scholarly journals Strength and Serviceability of Reinforced Concrete Deep Beams with Large Web Openings Created in Shear Spans

2018 ◽  
Vol 4 (11) ◽  
pp. 2560 ◽  
Author(s):  
Waleed A. Jasim ◽  
Abbas Abdulmajeed Allawi ◽  
Nazar K. Oukaili
Keyword(s):  
Load Capacity ◽  
Reference Beam ◽  
Experimental Studies ◽  
Load Level ◽  
Load Path ◽  
Deep Beams ◽  
Structural Concrete ◽  
Web Openings ◽  
Shear Span ◽  
Midspan Deflection

Deep beams are used in wide construction fields such as water tanks, foundations, and girders in multi-story buildings to provide certain areas free of columns. In practice it is quite often occurring to create web opening in deep beams to supply convenient passage of ventilation ducts, cable channels, gas and water pipes. Experimental studies of ten 10 deep beams were carried out, where two of them are control specimens without openings and eight with large web openings in the shear spans. The variables that have been adopted are the ratio of the shear span to the overall depth of the member cross-section, location and dimensions of the opening. Test results showed that there was a decrease in the load carrying capacity of deep beams with openings compared to the control deep beams. This reduction may reach 66% in particular cases. It is clear that, the position of opening in shear span has less effect on the performance of structural concrete deep beams at different serviceability stages. Only 11% increase in load capacity at failure was observed in specimens with openings adjacent to the interior edges of shear spans in comparison with specimens with openings at the center of shear span because the discontinuity of the load path is less. Also the midspan deflection at service load level of the reference beam in specimens with openings adjacent to interior edge of shear spans was less than the midspan deflection of reference specimens by 10% - 33%. Evaluating all these advantages facilitates to recommend, if it is very required, the creation of openings at the interior edges of shear spans of the structural concrete deep beams.

scholarly journals Effect of Shear Span to Effective Depth Ratio on the Behavior of Self-Compacting Reinforced Concrete Deep Beams Containing Openings Strengthened with CFRP

2019 ◽  
Vol 26 (1) ◽  
pp. 1-9
Author(s):  
Nabeel A. Al-Bayati ◽  
Bassman R. Muhammed ◽  
Muroj F. Oda
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
General Trend ◽  
Load Path ◽  
Deep Beams ◽  
Web Openings ◽  
Shear Span ◽  
Depth Ratio ◽  
Effective Depth ◽  
Strengthened Beam

Results of test on seven simply supported self-compacting reinforced concrete deep beams, including six of these beams containing circular openings in center of load path are reported in this paper. The objective of the tests was determined the influence of, changing shear span to effective depth ratio a/d, the existence of circular openings in shear span and using inclined strips of carbon fiber polymer (CFRP) on behavior of deep beams. The general trend in crack pattern, the load-deflection response, and the mode of failure of reinforced SCC deep beams were also investigated. All specimens had the same geometry, details of the flexure and shear reinforcement in both vertical and horizontal directions and they were tested under symmetrical two-point loads up to failure. The experimental results revealed that the web openings within shear spans caused an important reduction in the deep beam capacity by 50% when compared with the corresponding solid beam. The increase a/d ratio from 0.8 to 1.2 decreases the ultimate load by 21.7% and 22.5 % for the reference unstrengthened beam and strengthened beam, respectively, also it was found that the externally inclined CFRP strips in deep beams increased the ultimate strength up to 39.5%, and enhanced the stiffness of deep beams with openings.

scholarly journals Retrofitting of shear strength self-compacting reinforced concrete deep beams with FRP

2018 ◽  
Vol 162 ◽  
pp. 04016
Author(s):  
Nabeel Al-Bayati ◽  
Bassman Muhammad ◽  
Sarah Sadkhan
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Ultimate Load ◽  
Load Capacity ◽  
Experimental Program ◽  
Deep Beams ◽  
Ultimate Load Capacity ◽  
Failure Loads ◽  
Effective Depth ◽  
Midspan Deflection

Experimental program were carried out to investigate the behavior of self-compacting reinforced concrete deep beams retrofitting with carbon fiber reinforced polymer (CFRP). Six simply supported deep beams were tested under symmetrically two point loads, three beams were tested up to failure without strengthening as a control beams with different shear span to effective depth ratio (a/d) while the other two beams were loaded up to 60% from the ultimate load of control beams for each a/d ratio and then retrofitted by the same configuration of CFRP to study the effect of a/d ratio on the properties of deep beams retrofitted. a/d for tested beams were (0.8, 1, 1.2). Study was focused on determining failure loads, cracking loads, failure modes, load midspan deflection. All the beams had the same compressive strength, overall dimensions and flexural and shear reinforcement. It was concluded that using this retrofitted method is very efficient and a gain in the ultimate load capacity of the deep beams was obtained also the results showed that when a/d ratio increase from 0.8 to 1.2, the ultimate load was decrease by 25% and midspan deflection was increased approximately at all load stages for control and retrofitted beams.

scholarly journals Reinforced Concrete Semi Circular Deep Beams - Finite Element Investigation

2021 ◽  
Vol 14 (1) ◽  
pp. 130-147
Author(s):  
Khattab Saleem Abdul-Razzaq ◽  
Abdullah A. Talal ◽  
Wisam H. Khaleel ◽  
Yahyia M. Hameed
Keyword(s):  
Finite Element ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Load Capacity ◽  
Beam Width ◽  
Torsional Moment ◽  
Deep Beams ◽  
Element Analysis ◽  
Negative Moment ◽  
Midspan Deflection

This paper represents a parametric study utilizing finite element analysis for twenty-five reinforced concrete semi-circular deep beams. The parameters that were taken into consideration in the current work are radius, height, width, concrete compressive strength and number of supports. It is found that decreasing radius of beam by 16-66% leads to decrease the midspan positive moment, support negative moment, torsional moment and midspan deflection by about 0.3-20%, 2.4-25%, 2-24% and 29-85%, respectively, while the load capacity increases by about 23-158%. The midspan positive moment, support negative moment, torsional moment and load capacity increase by about 20-682%, 20-81%, 20-81% and 21-84%, respectively, whereas midspan deflection decreases by 7-17% when the beam height increases by about 16-66%. The positive moment, negative moment, torsional moment and load capacity increases by about 43-197%, 40-185%, 29-187% and 46-214%, respectively, whereas deflection decreases by about 1.4-3.3% when the beam width increases by about 16-66%. The positive moment, negative moment, torsional moment and load capacity increases by about 10-84%, 9-77%, 9-79% and 11-92%, respectively, whereas deflection decreases by about 0.1-0.5% when the compressive strength increases by 20-220%. Finally, it is found that the positive moment increases by about 36-47% when number of supports increased by 33-66%, while the negative moment increases by about 16-31% when number of supports decreases by 14-29%, whereas the torsional moments and deflection decreases by about 6-55% and 37-84%, respectively when number of supports increases by 33-133%, while load capacity increases by 156-969% when number of support increases by 33-133%.

scholarly journals Effect of Size and Location of Square Web Openings on the Entire Behavior of Reinforced Concrete Deep Beams

2019 ◽  
Vol 5 (1) ◽  
pp. 209 ◽  
Author(s):  
Waleed A. Jasim ◽  
Abbas A. Allawi ◽  
Nazar Kamil Ali Oukaili
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Shear Capacity ◽  
Load Carrying Capacity ◽  
Deep Beam ◽  
Deep Beams ◽  
Web Openings ◽  
Shear Span ◽  
Load Carrying

This paper presents an experimental and numerical study which was carried out to examine the influence of the size and the layout of the web openings on the load carrying capacity and the serviceability of reinforced concrete deep beams. Five full-scale simply supported reinforced concrete deep beams with two large web openings created in shear regions were tested up to failure. The shear span to overall depth ratio was (1.1). Square openings were located symmetrically relative to the midspan section either at the midpoint or at the interior boundaries of the shear span. Two different side dimensions for the square openings were considered, mainly, (200) mm and (230) mm. The strength results proved that the shear capacity of the deep beam is governed by the size and location of web openings. The experimental results indicated that the reduction of the shear capacity may reach (66%). ABAQUS finite element software program was used for simulation and analysis. Numerical analyses provided un-conservative estimates for deep beam load carrying capacity in the range between (5-21%). However, the maximum scatter of the finite element method predictions for first diagonal and first flexural cracking loads was not exceeding (17%). Also, at service load the numerical of midspan deflection was greater than the experimental values by (9-18%).

scholarly journals Stress-deformed state of proof areas of reinforced concrete beams

2021 ◽  
Vol 2 (92) ◽  
pp. 32
Author(s):  
Stepan Neutov ◽  
Zlata Holovata ◽  
Daria Kirichenko
Keyword(s):  
Concrete Beams ◽  
Experimental Studies ◽  
Breaking Load ◽  
Load Level ◽  
Reinforced Concrete Beams ◽  
Longitudinal Reinforcement ◽  
Shear Span ◽  
Long Acting ◽  
Inclined Cracks

Abstract. The results of experimental studies of the stress-strain state of the support sections of rein-forced concrete beams from some of the most signifi-cant factors are presented. It was found that during long-term loading such factors are the level of the initial loading; concrete class; the percentage of transverse reinforcement in the shear span; the per-centage of longitudinal reinforcement in the com-pressed zone; the percentage of longitudinal working reinforcement in the extended zone. With an increase in the class of concrete, the moment corresponding to the appearance of normal cracks and the shear force corresponding to the appearance of inclined cracks slightly increase, although they lag behind the growth of the class of concrete. The process of crack-ing in the investigated beams begins, as a rule, with the appearance of normal cracks in the zone of pure bending at a load level (0.15... 0.33) from breaking. Inclined cracks appeared somewhat later, at load levels close to 0.5 of breaking. With a relatively high percentage of longitudinal reinforcement, the first oblique cracks appeared in the middle of the beam height in the shear span. At load levels close to 0.7, the process of formation of new cracks practically stops, and already existing cracks open more inten-sively. During the period of exposure to a constant long-term load, the width of the opening of normal cracks increased on average by 1.2–1.5 times, and the width of the opening of inclined cracks increased by 2.5–3 times. In the process of loading before the destruction of previously long-loaded beams, the width of the opening of normal cracks remained practically unchanged, and the width of the opening of inclined cracks increased by 1.2–1.7 times, and the breaking load for beams loaded with a preliminary long-acting load of 0.85 from the breaking load in-creased by 13–15 % compared to short-term loading. The opening width of inclined cracks along the length was different, its maximum value was ob-served in the middle of the height of the section of the support sections of the beams.

scholarly journals Finite element analysis of reinforced concrete deep beam with large opening

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Elsayed Ismail ◽  
Mohamed S. Issa ◽  
Khaled Elbadry
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
The Other ◽  
Deep Beam ◽  
Web Openings ◽  
Design Load ◽  
Large Opening

Abstract Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

Numerical and experimental studies on the thermal and static characteristics of multi-leaf foil thrust bearing

2021 ◽  
pp. 135065012110110
Author(s):  
Yu Guo ◽  
Yu Hou ◽  
Qi Zhao ◽  
Xionghao Ren ◽  
Shuangtao Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Failure Process ◽  
Experimental Studies ◽  
Elastic Model ◽  
Static Characteristics ◽  
Bearing Load ◽  
Foil Thrust Bearing ◽  
Cooling Air

Foil bearing is considered to be a promising supporting technology in high-speed centrifugal machinery. Due to the high-speed shearing effect in the viscous lubricant film, heat generation could not be ignored. In this paper, a thermo-elastic model of the multi-leaf foil thrust bearing is proposed to predict its thermal and static characteristics. In the model, modified Reynolds equation, energy equation, and Kirchhoff equation are solved in a coupling way. The contact area between the foil and welding plate is taken into account. Besides, the effect of cooling air on the bearing temperature is investigated. The ultimate load capacity and transient overload failure process of the bearing is analyzed and discussed. The effect of rotation speed on the bearing temperature is more obvious than that of the bearing load. The bearing temperature drops obviously by introducing the cooling air, and the cooling effect is improved with the supply pressure. The transient overload failure of the bearing occurs when the bearing load exceeds the ultimate value.

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