lightweight concrete is achieved through natural lightweight aggregates, artificial lightweight aggregates, coconut shells, oil palm shells, aeration in concrete, etc. The mechanical properties like compressive strength, tensile strength, density depend upon lightweight aggregate, fine aggregate, super-plasticizer, cement content, water-cement ratio, etc. The mechanical properties can also be predicted using artificial intelligence from the existing data. This research aims to predict lightweight concrete's mechanical properties using MRA and ANN accurately.

Taguchi’s method of optimization of fracture toughness parameters of Al-SiCp composite using compact tension specimens

The objective of this work is to investigate the process parameters which influence the fracture toughness of aluminum-silicon carbide particulate composite prepared using the stir casting technique. The Taguchi’s design of experiments is conducted to analyze the process parameters. Three parameters considered are composition of material, grain size and a/W ratio. From the Taguchi’s analysis, on compact tension specimens, aluminum 6061 reinforced with 9 wt% of the silicon carbide particles composite and a/W ratio of 0.45 are considered to be optimized parameters. Taguchi's technique result shows that the increment in the a/W ratio causes decrement in the load carrying capacity of the composite. Whereas the fine grain size of silicon carbide have better toughness values. From the ANOVA outcomes it is clear that the composition and a/W ratio of the geometry has more influence on the fracture toughness than the grain size of reinforcement.

Behaviour of prestressed hollow core slabs strengthened with NSM CFRP strips around openings: A finite element investigation

Prestressed Hollow Core Slabs (PHCSs) have become widely used in the construction industry owing to their economic benefits. During their service life, changes that would require openings to be situated along their spans may arise. A strengthening technique to recover or improve the original serviceability and resistances becomes indispensable. Limited research interest has been given to develop appropriate strengthening methods for the PHCSs with openings. The Near Surface Mounted (NSM) strengthening technique is among the practical and feasible solutions to rehabilitate or enhance the performance of these PHCSs. This paper demonstrates a Finite Element (FE) analysis technique to predict the responses of the PHCSs with openings, either unstrengthened or strengthened with NSM strips. The Concrete Damage Plasticity (CDP) model was successfully implemented to model the non-linear behaviour of concrete. The prestressing transmission length and the bond behaviour between the epoxy adhesive and concrete interfaces were put into practice. Acceptable agreements were found, upon validating the FE analysis results against the experimental data available in the literature. Maximum differences, compared to the experimentally attained results in the ultimate loads and the corresponding deformations of nearly 4% and −8.4%, respectively, were detected. An extensive parametric study was executed to assess the effect of various parameters on the overall behaviour of the examined slabs. The PHCS cross-sectional shape, CFRP reinforcement percentage, average precompression, opening location and size and the concrete compressive strength were taken as parameters. Above all, a gap of knowledge exits regarding the presence of design guidelines that evaluate reductions in the ultimate capacities of the PHCSs associated with the presence of openings at multiple locations along their spans and improvements experienced by employing the NSM strengthening technique. This could be bridged by utilizing the suggested modelling approach and the parametric study results in this research.

Investigations on Hardness, Machinability and Electrical Conductivity of Stir Casted A356 Nanocomposites Reinforced with SiC Nanoparticles with Ultrasonic Assisted Cavitation

The mechanical properties like hardness, machinability and electrical conductivity of nanocomposites are analysed in current work. Inferable from its good castable property, A356 has been picked as matrix material and due to proximity with reference to density; nanosilicon carbide (SiC) is chosen as reinforcement material. A novel technique “Ultrasonic assisted cavitation” is followed for the synthesis of nancomposites for uniform dispersion and better properties. By keeping the size of reinforcement as 50 nm and varying the quantity from 0.1 to 0.5 by wt%; it is perceived that the hardness & drill thrust forces are increased and electrical conductivity is decreased when equated to pure alloy.

Effect of grain refining by cyclic extrusion compression (CEC) of Al-6061 and Al-6061/SiC on wear behavior

Cyclic extrusion compression (CEC) is an effective fabrication process for producing fine, ultrafine grains with superior physical and mechanical properties.In the present work, CEC process was applied on Al alloy 6061 and its silicon carbide (SiCp) composite containing 5 and 10 wt. % SiCp. . The specimens were pressed at room temperature up to 6 cycles for Al alloy 6061, 5 cycles for Al 6061 5 wt. % and 4 cycles for Al 6061 10 wt. % SiC corresponding to plastic strains of 3.72, 3.1 and 2.48 respectively. The evolution of microstructure, hardness and dry sliding wear tests were conducted. The samples were investigated before and after the CEC process by optical microscope, and the worn surfaces were investigated by Scanning Electron Microscope (SEM) and (EDX) analysis. The CEC cycles reduced the grain size, porosity % and SiC particle size. These microstructural parameters were reflected on the increase in hardness and reduction in wear rate and a slight reduction in coefficient of friction. In general, this improvement in properties is associated with the following parameters; grain refining, reinforcement volume fraction, size and distribution of SiCp as well as the number of CEC cycles. Regarding the composite samples, a significant improvement in wear resistance was obtained and the Al 6061 10 wt. % SiC, showed the best performance. The wear mechanism was also affected by the CEC process.

Reliability Analysis of Flexural Deflection of Reinforced Concrete Members under Ultra-Low Temperature

Based on the Monte Carlo method, the functional function under the normal use limit state given by the specification introduces the concrete tensile strength of each temperature gradient under ultra-low temperature, and the coefficient of change of concrete elastic modulus. By changing the temperature of the member, the thickness of the protective layer, the bending moment effect ratio, the reinforcement size,the concrete grade and the length of the bending beam. Analyze the reliable index of the deflection control of the flexural member under ultra-low temperature to obtain: When the reinforced concrete flexural member is reduced from normal temperature 20°C to-160°C, the reliable deflection index of the component increases non-linearly, reaches the maximum value at-130°C, and then decreases slightly, the concrete strength grade and the thickness of the protective layer under each temperature gradients have the greatest influence on the deflection control of the bending beam under ultra-low temperature, followed by beam length, steel bar size, load effect ratio,which is different from normal temperature.

Tribological characterisation of magnesium matrix nanocomposites: A review

Magnesium matrix nanocomposites (Mg-MNCs) are high grade materials widely used in aerospace, electronics, biomedical and automotive sectors for high strength to weight ratio, excellent sustainability and superior mechanical and tribological characteristics. Basic properties of Mg-MNCs rely on type and amount of reinforcement and fabrication process. Current study reviews existing literatures to explore contribution of different parameters on tribological properties of Mg-MNCs. Effects of particle size and amount of different reinforcements like SiC, WC, Al2O3, TiB2, CNT, graphene nano platelets (GNP), graphite on tribological behaviour are discussed. Incorporation of nanoparticles generally enhances properties. Role of different fabrication processes like stir casting (SC), ultrasonic treatment casting (UST), disintegrated melt deposition (DMD), friction stir processing (FSP) on wear and friction behaviour of Mg-MNCs is also reviewed. Contributions of different tribological process parameters (sliding speed, load and sliding distance) on wear, friction and wear mechanism are also examined.