Asala Dawood | University of Diyala (original) (raw)

Papers by Asala Dawood

Engineering Structures , 2021

This work proposed reinforced concrete two-span continuous deep beams by replacing the well-known... more This work proposed reinforced concrete two-span continuous deep beams by replacing the well-known conventional reinforcement by reinforcing struts and ties only and omitting the concrete where the struts and ties do not pass through. The strut and tie modelling recommended by ACI 318M-14 was adopted herein. The struts and ties were reinforced as compressive and tensile members, respectively. Twelve specimens, which were divided into four groups, were cast and tested. In every group, the first specimen was a conventionally reinforced reference beam, the second specimen was a specimen in which only the stress paths of the struts and ties were reinforced, and the third specimen was the proposed frame. The strut-tie angle, specimen width and loading type were taken into consideration as main parameters. Generally, the proposals gave less load capacity than the reference specimens, but they remained higher than the design load. In addition, the proposed specimens significantly reduced the weight.

IOP Conference Series: Materials Science and Engineering, 2021

The current paper presents a review of some previous experimental and theoretical studies concern... more The current paper presents a review of some previous experimental and theoretical studies concerning reinforced concrete (RC) curved or ring beams, behavior and strength. Due to curvature, it is necessary to include torsional effects in the analysis and design. The most effective parameters worth to be reviewed are; ring diameter, number of supports, width of beam, concrete compressive strength, and width of bearing plate. There are different analysis methods to estimate the load capacity and behavior in addition to finite element analysis. From the previous studies it was concluded that increasing ring diameter decreases the load capacity, while increasing number of supports, width of beam, concrete compressive strength, and width of bearing plate increases the load capacity due to the increase in beam section or its properties. RC ring beams fail in flexure, while the deep ring beams fail in shear in a manner similar to straight beams. Plastic analysis and strut and tie model (STM) are useful tools to analyze curved or ring deep beams effectively. Furthermore, the three-dimensional, nonlinear finite element modelling is ideal for predicting the behavior of RC curved deep beams.

IOP Conference Series: Materials Science and Engineering, 2021

View the article online for updates and enhancements. You may also like Content from this work ma... more View the article online for updates and enhancements. You may also like Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Journal of Bridge Engineering, 2022

This study reports on experimental test results of reinforced concrete pier caps with different s... more This study reports on experimental test results of reinforced concrete pier caps with different shear spans to effective depth ratios (a/d) of 0.5, 1, and 1.5. Each test specimen is then designed theoretically using both shear friction (SF) and strut-and-tie modeling (STM) approaches, according to Section 16.5 and Chapter 23 of ACI 318-14, respectively, and the results are compared with the pier caps experimental test results. The cracking load, failure load, deflection, crack pattern, crack width, steel reinforcement strains, concrete surface average strains, and failure modes are observed, recorded, and discussed. The experimental load capacities are compared with the theoretical load capacities of SF and STM. Experimental test results indicate that both STM and SF are conservative approaches and STM is more conservative than SF. The reason for this is because they do not take secondary reinforcement into direct consideration. That is why, a model is proposed, modifying STM, for estimating the ultimate capacity of pier caps based on calculating the strength of concrete and secondary reinforcement separately that gave more realistic results.

ACI Structural Journal, 2022

This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the ... more This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the familiar approach of secondary distributed reinforcement is substituted with modeling the corbel as a strut-and-tie system, in agreement with ACI 318 on strut-and-tie modeling (STM). The study consists of constructing and testing 15 corbel specimens until failure, including six conventionally reinforced reference specimens and nine proposed specimens in which only struts and ties were reinforced. The shear span-effective depth ratio (a/d) is variable: 0.5, 1, and 1.5, respectively. The test results show crack and strain evolution in both concrete and steel bars, together with load-deflection response. Conclusions show that corbel designs based on a strut-and-tie system provide substantial saving in weight of approximately 13 to 52% along with a less obvious but still substantial extra ultimate capacity of 12 to 50% compared to the nominal ACI 318-14 STM design load

AIP Conference Proceedings 2660, 020113 (2022), 2022

This paper displays the horizontal curvature (circular curvature) effect on deep beams using fini... more This paper displays the horizontal curvature (circular curvature) effect on deep beams using finite element analysis. Thirty-five reinforced concretes horizontally arched deep beams were analyzed. The parameters that were taken into consideration in the current work are the curvature angle (α) and beam height (H) while keeping one constant value for the beam length (L), i.e., different length to depth ratios (L/H). It is found that for L/H=2; the load capacity decreases by about 38-73% and 16-67%, respectively, when changing α from ∞ (straight beam) to 180 degrees, while torsional moments increase by about 74-174%. Negative bending moments decrease by about 13-56% when changing α from 30 to 180 degrees. The deflection decreases by about 0.1-1.8% when changing α from ∞ to 90 degrees. For L/H=2.5; The load capacity decreases by about 36-73% and 15-67%, respectively, when changing α from ∞ to 180 degrees, while torsional moments increase by about 73-168%. Negative bending moments decrease by about 14-57% when increasing α from 30 to 180 degrees. Decreasing deflection by about 4.1-5.9% when increasing α from 60 to 90 degrees. For L/H=3; load capacity decreases by about 34-73% and 14-68%, respectively, when changing α from 0 to 180 degrees, while torsional moments increase by about 71-161%. Negative bending moments decrease by about 15-58% when increasing α from 30 to 180 degrees. The deflection decreases by about 6-9.7% when increasing curvature angle from 60 to 90 degrees. For L/H=3.5; the load capacity decreases by about 34-73% and 14-69%, respectively, when changing α from 0 to 180 degrees, while torsional moments increase by about 70-156%. Negative bending moments decrease by about 15-59% when changing α from 30 to 180 degrees. Midspan deflection decreases by about 4.6-14.7% when changing α from 60 to 120 degrees. Finally, it is found that for L/H=4; The load capacity decreases by about 33-74% and 14-69%, respectively, when changing α from 0 to 180 degrees, while torsional moments increase by about 69-150%. Negative bending moments decrease by about 16-60% when changing α from 30 to 180 degrees. Changing α from 60 to 120 degrees leads to decrease deflection by about 9.1-19.4%.

AIP Conference Proceedings, 2022

The current work presents a parametric study for twenty-five reinforced concrete overhang curved ... more The current work presents a parametric study for twenty-five reinforced concrete overhang curved deep beams using finite element analysis. The parameters that were taken into consideration are radius, height, width, compressive strength of concrete and number of supports. It is found that the max positive moments increase by about 2.8-4.4% when decreasing the radius of beam by about 16-33%. The max negative bending moment, max torsional moments and max deflection decrease by about 1.9-12.4%, 0.4-8.9% and 30-87%, respectively, when beam radius decreases by 16-66%, whereas load capacity increases by about 23-195%. The max positive bending moment, max negative bending moment, torsional moment and load capacity increase by about 32-128%, 30-124%, 31-125% and 31-127% respectively, when the beam height increases by 12.5-100%, while deflection decrease by about 9-18%. The max positive bending moment, max negative bending moment, torsional moment, load capacity and max deflection increase by about 32-147%, 29-134%, 30-138%, 32-146% and 1.2-4.9%, respectively when beam width increases by 12.5-50%. The max positive bending moment, max negative bending moment, torsional moment, load capacity and max deflection increase by about 17-70%, 15-61%, 15-63%, 17-69% and 0.1-0.4%, respectively, when concrete compressive strength increase by 33-166%. Finally, it is found that the max positive bending moment increases by about 32% when increasing number of supports by 33%. Max negative bending moment and capacity of load increase by about 17-60% and 106-763%, respectively, when number of supports increases by 33-133%. Torsional moment and max deflection decrease by about 0.8-16% and 29-78%, respectively when number of supports increases by 33-133%.

ACI Structural Journal, 2023

The role of reinforcement in ring deep beams with horizontal curvature is studied. The study cons... more The role of reinforcement in ring deep beams with horizontal curvature is studied. The study consists of six ring deep beam specimens, including a conventionally reinforced reference specimen and five specimens in which flexural and web reinforcement were varied. In the second and third specimens, horizontal and vertical web reinforcement were omitted, respectively, while in the fourth specimen, both were omitted. In the fifth and sixth specimens, top and bottom flexural reinforcement were reduced and omitted, respectively. Conclusions illustrate that vertical web reinforcement has a greater effect on load capacity compared to horizontal, and both have a greater effect than upper and lower flexural reinforcement. Moreover, depending on the experimental failure modes of the tested specimens, analysis using STM, ACI 318-19 is considered logical and safe despite its reservations. Therefore, a model has been proposed to predict load capacity by taking the effect of web reinforcement and the torsional moments

ACI Structural Journal, 2023

This study aims to shed light on the inclined direct stress paths of curved struts in deep ring b... more This study aims to shed light on the inclined direct stress paths of curved struts in deep ring beams by converting them into real members. Five specimens were tested with three loading and three supporting points. Three specimens were conventional rings and two were in the form of a frame that took its cross-sectional dimensions from the strut-and-tie model (STM) in ACI 318-19. The effect of reinforcing struts was studied by reinforcing the rings with both proposed and conventional reinforcements, and the frames with the proposed reinforcement only. The findings show that the proposed reinforcement reduced weight and cost by approximately 18% and 13%, respectively, and provided openings for services by approximately 24%. Additionally, strut curvature was found to reduce load capacity by 3 to 6%, meaning that the STM is safe and can be used efficiently in this type of deep curved member.

AIP Conference Proceedings , 2023

The aim of this research work is to study the most important parameters that affect the loading c... more The aim of this research work is to study the most important parameters that affect the loading capacity and behavior of elliptical ring reinforced concrete beams with (L) section. Twenty specimens were modelled using ETABS Software to study the effect of changing the length of the major axis (while keeping the ratio of the major to minor axis equal to 0.64), width, height, thickness, and loading type. The maximum values of negative bending and torsional moments in addition to midspan deflection increase by 1.24-8.24%, 1.33-11.43%, and 32.5-131%, respectively when the major axis of beam increases by 20-60%. Whereas, major axis increase leads to decrease the maximum positive bending moments and load capacity by 5.91-4.45% and 26.5-52.9%, respectively. That happens due to the extending of span length that happened because of major axis increase. When the beam height increases by 25-75%, the maximum positive and negative bending moments (M+ve) and (M-ve), torsional moments and load capacity increase by 33.92-102.4%, 33.92-100%, 29.84-89.74% and 38.8-116.6%, respectively. While this increase in height leads to maximum deflection decrease by 5-8.4%. That happens because the beam sectional area increases due to increasing beam height. M+ve and M-ve, load capacity and midspan deflection decrease by 0.33-7.9%, 1.61-1.1%, 4-20%, and 11-30%, respectively when beam width increases by 46.6-140%. While this increase in width leads to torsional moment to increase by 2.15-0.87%. The sectional area of beam increases because of width increase, i.e., additional strength capacity. When thickness of beam increases by 100-500%, M+ve, M-ve, load capacity and maximum deflection decrease by 4.25-18.8%, 2.3-16.2%, 7.4-37% and 19.8-67%, respectively, whereas the torsional moments increase by 1.42-0.12%. Finally, torsional moments increase by 0.68-1.49 %, respectively due to testing through partial or full uniform load by 20-100% length of span.

AIP Conference Proceedings, 2023

The current work presents a study on strength and behavior of reinforced concrete T-section ellip... more The current work presents a study on strength and behavior of reinforced concrete T-section elliptical ring deep beams through the finite element technique. The parameters that were taken into consideration are diagonal axis (major axis) with the same major axis to minor axis ratio, height, flange thickness, web thickness, and compressive strength of concrete. It is found that the maximum values of positive bending moment (Mmax+ve), maximum negative bending moments (Mmax-ve), maximum torsional moments (Mmaxtor) and deflection increase by about 0.12-0.77%, 1.86-4.9%, 1.9-3.77% and 22.7-77.9%, respectively when the beam diagonal axis increases by 16-50%. Mmax+ve, Mmax-ve, Mmaxtor and load capacity increase by about 68.43-135.3%, 71.13-142%, 61.89-123.8%and 71-142%, respectively when the beam height increases by 50-100%. While the increase in height leads to decrease in the maximum deflection by about 4.62-5.33%. Mmax+ve, Mmax-ve, load capacity and max deflection decrease by about 0.38-4.04%, 1.135-6.25%, 1.51-6.06%, 13.5-30.9%, respectively when the flange thickness increases by 100-200%. While the increase in flange thickness leads to increase in the Mmaxtor by about 0.57-0.42%. Mmax+ve, Mmax-ve, Mmaxtor, load capacity and max deflection increase by about 210.4-446.8%, 156.63-374.9%, 216.5-494%, 215.4-469.2% and 82.4-129.8%, respectively, when concrete web thickness increases by 50-100%. Mmax+ve, Mmax-ve, Mmaxtor, load capacity and max deflection increase by about 15.69-42.49%, 15.78-41.62%,15.81-41.7%, 16.92-44.61% and -0.37-0.37%, respectively, when concrete compressive strength increases by 33.33-100%.

Journal of Bridge Engineering, 2021

This study reports on experimental test results of reinforced concrete pier caps with different s... more This study reports on experimental test results of reinforced concrete pier caps with different shear spans to effective depth ratios (a/d) of 0.5, 1, and 1.5. Each test specimen is then designed theoretically using both shear friction (SF) and strut-and-tie modeling (STM)
approaches, according to Section 16.5 and Chapter 23 of ACI 318-14, respectively, and the results are compared with the pier caps experimental test results. The cracking load, failure load, deflection, crack pattern, crack width, steel reinforcement strains, concrete surface average strains, and failure modes are observed, recorded, and discussed. The experimental load capacities are compared with the theoretical
load capacities of SF and STM. Experimental test results indicate that both STM and SF are conservative approaches and STM is more conservative than SF. The reason for this is because they do not take secondary reinforcement into direct consideration. That is why, a
model is proposed, modifying STM, for estimating the ultimate capacity of pier caps based on calculating the strength of concrete and secondary reinforcement separately that gave more realistic results. DOI: 10.1061/(ASCE)BE.1943-5592.0001758. © 2021 American Society of Civil Engineers.

ACI Structural Journal, 2021

This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the ... more This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the familiar approach of secondary distributed reinforcement is substituted with modeling the corbel as a strut-and-tie system, in agreement with ACI 318 on strut-and-tie
modeling (STM). The study consists of constructing and testing 15 corbel specimens until failure, including six conventionally reinforced reference specimens and nine proposed specimens in which only struts and ties were reinforced. The shear span-effective depth ratio (a/d) is variable: 0.5, 1, and 1.5, respectively. The test results
show crack and strain evolution in both concrete and steel bars, together with load-deflection response. Conclusions show that corbel designs based on a strut-and-tie system provide substantial saving in weight of approximately 13 to 52% along with a less obvious but still substantial extra ultimate capacity of 12

Structures, 2020

ACI 318-14 analyzes reinforced concrete corbel by shear friction (SF) and/or strut-and-tie modeli... more ACI 318-14 analyzes reinforced concrete corbel by shear friction (SF) and/or strut-and-tie modeling (STM). This work presents the results of experimental tests conducted on three reinforced concrete corbels that had a height of 390 mm and a width of 115 mm. The corbels had different shear span to effective depth ratios (a/d), which were 0.5, 1 and 1.5, respectively. Each test specimen was analyzed using both SF and STM to make a comparison between the experimental results. The cracking load, failure load, deflection, crack pattern, steel reinforcement strains, concrete surface average strains and locations of failure were recorded and discussed for the tested corbels. The findings revealed that, in the case of corbels with a/d = 0.5, the shear friction ultimate capacity (P) SF and the STM ultimate capacity (P) STM were less than the experimental failure load (P) f by about 15% and 22%, respectively. In addition, P P and SF STM were less than P f by about 18% and 27%, respectively, when a/ d = 1. In contrast, in the case of a/d = 1.5, P P and SF STM were less than P f by about 32% and 37%, respectively. In conclusion, in the case of a/d < 1, both STM and SF can be used, although STM is more conservative due to its safety factors. In the case of a/d = 1-2, STM is more accurate than SF. However, if a/d exceeds 2, the corbel should be treated as a conventional cantilever beam.

International Journal of Civil Engineering and Technology (IJCIET), 2018

Corbels are cantilever with small shear span to depth ratio (a/d) projected from columns or walls... more Corbels are cantilever with small shear span to depth ratio (a/d) projected from columns or walls to support precast members like beams, girders or dapped end beams. Shear friction (SF) method is used to analyze and design reinforced concrete (RC) corbels. Because of the small value of a/d, corbels are treated as deep beams. Using strut and tie modeling (STM), they can be analyzed. In both SF and STM, there are many parameters that affect the behavior of the corbels such as a/d, width (b), compressive strength of concrete (f'c), yield strength of reinforcement (fy), and horizontal to vertical load ratio (H/V). In the current study, according to ACI 318-14 provisions, the effect of these parameters were investigated using both SF and STM. It was found that the shear capacity increases by about 32.6%, 26.3% and 31.2% for SF and by about 54.1%, 50.4% and 30.9% for STM with increasing width, compressive strength, and yield strength by about (100-300) %, (15-35) % and (400-600) %, respectively. Whereas, shear capacity decreases by about 58.54% and 48.7% for SF and about 59.4% and 33.2% for STM with increasing a/d and H/V by about (0.1-1.9)% and (0-1)%, respectively. It was also seen that the results obtained by STM is more reliable than SF when compared with experimental works that were taken from literature.

What is meant by the wide corbel here is the corbel whose width (b) is more than two times its he... more What is meant by the wide corbel here is the corbel whose width (b) is more than two times its height (h).
Wide Corbels are short cantilevers that stand out from inner face of wide columns or shear walls to support uniformly
distributed loading that comes from wide beam. ACI 318-14 provisions allow the structural design of shear-controlled
corbels through either shear friction (SF) method or the Strut-and-Tie modeling (STM). The current study presents
analysis and design procedures using both SF and STM. Numerical examples for analyzing and designing one meter
wide corbel are presented here in detail. It is concluded that the calculated load capacity using SF is 21% greater than
that of STM. In other words, SF requires less reinforcement than STM by about 25%. That can be attributed to the
difference in the safety factors that adopted by both approaches. More specifically, SF considers the main reinforcement
as the reinforcement that resists moments, while STM considers it as the reinforcement that resists the direct tension of
the formed tie. On the other hand, SF considers that the concrete and the horizontal stirrups resist shear, while STM
considers that the shear is resisted by the formed inclined struts. The wide reinforced concrete corbel is designed here
in the same way of the narrow one, but with some important differences. The main differences that were adopted in
wide corbels are the applied load is a uniformly distributed load through the corbel width, repeating the frame
reinforcement through the corbel width in order to hold the secondary reinforcement, and distributing the secondary
reinforcement in a repetitive, overlapping and interchangeable way in order to ensure that the stirrups exist inside the
entire corbel core.

AIP, 2020

Unsymmetrical reinforced concrete double corbels have different shear spans (a) in each side. ACI... more Unsymmetrical reinforced concrete double corbels have different shear spans (a) in each side. ACI 318-14 provisions allow the structural analysis and design of double corbels through either shear friction (SF) method or the Strut-and-Tie modeling (STM). The current study presents analysis procedure using both SF and STM. Numerical examples for analyzing unsymmetrical reinforced concrete double corbels with two different right to left shear span ratios (ar/al = 3 and 2) are also presented here in detail. It is concluded that reducing ar/al from 3 to 2 increases capacity by about 10.65% in case of SF, and 9.62% in case of STM. More specifically, in case of ar/al=2-3, capacity calculated by SF exceeds that calculated by STM by about 23-24%. Finally, it is also concluded that the mode of failure dose not be the same at the both corbel sides, but in any case, the weaker side is the one who reports the failure.

AIP, 2020

Most codes of practice, like ACI 318-14, 9.9.1.3, require the use of strut-and-tie modeling (STM)... more Most codes of practice, like ACI 318-14, 9.9.1.3, require the use of strut-and-tie modeling (STM) to deal with reinforced concrete continuous deep beams (rc-cdbs). Though, investigations that conducted on rc-cdbs did not include all the most influential parameters. This work presents an analytical parametric study using STM stated by ACI 318-14 to calculate load capacity of 20 rc-cdbs with different parameters. The parameters took into consideration in the current work are shear span to overall depth ratio (a/h), width of beam (bw), width of bearing plate (BP), concrete compressive strength (f'c) and amount of vertical shear web reinforcement (pv). It is seen that the load capacity decreases by about 14% to 37% when a/h increases by about 33% to 100%. It is also seen that load capacity increases by about 33% to 100% when bw increases by about 33% to 100%, while the load capacity increases by about 10% to 30% when BP increases by about 33% to 100%. Finally, it is found that load capacity increases by about 35% to 100% when compressive strength increases by about 35% to 100%, while the load capacity increases by about 0% to 25% when pv increases by about 33% to 100%.

AIP, 2020

Most codes of practice, like ACI 318-14, require the use of strut-and-tie modeling to analyze and... more Most codes of practice, like ACI 318-14, require the use of strut-and-tie modeling to analyze and design
reinforced concrete deep beams. Though, investigations that conducted on deep beams do not include ring deep beams of
influential parameters. This work presents an analytical parametric study using strut-and-tie modeling stated by ACI 318-
14 to predict load capacity of 20 reinforced concrete ring deep beam specimens with different parameters. The parameters
that were under consideration in the current work are ring diameter (Dc), number of supports (NS), width of ring beam
(bw), concrete compressive strength (f'c) and width of bearing plate (Bp). It is found that the load capacity decreases by
about 14-36% when ring diameter increases by about 25-75%. It is also found that load capacity increases by about 62-
189% when number of supports increases by about 33-100%, while the load capacity increases by about 25-75% when the
beam ring width increases by about 25-75%. Finally, it is found that load capacity increases by about 24-76% when
compressive strength increases by about 24-76%, while the load capacity increases by about 5-16% when Bp increases by
about 25-75%.

Engineering Structures , 2021

This work proposed reinforced concrete two-span continuous deep beams by replacing the well-known... more This work proposed reinforced concrete two-span continuous deep beams by replacing the well-known conventional reinforcement by reinforcing struts and ties only and omitting the concrete where the struts and ties do not pass through. The strut and tie modelling recommended by ACI 318M-14 was adopted herein. The struts and ties were reinforced as compressive and tensile members, respectively. Twelve specimens, which were divided into four groups, were cast and tested. In every group, the first specimen was a conventionally reinforced reference beam, the second specimen was a specimen in which only the stress paths of the struts and ties were reinforced, and the third specimen was the proposed frame. The strut-tie angle, specimen width and loading type were taken into consideration as main parameters. Generally, the proposals gave less load capacity than the reference specimens, but they remained higher than the design load. In addition, the proposed specimens significantly reduced the weight.

IOP Conference Series: Materials Science and Engineering, 2021

The current paper presents a review of some previous experimental and theoretical studies concern... more The current paper presents a review of some previous experimental and theoretical studies concerning reinforced concrete (RC) curved or ring beams, behavior and strength. Due to curvature, it is necessary to include torsional effects in the analysis and design. The most effective parameters worth to be reviewed are; ring diameter, number of supports, width of beam, concrete compressive strength, and width of bearing plate. There are different analysis methods to estimate the load capacity and behavior in addition to finite element analysis. From the previous studies it was concluded that increasing ring diameter decreases the load capacity, while increasing number of supports, width of beam, concrete compressive strength, and width of bearing plate increases the load capacity due to the increase in beam section or its properties. RC ring beams fail in flexure, while the deep ring beams fail in shear in a manner similar to straight beams. Plastic analysis and strut and tie model (STM) are useful tools to analyze curved or ring deep beams effectively. Furthermore, the three-dimensional, nonlinear finite element modelling is ideal for predicting the behavior of RC curved deep beams.

IOP Conference Series: Materials Science and Engineering, 2021

View the article online for updates and enhancements. You may also like Content from this work ma... more View the article online for updates and enhancements. You may also like Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Journal of Bridge Engineering, 2022

This study reports on experimental test results of reinforced concrete pier caps with different s... more This study reports on experimental test results of reinforced concrete pier caps with different shear spans to effective depth ratios (a/d) of 0.5, 1, and 1.5. Each test specimen is then designed theoretically using both shear friction (SF) and strut-and-tie modeling (STM) approaches, according to Section 16.5 and Chapter 23 of ACI 318-14, respectively, and the results are compared with the pier caps experimental test results. The cracking load, failure load, deflection, crack pattern, crack width, steel reinforcement strains, concrete surface average strains, and failure modes are observed, recorded, and discussed. The experimental load capacities are compared with the theoretical load capacities of SF and STM. Experimental test results indicate that both STM and SF are conservative approaches and STM is more conservative than SF. The reason for this is because they do not take secondary reinforcement into direct consideration. That is why, a model is proposed, modifying STM, for estimating the ultimate capacity of pier caps based on calculating the strength of concrete and secondary reinforcement separately that gave more realistic results.

ACI Structural Journal, 2022

This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the ... more This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the familiar approach of secondary distributed reinforcement is substituted with modeling the corbel as a strut-and-tie system, in agreement with ACI 318 on strut-and-tie modeling (STM). The study consists of constructing and testing 15 corbel specimens until failure, including six conventionally reinforced reference specimens and nine proposed specimens in which only struts and ties were reinforced. The shear span-effective depth ratio (a/d) is variable: 0.5, 1, and 1.5, respectively. The test results show crack and strain evolution in both concrete and steel bars, together with load-deflection response. Conclusions show that corbel designs based on a strut-and-tie system provide substantial saving in weight of approximately 13 to 52% along with a less obvious but still substantial extra ultimate capacity of 12 to 50% compared to the nominal ACI 318-14 STM design load

AIP Conference Proceedings 2660, 020113 (2022), 2022

This paper displays the horizontal curvature (circular curvature) effect on deep beams using fini... more This paper displays the horizontal curvature (circular curvature) effect on deep beams using finite element analysis. Thirty-five reinforced concretes horizontally arched deep beams were analyzed. The parameters that were taken into consideration in the current work are the curvature angle (α) and beam height (H) while keeping one constant value for the beam length (L), i.e., different length to depth ratios (L/H). It is found that for L/H=2; the load capacity decreases by about 38-73% and 16-67%, respectively, when changing α from ∞ (straight beam) to 180 degrees, while torsional moments increase by about 74-174%. Negative bending moments decrease by about 13-56% when changing α from 30 to 180 degrees. The deflection decreases by about 0.1-1.8% when changing α from ∞ to 90 degrees. For L/H=2.5; The load capacity decreases by about 36-73% and 15-67%, respectively, when changing α from ∞ to 180 degrees, while torsional moments increase by about 73-168%. Negative bending moments decrease by about 14-57% when increasing α from 30 to 180 degrees. Decreasing deflection by about 4.1-5.9% when increasing α from 60 to 90 degrees. For L/H=3; load capacity decreases by about 34-73% and 14-68%, respectively, when changing α from 0 to 180 degrees, while torsional moments increase by about 71-161%. Negative bending moments decrease by about 15-58% when increasing α from 30 to 180 degrees. The deflection decreases by about 6-9.7% when increasing curvature angle from 60 to 90 degrees. For L/H=3.5; the load capacity decreases by about 34-73% and 14-69%, respectively, when changing α from 0 to 180 degrees, while torsional moments increase by about 70-156%. Negative bending moments decrease by about 15-59% when changing α from 30 to 180 degrees. Midspan deflection decreases by about 4.6-14.7% when changing α from 60 to 120 degrees. Finally, it is found that for L/H=4; The load capacity decreases by about 33-74% and 14-69%, respectively, when changing α from 0 to 180 degrees, while torsional moments increase by about 69-150%. Negative bending moments decrease by about 16-60% when changing α from 30 to 180 degrees. Changing α from 60 to 120 degrees leads to decrease deflection by about 9.1-19.4%.

AIP Conference Proceedings, 2022

The current work presents a parametric study for twenty-five reinforced concrete overhang curved ... more The current work presents a parametric study for twenty-five reinforced concrete overhang curved deep beams using finite element analysis. The parameters that were taken into consideration are radius, height, width, compressive strength of concrete and number of supports. It is found that the max positive moments increase by about 2.8-4.4% when decreasing the radius of beam by about 16-33%. The max negative bending moment, max torsional moments and max deflection decrease by about 1.9-12.4%, 0.4-8.9% and 30-87%, respectively, when beam radius decreases by 16-66%, whereas load capacity increases by about 23-195%. The max positive bending moment, max negative bending moment, torsional moment and load capacity increase by about 32-128%, 30-124%, 31-125% and 31-127% respectively, when the beam height increases by 12.5-100%, while deflection decrease by about 9-18%. The max positive bending moment, max negative bending moment, torsional moment, load capacity and max deflection increase by about 32-147%, 29-134%, 30-138%, 32-146% and 1.2-4.9%, respectively when beam width increases by 12.5-50%. The max positive bending moment, max negative bending moment, torsional moment, load capacity and max deflection increase by about 17-70%, 15-61%, 15-63%, 17-69% and 0.1-0.4%, respectively, when concrete compressive strength increase by 33-166%. Finally, it is found that the max positive bending moment increases by about 32% when increasing number of supports by 33%. Max negative bending moment and capacity of load increase by about 17-60% and 106-763%, respectively, when number of supports increases by 33-133%. Torsional moment and max deflection decrease by about 0.8-16% and 29-78%, respectively when number of supports increases by 33-133%.

ACI Structural Journal, 2023

The role of reinforcement in ring deep beams with horizontal curvature is studied. The study cons... more The role of reinforcement in ring deep beams with horizontal curvature is studied. The study consists of six ring deep beam specimens, including a conventionally reinforced reference specimen and five specimens in which flexural and web reinforcement were varied. In the second and third specimens, horizontal and vertical web reinforcement were omitted, respectively, while in the fourth specimen, both were omitted. In the fifth and sixth specimens, top and bottom flexural reinforcement were reduced and omitted, respectively. Conclusions illustrate that vertical web reinforcement has a greater effect on load capacity compared to horizontal, and both have a greater effect than upper and lower flexural reinforcement. Moreover, depending on the experimental failure modes of the tested specimens, analysis using STM, ACI 318-19 is considered logical and safe despite its reservations. Therefore, a model has been proposed to predict load capacity by taking the effect of web reinforcement and the torsional moments

ACI Structural Journal, 2023

This study aims to shed light on the inclined direct stress paths of curved struts in deep ring b... more This study aims to shed light on the inclined direct stress paths of curved struts in deep ring beams by converting them into real members. Five specimens were tested with three loading and three supporting points. Three specimens were conventional rings and two were in the form of a frame that took its cross-sectional dimensions from the strut-and-tie model (STM) in ACI 318-19. The effect of reinforcing struts was studied by reinforcing the rings with both proposed and conventional reinforcements, and the frames with the proposed reinforcement only. The findings show that the proposed reinforcement reduced weight and cost by approximately 18% and 13%, respectively, and provided openings for services by approximately 24%. Additionally, strut curvature was found to reduce load capacity by 3 to 6%, meaning that the STM is safe and can be used efficiently in this type of deep curved member.

AIP Conference Proceedings , 2023

The aim of this research work is to study the most important parameters that affect the loading c... more The aim of this research work is to study the most important parameters that affect the loading capacity and behavior of elliptical ring reinforced concrete beams with (L) section. Twenty specimens were modelled using ETABS Software to study the effect of changing the length of the major axis (while keeping the ratio of the major to minor axis equal to 0.64), width, height, thickness, and loading type. The maximum values of negative bending and torsional moments in addition to midspan deflection increase by 1.24-8.24%, 1.33-11.43%, and 32.5-131%, respectively when the major axis of beam increases by 20-60%. Whereas, major axis increase leads to decrease the maximum positive bending moments and load capacity by 5.91-4.45% and 26.5-52.9%, respectively. That happens due to the extending of span length that happened because of major axis increase. When the beam height increases by 25-75%, the maximum positive and negative bending moments (M+ve) and (M-ve), torsional moments and load capacity increase by 33.92-102.4%, 33.92-100%, 29.84-89.74% and 38.8-116.6%, respectively. While this increase in height leads to maximum deflection decrease by 5-8.4%. That happens because the beam sectional area increases due to increasing beam height. M+ve and M-ve, load capacity and midspan deflection decrease by 0.33-7.9%, 1.61-1.1%, 4-20%, and 11-30%, respectively when beam width increases by 46.6-140%. While this increase in width leads to torsional moment to increase by 2.15-0.87%. The sectional area of beam increases because of width increase, i.e., additional strength capacity. When thickness of beam increases by 100-500%, M+ve, M-ve, load capacity and maximum deflection decrease by 4.25-18.8%, 2.3-16.2%, 7.4-37% and 19.8-67%, respectively, whereas the torsional moments increase by 1.42-0.12%. Finally, torsional moments increase by 0.68-1.49 %, respectively due to testing through partial or full uniform load by 20-100% length of span.

AIP Conference Proceedings, 2023

The current work presents a study on strength and behavior of reinforced concrete T-section ellip... more The current work presents a study on strength and behavior of reinforced concrete T-section elliptical ring deep beams through the finite element technique. The parameters that were taken into consideration are diagonal axis (major axis) with the same major axis to minor axis ratio, height, flange thickness, web thickness, and compressive strength of concrete. It is found that the maximum values of positive bending moment (Mmax+ve), maximum negative bending moments (Mmax-ve), maximum torsional moments (Mmaxtor) and deflection increase by about 0.12-0.77%, 1.86-4.9%, 1.9-3.77% and 22.7-77.9%, respectively when the beam diagonal axis increases by 16-50%. Mmax+ve, Mmax-ve, Mmaxtor and load capacity increase by about 68.43-135.3%, 71.13-142%, 61.89-123.8%and 71-142%, respectively when the beam height increases by 50-100%. While the increase in height leads to decrease in the maximum deflection by about 4.62-5.33%. Mmax+ve, Mmax-ve, load capacity and max deflection decrease by about 0.38-4.04%, 1.135-6.25%, 1.51-6.06%, 13.5-30.9%, respectively when the flange thickness increases by 100-200%. While the increase in flange thickness leads to increase in the Mmaxtor by about 0.57-0.42%. Mmax+ve, Mmax-ve, Mmaxtor, load capacity and max deflection increase by about 210.4-446.8%, 156.63-374.9%, 216.5-494%, 215.4-469.2% and 82.4-129.8%, respectively, when concrete web thickness increases by 50-100%. Mmax+ve, Mmax-ve, Mmaxtor, load capacity and max deflection increase by about 15.69-42.49%, 15.78-41.62%,15.81-41.7%, 16.92-44.61% and -0.37-0.37%, respectively, when concrete compressive strength increases by 33.33-100%.

Journal of Bridge Engineering, 2021

This study reports on experimental test results of reinforced concrete pier caps with different s... more This study reports on experimental test results of reinforced concrete pier caps with different shear spans to effective depth ratios (a/d) of 0.5, 1, and 1.5. Each test specimen is then designed theoretically using both shear friction (SF) and strut-and-tie modeling (STM)
approaches, according to Section 16.5 and Chapter 23 of ACI 318-14, respectively, and the results are compared with the pier caps experimental test results. The cracking load, failure load, deflection, crack pattern, crack width, steel reinforcement strains, concrete surface average strains, and failure modes are observed, recorded, and discussed. The experimental load capacities are compared with the theoretical
load capacities of SF and STM. Experimental test results indicate that both STM and SF are conservative approaches and STM is more conservative than SF. The reason for this is because they do not take secondary reinforcement into direct consideration. That is why, a
model is proposed, modifying STM, for estimating the ultimate capacity of pier caps based on calculating the strength of concrete and secondary reinforcement separately that gave more realistic results. DOI: 10.1061/(ASCE)BE.1943-5592.0001758. © 2021 American Society of Civil Engineers.

ACI Structural Journal, 2021

This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the ... more This paper suggests a new perspective on reinforcement details for concrete corbels, whereby the familiar approach of secondary distributed reinforcement is substituted with modeling the corbel as a strut-and-tie system, in agreement with ACI 318 on strut-and-tie
modeling (STM). The study consists of constructing and testing 15 corbel specimens until failure, including six conventionally reinforced reference specimens and nine proposed specimens in which only struts and ties were reinforced. The shear span-effective depth ratio (a/d) is variable: 0.5, 1, and 1.5, respectively. The test results
show crack and strain evolution in both concrete and steel bars, together with load-deflection response. Conclusions show that corbel designs based on a strut-and-tie system provide substantial saving in weight of approximately 13 to 52% along with a less obvious but still substantial extra ultimate capacity of 12

Structures, 2020

ACI 318-14 analyzes reinforced concrete corbel by shear friction (SF) and/or strut-and-tie modeli... more ACI 318-14 analyzes reinforced concrete corbel by shear friction (SF) and/or strut-and-tie modeling (STM). This work presents the results of experimental tests conducted on three reinforced concrete corbels that had a height of 390 mm and a width of 115 mm. The corbels had different shear span to effective depth ratios (a/d), which were 0.5, 1 and 1.5, respectively. Each test specimen was analyzed using both SF and STM to make a comparison between the experimental results. The cracking load, failure load, deflection, crack pattern, steel reinforcement strains, concrete surface average strains and locations of failure were recorded and discussed for the tested corbels. The findings revealed that, in the case of corbels with a/d = 0.5, the shear friction ultimate capacity (P) SF and the STM ultimate capacity (P) STM were less than the experimental failure load (P) f by about 15% and 22%, respectively. In addition, P P and SF STM were less than P f by about 18% and 27%, respectively, when a/ d = 1. In contrast, in the case of a/d = 1.5, P P and SF STM were less than P f by about 32% and 37%, respectively. In conclusion, in the case of a/d < 1, both STM and SF can be used, although STM is more conservative due to its safety factors. In the case of a/d = 1-2, STM is more accurate than SF. However, if a/d exceeds 2, the corbel should be treated as a conventional cantilever beam.

International Journal of Civil Engineering and Technology (IJCIET), 2018

Corbels are cantilever with small shear span to depth ratio (a/d) projected from columns or walls... more Corbels are cantilever with small shear span to depth ratio (a/d) projected from columns or walls to support precast members like beams, girders or dapped end beams. Shear friction (SF) method is used to analyze and design reinforced concrete (RC) corbels. Because of the small value of a/d, corbels are treated as deep beams. Using strut and tie modeling (STM), they can be analyzed. In both SF and STM, there are many parameters that affect the behavior of the corbels such as a/d, width (b), compressive strength of concrete (f'c), yield strength of reinforcement (fy), and horizontal to vertical load ratio (H/V). In the current study, according to ACI 318-14 provisions, the effect of these parameters were investigated using both SF and STM. It was found that the shear capacity increases by about 32.6%, 26.3% and 31.2% for SF and by about 54.1%, 50.4% and 30.9% for STM with increasing width, compressive strength, and yield strength by about (100-300) %, (15-35) % and (400-600) %, respectively. Whereas, shear capacity decreases by about 58.54% and 48.7% for SF and about 59.4% and 33.2% for STM with increasing a/d and H/V by about (0.1-1.9)% and (0-1)%, respectively. It was also seen that the results obtained by STM is more reliable than SF when compared with experimental works that were taken from literature.

What is meant by the wide corbel here is the corbel whose width (b) is more than two times its he... more What is meant by the wide corbel here is the corbel whose width (b) is more than two times its height (h).
Wide Corbels are short cantilevers that stand out from inner face of wide columns or shear walls to support uniformly
distributed loading that comes from wide beam. ACI 318-14 provisions allow the structural design of shear-controlled
corbels through either shear friction (SF) method or the Strut-and-Tie modeling (STM). The current study presents
analysis and design procedures using both SF and STM. Numerical examples for analyzing and designing one meter
wide corbel are presented here in detail. It is concluded that the calculated load capacity using SF is 21% greater than
that of STM. In other words, SF requires less reinforcement than STM by about 25%. That can be attributed to the
difference in the safety factors that adopted by both approaches. More specifically, SF considers the main reinforcement
as the reinforcement that resists moments, while STM considers it as the reinforcement that resists the direct tension of
the formed tie. On the other hand, SF considers that the concrete and the horizontal stirrups resist shear, while STM
considers that the shear is resisted by the formed inclined struts. The wide reinforced concrete corbel is designed here
in the same way of the narrow one, but with some important differences. The main differences that were adopted in
wide corbels are the applied load is a uniformly distributed load through the corbel width, repeating the frame
reinforcement through the corbel width in order to hold the secondary reinforcement, and distributing the secondary
reinforcement in a repetitive, overlapping and interchangeable way in order to ensure that the stirrups exist inside the
entire corbel core.

AIP, 2020

Unsymmetrical reinforced concrete double corbels have different shear spans (a) in each side. ACI... more Unsymmetrical reinforced concrete double corbels have different shear spans (a) in each side. ACI 318-14 provisions allow the structural analysis and design of double corbels through either shear friction (SF) method or the Strut-and-Tie modeling (STM). The current study presents analysis procedure using both SF and STM. Numerical examples for analyzing unsymmetrical reinforced concrete double corbels with two different right to left shear span ratios (ar/al = 3 and 2) are also presented here in detail. It is concluded that reducing ar/al from 3 to 2 increases capacity by about 10.65% in case of SF, and 9.62% in case of STM. More specifically, in case of ar/al=2-3, capacity calculated by SF exceeds that calculated by STM by about 23-24%. Finally, it is also concluded that the mode of failure dose not be the same at the both corbel sides, but in any case, the weaker side is the one who reports the failure.

AIP, 2020

Most codes of practice, like ACI 318-14, 9.9.1.3, require the use of strut-and-tie modeling (STM)... more Most codes of practice, like ACI 318-14, 9.9.1.3, require the use of strut-and-tie modeling (STM) to deal with reinforced concrete continuous deep beams (rc-cdbs). Though, investigations that conducted on rc-cdbs did not include all the most influential parameters. This work presents an analytical parametric study using STM stated by ACI 318-14 to calculate load capacity of 20 rc-cdbs with different parameters. The parameters took into consideration in the current work are shear span to overall depth ratio (a/h), width of beam (bw), width of bearing plate (BP), concrete compressive strength (f'c) and amount of vertical shear web reinforcement (pv). It is seen that the load capacity decreases by about 14% to 37% when a/h increases by about 33% to 100%. It is also seen that load capacity increases by about 33% to 100% when bw increases by about 33% to 100%, while the load capacity increases by about 10% to 30% when BP increases by about 33% to 100%. Finally, it is found that load capacity increases by about 35% to 100% when compressive strength increases by about 35% to 100%, while the load capacity increases by about 0% to 25% when pv increases by about 33% to 100%.

AIP, 2020

Most codes of practice, like ACI 318-14, require the use of strut-and-tie modeling to analyze and... more Most codes of practice, like ACI 318-14, require the use of strut-and-tie modeling to analyze and design
reinforced concrete deep beams. Though, investigations that conducted on deep beams do not include ring deep beams of
influential parameters. This work presents an analytical parametric study using strut-and-tie modeling stated by ACI 318-
14 to predict load capacity of 20 reinforced concrete ring deep beam specimens with different parameters. The parameters
that were under consideration in the current work are ring diameter (Dc), number of supports (NS), width of ring beam
(bw), concrete compressive strength (f'c) and width of bearing plate (Bp). It is found that the load capacity decreases by
about 14-36% when ring diameter increases by about 25-75%. It is also found that load capacity increases by about 62-
189% when number of supports increases by about 33-100%, while the load capacity increases by about 25-75% when the
beam ring width increases by about 25-75%. Finally, it is found that load capacity increases by about 24-76% when
compressive strength increases by about 24-76%, while the load capacity increases by about 5-16% when Bp increases by
about 25-75%.