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Comprehensive Empirical Modeling of Shear Strength Prediction in Reinforced Concrete Deep Beams

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18 March 2024

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21 March 2024

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Abstract
This paper presents a thorough investigation into the shear strength capacity of reinforced concrete deep beams, with a focus on improving predictive accuracy beyond existing code provisions. Analyzing 198 deep beams from 15 investigations, the study considers parameters such as concrete compressive strength (fc’), shear span to effective depth ratio (av/d), and reinforcement ratios (ρs, ρv, ρh ). Introducing a novel predictive model (Equation 7), the study rigorously evaluates it using nonlinear regression analysis and statistical metrics (MAE, RMSE, R2). The proposed model demonstrates a significant reduction in the coefficient of variation (COV) to 27.08%, surpassing existing codes' limitations. Comparative analyses highlight the model's robustness, revealing improved convergence of data points and minimal sensitivity to variations in key parameters. The findings suggest that the proposed model offers enhanced predictive accuracy across diverse scenarios, making it a valuable tool for structural engineers. This research contributes to advancing the understanding of shear strength in reinforced concrete deep beams, offering a reliable and versatile predictive model with implications for refining design methodologies and enhancing the safety and efficiency of structural systems.
Keywords: 
Subject: Engineering  -   Civil Engineering

1. Introduction

A deep beam, conventionally defined by a span-to-depth ratio (h/L) of ≤ 4 or with a shear span smaller than twice the depth, is primarily governed by shear strength rather than flexure, given sufficient longitudinal reinforcement utilization, as depicted in Figure 1(b) [1]. Additionally, deep beams with a span ratio (h/L ≤ 2.5) are classified as such and find extensive applications in constructions like squat walls, foundation pile caps, and deep foundations, as illustrated in Figure 1(c) [2].
Numerous studies have explored the structural behavior of reinforced concrete (RC) deep beams, employing experimental, analytical, and numerical approaches. Eyad et al. (2018) [3], investigated a simply supported deep beam subjected to a uniform distributed load, providing a comprehensive analysis of cracking effects and ultimate shear strength.
Albidah (2023) [4], conducted tests on six metakaolin-fly ash-based geopolymer concrete beams, considering parameters such as steel fiber content and shear reinforcement percentage. The study demonstrated a significant enhancement in shear strength by 16.7% and 31.6% with the addition of steel fibers at rates of 0.35% and 0.70%, respectively. Eyad et al.[5], explored the impact of confining the strut region through the use of struts reinforcement, while Eyad et al. [6], proposed an empirical formula for the strut efficiency factor (Bs) in RC deep beams, derived from a comprehensive analytical study based on the strut and tie model. Other researchers have numerically investigated main parameters influencing the behavior and shear capacity of RC deep beams [7,8].
Despite numerous experimental and numerical investigations into reinforced concrete deep beams, which have considered factors such as concrete compressive strength, (av/d) ratio, and reinforcement directions in relation to shear capacity, the current ACI 318R-5 [1] code and BS 8110 [9] codes still do not incorporate these factors comprehensively. The formulas that provided in these codes are primarily limited to the concrete compressive strength, web width (bw) and depth (d) factors only as presented in equations 1, 2 and 3, respectively. Due to this fact, the current study found that the predictive accuracy of ACI 318R-5 code [1] and BS 8110 code [9] is restricted, with coefficients of variation (CV) for shear capacity prediction. This study offers a thorough examination of deep beams, taking into account pivotal factors that influence the concrete compressive strength (fc'), shear span-to-depth ratio (av/d), web width (bw), ratios of longitudinal (Ps), vertical (Pv), and horizontal (Ph) reinforcement, depth (d), yield strength of vertical stirrups (fyv), and the concrete area (web width × depth (bw×d)). The assessment relies on an extensive dataset comprising 198 deep beams sourced from 15 investigations [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. These studies were chosen for their detailed information on test conditions and material properties, thus forming a robust database conducive to scrutinizing code provisions and affirming the proposed predictive model.
Introducing a novel model for predicting the shear strength of reinforced concrete deep beams generated from the analysis of 198 experimental simply supported RC deep beams subjected to concentrated and uniform loads. The proposed model demonstrates a remarkable improvement in accuracy, outperforming the predictions of both ACI 318R-5 and BS 8110 by a remarkable percentage. This significant enhancement can be credited to the model's comprehensive consideration of (10) various factors influencing the shear strength of reinforced concrete deep beams, unlike the restrictive focus solely on concrete compressive strength found in the ACI and BS standards.

2. Methodology

To achieve the research objective, twelve (12) empirical equations were developed to theoretically predict the shear strength of reinforced concrete deep beams. A total of 198 experimental simply supported RC deep beams subjected to concentrated and uniform loads have been used to establish the empirical factors. The effects of several parameters (Table 1) were considered, such as the concrete compressive strength (fc'), shear span-to-depth ratio (av/d), web width (bw), ratios of longitudinal (Ps), vertical (Pv), and horizontal (Ph) reinforcement, depth (d), yield strength of vertical stirrups (fyv), and the concrete area (web width × depth (bw×d)). The conducted results from the experimental tests were used to verify the developed empirical formula.
To develop the empirical equations, various input data from the selected parameters, as well as the results from experimental simply supported RC deep beams were exported manually into Microsoft Excel software. The study suggests writing program using the ‘Microsoft Visual Basic’ (MVB) in Microsoft Excel software to calculate relevant results/values required to establish twelve (12) empirical equations. In addition, the MVB was used to compute the relevant results based on codes methods formulas in order to be compared with the developed empirical formula.
To improve the readability and clarity, this study suggests organizing the methodology in three separate phases, existing experimental investigations, codes methods for determining RC deep beam shear strength, and an examination of the statistical properties of the dataset.

2.1. Existing Experimental Investigations

The dataset of the current study, generated from 15 literature references [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25], consists of 198 simply supported RC deep beam subjected to shear testing. The main variables that imported from these tests including concrete compressive strength (fc'), shear span-to-depth ratio (av/d), web width (bw), ratios of longitudinal (Ps), vertical (Pv), and horizontal (Ph) reinforcement, depth (d), yield strength of vertical stirrups (fyv), and the concrete area (web width × depth (bw×d)), as presented in Table 1. The study found that, the resulting range of ultimate shear forces (Vu) varied from 77.8 kN to 6294 kN, providing a comprehensive dataset for assessing the shear behavior of RC deep beams. This study reviewed the literature to selects all these key variables which considered influential in shear failure. By assembling this diverse dataset, this research facilitates a comprehensive exploration of how these variables impact the shear capacity of deep beams. This approach affords deep understanding of the relationship between these variables and the ultimate shear strength, thereby enhancing the ability to develop new empirical equation to predict and interpret accurate shear failure. Figure 2 shows the typical design, geometry, and failure pattern characterized by a shear diagonal fracture in a representative deep beam, all the variable that considered in this study were pointed in the figure as well.

2.2. Codes Procedure, for Calculating the Resistance of RC Beams

When determining the shear strength of RC deep beams, different design codes provide unique methods for assessment. The upcoming sections detail the approaches outlined by two standards, ACI 318 R 15 [1] and BS 8110 [9], explaining the formulas for computing the nominal shear strength. These methods are available, in assisting engineers to design RC beams safely against shear force. The equations of both codes were offers limited variables form the factors that affected on the nominal shear strength of the deep beams such as: shear span-to-depth ratio (av/d), ratios of longitudinal (Ps), vertical (Pv), and horizontal (Ph) reinforcement, yield strength of vertical stirrups (fyv), and the concrete area (web width × depth (bw×d)).
  • ACI 318 R-15 [1]
The ACI 318R-15 code delves into the details of shear strength (Vn ACI) determination, limited to a few factors such as concrete compressive strength (f’c), web width (bw), and depth (d) as presented in Equation (1).
V n   ACI = 5 6   f ' c b w d
  • BS 8110 [9]
BS 8110 code is a very popular analytical method for calculating the nominal shear strength in RC deep beams. the formulas of this code were presented through Equations (2) and (3), involves considerations of shear stress limits based on the concrete compressive strength (f’c), web width (bw), and depth (d), highlighting safety and efficiency in FC deep beams structural design.
v n   BS 0.8 f cu o r 5 N / mm 2
V n   BS = v n   BS b w d

2.3. Statistical Properties of Dataset

The study suggests presenting very simple equation for predicting the nominal shear strength (Vn). The suggested equation of calculating the nominal shear strength of the deep beams can be divided into two terms, concrete shear strength (Vc) and shear reinforcement strength (Vs) as presented in equation (4):
V n = V c + V s
It was suggested to analyze the effect of each term (Vc and Vs) in separate sections, to provide a clear understanding of how this study suggests developing the new empirical equation encompassing various factors affecting the shear strength of RC deep beams, including the concrete compressive strength (f’c), shear span-to-depth ratio (av/d), web width (bw), ratios of longitudinal (Ps), vertical (Pv), and horizontal (Ph) reinforcement, depth (d), yield strength of vertical stirrups (fyv), and the concrete area (web width × depth (bw×d)).
  • Concrete Shear Strength Term (Vc)
The concrete shear strength (Vc) term is formulated in eight equations (Equations 5-8 and Equations 11-14), each tailored to specific conditions. These equations will be divided into three different stages, each stage carrying the effect of different variables.
The first stage comprises four equations (Equation 5 to Equation 8), which are related to concrete compressive strength (f’c) and longitudinal reinforcing percentage (ps) variables, a phenomenon known as dowel action.
A *   f ʻ c B *   p s C
A * (   f ʻ c B + p s C )
A * (   f ʻ c B + C   * p s C )
A *   f ʻ c B *   K C
The value of the uncracked compression zone depth (K) is introduced as an essential parameter in this term, it can be calculated based on multiplying the longitudinal reinforcing percentage (ps) by the ratio of the modulus of elasticity of longitudinal reinforcement (Es) to the modulus of elasticity of concrete (Ec) as presented in equation (9) and equation (10).
K = p s C n 2 + 2 p s C   n   -   p s C   n
n = E s E c
Derived from deep beam geometry, the second stage comprises three equations (Equation 11, 12 and 13) which are related to the shear span to effective depth ratio (av/d) variable.
( a v / d ) F
D E + ( a v / d ) F
D + E ( a v / d ) F
Accounting for the size effect of diagonal shear strength in deep beams, the third stage comprises one Equation (Equation 14) which related to the effective depth (d) variable.
G d H
  • Shear Reinforcement Strength Term (Vs)
The shear reinforcement strength (Vs) term is expressed in four equations (Equation 15 to Equation 17), each customized for specific conditions. These equations will be segmented into two different stages, with each stage reflecting the influence of distinct variables.
The first stage comprises two equations (Equation 15 and Equation 16) related to the transverse vertical shear reinforcement (pv) which can be presented as following.
k v *   p v *   f yv
k v = 1 + a v d 6
The second stage comprises two equations as well (Equation 17 and Equation 18) but these equations were related to the transverse horizontal shear reinforcement (ph), which can be represented as following:
k h *   p v *   f yv
k h = ( 5 - a v d 6 )
The coefficients (kv) and (kh) are determined based on the ratio (av/d) instead of clear span to effective depth ratio (ln/d), reflecting the influence of shear reinforcement on the deep beam. The sum of kv and kh is constrained to unity (kv+kh=1) emphasizing the proportionality of vertical and horizontal shear reinforcement. Figure 3 shows the variation of the coefficient (kv and kh) with respect to (av/d).
When the ratio (av/d) is low, the angle (θ) between vertical reinforcement and the failure line (diagonal shear crack) is minimal. In such cases, horizontal reinforcement proves more effective in resisting tension stresses (those that cannot be borne by the concrete) compared to vertical reinforcement, (kv > kh), as the ratio (av/d) increases, the significance of vertical reinforcement in resisting tension stresses becomes more pronounced. When ((av/d) = 2), both types of reinforcement exhibit equal effectiveness, with (kv = kh = 0.5).

3. The Proposed Empirical Equations

This study suggests presenting 12 different combinations to develop the empirical equation for estimating the nominal shear strength (Vn) of RC deep beams, as presented in Table 2. Then, collinear regression analysis served as the cornerstone for determining the coefficients (A-H) in the proposed empirical equations. This intricate process involved the utilization of Microsoft Excel Software which replaced the test results for the nominal shear strength of the selected 198 deep beams (Vn) in these calculations. The main objective of this study was to increase the accurate and find reliable estimation of the nominal shear strength through the proposed equations. So, the study suggests adopting the error values and calculate it to assess the precision and efficacy of each suggested term in each developed equation. Three key statistical metrics were employed to verify the developed equations, mean absolute error (MAE), root mean square error (RMSE), and the coefficient of multiple determinations (R2).
MAE represents the average absolute discrepancy between expected and observed values in the verification model. It is a collinear score that weighs each variable similarly. RMSE represent the root mean square error, which it is a squared and averaged measure of the difference between expected and observed values. MAE and RMSE work in tandem to diagnose erroneous variations in predicted values, with individual mistakes in a sample always being equal to or greater than RMSE. The coefficient of multiple determinations (R2) gauges how much variability the regression model can account for. A value of (R2 = 1) suggests that the regression models accurately describe the data, while (R2 = 0) indicates otherwise. As the optimum empirical equations, the recommended models are chosen based on having the lowest MAE and RMSE values and the highest (R2) value, aligning with the desired precision and reliability. These coefficients were calculated using Equations 19, 20 and 21 respectively.
MAE = 1 N i = 1 N x i - y i  
RMSE = i = 1 N x i - y i 2 N
R 2 = 1 - SSE SST = 1 - i = 1 N x i - y i 2 i = 1 N x i - x - 2
Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8, showed the relationship between the effect of the main parameters on the shear resistance prediction and the value of Vexp/Vn .
Despite variations in f’c between 16.08 and 47.6 MPa as presented in Figure 4, the proposed method (proposal 7) exhibits minimal change, contrasting with other methods (ACI and BS) that yield significantly uneconomic strength predictions with increasing f’c).
Figure 5 shows little change in prediction for the proposed method with (av/d) ranging from 0.19 to 2.5. Conversely, other methods experience a decline in the ratio of (Vexp/Vn) with the highest values of (av/d).
Figure 6, Figure 7 and Figure 8 highlight the substantial influence of (pvfyv), (psfy), and (phfyv) on the proposed method, varying between 0.053 and 10.29 MPa, 0.405 to 14.11 MPa, and 0 to 5.56 MPa, respectively. This influence surpasses that of other methods.
Following a meticulous regression analysis, the proposed Equation (22) is selected as the forecast model for the nominal shear strength of deep beams (Vn Prop) (proposal 7 in Table 2). This decision is grounded in its exceptional performance, boasting the lowest MAE and highest RMSE values, coupled with an (R2) value that closely approaches unity. The study suggests presenting the redemption factors that adopted in the proposed equation in a tabular form (Table 3) for clear understanding.
V n , Prop . = 0.004   ( f c ' 0.17 + 0.65   p s )   a v d - 0.3 1 d 0.17 )     b w d + ( 1 + a v d 6 ) p v + ( 5 - a v d 6 ) p h * 10 - 6 f y v   b w d

4. Evaluation of the Developed Empirical Equation

As a result, this study assesses the performance of nominal shear strength predictions of RC deep beams by comparing the proposed method with existing approaches, through a comprehensive evaluation of existing experimental results.
In the comparison shown in Figure 9, the proposed empirical equation demonstrates a strong correlation between experimental and theoretical results. The data points of the proposed equation are more convergent compared to other methods, indicating its superior predictive accuracy.
Mean value (Mean) Equation (23): Represents the average of ratios of experimental (Vexp) to predicted shear strength values (Vn) for all deep beams. Where, (N) is the total number of deep beams, equal to 198 in this study.
Mean = i = 1 N ( V exp / V n ) i / N
Standard deviation (S.D.) Equation (24): Measures the dispersion of values of (Vexp/Vn), Avg representing the average of the Vexp/Vn.
S . D . = i = 1 N ( ( V e x p / V n ) i A v g . ) 2 N
Coefficient of variation (CV %) Equation (25): Indicates the relative variability of values of (Vexp/Vn), Avg representing the average of the Vexp/Vn.
CV % = S . D . Avg . x 100
Maximum value (Max.): Represents the maximum shear strength ratio.
Minimum value (Min.): Represents the minimum shear strength ratio.
Range value (Range) Equation (26): Indicates the spread between the maximum and minimum values.
Range = Max . / Min .
The detailed comparison involves examining the ratio of the shear resistance of tested beam (Vexp) to the calculated nominal shear resistance based on different methods of prediction (Vn), denoted as (Vexp/Vn). This evaluation is detailed in Appendix A, and Table 3 presents the outcomes for all 198 tested beams using different prediction methods. The last column in Table 3 illustrates the results of the proposed method (Equation 7). Notably, the coefficient of variation (CV %) values range between 29.03% and 29.53% for ACI and BS methods. However, by incorporating the effects of vertical and horizontal reinforcement ratios, the proposed method significantly improves CV% to a value of 27.08%.
Table 4. Comparative Analysis of Shear Strength Ratios.
Table 4. Comparative Analysis of Shear Strength Ratios.
Details ACI Method [1] BS 8110 Method [9] Proposed method
Equation (1) (3) (7)
Mean 1.15 1.10 1.15
Standard deviation 0.34 0.32 0.31
CV % 29.53 29.03 27.08
Max. ratio 2.49 2.25 2.23
Min. ratio 0.43 0.45 0.44
Range (max/min) 5.55 4.97 5.11
Number of tested beams that Vexp ˂ Vn 70 80 65

5. Discussion

The findings of this study underscore the significance of considering multiple factors such as: concrete compressive strength (f’c), shear span-to-depth ratio (av/d), web width (bw), ratios of longitudinal (Ps), vertical (Pv), and horizontal (Ph) reinforcement, depth (d), yield strength of vertical stirrups (fyv), and the concrete area (web width × depth (bw×d)). By analyzing a comprehensive dataset consists of 198 experimental simply supported RC deep beams, this study proposes a novel empirical equation for predicting the nominal shear strength of RC deep beams, outperforming the existing codes such as ACI and BS.
Twelve different sets of empirical equations were developed to create a new empirical equation to estimate the nominal shear strength (Vn) of RC deep beams. Hence, collinear regression analysis served as the cornerstone for determining the coefficients (A-H) in the proposed empirical equations.
The coefficient of multiple determinations (R2) was used to make a comprehensive comparison between the results of the proposed variables. The results of R2 showed a difference in the range from 0.001 to 0.4, which is considered less than 0.5, but the study suggested specifying the coefficients (A-H) and applying them to the proposed components of the equation. Then, the coefficient (R2) was calculated for the results of the proposed empirical equation, and it was equal to 0.94, which is considered a truly acceptable value, especially when compared to the value of R2 for ACI and BS, which was equal to 0.8 and 0.7, respectively.
The study presented a detailed comparison between the current empirical equation and the ACI and BS codes equations to evaluate the ratio of the nominal shear strength of the experimental beam to the calculated nominal shear strength (Vexp/Vn). Based on the comparison results, the study found that the proposed equation outperformed the equations of the ACI and BS codes in all details, such as: Mean, Standard deviation CV%, Max. ratio, Min. ratio and Range(max/min).
The findings of this study bring positive improvements for code development and structure design. By using the proposed empirical equation, the structural designers can improve the effectiveness of structural designs by obtaining higher accuracy in predictions the nominal shear strength for the RC deep beams. As presented earlier, code committees may think about including the examined factors that effect on the shear behavior into the existing standards, like ACI 318R-15 and BS 8110.

6. Conclusions

This study suggests investigating the effect of various parameters on the shear strength capacity of RC deep beams, including the concrete's compressive strength (f’c), shear span-to-depth ratio (av/d), web width (bw), ratios of longitudinal (Ps), vertical (Pv), and horizontal (Ph) reinforcement, depth (d), vertical stirrups' yield strength (fyv), and the concrete area (web width × depth (bw×d)). This inquiry goes beyond what can be done with current codes, such BS 8110 and ACI 318R-5, which have a large coefficient of variation (CV) when it comes to forecasting shear capacity.
Through a comprehensive evaluation of 198 deep beams, imported from an extensive dataset around 15 investigations, this research proposes a novel predictive empirical equation for shear strength. The proposed equation (22), take into account all the mentioned key parameters and it is rigorously assessed through collinear regression analysis and statistical metrics, MAE, RMSE and R2.
The results proved that the proposed empirical equation was significantly enhanced the prediction accuracy compared to the ACI and BS codes achieving a CV, SD, Max. ratio, Min ratio equal to 27.08%, 31.10%, 2.23% and 0.44% respectively, and the range was equal to 5.11. Both vertical and horizontal reinforcement ratios was considered in the proposed empirical equation and it leads for this improvement. The suggested empirical equation outperforms Aci and BS codes in a wide range of cases and exhibits robustness to changes in f'c and av/d.
Furthermore, the comparative study highlights how were the accuracy of the suggested model, with better data point convergence and little susceptibility to changes in important parameters. This present that the suggested model has a higher degree of predictability for shear strength, which makes it a useful tool for structural engineers and practitioners.
This study advances the knowledge of shear strength in the simply supported RC deep beams by providing a more precise and adaptable predictive empirical equation that takes into account the complexities of real-world applications. The results of this study have significance for improving design techniques and raising the security and effectiveness of deep beam structural systems.

Author Contributions

Conceptualization: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo.; Data curation: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih.; Formal analysis: Eyad. K. Sayhood and Salam J. Hilo.; Funding acquisition: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih.; Investigation: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih.; Methodology: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih. ;Project administration: Eyad. K. Sayhood, Nisreen S. Mohammed.; Validation: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih.; Resources: Eyad. K. Sayhood and Salam J. Hilo.; Software: Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih.; Supervision: Eyad. K. Sayhood, Nisreen S. Mohammed.; Visualization: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih.; Writing—original draft: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih .; Writing—review and editing: Eyad. K. Sayhood, Nisreen S. Mohammed, Salam J. Hilo and Salih S. Salih.

Funding

This research received no external funding.

Data Availability Statement

The data are presented in the article.

Acknowledgments

The authors highly acknowledge their institutes and universities for their support in preparing and completing this research.

Conflicts of Interest

The authors declare no conflicts of interest.

Appendix A

Comparison of the ratio (Vexp/Vn) for all 198 beams with codes
Ref. No. Beam No. V E x p . ( k N ) V n A C I ( k N ) V E x p . / V n A C I V n B S ( k N ) V E x p . / V n B S V n , P R O P . ( k N ) V E x p . / V n , P R O P .
[19] 1 2530 2627.04 0.96306 2623.4 0.96440 1964 1.28819
2 2922 2648.78 1.10315 2623.4 1.11382 1971 1.48250
3 2019 2280.33 0.88540 2417.48 0.83517 1865 1.08257
4 2348 2338.28 1.00416 2478.91 0.94719 1877 1.25093
5 2224 2078.59 1.06996 2203.6 1.00926 1916 1.16075
6 2121 2142 0.99020 2270.82 0.93402 1925 1.10182
7 2824 2354.58 1.19936 2496.19 1.13132 1956 1.44376
8 2655 2410.74 1.10132 2555.73 1.03884 1964 1.35183
9 1783 2027.37 0.87946 2149.3 0.82957 1833 0.97272
10 1490 2032.08 0.73324 2154.29 0.69164 1834 0.81243
11 1463 2467.56 0.59289 2615.97 0.55926 1897 0.77122
12 2522 2499.51 1.00900 2623.4 0.96135 1901 1.32667
13 2170 2321.87 0.93459 2461.51 0.88157 1877 1.15610
14 2295 2321.87 0.98843 2461.51 0.93235 1888 1.21557
15 1832 2564.44 0.71439 2623.4 0.69833 1959 0.93517
16 1214 2569.65 0.47244 2623.4 0.46276 1862 0.65199
17 2095 2085.47 1.00457 2210.9 0.94758 1900 1.10263
18 2081 2085.47 0.99786 2210.9 0.94125 1842 1.12975
19 3763 2326.49 1.61746 2466.41 1.52570 2121 1.77416
20 3687 2360.82 1.56175 2502.8 1.47315 2184 1.68819
21 1325 2474.46 0.53547 2623.28 0.50509 1744 0.75975
22 2295 2539.12 0.90386 2627.85 0.87334 1810 1.26796
23 3393 4563.6 0.74349 4696.6 0.72244 3148 1.07783
24 3745 4563.6 0.82062 4696.6 0.79739 3244 1.15444
25 2268 4599.41 0.49311 4698.34 0.48272 2902 0.78153
26 5440 4594.16 1.18411 4692.98 1.15918 3563 1.52680
27 1463 1183.85 1.23580 1255.05 1.16569 1088 1.34467
28 1543 1190.44 1.29616 1262.04 1.22262 1061 1.45429
29 716 1244.22 0.57546 1319.05 0.54281 983 0.72838
30 2633 1252.06 2.10293 1327.37 1.98362 1214 2.16886
31 5017 4116.49 1.21876 4364.07 1.14961 3781 1.32690
32 4136 3521.41 1.17453 3733.19 1.10790 3694 1.11965
33 6294 4116.49 1.52897 4364.07 1.44223 4200 1.49857
34 4901 3401.89 1.44067 3606.48 1.35894 3598 1.36215
35 4875 4500.61 1.08319 4646.14 1.04926 3833 1.27185
[10] 36 369.35 259.958 1.42081 275.592 1.34021 364.4 1.01358
37 467.25 277.967 1.68095 294.685 1.58559 383.5 1.21838
38 493.95 280.903 1.75844 297.797 1.65868 421 1.17328
39 407.15 289.763 1.40511 307.19 1.32540 386 1.05479
40 416.05 290.266 1.43334 307.723 1.35203 430 0.96756
41 445 288.247 1.54381 305.583 1.45623 383 1.16188
42 389.35 280.176 1.38966 297.026 1.31083 392.1 0.99299
43 262.55 147.103 1.78480 155.95 1.68355 228.2 1.15053
44 333.75 157.294 2.12182 166.754 2.00145 170.9 1.95290
45 378.25 158.955 2.37960 168.515 2.24461 288.6 1.31064
46 302.6 158.68 1.90698 168.223 1.79880 234.1 1.29261
47 300.35 158.955 1.88953 168.515 1.78233 286.7 1.04761
48 295.9 157.85 1.87456 167.343 1.76822 231.7 1.27708
49 289.25 148.48 1.94807 157.41 1.83756 255 1.13431
[12] 50 449.7 355.34 1.26555 363.141 1.23836 283.4 1.58680
51 465.2 355.34 1.30917 363.141 1.28105 283.4 1.64150
52 434.1 299.234 1.45070 305.803 1.41954 243.6 1.78202
53 452.1 299.234 1.51086 305.803 1.47840 243.6 1.85591
54 443 241.934 1.83108 247.245 1.79175 217.3 2.03866
55 419.1 241.934 1.73229 247.245 1.69508 217.3 1.92867
[22] 56 161 111.669 1.44176 118.385 1.35997 156.7 1.02744
57 148 109.559 1.35087 116.148 1.27424 157.7 0.93849
58 141 107.097 1.31656 113.538 1.24187 158.6 0.88903
59 170.5 117.205 1.45472 124.254 1.37219 161.2 1.05769
60 184 118.619 1.55118 125.753 1.46319 163.1 1.12814
61 174.5 120.294 1.45061 127.528 1.36833 168.6 1.03499
62 170.5 114.907 1.48381 121.817 1.39964 168.7 1.01067
63 171.5 116.348 1.47403 123.346 1.39040 170.7 1.00469
64 161.5 112.857 1.43101 119.645 1.34983 171.4 0.94224
65 161 110.77 1.45346 117.432 1.37101 183.4 0.87786
66 172.5 113.152 1.52450 119.957 1.43802 185.5 0.92992
67 178.5 117.773 1.51563 124.856 1.42965 188.3 0.94796
68 168 115.196 1.45838 122.125 1.37564 189.2 0.88795
69 147 121.397 1.21090 128.698 1.14221 146.3 1.00478
70 143.5 115.774 1.23948 122.737 1.16917 146.5 0.97952
71 140 117.773 1.18873 124.856 1.12129 148.5 0.94276
72 153 114.033 1.34172 120.891 1.26560 149.3 1.02478
73 128.5 112.561 1.14160 119.331 1.07684 149.3 0.86068
74 131 112.561 1.16381 119.331 1.09779 150.8 0.86870
75 126 108.027 1.16638 114.524 1.10021 151.3 0.83278
76 150 120.57 1.24409 127.822 1.17351 154.2 0.97276
77 145 114.907 1.26189 121.817 1.19031 154.5 0.93851
78 130.5 106.472 1.22567 112.876 1.15614 153.7 0.84906
79 158.5 115.485 1.37247 122.431 1.29461 159.7 0.99249
80 158 112.561 1.40368 119.331 1.32405 160.5 0.98442
81 155 113.152 1.36984 119.957 1.29213 162.2 0.95561
82 166 117.205 1.41632 124.254 1.33597 164.7 1.00789
83 153.5 106.472 1.44169 112.876 1.35990 136.5 1.12454
84 118.5 113.152 1.04726 119.957 0.98785 131.7 0.89977
85 123 120.847 1.01782 128.115 0.96007 134.8 0.91246
86 131 123.034 1.06475 130.434 1.00434 136.8 0.95760
87 122 120.57 1.01186 127.822 0.95445 137.9 0.88470
88 124 115.196 1.07643 122.125 1.01535 135.7 0.91378
89 103.5 113.152 0.91470 119.957 0.86281 136.8 0.75658
90 115 113.446 1.01370 120.269 0.95619 136.8 0.84064
91 124.5 116.635 1.06743 123.649 1.00688 139.1 0.89504
92 124 117.773 1.05287 124.856 0.99314 140.9 0.88006
93 140.5 118.337 1.18729 125.455 1.11992 143.3 0.98046
94 124.5 106.785 1.16589 113.207 1.09976 142.3 0.87491
95 127.5 110.468 1.15418 117.112 1.08870 144.7 0.88113
96 137 112.561 1.21712 119.331 1.14807 146.8 0.93324
97 146.5 114.325 1.28143 121.201 1.20874 148.3 0.98786
98 128.5 111.37 1.15381 118.068 1.08836 145.3 0.88438
99 152 113.152 1.34333 119.957 1.26712 151.1 1.00596
100 152.5 111.07 1.37301 117.75 1.29512 152.3 1.00131
101 159.5 118.9 1.34146 126.05 1.26537 149.3 1.06832
102 87 103.551 0.84017 109.779 0.79250 122.1 0.71253
[20] 103 754 822.787 0.91640 872.272 0.86441 576.3 1.30835
104 350.3 572.572 0.61180 536.524 0.65291 339.3 1.03242
105 206 480.714 0.42853 456.045 0.45171 262.3 0.78536
[23] 106 874.2 575.944 1.51786 610.583 1.43175 663.1 1.31835
107 650.9 589.867 1.10347 618.963 1.05160 594.9 1.09413
108 437.4 572.598 0.76389 607.036 0.72055 542.9 0.80567
109 1175 834.823 1.40748 874.713 1.34330 893.7 1.31476
110 952.3 877.025 1.08583 874.713 1.08870 801.1 1.18874
111 804.4 866.789 0.92802 875.326 0.91897 732.1 1.09876
112 1636.3 1151.22 1.42136 1092.14 1.49825 1094 1.49570
113 1244 1155.41 1.07667 1090.82 1.14043 969.2 1.28353
[24] 114 1615.5 1908.61 0.84643 1924.72 0.83934 1448 1.11568
115 1592.9 1897.8 0.83934 1924.72 0.82760 1446 1.10159
[26] 116 2563.7 2410.19 1.06369 2447.87 1.04732 2155 1.18965
[17] 117 284.8 263.28 1.08174 279.114 1.02037 270.2 1.05403
118 377.6 263.28 1.43421 279.114 1.35285 275.5 1.37060
119 358.1 263.28 1.36015 279.114 1.28299 281.8 1.27076
120 228.7 263.28 0.86866 279.114 0.81938 242 0.94504
121 255.7 263.28 0.97121 279.114 0.91611 242 1.05661
122 208.7 263.28 0.79269 279.114 0.74772 242 0.86240
[20] 123 276.9 466.875 0.59309 437.482 0.63294 267.9 1.03359
124 455.8 461.146 0.98841 437.482 1.04187 301 1.51429
[13] 125 350.8 305.71 1.14749 324.096 1.08240 269.3 1.30264
126 305.8 321.653 0.95071 335.448 0.91162 234 1.30684
127 257.8 298.99 0.86224 316.972 0.81332 203.8 1.26497
128 156.1 179.872 0.86784 190.69 0.81861 153.9 1.01429
129 140.4 196.011 0.71629 207.799 0.67565 138.4 1.01445
130 123.6 184.235 0.67088 195.316 0.63282 124.8 0.99038
[25] 131 606.7 392.608 1.54531 413.845 1.46601 364.9 1.66265
132 351.8 383.198 0.91806 406.245 0.86598 298.9 1.17698
[21] 133 116.75 186.528 0.62591 197.746 0.59040 249.9 0.46719
134 114.53 191.167 0.59911 202.664 0.56512 251.5 0.45539
135 105.65 192.993 0.54743 204.601 0.51637 256.2 0.41237
136 166.8 191.952 0.86897 203.497 0.81967 219.3 0.76060
137 177.93 188.856 0.94215 200.214 0.88870 219.5 0.81062
138 205.75 193.788 1.06173 205.442 1.00150 234.4 0.87777
[16] 139 239.2 197.718 1.20980 209.609 1.14117 221.2 1.08137
140 208.1 166.239 1.25181 176.237 1.18080 184.9 1.12547
141 172.5 133.883 1.28844 141.935 1.21535 149.1 1.15694
142 127.16 101.956 1.24720 108.087 1.17646 114 1.11544
143 77.8 65.0963 1.19515 69.0114 1.12735 78.68 0.98882
[20] 144 348 570.945 0.60952 535 0.65047 331.1 1.05104
[17] 145 284.1 263.698 1.07737 279.557 1.01625 268.8 1.05692
146 377 263.698 1.42967 279.557 1.34856 273.3 1.37944
147 357.5 263.698 1.35572 279.557 1.27881 278.6 1.28320
[11] 148 1357 1137.29 1.19319 1205.69 1.12550 845.3 1.60535
149 1134 1032.33 1.09849 1094.42 1.03617 774.2 1.46474
150 1286 1077.28 1.19375 1142.07 1.12603 830.4 1.54865
[18] 151 251 216.932 1.15704 229.979 1.09140 267.8 0.93727
152 237 216.932 1.09251 229.979 1.03053 267.8 0.88499
153 456 266.817 1.70904 281.25 1.62133 276.2 1.65098
154 426 266.817 1.59660 281.25 1.51467 276.2 1.54236
[16] 155 239 212.613 1.12411 225.4 1.06034 291.1 0.82102
156 224 187.532 1.19446 198.81 1.12670 243.6 0.91954
157 190 137.056 1.38629 145.299 1.30765 192.2 0.98855
158 164 100.022 1.63964 106.037 1.54663 144.7 1.13338
159 90 63.7259 1.41230 67.5585 1.33218 97.9 0.91931
160 249 200.919 1.23931 213.003 1.16900 228.3 1.09067
161 224 163.066 1.37368 172.873 1.29575 188 1.19149
162 216 132.787 1.62667 140.774 1.53437 152.4 1.41732
163 140 103.727 1.34970 109.966 1.27312 117.3 1.19352
164 100 61.3316 1.63048 65.0202 1.53798 79.54 1.25723
[14] 165 222.5 327.225 0.67996 346.906 0.64138 356.2 0.62465
166 209.1 320.505 0.65241 339.781 0.61540 355.1 0.58885
167 222.5 319.144 0.69718 338.339 0.65762 354.9 0.62694
168 244.7 328.553 0.74478 348.313 0.70253 356.4 0.68659
169 278.8 319.144 0.87359 338.339 0.82403 372.9 0.74765
170 256.6 332.504 0.77172 352.501 0.72794 375.2 0.68390
171 284.8 321.184 0.88672 340.501 0.83641 373.3 0.76293
172 268.1 318.462 0.84186 337.615 0.79410 372.8 0.71915
173 241.5 327.225 0.73802 346.906 0.69615 374.3 0.64520
174 301.1 317.778 0.94752 336.89 0.89376 372.7 0.80789
175 322.2 338.343 0.95229 358.692 0.89826 376.1 0.85669
176 334.9 329.215 1.01727 349.014 0.95956 374.6 0.89402
177 379.3 428.076 0.88606 395.85 0.95819 389.8 0.97306
178 277.7 333.81 0.83191 353.886 0.78472 330.7 0.83973
179 311.1 338.343 0.91948 358.692 0.86732 331.5 0.93846
180 245.9 323.21 0.76081 342.649 0.71764 328.7 0.74810
181 285.9 355.286 0.80470 376.654 0.75905 334.4 0.85496
182 290 320.505 0.90482 339.781 0.85349 349.9 0.82881
183 301.1 329.875 0.91277 349.715 0.86099 351.6 0.85637
184 323.7 323.883 0.99943 343.362 0.94274 350.5 0.92354
185 288.2 342.816 0.84068 363.434 0.79299 353.9 0.81435
186 309.3 326.56 0.94715 346.2 0.89341 390.8 0.79145
187 423.8 443.556 0.95546 395.85 1.07061 409.8 1.03416
188 434.9 441.096 0.98595 395.85 1.09865 409.4 1.06229
189 428.6 455.18 0.94161 395.85 1.08273 411.5 1.04156
190 301.1 337.699 0.89162 358.009 0.84104 335.4 0.89773
191 356.7 337.054 1.05829 357.325 0.99825 335.3 1.06382
192 256.6 326.56 0.78577 346.2 0.74119 333.2 0.77011
193 290 323.21 0.89725 342.649 0.84635 341.8 0.84845
194 312.2 335.76 0.92983 355.954 0.87708 344.3 0.90677
195 334.4 328.553 1.01780 348.313 0.96006 342.9 0.97521
196 334.9 326.56 1.02554 346.2 0.96736 342.5 0.97781
197 394.9 350.351 1.12716 371.423 1.06321 423.9 0.93159
198 312.2 317.092 0.98457 336.163 0.92872 378.3 0.82527

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Figure 1. Deep beams application in reinforced concrete structures.
Figure 1. Deep beams application in reinforced concrete structures.
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Figure 2. Simply supported RC deep beam showing the typical design, geometry, and failure pattern.
Figure 2. Simply supported RC deep beam showing the typical design, geometry, and failure pattern.
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Figure 3. Coefficient of effectiveness for vertical and horizontal transverse shear reinforcement.
Figure 3. Coefficient of effectiveness for vertical and horizontal transverse shear reinforcement.
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Figure 4. Effect of f c ' (MPa) on the ratio of (Vexp/Vn) for the ACI, BS and proposed methods.
Figure 4. Effect of f c ' (MPa) on the ratio of (Vexp/Vn) for the ACI, BS and proposed methods.
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Figure 5. Effect of av/d on the ratio of (Vexp/Vn).
Figure 5. Effect of av/d on the ratio of (Vexp/Vn).
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Figure 6. Effect of pvfyv (MPa) on the ratio of (Vexp/Vn).
Figure 6. Effect of pvfyv (MPa) on the ratio of (Vexp/Vn).
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Figure 7. Effect of psfy on the ratio of (Vexp/Vn).
Figure 7. Effect of psfy on the ratio of (Vexp/Vn).
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Figure 8. Effect of phfyv on the ratio of (Vexp/Vn).
Figure 8. Effect of phfyv on the ratio of (Vexp/Vn).
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Figure 9. Comparison between experimental Vexp and predicted Vn shear strength for existing and proposed equations.
Figure 9. Comparison between experimental Vexp and predicted Vn shear strength for existing and proposed equations.
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Table 1. The range data of the selected variables.
Table 1. The range data of the selected variables.
No. Variable Unit Range
1 f’c MPa 16.08 -47.6
2 av/d ---- 0.19-2.5
3 bw mm 76-914.4
4 ps ---- 0.176-3.1%
5 pv --- 0.13-2.45%
6 ph ----- 0-1%
7 d mm 215.9-1752
8 fyv MPa 230-590
9 bw×d mm2 16416-939667.7
10 Vu kN 77.8 -6294
Table 2. Empirical Equations for Estimating the nominal Shear Strength (Vn) RC Deep Beam.
Table 2. Empirical Equations for Estimating the nominal Shear Strength (Vn) RC Deep Beam.
Proposal No. Combination of Equations Proposed Empirical Equations
1 5×11×14+(15+17) A *   f ʻ c B *   p s C * ( a v d ) F   *   ( G d ) H * b w d + k v p v + k h p h * f yv   * b w d
2 5×12×14+(15+17) A *   f ʻ c B * p s C   * D E + ( a v / d ) F *   ( G d ) H * b w d + k v p v + k h p h   * f yv   * b w d
3 5×13×14+(15+17) A * f ʻ c B *   p s C   *   D + E / ( a v / d ) F * ( G d ) H * b w d + k v p v + k h p h * f yv * b w d
4 6×11×14+(15+17) A   * f ʻ c B + p s C   * ( a v d ) F * ( G d ) H * b w d + k v p v + k h p h   * f yv   * b w d
5 6×12×14+(15+17) A * f ʻ c B + p s C   * D E + ( a v / d ) F * ( G d ) H * b w d + k v p v + k h p h * f yv * b w d
6 6×13×14+(15+17) A * f ʻ c B + p s C * D + E ( a v / d ) F * ( G d ) H * b w d + k v p v + k h p h   * f yv   * b w d
7 7×11×14+(15+17) A   * f ʻ c B + C * p s * ( a v d ) F * ( G d ) H * b w d + k v p v + k h p h   * f yv   * b w d
8 7×12×14+(15+17) A * f ʻ c B   + C   * p s * D E + a v / d ) F * ( G d ) H * b w   d + k v p v + k h p h   * f yv   * b w   d
9 7×13×14+(15+17) A   * f ʻ c B   + C   * p s * D + E ( a v / d ) F * ( G d ) H * b w   d + k v p v + k h p h   * f yv   * b w   d
10 8×11×14+(15+17) A   * f ʻ c B   * K C * ( a v d ) F * ( G d ) H * b w   d + k v p v + k h p h   * f yv   * b w   d
11 8×12×14+(15+17) A   * f ʻ c B   * K C * D E + ( a v / d ) F * ( G d ) H * b w   d + k v p v + k h p h   * f yv   * b w   d
12 8×13×14+(15+17) A   * f ʻ c B   * K C * D + E ( a v / d ) F * ( G d ) H * b w   d + k v p v + k h p   * f yv   * b w   d
Table 3. Values of the Coefficients (A-C and F-H) that used in the Selected Empirical Equation.
Table 3. Values of the Coefficients (A-C and F-H) that used in the Selected Empirical Equation.
Coefficients A B C F G H
Values 0.004 0.17 0.65 -0.3 1 0.17
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