Reinforced Concrete Semi Circular Deep Beams - Finite Element Investigation

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%. Conclusions Most of the parameters influencing the behavior and strength of the semicircular reinforced concrete deep beams were investigated in the current study. The use of the ETABS 2016 software, which relies on the finite element method, was easy and practical. Accordingly, the following conclusions were reached: • The maximum positive bending moment, maximum negative bending moment, maximum torsional moments and midspan deflection decrease by about 0.3-20%, 2.4-25%, 2-24% and 29-85%, respectively, when beam radius decreases by 16-66%. Whereas this radius decrease leads to increase the load capacity by about 23-158%. That can be attributed to span length shortening that caused be radius decrease. • The maximum positive bending moment, maximum negative bending moment, torsional moment and load capacity increase by about 20-82%, 20-81%, 20-81% and 21-84% respectively, when the beam height decreases by 16-66%. While this height decrease leads to midspan deflection decrease by about 7-17%. The beam sectional area increases when increasing beam height, i.e., causes strength increase. • The maximum positive bending moment, maximum negative bending moment, torsional moment and load capacity increase by about 200-1113%, 167-958%, 172-989% and 230-1368%, respectively when beam width increases by 50-200%. While this width increase leads to midspan deflection decrease by about 3-5%. The beam sectional area increases when increasing width, i.e., more strength. • The maximum positive bending moment, maximum negative bending moment, torsional moment and load capacity increase by about 10-84%, 9-77%, 9-79% and 11-92%, respectively, when concrete compressive strength increase by 20-220%. While this concrete compressive strength increase leads to deflection decrease by about 0.1-0.5%. Increasing concrete compressive strength increases shear stress resistance. • The maximum positive bending moment increases by about 36-47% when increasing number of supports by 33-66%. Maximum negative bending moment increases by about 16-31% when decreasing number of supports by 14-29%. Torsional moment and midspan deflection decrease by about 6-55% and 37-84%, respectively when number of supports increases by 33-133%. Whereas the load capacity increases by about 156-969%, when number of supports increases by 33-133%. The length of span decreases when increasing number of supports, resulting in higher strength capacity.