Nine **continuous** **concrete** **deep** **beams** **reinforced** with glass fibre **reinforced** polymer (**GFRP**) **bars** were experimentally tested to failure. Three main parameters were investigated, namely, shear span-to-overall depth ratio, web reinforcement and size effect. The experimental results confirmed the impacts of web reinforcement and size effect that were not considered by the strut-and-tie method (STM) of the only code provision, the Canadian S806-12, that addressed such elements. The experimental results were employed to evaluate the applicability of the methods suggested by the American, European and Canadian codes as well as the previous studies to predict the **load** capacities of **continuous** **deep** **beams** **reinforced** with **GFRP** **bars**. It was found that these methods were unable to reflect the influences of size effect and/or web reinforcement, the impact of which has been confirmed by the current experimental investigation. Therefore, a new effectiveness factor was recommended to be used with the STM. Additionally, an upper-bound analysis was developed to predict the **load** **capacity** of the tested specimens considering a reduced bond strength of **GFRP** **bars**. A good agreement between the predicted results and the experimental ones was obtained with the mean and coefficient of variation values of 1.02 and 5.9%, respectively, for the STM and 1.03 and 8.6%, respectively, for the upper-bound analysis.

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FRP has been used extensively for strengthening structural components including the application of FRP sheets or plates as external reinforcement to the exterior surface of **beams** [1] and slabs [2]. Also, FRP sheets have been used to repair damaged **reinforced** **concrete** (RC) columns [3]. The use of FRP as external reinforcement not only provides additional strength but also provides confinement to a deteriorated structure. FRP **bars** have also been used as internal reinforcement in **reinforced** **concrete** **beams** [4] and slabs [5]. The use of FRP **bars** in civil infrastructures is advantageous especially for structures located in marine and salt environments. As FRP is a non-corrosive material, they are resistant to corrosion due to the exposure to de-icing salts. It is noted that, for conventional steel RC structures, exposure to harsh environments including moisture and temperature reduces the alkalinity of the **concrete** and causes corrosion of the steel reinforcement and ultimately results in the loss of serviceability and strength. Internal FRP reinforcement is also beneficial in increasing the **load** carrying **capacity** of **beams**, especially for **beams** constructed with high strength **concrete** [6]. Also, increasing the FRP tensile reinforcement ratio is a key factor in enhancing **load** carrying **capacity** and controlling deflection [7].

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Comparisons between test results and **predictions** obtained from the strut-and-tie model recommended by ACI 318-05 as developed above are shown in Table 3 and Fig. 11: Fig. 11 (a) for simple **deep** **beams** given in appendix A and Fig. 11 (b) for **continuous** **deep** **beams** including Rogowsky et al.’s and Ashour’s test results. In simple **deep** **beams**, the width of strut can be calculated from w t ' cos ( l p ) E sin , and the total **load** is 2 F E sin . Although Eq. (7) proposed by ACI 318-05 is recommended for **deep** **beams** having **concrete** strength of less than 40 MPa, the **load** **capacity** of H-series **beams** were also predicted using this equation to evaluate its conservatism in case of high-strength **concrete** **deep** **beams**. The mean and standard deviation of the ratio,

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Generally, both prediction equations underestimated the flexural **capacity** of all the tested **beams**. The average theoretical strengths of the **beams** based on ACI 440.1R-06 and CSA S806- 12 are 76 % and 81%, respectively, of the experimental flexural strengths. Generally, this finding can be attributed to three major factors. First, the assumed **concrete** compressive strains (0.003~0.0035) used in the **predictions** are lower compared to the actual strain recorded during the flexural tests, which reached higher values ranging from 0.0042 to 0.0048. Second, the prediction equations did not include the contribution of the reinforcement in the compression zone. Finally, the confinement effect due to the lateral ties (stirrups) provided in the pure bending-moment zone were not considered.

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shown that strut and tie models could be usefully applied to **deep** **beams** and corbels. From that point, the present authors began their efforts to systematically expand such models to entire structures and all structures. The approaches of the various authors cited above differ in the treatment of the prediction of ultimate **load** and the satisfaction of serviceability requirement. Form a practical viewpoint, true simplicity can only be achieved if solutions are accepted with sufficient accuracy. Therefore, it is proposed here to treat in general the ultimate limit state and serviceability in the cracked state by using one and the same model for both.

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This paper presents experimental and analytical study related to the flexural behavior of **concrete** **beams** longitudinally **reinforced** with **GFRP** **bars**. The specimens consist of simply supported **reinforced** **concrete** **beams** with two point **load**. Totally 16 **concrete** **beams** includes 8 **beams** **reinforced** with steel and 8 **beams** **reinforced** with **GFRP** **bars** were tested to failure. Flexural **capacity** of the beam was observed experimentally and analytically. A computer program of cross sectional analysis using discrete element model was developed in this study to determine the flexural **capacity** of the **beams**. In addition, available stress-strain model proposed by the other researchers was used in order to simulate the behavior of material in calculation process. Finally, the flexural **capacity** obtained from analytical calculation was compared to that obtained from the test in term of moment-curvature curves and **load** deflection curves. The results show that beam **reinforced** with **GFRP** experienced larger ultimate **load** and larger deflection at same **load** level compared to beam **reinforced** with steel.

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The shear **capacity** of **deep** **beams** is a major issue in their design. The behavior of **reinforced** **concrete** **deep** **beams** is dif- ferent from that of slender **beams** because of their relatively larger magnitude of shearing and normal stresses. Unlike slen- der **beams**, **deep** **beams** transfer shear forces to supports through compressive stresses rather than shear stresses. There are two kinds of cracks that typically develop in **deep** **beams**: ﬂexural cracks and diagonal cracks. Diagonal cracks eliminate the inclined principal tensile stresses required for beam action and lead to a redistribution of internal stresses so that the beam acts as a tied arch. The arch action is a func- tion of a/d (shear span/depth) and the **concrete** compressive strength, in addition to the properties of the longitudinal reinforcement. It is expected that the arch action in FRP rein- forced **concrete** would be as signiﬁcant as that in steel rein- forced **concrete** and that the shear strength of FRP- **reinforced** **concrete** **beams** having a/d less than 2.5 would be higher than that of **beams** having a/d of more than 2.5 [2]. The application of the **reinforced** **concrete** **deep** **beams** within structural engineering practice has risen substantially over the last few decades. More specially, there has been an increased practice of including **deep** **beams** in the design of tall buildings, offshore structures, wall tanks and foundations. They differ from shallow **beams** in that they have a relatively larger depth compared to the span length. As a result the strain distribution across the depth is non-linear and cannot be described in terms of uni-axial stress strain characteristics [3]. Prediction of behavior of **deep** **beams** by design codes which contain empirical equations derived from experimental tests has some limitations. They are only suitable for the tests con- ditions they were derived from, and most importantly, they fail to provide information on serviceability requirements such as structural deformations and cracking. Likewise, the strut and tie model, although based on equilibrium solutions thus pro- viding a safe design, does not take into account the non-linear material behavior and hence also fails to provide information on serviceability requirements. Cracking of **concrete** and yielding of steel are essential features of the behavior of

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ABSTRACT: The main purpose of this study investigated the effects of hybrid use of micro glass fiber (GF), micro polypropylene fiber (PF) and macro steel fiber (SF) on the flexural **capacity**, energy absorption, ultimate **load** carrying, failure mode and ductility behavior of lightweight aggregate **concrete** (LWC) **beams** **reinforced** with glass fiber **reinforced** polymer (**GFRP**) **bars**. A total of eight **beams** with a rectangular cross-section and 100 mm wide × 200 mm **deep** × 1500 mm long, were cast and tested up to failure under four-point bending. The correction factor (φ) calculated compared with American design codes of ACI 440.1R-06 and ISIS design manual No. 3. The φ factor for **beams** made of hybrid PF, SF into the LWC mixes (PSLWC) and **reinforced** with 0.9 ρ fb ; where ρfb is the balanced reinforcement ratio of the **GFRP** **bars** is approximately 1.38

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The loads and reactions have been measured using a **load** cell of **capacity** 2000 kN and 0.1 kN accuracy. The **load** cell readings were recorded automatically using the data logger. The corresponding vertical deflections of test **beams** at the locations of the mid- span point were measured using LVDT's of 100 mm **capacity** and 0.01 mm accuracy. Electrical strain gauges of length 10 mm, with resistance 120.4 ± 0.4 ohm, and a gauge factor of 2.11 were used to measure the strains in the main longitudinal top and bottom flexural steel, vertical stirrups, and horizontal shear reinforcement. The gauges were fixed on the steel **bars** before casting. The surface of the steel was cleaned and smoothed, and the gauges were installed on the steel **bars** using adhesive material and then they were covered with a water proofing material for protection. For all **beams**, two gauges were fixed on the top bar at the interior support and on the bottom bar at the mid span. In addition, four gauges were fixed on two vertical stirrups and horizontal shear reinforcement at intersection points of these stirrups and horizontal reinforcement with the strut lines joining the point **load** with the internal and external supports. The **load**, deflections, and steel strains were measured and recorded automatically by connecting the **load** cell, LVDT's, and the electrical strain gauges to data acquisition system.

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The present paper reports test results of nine two-span RC **deep** **beams** [10]. The tested variables were shear span-to-depth ratio, vertical web reinforcement ratio, horizontal web reinforcement ratio, and **concrete** compressive strength. The specimens were tested in a compression machine where increasing monotonic static loads were at each mid-span. All tested **beams** were loaded until failure. The failure planes evolved along the diagonal crack formed at the **concrete** strut along the edges of the **load** and intermediate support plates. The test results were measured at different loading levels for the mid-span deflection, mid- span bottom steel strain, middle-support top steel strain, middle-support stirrups strain, and end-support stirrups strain. Also, the cracking patterns were identified. The effects of testing variables on the first diagonal crack **load**, ultimate shear **load**, deflection, stiffness, and failure mechanisms were studied. Finally, the obtained test results are compared to the **predictions** of finite element analysis for **continuous** **deep** **beams** and a well agreement between the experimental and analytical results was found.

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geopolymer **concrete** and this has been the key motivation of this undertaking. This study presents an investigation of the flexural response of geopolymer **concrete** **beams** **reinforced** with sand-coated glass FRP (**GFRP**) **bars** subjected to four-point static bending test. Three full-scale **beams** with nearly same amount of bottom **GFRP** **bars** but with varying diameter were cast and tested. The crack patterns and failure modes, **load** versus deflection relationships, bending-moment and deflection capacities, and strains in the **bars** and geopolymer **concrete** are presented. Furthermore, the experimental flexural **capacity** of **beams** are compared with the predicted values using the current standards and with their **GFRP**- **reinforced** **concrete** (**GFRP**-RC) counterparts to verify the suitability of the proposed system for structural applications.

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Abstract: This paper reports and compares experimental studies on flexural performance of **concrete** **beams** **reinforced** with hybrid fiber **reinforced** polymer (FRP) and steel HRB **bars** with this study and other literatures. The objective of this study is to examine the effect of hybrid FRPs on structural behavior of retrofitted RC **beams** and to investigate if different sequences of BFRP and **GFRP** **bars** of the hybrid FRPs have influences on improvement of strengthening RC **beams**, Total 3 steel **reinforced** **concrete** **beams** and 8 hybrid **reinforced** **beams** were designed using only HRB steel **bars** and hybrid G/BFRP-steel **bars** respectively. The flexural bearing **capacity**, the maximum crack width and the deflection of the test **beams** were obtained and analyzed. Results show that the ultimate bending moment of hybrid **reinforced** is slightly less than that of steel **reinforced** **concrete** beam with the same reinforcement ratio. It can be concluded that it is feasible to replace the corner steel **bars** of **concrete** members with FRP **bars** without reducing the flexural bearing **capacity**. However, the deflection and maximum crack of hybrid **reinforced** **concrete** **beams** are much higher than those of steel **reinforced** **concrete** **beams** at the same **load** levels. The theoretical calculation method can effectively predict the flexural bearing **capacity**, crack spacing, maximum crack width and deflection of hybrid **reinforced** **concrete** **beams**, which can be used in engineering design reference.

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performance. However, unlike slender **beams**, non- linear strain distribution is nominal in **deep** **beams**. The direct compression strut formed between the **load**- ing point and support tends to increase shear strength. This created a distinctive failure mode compared to slender **beams**. In **deep** **beams**, shear reinforcement controls the **concrete** strut and increases **load**-carrying **capacity**. Therefore, an increase in shear performance is expected by applying the high tensile strength of FRP shear reinforcement in **deep** **beams**. To verify the performance of the proposed shear reinforcement, this paper aims to experimentally investigate the shear performance of **GFRP** plate shear **reinforced** **deep** **beams**. Also the strut-and-tie modeling approach used in the steel reinforcement was examined to see its validity for **deep** beam shear **reinforced** with **GFRP** plate.

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analytical investigation of flexural behaviors of **concrete** **beams** **reinforced** with glass-**reinforced**-polymer (**GFRP**) **bars** were studied. The **GFRP** rebar having the tensile strength of 902 MPa and Young’s modulus of 46 GPa. The **beams** were 1800 mm long with a rectangular cross section of 150 mm in width and 200 mm in depth. Totally Four **beams** were tested. One beam was **reinforced** with glass-FRP **bars**, two **beams** were **reinforced** with both glass-FRP **bars** and steel and one was **reinforced** with steel, serving as a control specimen. The **beams** were tested to failure in four-point bending over a clear span of 1600 mm. The test results were reported in terms of ultimate **load** carrying **capacity**, deflection and cracks. The experimental results were used to predict the **load** vs. deflection of **Concrete** **beams** **reinforced** with hybrid **bars**. The measured **load** vs. deflections was analyzed and compared with the predicted FEM model using ABAQUS. The results indicate that the reaction forces and deflections obtained from the finite element model (FEM) were well matched with the experimental results.

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Grace et al (1998) reported that continuously supported T-section **concrete** **beams** **reinforced** with different combinations of longitudinal reinforcing **bars** and stirrups made of glass FRP (**GFRP**) and carbon FRP (CFRP) demonstrated the same **load** **capacity** as steel **reinforced** **concrete** **beams** but lower ductility and different failure modes. Continuously supported FRP **reinforced** **concrete** **beams** tested by Ashour and Habeeb (2008), and Habeeb and Ashour (2008) exhibited a small amount of moment redistribution, whereas El-Mogy et al. (2010) reported that moment redistribution in **continuous** FRP **reinforced** **concrete** **beams** is possible if the reinforcement configuration is suitably selected. More recently, Mahroug et al. (2014a&b) concluded that **continuous** CFRP and BFRP **reinforced** **concrete** slabs developed earlier and wider cracks and larger deflections compared with the counterpart steel **reinforced** **concrete** slab. It was also observed that combined shear and flexural failure was the dominant mode of failure for all **continuous** FRP **reinforced** **concrete** slabs tested. These investigations also showed that ACI 440 1R-06 equations can reasonably predict the **load** **capacity** and deflection of simply supported **GFRP** **beams** but significantly underestimate deflections of continuously supported FRP **reinforced** **concrete** **beams** after first cracking.

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The **load** **capacity** and behavior of a reinforcement **concrete** **deep** beam at each loading stage based on the geometric property of the section, steel arrangement, **load** and support condition. The current study used to inspect the structural response of **continuous** reinforcement **concrete** **deep** T-**beams** **reinforced** with the carbon fiber **reinforced** polymer (CFRP) failed in shear. The study analyzed three **concrete** **deep** T- **beams**, these **beams** contain CFRP reinforcement and three **concrete** **deep** T- **beams**, these **beams** contain steel reinforcement for comparison. The deflection, failure mode, crack pattern also studied at analysis. the shear failure is predominant for all analysis T-**beams**. And the result shows when keeping the rate of the CFRP reinforcement constant and increasing a/d ratio substantially affects the shear strength and the collapse loads decreasing, also the CFRP **reinforced** T-**beams** can be showed the shear strength value higher than those of similar steel **reinforced** T- **beams**.

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Ashour et al., (2004) tried 16 strengthened cement (RC) **continuous** **beams** with various reinforcements of inner steel **bars** and outside CFRP covers. Every single test example had the same geometrical measurements and were ordered into three gatherings as per the measure of interior steel support. Every gathering incorporated one non-**reinforced** control beam intended to fizzle in flexure. Three types of failure modes were watched, to be peeling failure of the **concrete** cover, laminate rupture and cover detachment. The ductility of every single **reinforced** beam was diminished in examination with their particular reference beam. Moreover, rearranged routines for assessing the flexural **load** **capacity** and the interface shear stresses between the **concrete** and the adhesive material were displayed. As in past studies, they watched that expanding the CFRP sheet length did not counteract peeling failure of the CFRP laminates.

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and complexity of manufacturing process. More practical solutions have been suggested such as; confinement of **concrete** in compression zone [14], addition of fibres to **concrete** [15-17] and use of a hybrid combination of FRP and steel re-**bars** [18-26]. Such hybrid reinforcement system shows improved serviceability and ductility, and enhancement of **load**-carrying **capacity** compared to traditional reinforcement [19,21]. In spite of the fact that the literature shows some research on simply supported **beams** **reinforced** with hybrid FRP and steel rebars [18-25], none of these research projects was carried out to investigate the structural behaviour and failure modes of multi- span **continuous** hybrid **reinforced** **concrete** **beams** which are considerably different from those of simply supported ones. Therefore, **concrete** **continuous** **beams** are not well represented by statically determinate specimens tested in previous studies. For instance, the moment redistribution characteristics and the changes in the beam curvature from sagging to hogging do not exist in simply supported **beams**. Moreover, the majority of **concrete** structures in practice are multi-span **continuous** members.

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