Steel Fiber-reinforced Concrete Panels Research Articles

Correlation between shear stress and strain measured on steel fiber reinforced concrete panels and walls

Previous studies have reported that steel fibers increase concrete shear strength and energy dissipation capacity. Existing strength prediction models focus on Steel Fiber Reinforced Concrete (SFRC) beams since code requirements already allow steel fibers to increase shear strength in these structural elements. However, the advantages of the SFRC have stimulated the investigation of its use in concrete walls subjected to shear demands. Unfortunately, the shear behavior assessment in SFRC walls requires significant investment that is not accessible for all research studies. Diagonal tension tests on SFRC panels could result in a more economical and viable option. Still, the shear response of RC panels differs from that of walls because of the test setup and the loading protocol. This study aims to correlate the maximum shear stresses and displacements measured in SFRC walls and SFRC panels from a database that includes 20 diagonal tension tests on panels and 33 quasi-static cyclic tests on walls. The 20 panels tests include three monotonic and 17 quasi-static cyclic tests from two previous studies. The other 33 wall tests include six dynamic shake table tests and 27 cyclic quasi-static tests from 9 previous studies. The current study showed that the maximum shear stresses in SFRC panels are approximately 2.3 times greater than those in SFRC walls. Additionally, the displacements associated with the maximum shear stresses in SFRC panels were about six times less than those registered in SFRC walls. The differences are mainly because the walls are affected by flexural, shear sliding, and web shear stresses, and the panels are predominantly affected by shear forces. As a result, two correlation models for stresses and displacements of SFRC walls are proposed as an effective tool for research with limited resources to implement cyclic tests on SFRC walls. The study also proposed stiffness degradation values associated with limit states and performance levels in SFRC walls for low-rise housing.

Experimental and MCFT-Based Study on Steel Fiber-Reinforced Concrete Subjected to In-Plane Shear Forces

Testing of concrete panels subjected to pure in-plane shear loading is necessary to elucidate the shear behavior of concrete. However, available data for predicting the shear capacity and behavior of steel fiber-reinforced concrete are rather limited. This study aims to evaluate the shear capacity and behavior of fiber-reinforced concrete made of highly flowable strain hardening fiber-reinforced concrete (HF-SHFRC) experimentally and analytically, respectively, using a panel tester loaded under pure shear and modified compression field theory (MCFT). The test was conducted using a panel test machine at the University of Toronto. The test results of the HF-SHFRC demonstrated strain hardening behavior at tension after the first crack, as indicated by the increase in the shear stress after the first crack in the HF-SHFRC panel. An analysis procedure is proposed for predicting the shear strength of steel fiber-reinforced concrete (SFRC) based on experimental data of the SFRC panels to obtain reliable results. A comparison of results obtained from the proposed analysis procedure and experiments show that it accurately predicted the response of the HF-SHFRC. The proposed MCFT-based analysis procedure can provide valuable insight for understanding the behavior of the SFRC panels under shear loading.

Diagonal tension performance of concrete panels reinforced with hooked end steel fibers

The increase in strength of Steel Fiber Reinforced Concrete (SFRC) depends mainly on factors such as the dosage, aspect ratio and number of hooked ends of the fibers. Previous studies proposed models to estimate the flexural and shear strength of SFRC beams, but the shear behavior of SFRC panels has not been extensively studied. The study includes diagonal tension tests on concrete panels to assess the shear performance of SFRC. The experimental program comprises 19 square concrete panels having 600 mm side and 75 mm thickness, including three nominal dosages of steel fibers (20, 40 and 60 kg/m3) and three different number of hooked ends (1, 1.5 and 2). The study proposes models to predict the shear strength and deformation capacity, stiffness degradation and toughness of SFRC panels with different number of hooked ends when subjected to diagonal tension. The models include four characteristic limit states of diagonal cracking, maximum residual strength, code-based acceptable degradation, and maximum deformation.

Behavior of Steel Fiber Reinforced Concrete Panels under Surface Pressure

In this study, it is aimed to investigate the importance of the affecting parameters on the pressure–displacement relationship of steel fiber reinforced concrete panels. Among these parameters, panel thickness, panel dimensions, material type, and boundary conditions of the panels are the parameters that were examined. In this context, the effects of surface pressure on the steel fiber reinforced concrete panels were investigated. It was observed that as the thickness and the fiber ratio increased, the ultimate bearing capacity increased. It was determined that it may not be enough to support the panels only at the corner points, and intermediate supports are needed. As the support spacing decreased, the absorbed surface pressure increased. In addition, it was concluded that the increase in the amount of steel fiber in the concrete material increased the strength, deflection, and ductility values.

การพัฒนาผนังคอนกรีตเสริมเส้นใยเหล็กสำหรับการต้านทานแรงกระแทกของกระสุนขนาด 7.62 x 51 มิลลิเมตร

การพัฒนาผนังคอนกรีตเสริมเส้นใยเหล็กสำหรับการต้านทานแรงกระแทกของกระสุนขนาด 7.62 x 51 มิลลิเมตร

Strengthening of Masonry Walls Produced from Two Different Materials with Steel Fiber-Reinforced Concrete Panels

The use of steel fiber-reinforced concrete panels to strengthen masonry walls is examined. Within the scope of this study, 18 of a total of 24 specimens are manufactured by using concrete panels containing steel fibers at specific ratios to strengthen hollow brick and clay brick walls, while the remainder serve as reference specimens. The shear strength, deformation and energy consumption capacities are then evaluated for each of the different strengthening methods.

Strengthening of Masonry Walls Produced from Two Different Materials with Steel Fiber-Reinforced Concrete Panels

Strengthening of Masonry Walls Produced from Two Different Materials with Steel Fiber-Reinforced Concrete Panels

Impact Resistance of Steel Fiber-Reinforced Concrete Panels Using Genetic Algorithm Optimization

Abstract In designing protective concrete structures, optimum response against projectile impact is achieved by minimizing damage and, more importantly, controlling its failure mode to ensure life safety. Recently, steel fiber–reinforced concrete (SFRC) has gained attention for its superior toughness and damage control against impact loads. However, in designing SFRC panels to protect against projectile impact, a knowledge gap exists in the selection of optimum parameters, such as steel fiber volumetric fraction, maximum aggregate size, and panel thickness. To fill this gap, this article proposes a model that is capable of predicting SFRC response to impact loading using an artificial neural network. This model has been introduced to a multiobjective genetic algorithm to optimize the SFRC panel design against a given impact energy. Simple guidelines for the selection of optimum thickness, steel fiber volumetric fraction, and aggregate size are developed.

Shear behavior of aerated concrete and hollow brick walls strengthened with steel fiber-reinforced concrete panels

Walls are the main carrying units of masonry buildings. They have certain advantages, like being economical and easily constructed. Therefore, many experimental studies have been performed. In this study, walls produced from aerated concrete (AC) and hollow brick (HB) strengthened with steel fiber-reinforced concrete panels were tested. Eighteen of 24 walls were strengthened with concrete panels that were produced by using steel fibers at certain ratios. The other six ones were reference specimens. The results obtained were expressed as mean values. The strengthening method significantly increased energy consumption capacities and shear strengths.

Using Steel Fiber‐Reinforced Concrete Precast Panels for Strengthening in Shear of Beams: An Experimental and Analytical Investigation

In this paper, the performances of reinforced concrete (RC) beams strengthened in shear with steel fiber‐reinforced concrete (SFRC) panels are investigated through experiment, analytical computation, and numerical analysis. An experimental program of RC beams strengthened by using SFRC panels, which were attached to both sides of the beams, is carried out to investigate the effects of fiber volume fraction, connection type, and number and diameter of bolts on the structural responses of the retrofitted beams. The current shear resisting model is also employed to discuss the test data considering shear contribution of SFRC panels. The experimental results indicate that the shear effectiveness of the beams strengthened by using SFRC panels is significantly improved. A three‐dimensional (3D) nonlinear finite element (FE) analysis adopting ABAQUS is also conducted to simulate the beams strengthened in shear with SFRC panels. The investigation reveals the good agreement between the experimental and analytical results in terms of the mechanical behaviors. To complement the analytical study, a parametric study is performed to further evaluate the influences of panel thickness, compressive strength of SFRC, and bolt pattern on the performances of the beams. Based on the numerical and experimental analysis, a shear resisting model incorporating the simple formulation of average tensile strength perpendicular to the diagonal crack of the strengthened SFRC panels is proposed with the acceptable accuracy for predicting the shear contribution of the SFRC system under various effects.

Strain Behavior of Concrete Panels Subjected to Different Nose Shapes of Projectile Impact.

This study evaluates the fracture properties and rear-face strain distribution of nonreinforced and hooked steel fiber-reinforced concrete panels penetrated by projectiles of three different nose shapes: sharp, hemispherical, and flat. The sharp projectile nose resulted in a deeper penetration because of the concentration of the impact force. Conversely, the flat projectile nose resulted in shallower penetrations. The penetration based on different projectile nose shapes is directly related to the impact force transmitted to the rear face. Scabbing can be more accurately predicted by the tensile strain on the rear face of concrete due to the projectile nose shape. The tensile strain on the rear face of the concrete was reduced by the hooked steel fiber reinforcement because the hooked steel fiber absorbed some of the impact stress transmitted to the rear face of the concrete. Consequently, the strain behavior on the rear face of concrete according to the projectile nose shape was confirmed.

Evaluation of Impact Resistance of Steel Fiber-Reinforced Concrete Panels Using Design Equations

Evaluation of Impact Resistance of Steel Fiber-Reinforced Concrete Panels Using Design Equations

Shear Behavior and Crack Control Characteristics of Hybrid Steel Fiber-Reinforced Concrete Panels

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Analysis of Steel Fiber-Reinforced Concrete Elements Subjected to Shear

In this paper, a rational analysis procedure is presented for modeling the shear behavior of steel fiber-reinforced concrete (SFRC) elements. In the development of the analysis procedure, the Disturbed Stress Field Model (DSFM), based on the Modified Compression Field Theory (MCFT), is modified by implementing constitutive models for SFRC, which are derived from the Diverse Embedment Model (DEM). For the contribution of steel fibers, a local stiffness matrix for fibers has been developed separately from those for concrete matrix and conventional reinforcement. The composite element stiffness matrix for an SFRC element with conventional reinforcement is then derived by superposing the three local stiffness matrixes. In the element stiffness matrix, the effect of shear slip at a crack is also taken into account by considering the resistance due to steel fibers against shear stress on crack surface. Through comparisons with the test results of SFRC panels previously reported in the literature, it is shown that the actual shear behavior of SFRC panels are accurately predicted by the proposed analysis procedure, not only for the shear strength but also for the shear strain at the failure. Through implementation into finite element analysis programs, the analysis procedure devel oped in this paper can be useful in the modeling of SFRC members and structures also containing conventional reinforcement.

구형 비상체에 의한 충격하중을 받는 강섬유보강 콘크리트 패널의 손상특성

This paper investigates the effects of fiber volume fraction and panel thickness on face damage characteristics of steel fiber-reinforced concrete (SFRC) under high-velocity globular projectile impact. The target specimens were prepared with 200 × 200 mm prismatic panels with thickness of 30 or 50 mm. All panels were subjected to the impact of a steel projectile with a diameter of 20 mm and velocity of 350 m/s. Specifically, this paper explores the correlation between mechanical properties and face damage characteristics of SFRC panels with different fiber volume fraction and panel thickness. The mechanical properties of SFRC considered in this study included compressive strength, modulus of rupture, and toughness. Test results indicated that the addition of steel fiber significantly improve the impact resistance of conventional concrete panel. The front face damage of SFRC panels decreased with increasing the compressive toughness and rear face damage decreased as the modulus of rupture and flexural toughness increased. To evaluate the damage response of SFRC panels under high-velocity impact, finite element analysis conducted using ABAQUS/Explicit commercial program. The predicted face damage of SFRC panels based on simulation shows well agreement with the experimental result in similar failure mode.

Crack Model for Steel Fiber-Reinforced Concrete Members Containing Conventional Reinforcement

This paper proposes a new model for the calculation of crack spacings and crack widths in steel fiber-reinforced concrete members containing conventional steel reinforcing bars (R/SFRC). The model considers the effects of various fiber and conventional reinforcement parameters. Predictions are compared against the test results of 17 plain reinforced concrete (RC) and 53 large-scale R/SFRC specimens subjected to uniaxial tension available in the literature. It is found that the proposed model predicts the crack spacings and widths of R/SFRC with reasonable accuracy and outperforms other steel fiber-reinforced concrete (SFRC) crack spacing models currently available. The model is expanded to include biaxial stress conditions to facilitate the analysis of elements such as SFRC panels subjected to shear. Here, too, the model is found to give sufficiently accurate predictions of the average crack conditions.

Steel Fiber-Reinforced Concrete Panels in Shear: Analysis and Modeling

Finite element (FE) studies are undertaken to investigate the accuracy of currently available concrete constitutive models in predicting the behavior of steel fiber-reinforced concrete (SFRC) panels tested in pure shear. The tension-stiffening, tension-softening, and compression-softening behaviors of the panels are evaluated and compared with predictions made using the disturbed stress field model and currently available concrete constitutive models. In addition, the effects of crack slip and crack spacing parameters on the modeling accuracy are assessed. The FE analysis results indicate that although current constitutive models are able to simulate the behavior of conventionally reinforced concrete panels accurately, the models overestimate the strength and deformation capacity of SFRC elements. Three factors are found to significantly influence the calculation accuracy: the tension stiffening/softening model, the consideration of shear slip on crack surfaces, and the crack spacing parameters.

Shear behavior model for steel fiber-reinforced concrete members without transverse reinforcements

Due to the complex shear mechanism of steel fiber-reinforced concrete (SFRC) members, there is lack of comprehensive shear behavior models for SFRC members. The shear behavior model, based on a smeared crack model, requires the tensile stress–strain constitutive equation of SFRC membrane subjected to biaxial stresses. After SFRC panel tests under biaxial stresses were recently conducted, it has been possible to create a more complete smeared crack model for estimating the shear behavior of SFRC members. It is, however, very difficult to conduct such experiments for different types of steel fibers, various amount of steel fibers, different ranges of concrete strengths, etc. Thus, in this study, steel fibers are modeled as average direct tensile contribution elements in a modified smeared crack truss model, considering directionality and distribution of fibers. In this way, only simple bond tests are required to reflect the effects of different characteristics of SFRC. In addition, the shear contribution of steel fibers can be obtained considering the bond failure of steel fibers. The proposed model was compared to the test results of 8 SFRC panels and 80 SFRC beams, and the shear behavior of the SFRC members was well estimated.

Shear strength of dry joints of concrete panels with and without steel fibres: Application to precast segmental bridges

This work presents a study of the behavior of segmental bridges, focussing on the response of dry castellated joints under shear, in service and ultimate limit states. Tests have been performed on panels with different levels of prestressing, evaluating the behavior of castellated dry joints under direct shear. The possible benefit of using steel fiber reinforced concrete (SFRC) is also evaluated, casting and testing reinforced and SFRC panels. The results obtained in these tests, as well as those found in the literature, have been compared with several design formulae for assessing the load-carrying capacity of dry interlocked joints without epoxy, identifying the formula that gives the best predictions.