Effect Of Steel Reinforcement Research Articles

A piece-wise linear model for modelling the tension-stiffening effect in steel-reinforced UHPC composites

This study examines the tensile behaviour of Ultra-High Performance Concrete (UHPC) specimens reinforced with varying steel fibre content and rebar diameters. An experimental campaign involving 18 reinforced UHPC specimens was conducted, following individual tensile response characterizations of UHPC and reinforcing steel. These specimens were designed and fabricated with threaded welded steel cages to transfer loads to the central measurement area. Force–displacement curves were measured to derive stress–strain curves for the UHPC component, evaluating the impact of reinforcement rebar and steel fibre content on UHPC’s mechanical response. The analysis revealed that steel fibre volume content significantly influences the tensile response of UHPC reinforcement more than the steel bar diameter and yield strength. Comparing the strain in steel bars to the average strain in reinforced UHPC specimens indicated that post-cracking deformation concentrates at the crack. At the same time, the bond between reinforcement and UHPC remains intact in uncracked sections, allowing effective load transfer. UHPC specimens reinforced with 14 mm diameter steel bars displayed a significant horizontal segment in the descending phase of the stress–strain curve. In contrast, specimens with 18 mm or 22 mm diameter bars exhibit a progressive stress reduction at a nearly constant rate. Stress–strain curves of UHPC were fitted with a five-fold piecewise empirical model applicable to UHPC with a reinforcement ratio higher than 0.09%. The resulting model can be used to model the axial behaviour in UHPC, considering the effects of steel reinforcement.

Experimental and Theoretical Analysis of Cracking Moment of Concrete Beams Reinforced with Hybrid Fiber Reinforced Polymer and Steel Rebars

This study aims at experimentally and theoretically investigating the cracking moment (Mcrc) of hybrid Fiber Reinforced Polymer (FRP)/steel Reinforced Concrete (RC) beams. Six hybrid Glass FRP (GFRP)/steel and three GFRP RC beams with various GFRP and steel reinforcement ratios are tested in four-point bending scheme. Experimental results indicate that both GFRP and steel rebars affect Mcrc, but the effect of steel reinforcement is more significant. When the steel reinforcement ratio increases to 1.17%, Mcrc goes up to 15.9%, while the same value for GFRP is only 9.7%. An analytical method is proposed based on the plain section assumption and nonlinear behavior of materials for estimating Mcrc. The proposed model shows a good agreement with the experimental data conducted in this study and collected from the literature. The results of the parametric study give evidence of the positive effects of hybrid reinforcement ratios and elastic modulus of FRP on Mcrc of hybrid RC beams.

Temporal Evaluation of ASR Cracking in Concrete Specimens Using Acoustic Emission

AbstractThe effect of steel reinforcement on the distribution of alkali-silica reaction (ASR) damage in concrete blocks is studied by leveraging acoustic emission sensing with a data-driven approac...

Projectile penetration of reinforced concrete considering the effect of steel reinforcement: Experimental study and theoretical analysis

In this study, experiments in which projectiles penetrated into plain and reinforced concrete targets were conducted by controlling single variables for a differential experimental design including projectile impact locations, reinforcement arrangements, reinforcement buried depths, and reinforcement bonding conditions. Based on cavity expansion theory and the dynamic response analysis of the steel reinforcement, a reinforced concrete target penetration resistance model was established. The accuracy of the model was verified using the experimental data, and the influence of the steel reinforcement arrangement on projectile penetration was analyzed. The results show that the reinforcing steel bonding effect exert an indirect resistance while the impact of the projectile with the reinforcement exert a direct resistance, which is different from direct penetration into concrete. The indirect and direct resistances against the projectile act to reduce penetration depth and target surface damage. The results calculated using the derived numerical method clearly describe the observed details of the projectile impact with the steel reinforcement, and are in good agreement with the experimental data. The indirect and direct resistances of the steel reinforcement were observed to be affected by the initial conditions of the projectile and the target including impact locations and reinforcement arrangements. It was found that increasing the reinforcement ratio and adopting a denser reinforcement arrangement can reduce the penetration depth of projectile, and better protecting the integrity of the target.

Ballistic behavior of plain and reinforced concrete slabs under high velocity impact

This work presents a numerical simulation of ballistic penetration and high velocity impact behavior of plain and reinforced concrete slabs. In this paper, we focus on the comparison of the performance of the plain and reinforced concrete slabs of unconfined compressive strength 41 MPa under ballistic impact. The concrete slab has dimensions of 675 mm × 675 mm × 200 mm, and is meshed with 8-node hexahedron solid elements in the impact and outer zones. The ogive-nosed projectile is considered as rigid element that has a mass of 0.386 kg and a length of 152 mm. The applied velocities vary between 540 and 731 m/s. 6 mm of steel reinforcement bars were used in the reinforced concrete slabs. The constitutive material modeling of the concrete and steel reinforcement bars was performed using the Johnson-Holmquist-2 damage and the Johnson-Cook plasticity material models, respectively. The analysis was conducted using the commercial finite element package Abaqus/Explicit. Damage diameters and residual velocities obtained by the numerical model were compared with the experimental results and effect of steel reinforcement and projectile diameter were studies. The validation showed good agreement between the numerical and experimental results. The added steel reinforcements to the concrete samples were found efficient in terms of ballistic resistance comparing to the plain concrete sample.

The Effect of Steel Reinforcement on Seismic Damage to Concrete Gravity Dams Based on Distributed-Steel Model

Tensile cracking at the position where geometry changes is a typical failure mode of gravity dams under strong earthquakes. Steel reinforcement has been proposed to reduce the degree of dam cracking. In this paper, a nonlinear model is presented to consider the interaction effect between the steel reinforcement and the dam concrete in a combined concrete damage model and distributed-steel model. In the model, a composite constitutive model of a steel reinforcement-concrete element is proposed. The approach can model the process of gradual degradation of the concrete loading capacity and load transfer to the steel reinforcement by establishing the concrete and steel models separately. Taking a typical gravity dam with positions where geometry changes upstream and downstream as a case study, the influence of steel reinforcement on seismic damage of the gravity dam is investigated. The analytical results show that the steel reinforcement strengthening prevents cracks thoroughly around the elevation of the downstream slope change. However, the cracking around the elevation of the upstream slope change extends to the downstream direction. This reflects the transfer of fracture energy release during the cracking process.

Effect of Steel Reinforcement on the Minimum Depth-Span Ratio

Effect of Steel Reinforcement on the Minimum Depth-Span Ratio

Effect of steel reinforcement with different degree of corrosion on degeneration of mechanical performance of reinforced concrete frame joints

Beam-column joints which shoulders high-level and vertical shearing effect that maintains balance of beam and column end is the major component influencing the performance of the whole framework. Post earthquake investigation suggests that collapse of frame structure is induced by failure of joints in most cases. Thus, beam-column joints must have strong bearing capacity and good ductility, and reinforced concrete structure just meets the above requirement. But corrosion caused by long time use of reinforced concrete framework will lead to degeneration of mechanical performance of joints. To find out the rule of effect of steel reinforcement with different corrosion rate on degeneration of bearing capacity of reinforced concrete framework joints, this study made a nonlinear numerical analysis on fifteen models without stirrup in the core area of reinforced concrete frame joints using displacement method considering axial load ratio of column end and constraint condition. This work aims to find out the key factor that influences mechanical performance of joints, thus to provide a basis for repair and reinforcement of degenerated framework joints.

Study of the Combined Effect of Steel Reinforcement and Expansion Agent on the Crack Resistance of Ready-Mixed Concrete

The objective of this work is to find the law of combined effect of steel reinforcement and expansion agent (EA) on the crack resistance of ready-mixed concrete by doing flat-plate method experimental study on the crack resistance of ready-mixed concrete with EA, also with EA and steel reinforcement, with a deep analysis of the mechanism of reinforcement and EA on ready-mixed concrete. The paper comes to the role of ready-mixed concrete cracking performance which is influenced by reinforcement steel and EA.

Shrinkage-induced strains on cross-sections of reinforced concrete prisms

This paper describes experimental testing to investigate the effects of steel reinforcement on the distribution of shrinkage strains over cross-sections of reinforced concrete (RC) prisms. Measurements were taken in a harsh environment (50°C and 5% relative humidity (RH) and a moderate environment (28°C and 50% RH) on prisms of dimensions (80 × 150 × 500 mm). The research provides experimental measurements that supplement the scarce database for the distribution of induced drying shrinkage strains over RC cross-sections. As expected, the presence of steel restrains the development of shrinkage strains and the degree of restraint depends on the amount of steel. The effect of reinforcing steel on induced strains at the upper levels of the cross-sections increases as the steel ratio increases, particularly for specimens cured in the harsh environment. Over time, the distributions of total strains over cross-sections were found to approach linearity, with a higher rate towards linearity as the steel ratio was increased.

Finite Element Modelling for Service Life Prediction of Repaired Concrete in Marine Environment

SummaryService life of concrete structures subjected to a chloride environment can be predicted using chloride transport models based on the partial differential equation (PDE) of Fick’s second law of diffusion. In this paper, a numerical finite element based formulation is proposed for the service life prediction of reinforced concrete structures in general cases, including those that the PDE cannot be solved analytically or by finite difference method. The proposed model effectively accommodates time- and space-dependent chloride transport, chloride binding, as well as the effect of steel reinforcement and the effect of concrete cover replacement/repair. Practical applications are also analysed and discussed, which highlights the model’s validity and capability.

Monitoring and Performance of AC Pavements Reinforced with Steel Mesh

The work focuses on the monitoring of an experimental stretch of road over a five year period in order to measure the effects of steel reinforcement on Asphalt Concrete (AC) pavement performance. The experimental stretch of road was constructed in 2001 alternating sections with and without steel reinforcement. This paper presents the results regarding the effects of steel reinforcement that were obtained by monitoring the AC pavements with nondestructive test (NDT) and visual inspection techniques and comparing the performances of pavements with and without reinforcement. In general, all the analyses confirm that the installation of the steel reinforcement produces a significant improvement in pavement performance. After five years of service, an analysis of the pavement sections with steel reinforcement showed an extension of Residual Life by a factor of two when compared with the equivalent pavements without reinforcement.

Nondestructive Testing and Evaluation of Concrete Parking Garages

Public works departments need test procedures for assessing the current condition of concrete in public facilities such as parking garages. Nondestructive testing can provide ultrasonic pulse velocities that can be used as an indicator of concrete quality. A procedure is presented that can be used to collect and analyze ultrasonic measurements. The procedure was applied for all of the public garages in Montgomery County, Md., to identify garages that needed immediate maintenance. Based on the measured data, the effect of the age of the concrete on the pulse velocity was investigated and a model was developed. The model can be used to determine where a garage is in its life cycle. The effect of elastomeric membranes, used to protect the concrete slabs on pulse velocities, was evaluated with the results indicating that the use of membranes extended the life of the concrete by about 10%, or an equivalent of 3 years of design life. A method of evaluating the effect of steel reinforcement on the pulse velocity was developed and applied. The method can be used to identify the optimum spacing between the transmitter and receiver in nondestructive testing.

Flange-to-Flange Moment Connections for Precast Concrete Deck Bulb-Tee Bridge Girders

This paper reports findings on new flange-to-flange moment connections for precast concrete deck bulb-tee (DBT) bridge girders. In bridge systems made of precast concrete DBT girders, the concrete deck slab is cast with the prestressed, precast concrete girders at the production facility and then shipped to the bridge site. To make the deck continuous and allow for live load distribution, a concrete closure strip is placed between the precast concrete DBT girders. The objectives of this study are to develop a moment connection for DBT bridge girders and provide experimental data on the ultimate strength of the connection system. Study parameters include identifying crack formation and propagation patterns, failure modes, and ultimate load-carrying capacities. Four moment connections were designed and six full-sized bridge panels were fabricated and loaded to failure to test the developed connections. Effects of steel reinforcement, joint width, and location of the simulated wheel load on the connection designs are discussed. A joint design is considered successful if, prior to failure, the experimental wheel load satisfies North American bridge code requirements. Data show that most of the connection designs satisfy the wheel load specifications. Results indicate that the location of the wheel load on the deck slab affects the ultimate load-carrying capacity of the developed connections. Connections typically failed due to flexure.

Finite Element Method Modeling of Reflective Cracking Initiation and Propagation

In overlaid pavements, working cracks in existing pavement systems propagate upward to the new pavement surface and cause reflective cracking, one of the most serious causes of deterioration in overlay systems. Several techniques to reduce reflective cracking have been introduced. However, the reflective cracking mechanism is not yet well understood. Fracture mechanics have been applied in pavement analysis to investigate crack development. A single-edge notched beam test was simulated with the finite element method with the cohesive zone model, which has been widely used to simulate a cohesive crack. The effects of steel reinforcement, interface, and hot-mix asphalt (HMA) properties on crack initiation time and crack propagation rate were investigated. A damage value, an indication of the degradation of the initial stiffness of the material in cohesive elements, was used to define the degree of softening and to trace crack formation. On the basis of elastic analysis, the crack initiation time for the reinforced beam was five times greater than that of the unreinforced beam, and crack propagation rate was reduced by two and one half to six times at –10°C. Conversely, when viscoelastic analysis, which is a more realistic simulation of HMA behavior, is used, the improvement in controlling reflective cracking is approximately half the improvement for the same loading and temperature conditions. This improvement depends on shear stiffness at the interface, crack length, and HMA temperature. In general, steel reinforcement, when installed properly, enhanced the resistance to reflective cracking.

Finite Element Method Modeling of Reflective Cracking Initiation and Propagation: Investigation of the Effect of Steel Reinforcement Interlayer on Retarding Reflective Cracking in Hot-Mix Asphalt Overlay

In overlaid pavements, working cracks in existing pavement systems propagate upward to the new pavement surface and cause reflective cracking, one of the most serious causes of deterioration in overlay systems. Several techniques to reduce reflective cracking have been introduced. However, the reflective cracking mechanism is not yet well understood. Fracture mechanics have been applied in pavement analysis to investigate crack development. A single-edge notched beam test was simulated with the finite element method with the cohesive zone model, which has been widely used to simulate a cohesive crack. The effects of steel reinforcement, interface, and hot-mix asphalt (HMA) properties on crack initiation time and crack propagation rate were investigated. A damage value, an indication of the degradation of the initial stiffness of the material in cohesive elements, was used to define the degree of softening and to trace crack formation. On the basis of elastic analysis, the crack initiation time for the rei...

A plasticity analysis of anchorage zones

This Paper is the second of three on the behaviour of anchorage zones for prestressed concrete. Details are presented of a plasticity approach to the ultimate strength analysis of concrete prisms strip-loaded through rigid steel plates. Such a loading arrangement is assumed to represent adequately the transfer of force from tendon to concrete at the anchorage of a prestressed concrete structure. The effects of steel reinforcement are included in the analysis, which is assumed to satisfy plane strain conditions. lke Mod$ed Mohr-Coulomb failure criterion with non-zero tension cut-off is used for the concrete. A model, based on experimental evidence, is used as the basis for the plastic analysis, and good correlation is obtained between the theory developed here and the observed test results. It is concluded that such a plasticity approach is useful in assessing the strength of concrete under concentrated load.