T-**beams** are acknowledged as economic and efficient structural members widely used for floor slab construction systems. In many cases, according to practice in some countries, the **beams** do not present transverse **reinforcement**, and their **shear** strength is governing for dimensioning the width of the **web**. Although experimen- tal investigations have shown that the presence of the compression flange enhances the **shear** **capacity** with respect to equivalent rectangular cross sections, most cur- rent design codes neglect this phenomenon, which leads to the overdesign of these members. In this paper, the role of the compression flange of slender T-**beams** with concentrated loads is investigated with reference to its **influence** on the shape of the critical **shear** crack and to the associated **shear** transfer actions (STA) of the beam. The **flanges** are considered elements that allow the smearing of applied loads over a certain length of the **web**. This consideration, in combination with the mechanical model of the Critical **Shear** Crack Theory (CSCT), allows a consistent treatment of the phenomenon and leads to simple design expressions accounting for the role of **flanges**. The results of the proposed model are compared together with design codes (Model Code 2010, Eurocode 2, and ACI 318-11) and other **shear** design approaches to a database of 239 **beams** on T-shaped members. The comparison shows that the role of **flanges** is finely accounted with the proposal based on the CSCT, leading to consistent agreement and to strength predictions that are more suitable for design purposes than the other investigated design models.

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This paper reports the testing of fifteen **reinforced** **concrete** deep **beams** with openings. All **beams** tested had the same overall geometrical dimensions. The main variables considered were the opening size and amount of inclined **reinforcement**. An effective inclined **reinforcement** factor combining the **influence** of the amount of inclined **reinforcement** and opening size on the structural behaviour of the **beams** tested is proposed. It was observed that the diagonal crack width and **shear** strength of **beams** tested were significantly dependent on the effective inclined **reinforcement** factor that ranged from 0 to 0.318 for the test specimens. As this factor increased, the diagonal crack width and its development rate decreased, and the **shear** strength of **beams** tested improved. **Beams** having effective inclined **reinforcement** factor more than 0.15 had higher **shear** strength than that of the corresponding solid **beams**. A numerical procedure based on the upper bound analysis of the plasticity theory was proposed to estimate the **shear** strength and load transfer **capacity** of **reinforcement** in deep **beams** with openings. Predictions obtained from the proposed formulas have a consistent agreement with test results.

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equations. For the ACI318-11 provisions the ratio equals 1.44, 1.26 for EC-2, 1.35 for Model Code 2010 and 1.33 for CSA A23.3-14, using for the Model Code the better results obtained for the different levels of approximation. The CoV is 18.6% for the simplified model proposed in this paper. For ACI318-04, EC-2, MC- 2010 and CSA A23.3-14 the CoV equals 35.3%, 34.1%, 31.4% and 26.9% respectively. A recently published paper studied the scatter in the **shear** **capacity** of slender RC members **without** **web** **reinforcement** [46]. The authors concluded that the scatter of the **shear** **capacity** seems to be mainly due to the randomness of the tensile strength of **concrete**. Also recently, other authors confirmed that a comparison with different **shear** design models revealed that models that use the **concrete** tensile strength predict the **shear** **capacity** of continuous prestressed **concrete** **beams** with external prestressing more accurately [47] that the models that do not explicitly consider the tensile strength of the **concrete**. In this sense, the coefficient of variation of the predictions by the Compression Chord **Capacity** Model for the beam tests included in the four databases is not much higher than the coefficient of variation of the splitting tensile strength. In a published database of 78 splitting tensile tests [48], the coefficient of variation (COV) for the prediction of the tensile strength was 15.1%. This fact seems to indicate that the **shear** transfer mechanisms at failure have been well captured by the model.

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Abstract: For **shear**-critical structural elements where the use of stirrups is not desirable, such as slabs or **beams** with **reinforcement** congestion, steel fibers can be used as **shear** **reinforcement**. The contribution of the steel fibers to the **shear** **capacity** lies in the action of the steel fibers bridging the **shear** crack, which increases the **shear** **capacity** and prevents a brittle failure mode. This study evaluates the effect of the amount of fibers in a **concrete** mix on the **shear** **capacity** of steel fiber **reinforced** **concrete** **beams** with mild steel tension **reinforcement** and **without** stirrups. For this purpose, twelve **beams** were tested. Five different fiber volume fractions were studied: 0.0%, 0.3%, 0.6%, 0.9%, and 1.2%. For each different steel fiber **concrete** mix, the **concrete** compressive strength was determined on cylinders and the tensile strength was determined in a flexural test on beam specimens. Additionally, the **influence** of fibers on the **shear** **capacity** is analyzed based on results reported in the literature, as well as based on the expressions derived for estimating the **shear** **capacity** of steel fiber **reinforced** **concrete** **beams**. The outcome of these experiments is that a fiber percentage of 1.2% or fiber factor of 0.96 can be used to replace minimum stirrups according to ACI 318-14 and a 0.6% fiber volume fraction or fiber factor of 0.48 to replace minimum stirrups according to Eurocode 2. A fiber percentage of 1.2% or fiber factor of 0.96 was observed to change the failure mode from **shear** failure to flexural failure. The results of this presented study support the inclusion of provisions for steel fiber **reinforced** **concrete** in building codes and provides recommendations for inclusion in ACI 318-14 and Eurocode 2, so that a wider adoption of steel fiber **reinforced** **concrete** can be achieved in the construction industry.

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failed **shear** span was the only output of the NNs developed. Table 1 gives the ranges of input data in training, validation and test subsets used to develop the NNs. In the database, beam width of deep and slender **beams** ranged from 20 to 300 mm and from 100 to 457 mm, respectively, effective section depth is between 80 and 1,559 mm for deep **beams** and between 110 and 1,090 mm for slender **beams**, and longitudinal **reinforcement** ratio ranged between 0.0011 and 0.066 for deep **beams** and between 0.0028 and 0.066 for slender **beams**. The maximum ver- tical **web** **reinforcement** indices for deep and slender **beams** were 0.964 and 0.14, respectively, and the maximum horizontal **web** **reinforcement** index for deep **beams** was 1.847. The test speci- mens were made of **concrete** having a very low compressive strength of 11.2 MPa and 14.7 MPa for deep and slender **beams**, respectively, and a high compressive strength of 120 MPa and 125 MPa for deep and slender **beams**, respectively. Training, vali- dation and test subsets had 50%, 25%, and 25% of all specimens in the database, respectively. The input data in each subset were selected at equally spaced points throughout the database so that the range of input in training subset would cover the entire distri- bution of database and input in validation subset would stand for all points in training subset as shown in Table 1.

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Since the **beams** were prepared with different **shear** span length, significant **influence** can be seen from two types of failure mode. It is clearly shown that the **beams** with lesser a/d ratio (i.e.; BSM-01 to BSM-04) experienced higher **capacity** compared to **beams** which have greater a/d ratios (i.e.; BSM-05 to BSM-08). Similar results was found in **beams** which **reinforced** with GFRP bars i.e.; BGM-01 with 1.6 a/d ratios exhibit high **capacity** up to 233.2 kN rather than BGM-05 with a/d=3.1 that only reached 99.0 kN when it failed. It is shown that the ultimate **capacity** increases as the **shear** span-to-depth ratios decreases. In addition, two modes of failure, **shear** and flexure were observed from the test results. Sudden formation of diagonal crack can be found in the **shear** span zone followed by beam failure (BSM-03, BSM-04, BGM-03 and BGM-04). Additionally, the inclination of **shear** cracks growth rapidly as the load increase. While, beam failed in flexure experienced by one of the following condition i.e.; rupture of tensile longitudinal **reinforcement** for beam BGM-01, BGM-05, BGM-06, BGM-07 and BGM-08 and also **concrete** crushing on the top of

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In this study, three **reinforced** **concrete** **beams** were tested using the new **shear** **reinforcement** swimmer bar system and the traditional stirrups system. Several shapes of swimmer bars are used to study the effect of swimmer bar configuration on the **shear** load **carrying** **capacity** of the **beams** (Al-Nasra et al 2013). Only three **beams** will be presented in this study. The first beam, BC, is used as a reference control beam where stirrups are used as **shear** **reinforcement**. The other two **beams** were **reinforced** by swimmer bars. Beam, WSB is the beam which is **reinforced** by two swimmer bars welded to the longitudinal top and bottom bars. Beam, SSB is the beam which is **reinforced** by swimmer bars spliced with the longitudinal steel **reinforcement**. Extra stirrups were used to make sure that the prepared **beams** will fail by **shear** in the swimmer bars side. In this investigation, all of the **beams** are supposed to fail solely in **shear**, so adequate amount of tension **reinforcement** were provided to give sufficient bending moment strength. This study aims at investigating a new approach of design of **shear** **reinforcement** through the use of splicing swimmer bars provided in the high **shear** region. The main advantages of this type of **shear** **reinforcement** system are: flexibility, simplicity, efficiency, and speed of construction. AlNasra and Asha (2013) studied the use of swimmer bars welded to the longitudinal steel **reinforcement**, and concluded that the beam **reinforced** with welded swimmers bars exhibit better **shear** resistance compared with the control sample beam **reinforced** with regular stirrups.

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Moody et.al [28 & 29] in 1954 presented experimental works on 40 NWC **beams** casted **without** **shear** **reinforcement** and 2 NWC **beams** casted with **shear** **reinforcement**, which were segregated into three series to observe the **influence** of the variables: (i) percentage of longitudinal and **web** **reinforcement** and method of anchorage, (ii) size and percentage of longitudinal **reinforcement** and cylindrical **concrete** strength and (iii) **concrete** mixture and method of curing. The concept of redistribution of internal stresses was introduced for the predictions of **shear** failure for NWC **beams**. For each of the 3 series, the sizes of the **beams** were different and the **beams** were tested with one or two concentrated load. It was observed that all **beams** failed in **shear**. It is observed that the **shear** **capacity** of the NWC beam specimens increased with the increment of **concrete** strength and percentage of longitudinal steel. It was also noted that the test results indicated that the beam strength tested at higher a/d ratio is governed by the first cracking load whilst the beam strength tested at lower a/d ratio is governed by the load, which caused destruction to the **concrete** compression zone. Hence, it is suggested by Moody et. al that instead of cracking load, ultimate load should be taken as the measured value for **shear** **capacity**.

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combined action of moment and **shear** taking the size effect into consideration is evaluated at the formation of diagonal tension cracks and at ultimate **shear** failure by using a method that combines both dimensional analysis and statistical analysis. Several sets of experimental data were carefully selected such that the **influence** of each basic variable (i.e., longitudinal steel ratio , **concrete** compressive strength f c ' , **shear** span to depth ratio a / d or beam size d ) can be separately evaluated. Comparison with existing experimental results as well as with four existing models supports the validity of the two proposed models in predicting and explaining the observed behavior of slender RC **beams** ( a / d 2 . 5 ) **without** **web** **reinforcement**.

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Abstract—This study presents test results of simply supported **concrete** **beams** longitudinally **reinforced** either by steel or glass fiber-**reinforced** polymer (GFRP). A total of sixteen large-scale **concrete** **beams** with steel stirrups were constructed and tested under four-point monotonic loading until failure. Half of the **beams** were longitudinally **reinforced** with GFRP bars, while the other half was **reinforced** with conventional steel bars as control specimens. To examine the **shear** behavior of the GFRP **reinforced** **concrete** (RC) **beams**, the main parameters investigated in the study included **shear** span-effective depth ratios, longitudinal **reinforcement** ratios and stirrup ratios. Two modes of failure, namely flexure and **shear** were observed. Due to low modulus elasticity of FRP bars, it was found that lesser **shear** strength resulted in **concrete** **beams** **reinforced** with GFRP bars compared to **beams** **reinforced** with steel bars. Moreover, the **influence** of the **shear** span-effective depth ratios and longitudinal **reinforcement** ratios significantly affect the distribution of internal forces in GFRP **reinforced** **concrete** **beams**. The test results correlated well with the prediction values provided by standard codes and design guidelines except in the case of GFRP **reinforced** **concrete** **beams** failed on **shear**.

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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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Abstract— This study presents test results of simply supported **concrete** **beams** longitudinally **reinforced** either by steel or glass fiber-**reinforced** polymer (GFRP). A total of sixteen large-scale **concrete** **beams** with steel stirrups were constructed and tested under four-point monotonic loading until failure. Half of the **beams** were longitudinally **reinforced** with GFRP bars, while the other half was **reinforced** with conventional steel bars as control specimens. To examine the **shear** behavior of the GFRP **reinforced** **concrete** (RC) **beams**, the main parameters investigated in the study included **shear** span-effective depth ratios, longitudinal **reinforcement** ratios and stirrup ratios. Two modes of failure, namely flexure and **shear** were observed. Due to low modulus elasticity of FRP bars, it was found that lesser **shear** strength resulted in **concrete** **beams** **reinforced** with GFRP bars compared to **beams** **reinforced** with steel bars. Moreover, the **influence** of the **shear** span-effective depth ratios and longitudinal **reinforcement** ratios significantly affect the distribution of internal forces in GFRP **reinforced** **concrete** **beams**. The test results correlated well with the prediction values provided by standard codes and design guidelines except in the case of GFRP **reinforced** **concrete** **beams** failed on **shear**.

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Abstract There is no general consensus or accepted theory for evaluating the ultimate **shear** **capacity** of **reinforced** **concrete** **beams** **without** **web** **reinforcement** as a result the requirements in most of Codes of practice are provided in the form of empirical equations for predicting the **shear** **capacity** of **reinforced** **concrete** **beams**. In this paper, a study is conducted to evaluate the predictive accuracy of 6 empirical equations used in different Code of practice to predict the **shear** **capacity** of **reinforced** **concrete** slender **beams**. Empirical equations used in some Codes are identified to be superior to other equations. In addition, a study was also conducted to assess predictive accuracy of 17 empirical equations proposed in the literature by several researchers to predict the **shear** **capacity** of **reinforced** **concrete** slender **beams**. Among these 17 empirical equations some equations are identified to be superior to the other proposed equations. On the basis of experimental results of **reinforced** **concrete** **beams** having **shear** span to depth ratio a/d ≥2.5, empirical equations are proposed which include basic parameters i.e. **concrete** compressive strength , **shear**

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The effect of small circular opening on the **shear** and flexural and ultimate strength of **beams** were investigated. The main factors of the test are the diameter changes and the opening position. In this study, five **beams** were casted and tested using C20 **concrete** and Fy415 steel. The first beam was solid and was used as control for comparison with other **beams** with an opening. The second beam opened at distance of L/8 by 110mm (0.55D), third beam opened at distance of L/8 by 90mm (0.45D). Beam number four and beam number five had openings at distance L/4 as mentioned above. The tested **beams** were loaded with two concentrated and symmetrical load as simple beam. They conclude that the reduction of ultimate strength increased and cracking patterned as well as the beam failure mode when the opening diameter increased. To increase the ultimate **shear** strength of the beam, they recommended the use of diagonal **reinforcement** and stirrups in top and bottom chords of opening. They also concluded that the most critical opening position to achieve the ultimate strength in **beams** is near the support and that the best opening place in these **beams** is mid span (flexure zone) [18].

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and SFRC members are shown in order to clarify the differences. The ratios based on theoretical values calculated by predicted equations showed an approximate uniform consistency while the rates based on the codes calculations a great gap. This is due to the fact that the codes neglect the effect of steel fibres in their equations whereas the predicted equations by investigators were specifically designed for SFRC **beams**. It can be noticeable from 5.6 that the average ratios of the experimental **shear** strengths to the theoretical code values are conservative for all **beams**. All ratios are highly conservative for SFRC **beams** in particular for the reason mentioned previously about ignoring the effect of the presence of steel fibres. ACI and CSA codes slightly underestimated the nominal **shear** strength for all **beams** except NNB sample that showed lower experimental **shear** strength than ACI result for the same beam. ACI and CSA did not consider steel fibres in **beams** in predicting **shear** strength. Therefore, experimental **shear** resitance values of **beams** with steel fibres were noticeably greater than the codes predictions. This is definitely attributed to the higher flexural **capacity** gained by the presence of steel fibres in those **beams**. Those samples in fact failed in flexure **without** even knowing how much **shear** stresses they could resist. That is, the actual **shear** strength of **beams** failed in flexure is highly greater than codes prediction. On the other hand, the underestimation predictions by codes for reference RC **beams** are purposely reduced by codes for safety reasons in order to keep the designed **beams** in the safe side.

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Asghari et al. (2013), presented an experimental investigation on **shear** strength enhancement of **reinforced** **concrete** lightweight deep **beams** externally **reinforced** with vertical CFRP sheets. The **shear** span/depth ratio was taken equal to 1, and the percentage of **shear** strength improving by strengthening was 30%. Khudair and Atea (2015), studied the **shear** behavior of self-compacting **concrete** deep **beams** strengthened with CFRP sheets. The experimental work includes testing of **reinforced** **concrete** self-compacting **concrete** (SCC) deep **beams** with **shear** span/depth ratio of 2. The tested results show that the specimens strengthened by vertical CFRP sheets provided enhancement in ultimate loads reached 30%.

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In this study, the failure modes of BSM are governs by steel yielding before the **concrete** strain at the compression area reached the maximum permissible value of 0.0035 [11]. For **shear** **reinforcement**, 2-legged steel stirrups of 8 mm diameter (mild steel) were spaced at 50 mm and 150 mm centre to centre at the **shear** region. These two kinds of spacing were calculated based on BS8110 code provisions in order to investigate the **shear** performance of the **beams** with minimum and adequate amount of stirrups. In each specimen, strain gauges were position at selected locations at longitudinal bars, stirrups and **concrete** which were labelled as X (see Fig. 1). The deflection of the beam was measured by at mid-span and two loading points.

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Moreover, in order to picture confirmation of the SR development model, a parametric analysis was accomplished based on the procedure that proposed in [41]. The mentioned procedure examines the response of the developed formulae to a set of assumed data. Based on this method, one input is changed while the other inputs are remained constant at their average. If this analysis yields conformed results to the underlying of problem, the strength of developed formulae is proved. For this study, the results of the mentioned parametric analysis show in Fig. 3. In fact, Fig. 3 illustrates the tendency of the **shear** **capacity** of SFRC **beams** to the variations of 𝑉 𝑓 , 𝑙 𝑓 ⁄ 𝑑 𝑓 , 𝜌 𝑙 , 𝑑, 𝑎 𝑑 ⁄ and 𝑓 𝑐 ′ . Therefore,

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The test results revealed that the inclusion of different volumes of macro synthetic fibre enhanced the shear failure behaviour of GFRP reinforced concrete beams, and [r]

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