Transverse Reinforcement Spacing Research Articles

Non-linear response of confined concrete beam-column structures under horizontal loading

In this study, a behavior law for confined concrete is considered with the introduction of transverse reinforcement to increase the compressive strength of concrete, using the model of Mander et al. This model integrates the confinement effects provided by transverse reinforcement, enhancing the load-bearing capacity of concrete under compressive stress. A pushover analysis is carried out on a full-scale, four- levels structure, using the N2 method. This advanced technique combines non-linear static analysis with inelastic response spectra. Using this approach, the structure's seismic performance can be estimated, accounting for its ductility and the non-linear effects at each loading stage. The inelastic response spectra are adjusted using reduction factors based on the structure's capacity to dissipate seismic energy through inelastic deformations. By varying the confinement rate of the concrete sections, different performance points of the structure can be obtained. The confinement ratio is a crucial parameter influencing the ductility and strength of confined concrete. Closer spacing of transverse reinforcement increases the confinement ratio, which improves the concrete's deformation capacity and ultimate strength. The results show the effect of the behavior law used to consider concrete confinement on the performance points of the structure. In particular, it is observed that increasing the confinement leads to significant gains in the strength and ductility of the structure. These results highlight the importance of optimally using transverse reinforcement to design structures that ensure their performance and safety under seismic loads.

Experimental study on the behavior of damaged CFRP and steel rebars RC columns retrofitted with externally bonded composite material

The structural behavior of concrete columns reinforced with CFRP bars has been the focus of many researches over the past two decades. There is a dearth of comprehensive research concerning the axial compressive performance of retrofitted CFRP bars reinforced concrete (RC) columns. To fill this gap a thorough investigation was carried out to understand failure mode, load–displacement response, axial deflection, axial load-bearing strength, ductility index (DI), stiffness index (KI), and strength index (SI) of retrofitted CFRP bars RC columns. The experimental matrix comprised 14 short circular columns, seven reinforced with CFRP bars and hoops and the other seven with steel bars and hoops. Initial damage was induced through axial loading until a 35% reduction in peak axial strength was observed, after which damaged columns were repaired and retrofitted using CFRP sheets. The parameters of the study include concentric and eccentric compressions, transverse reinforcement spacing, CFRP wrapping, steel, and CFRP reinforcements. According to the findings, lowering transverse hoop spacing enhanced the utmost capacity and ductility of both types of retrofitted columns. The average peak strength and corresponding axial displacement of CFRP RC columns were 22.63% and 14.87%, and ductility (at a 20% load decrease) was 118% higher after CFRP retrofitting. The axial stiffness of damaged CFRP bars RC columns after strengthening with CFRP sheet were not fully rehabilitated and on average SI under concentric loading was 3.22% lower while DI under eccentric loading was 2.71% higher than steel RC columns.

Experimental investigation on the effect of hoop spacing and crosstie configuration on the cyclic performance of reinforced concrete beams

According to ACI 318-19(SI), in the plastic hinge zone of RC beams, the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties. However, in RC construction practice, the longitudinal reinforcement of RC beams is densely arranged, making construction difficult. In this study, four large RC beam specimens were designed and fabricated to conduct experiments to verify the effect of hoop spacing and crosstie configuration on the cyclic performance of reinforced concrete beams. It is found that: (1) The crosstie configuration with seismic hook engaging the longitudinal reinforcement at the bottom is recommended and that during construction, within the range of twice the beam depth from the RC column outer face, the bottom and side formwork should be completed after the crossties are assembled, which should solve the problem of difficult construction. (2) The transverse reinforcement spacing between 4 and 6 times the smallest longitudinal reinforcement diameter of RC beams may have no significant effect on the cyclic performance of RC beams. (3) The requirement that in the plastic hinge zone of RC beams, every corner and alternate longitudinal bar on the perimeter must have lateral support provided by the corner of a tie or crosstie in ACI 318-19(SI) may not have a major impact on the cyclic performance of the RC beam. (4) The ultimate drift angle of each specimen in the negative direction was between 4.3% rad and 4.5% rad; thus, all the specimens satisfied the ACI requirement. However, the cyclic performance (plasticity rotation angle) of all specimens basically did not meet the requirement of 3.0% rad for earthquake-resistant structures.

Nonlinear finite element and machine learning modeling of tubed reinforced concrete columns under eccentric axial compression loading

There is still insufficient data on the behavior of tubed-reinforced concrete columns (TRCCs) under the eccentric compression. Thus, this research work comprehensively examines the eccentric compression behavior of TRCCs using nonlinear finite element modeling and machine learning (ML). To do this, numerical simulation and parametric analysis based on existing investigations were conducted. In addition to the existing 22 specimens with limited test variables, additional 188 specimens were developed to cover a wide range of parameters, including the load eccentricity, transverse reinforcement spacing, columns’ slenderness ratio, yield strength of steel, and outer steel tube diameter. Additionally, six ML models were created to estimate the ultimate load results. The results indicated that increasing the outer steel tube yield strength and diameter, and reducing the load eccentricity, slenderness ratio, and spacing of the transverse reinforcement enhanced the load-carrying capacity of the columns. The Gaussian process regression model demonstrated superior performance metrics in comparison to other ML models, with the highest R2 values (0.998613 in training and 0.99823 in testing stages) and lowest root mean square error values (0.007213 in training and 0.008471 in testing stages). To save money, time, and resources compared to laboratory testing, an online-based prediction program is finally presented to predict the columns’ ultimate load.

Experimental and finite element analysis of reinforced concrete multi-cell box girders retrofitted with carbon fiber reinforced polymer strips under torsion

This study expands the state of the art in studies that assess torsional retrofit of reinforced concrete (RC) multi-cell box girders with carbon fiber reinforced polymer (CFRP) strips. The torsional behavior of non-damaged and pre-damaged RC multi-cell box girder specimens externally retrofitted by CFRP strips was investigated through a series of laboratory experiments. It was found that retrofitting the pre-damaged specimens with CFRP strips increased the ultimate torsional capacity by more than 50% as compared to the un-damaged specimens subjected to equivalent retrofitting. This indicated that the retrofit has been less effective for the girder specimen that did not develop distortion beforehand as a result of pre-loading. From experimental observations, when the girder specimen was cracked and the transverse steel reinforcement bars started straining, the CFRP strips started to work more effectively and contributed together with the transverse steel reinforcement to resist torsion load. Additionally, Finite Element (FE) simulations were developed using Abaqus to model the torsional behavior of the retrofitted girders, the results of which were validated with the experimental data. With the numerical model, the effect of concrete compressive strength, transverse reinforcement spacing, and CFRP strip spacing were examined. The effectiveness of the CFRP strips in enhancing the torsional strength of the girder was found to increase with increasing the spacing between the transverse reinforcement.

Nonlinear finite element and analytical modelling of reinforced concrete filled steel tube columns under axial compression loading

Local buckling of steel and excessive spalling of concrete have necessitated the need for the evaluation of reinforced concrete columns subjected to axial compression loading. Thus, this study investigates the behaviour of concrete filled steel tube (CFST) columns and reinforced concrete filled steel tube (RCFST) columns under the axial compression using the finite element modelling and machine learning (ML) techniques. To achieve this aim, a total of 85 columns from existing studies were analysed utilising the finite element modelling. The ultimate load of the generated datasets was predicted employing various ML techniques. The findings showed that the columns' compressive strength, ductility, and toughness were improved by reducing transverse reinforcement spacing, increasing the number of reinforcing bars, and increasing the thickness and yield strength of outer steel tube. Under the axial compression loading, the finite element modelling analysis provided an accurate assessment of the structural performance of the RCFST columns. Compared to other ML approaches, gradient boosting exhibited the best performance metrics with R2 and root mean square error values of 99.925% and 0.00708 and 99.863% and 0.00717 respectively in training and testing stages, to predict the columns' ultimate load. Overall, gradient boosting can be applied in the ultimate load prediction of CFST and RCFST columns under the axial compression, conserving resources, time, and cost in the investigation of the ultimate load of columns through laboratory testing.

Lateral load resistance of reinforced concrete columns with brittle details

AbstractAnalytical models for shear strength and deformation capacity estimation of reinforced concrete members are essential for the practical implementation of performance‐based seismic evaluation of existing structures and form a key part of current seismic assessment codes (e.g., EN 1998‐3 (2005), (2022), ASCE/SEI 41‐17). Although these models have been derived from regression or calibration of large datasets collected from experimental literature, discrepancy persists between experimental and analytical estimates, especially in cases of members with old‐type detailing. The evident uncertainty about parametric dependencies of the underlying mechanistic problem motivated the present work, where a set of benchmark columns that represent older structural detailing are studied parametrically through advanced finite element simulation. Parameters considered were, the axial load ratio, transverse reinforcement amount and spacing, longitudinal reinforcement ratio, and anchorage/lap splice detailing; results were gauged in terms of the resulting drift ratio (deformation capacity) at the performance limit states and were compared with the Code estimates to evaluate their limits and conservatism. The simulation results were used to vet the assumptions that underlie the simple mechanistic models used in deriving seismic design expressions for yield and ultimate deformation capacities, shear strength, and the rate of its degradation with increasing ductility.

Nonlinear Behavior of the Concrete Core of the Diagonally Reinforced Coupling Beams

Coupled shear walls with coupling beams are constructed because of openings such as doors, windows, or other installations that are left behind due to functional reasons in shear walls. In coupling beams having a ratio of span-to-depth less than two, shear fracture occurs rather than flexural fracture. In order to meet the shear force and the bending moment formed by the coupling beams, diagonal bundles are used in the coupling beams. Diagonal reinforced coupling beams are generally preferred because diagonal reinforced coupling beams exhibit better behaviour than conventional reinforced coupling beams. The diagonal reinforcement bundles have to be confined by transverse reinforcements prescribed in the codes. Confined concrete in the diagonal reinforcement bundles has stress-strain characteristics that are distinctly different from those of plain concrete. The effects of longitudinal and transverse reinforcement ratios on the stress-strain behaviour of confined concrete inside the diagonal reinforcement bundles were investigated. Fifty-four reinforced concrete coupling beams with different confining parameters of the diagonal reinforcement bundles and different variables were analysed using the program. It was demonstrated that the strength and the maximum strain of the concrete inside the diagonal reinforcement bundles increase with the reinforcement ratio of the confinement reinforcement. The increase in the diameter of the transverse reinforcement and the decrease in the spacing of the transverse reinforcement diagonal bundles, increase the confining effect, strength, and ductility in the concrete sections. The increase in the ratio of transverse and diagonal reinforcement significantly affects the seismic behaviour of the coupling beams.

Cyclic behavior of self-slitting squat composite shear walls with concrete-filled steel tubes: Experiment

To improve the deformation capacity of low-rise shear walls, an alternative approach of self-slitting squat composite shear wall with concrete-filled steel tubular columns (SSLSST) was proposed by the authors. This paper presents the experimental results of five SSLSST specimens subjected to cyclic loading, experimental parameters included steel tube thickness (ts), spacing of transverse reinforcement (S), axial compression ratio (n), and shear stud arrangement of inner steel tube. The results showed that owing to weakened effects of both horizontal anchorage to concrete and vertical shear resistance, the self-slit occurred in the SSLSST specimen with half-section shear studs of inner steel tube; SSLSST specimens maintained integrality to resist lateral force like the normal shear wall before the yielding status; with the lateral deformation increasing, the SSLSST specimens were divided into three independent column-type segments to jointly resist both lateral and compressive forces, and the seismic damage mainly concentrated within the slits, resulting in the seismic damage of the whole shear wall body was reduced. Increasing both S and ts can not only greatly improved the seismic resistance and ductility but also reduced the seismic damage and post-earthquake residual deformation (PERD). As expected, high n was not beneficial for the ductility ratio, energy dissipation, and PERD. Generally, the proposed SSLSST showed slight seismic damage, good seismic resistance capacity, ductility, and self-centering ability. Therefore, it is worthy to promote this new type of low-rise shear wall system to actual engineering.

Numerical study on the behaviour of concrete-encased composite slender columns under biaxial loading

Slender steel–concrete composite structural members that utilise the merits of steel and concrete are becoming integral elements in modern-day construction. Encased Steel-Concrete [ESC] has encased outer concrete portion that provides higher stiffness against buckling and protects the inner core steel. The steel portion has greater bending resistance and provides ductility. Amongst the various structural elements, the ESC Column [ESCC] members are often implemented in construction. The present study comprises the behaviour of slender ESCCs subjected to biaxial loading through Finite Element [FE] parametric studies using ABAQUS. The FE model and analysis are validated against the experimental results from existing research work. In this study, a total of 54 slender ESCC- FE models is analysed to access the effect of the governing factors: slenderness ratio, compressive strength of concrete, yield strength of steel, steel contribution ratio, load eccentricity ratio and transverse reinforcement spacing It is found that the ultimate load-carrying is increased about 5.09%, 17.49% and 20.11% for increased structural steel contribution ratio, yield strength of steel, and concrete strength, respectively. Further, the load-carrying capacity (0% to 7.08%) decreases when the eccentricity (0 mm to 200 mm) and slenderness increase.

Behavior of UHPC columns confined by high-strength transverse reinforcement under eccentric compression

This paper presents the experimental and analytical studies on the compressive behavior of ultra-high performance concrete (UHPC) columns confined by high-strength transverse reinforcement under eccentric compression. Nine columns including test variables of spacing, strength and arrangement type of transverse reinforcements, steel fiber content and eccentricity were tested to analyze the load-lateral deflection behavior, failure modes and carrying capacity. The experiment results showed that the deformation capacity, peak load and residual carrying capacity of UHPC columns confined by high-strength transverse reinforcement under eccentric loading were significantly better than those of ordinary-strength transverse reinforcement. Reducing the spacing of transverse reinforcement and increasing the volume fraction of steel fiber could also improve the ductility and carrying capacity of UHPC columns. Then, a mesoscale model was proposed to characterize the tensile behavior of UHPC which considered the fiber inclination, fiber-matrix interface bonding and fiber embedded length. Based on the proposed tensile model, a simplified method for calculating the carrying capacity of UHPC columns under large eccentric compression was developed, where the tensile behavior of UHPC and the confinement effect of transverse reinforcements were considered. The errors between the theoretical and test values were within 10%, indicating that this method can be used to guide the design of UHPC columns.

Experimental and numerical study of recycled aggregate concrete column

AbstractThe improved mechanical properties of recycled aggregate concrete (RAC) by employing the particle packing method (PPM) of the mix design approach encourages its application to study the performance of structural members. The experimental investigation is conducted on the axial compressive behavior of reinforced natural aggregate concrete (NAC) and RAC columns using two different tie spacing conditions. A reduction of 18% in the axial load of RAC columns is observed with respect to the NAC columns and only 2.7% improvement in axial load is recorded as the tie spacing reduces by 22.5%. Subsequently, the finite element (FE) analysis is conducted to investigate the axial compressive strength of both NAC and RAC columns using different tie spacing conditions. The FE analyses of RAC columns with different tie spacing support to modify the spacing of transverse reinforcement as half as that of the spacing specified in the prevailing design for NAC columns.

Evaluating the effects of loading protocol on the strength and deformation capacity of Flexure-Shear critical concrete columns

Columns are considered critical elements with respect to the stability of buildings during earthquakes. Concrete columns with light confinement can sustain shear and axial load failures, which can lead to partial or complete building collapse. Moreover, tests have indicated that lateral cycling of non-ductile columns can impart damage that is cumulative. However, most experiments on concrete columns have used fully reversed cyclic loading protocols, whileearthquake ground motions tend to impart different types of lateral histories. Due to a lack of experimental evidence considering the effects of lateral loading protocols on the strength and deformation capacity of reinforced concrete columns, nonlinear continuum finite element models were calibrated to experimental tests for seven columns subjected to varying lateral loading protocols. Selected columns sustained flexural-shear modes of lateral strength degradation. Columns were selected to cover a range of shear stresses, cross-section, axial loads, transverse reinforcement spacing and ratios, and longitudinal reinforcement ratios. All tested columns sustained axial collapse after cumulative damage from lateral loading. Calibrated column models were then subjected to a series of loading protocols, including monotonic pushover and fully reversed cyclic loading protocols with varying number of cycles. The effects of the lateral loading protocols on damage progression, strength, and deformation capacities are discussed for the columns in light of differences in peak lateral strength, drift at peak lateral strength, drift at the initiation of lateral strength degradation, and drift at the initiation of axial strength degradation.

Confinement detailing of concrete encased steel concrete composite columns

Steel concrete composite construction is now gaining popularity in our country. Concrete-encased steel columns have several advantages, but like RC columns, there is a need to ensure adequate concrete confinement so that it has sufficient ductility under seismic loads. This study investigates the confinement of the concrete based on the detailing of the transverse reinforcement. The ductilities of a typical encased section that satisfies the minimum reinforcement criteria and a highly confined section with special detailing are compared. A nonlinear 3D finite element model is developed in ABAQUS for this purpose. The confined stress-strain curve for M30 grade of concrete is carefully incorporated in the special confined section. The interaction between structural steel and concrete is modelled with an 'embedded region' interaction tool available in the ABAQUS library. Based on the eigen mode of the section, the initial geometric imperfection was given. The significant increment in displacement ductility factor, plastic hinge rotation and drift ratio are observed for a special confined encased column. A parametric study has been carried out by varying the parameters; the axial load ratio, steel contribution ratio, steel width to depth ratio and transverse reinforcement spacing. It was observed that structural section aspect ratio (steel width to depth) and transverse reinforcement spacing significantly affect the ductility of the section. The plastic hinge rotation and drift ratios were also calculated for different sections.

Investigation of Nonlinear Behavior of the Reinforced Concrete Columns for Different Confined Concrete Models

Stress-strain and moment-curvature behavior of the reinforced concrete (RC) square columns have been analytically investigated according to different confined concrete models. The effect of transverse reinforcement diameter, transverse reinforcement spacing and concrete grade on the behavior of RC column models were investigated. For different confined concrete models, the confinement effectiveness coefficient, effective lateral confining stress, confined concrete compressive strength, strain at maximum concrete stress and ultimate concrete compressive strain values were calculated. In the second part, a parametric investigation was carried out for examining the effects of different design parameters on the moment-curvature relationships. Analytical moment-curvature relationships were obtained for RC cross-sections by using the TBEC (2018), Mander model (1988), Saatcioglu and Ravzi (1992) confined concrete models. The effects of the design parameters on the RC square column behavior were evaluated in terms of moment capacity and the curvature of the cross-section. In RC column models, stress-strain and moment-curvature relationships are obtained and compared according to different parameters. Confined concrete strength and the ultimate moment values obtained from the Mander model were higher than the Saatcioglu and Ravzi model when the transverse reinforcement close to the minimum spacing values. The results obtained from the Mander model and TBEC (2018) are close to each other.

Shear strength estimations and shear designs on RC beams with limited ductility by FL and FIL methods

In this study, a fuzzy logic model was constituted by using the Fuzzy Logic (FL) method, which is one of the traditional artificial intelligence (AI) methods, in order to estimate the shear strength of reinforced concrete (RC) beams with limited ductility. In this model, beam width(bw), beam height(h), characteristic concrete compressive strength(fck), transverse reinforcement diameter(T), the number of arms bearing the shear force of the transverse reinforcement(n) and transverse reinforcement spacing(s) were taken into account as variable parameters. The model developed by using the problem data containing the solutions of shear force strength of 2640 beams with different cross-section properties were tested with 480 beam solutions different from these data. In the tests of the developed FL model, maximum percentage error, minimum percentage error, average percentage error and correlation coefficient values were obtained as 3.604, -0.091, 1.514 and R2=0.999678. By applying the fuzzy inverse logic method (FIL), which was recently developed by the author of this study, on the FL model, which is seen to have been developed quite sensitively from the test results, a total of 521 designs were obtained for 15 different RC beams with limited ductility subjected to shear. In order to check the accuracy of these designs, after shear strengths were obtained by conventional computations for these designs, % error and correlation coefficients were computed between the obtained strength values and the shear force values taken into account for the design. The promising results show that the FIL method can be used in the design of RC beams under shear force and even in other scientific studies such as design, optimization and control.

Torsional capacity evaluation of RC beams using an improved bird swarm algorithm optimised 2D convolutional neural network

This study presents the application of deep learning technology in torsional capacity evaluation of reinforced concrete (RC) beams. A data-driven model based on 2D convolutional neural network (CNN) is established, where model inputs contain the beam width, beam height, stirrup width, stirrup height, concrete compressive strength, steel ratio of longitudinal reinforcement, yield strength of longitudinal reinforcement, steel ratio of transverse reinforcement, yield strength of transverse reinforcement and stirrup spacing. To enhance the prediction accuracy of the proposed model, an improved bird swarm algorithm (IBSA) is leveraged to optimise the hyperparameters of CNN in the training phase. A comprehensive dataset, comprising 268 groups of laboratory tests of RC beams collected from published articles, is used for model development and validation. The results show that the proposed 2D CNN with hyperparameter optimisation exhibits high performance in predicting torsional strength of RC beams, which outperforms other machine learning models, building codes and empirical formula in terms of a series of evaluation metrics.

GFRP REINFORCED INVERTED T BEAMS: AN EXPERIMENTAL STUDY

The shear behavior of four Inverted T beam specimens totally reinforced with GFRP (glass fiber reinforced polymer) transverse and flexural reinforcement is presented to analyze the effects of transverse reinforcement spacing and flexural reinforcement ratio on the beam structural performance. All beams had a span-to-depth ratio of 1.4. Main parameters comprised GFRP flexural reinforcement ratio of 2.5 and 4 times the balance reinforcement ratio and stirrups spacing of 75 and 120 mm. The load-displacement curves and the load-strain results of the stirrups and flexural reinforcement are reported in detail. Increasing the transverse reinforcement area notably improved both the loadcarrying capacity and the stiffness of the beams. Similarly, the ductility and capacity were upgraded when the flexure reinforcement ratio of the beams was increased. It can be concluded that increasing the transverse reinforcement area and flexural reinforcement ratio substantially improved the structural safety and crack control of the inverted T beams.

STRENGTH MODEL FOR CALCULATING CENTRALLY COMPRESSED CONCRETE ELEMENTS WITH COMPOSITE REINFORCEMENT, TAKING INTO ACCOUNT THE SPACING OF STIRRUPS

The article discusses the relevance of developing techniques for confined elements with FRP reinforcement. The method for calculating centrally confined concrete columns with non-metallic GFRP reinforcement (without regard to its compression work) is proposed for the first time in the Russian Federation. The strength model was developed based on the well-known theoretical model of confined concrete. The article considers the effect of strengthening the concrete core of the columns, which is obtained due to the more frequent placement of both transverse and longitudinal reinforcement. The dependence of the bearing capacity of concrete columns on the strength of the transverse reinforcement material is shown. It was proved that with a decrease in the spacing of the longitudinal reinforcement, the area of ​​the effectively confined concrete core inside the reinforcement cage increases. It was shown that, due to the low compressive modulus of elasticity of the FRP reinforcement, the stress in it will be comparable to the concrete stress. Therefore, the compressive strength of the FRP reinforcement can be neglected in the case of determining the bearing capacity of centrally confined concrete elements. As a result, a strength model for calculating confined concrete elements with FRP reinforcement was proposed, considering the spacing of transverse reinforcement, the longitudinal and transverse reinforcement ratio, and the strength of the material of transverse reinforcement. The developed strength model can be applied not only for square, but also for columns of round and rectangular sections.

Compressive behavior and stress-strain model of square confined ambient-cured fly ash and slag-based geopolymer concrete

Although a great deal of work has been completed towards the study on geopolymer concrete (GC), most of the efforts have focused on the material mechanical behavior. The objective of this paper is to present the results of an experimental study aimed to investigate the stress-strain behavior of confined fly ash and slag-based GC (FASGC) through the compression testing of a total of fourteen square ambient-cured short columns. The experimental results indicated that the increase in the slag content resulted in higher unconfined compressive strength but more obvious brittle property of confined FASGC. The effectiveness of lateral steel confinement was higher for FASGC than that for ordinary Portland cement-based concrete (OPCC), despite the lateral confinement index Kn of the former one was a little smaller compared to the latter one, the maximum differences in both fcc/fc0 and εcc/εc0 between them were 20.8% and 59.3%, respectively. Both fcc/fc0 and εcc/εc0 were not strongly related to the variation of the spacing of transverse reinforcement. The increase in the diameter of transverse reinforcement was not obviously improve the fcc/fc0 but resulted in the increase in the εcc/εc0, nonetheless, the εcc/εc0 was only increased by 70.9% as the Kn increased 3 times. The models were proposed to predict both ultimate stress and strain and to describe the stress-strain behavior of FASGC with good accuracy, more test data is further need to refine the proposed models. In light of the results, it is recommended to further investigate the effect of the fibers such as steel fiber, FRP fiber on the improvement of the brittle behavior of FASGC.