NUMERICAL INVESTIGATION OF THE EFFECTS OF REINFORCEMENT ARRANGEMENT ON BEHAVIOUR OF HAUNCHED BEAMS

Abstract

Reinforced concrete structures are the most widely used forms to construct buildings in the world. In such building structures, beams are one of the skeletal elements to carry and transmit loads and stresses in addition to restraining structural systems. Reinforced concrete haunched beams are one of the structural elements which resist super imposed effects and stresses by arching mechanisms. In such elements, compressive forces are resisted by concrete sections and tensile forces are resisted by reinforcements. Thus, failure of these beams will be the effect of either reinforcement, concrete or both. This thesis presented numerical analysis of haunched beams to examine the effects of reinforcement arrangement on load carrying capacity using variety in rebar layers, haunch depth ratio and support conditions. Finite element and strut-and-tie model analysis is attempted to determine the effects of the parameters under static loading regime. Twenty four specimens modelled and results are compared under each parameter. Results obtained from simulation showed that as reinforcement arrangement increased from single to double layered, mid-span deflection increased by about 10.11% whereas plastic strain decreased by about 15.23%. Thus, issue of sudden shear failure is decreased and ductile failure insured by increasing layer number, which correlates with effective concrete tension area. Effects of depth ratio showed that the decrease in depth ratio decreased the mi-span deflection and cracking strain by about 41.6%, and 27.4% for single layered, 39.54% and 52.34% for double layered specimens respectively. Fixed supported beam specimens, as observed from the results, increased the resistance capacity by about 9.43% mid-span deflection and 5% cracking strain over continuous beam specimens. Result observation of Abaqus and Strut-and-Tie model outputs, Abaqus results showed an over estimated resistance capacity than strut-and-tie model by about 26.54%. This result demonstrated that nonlinear finite element analysis is used to optimization of the design capacity, for economical and efficiency considerations. In contrast to FEM, Strut-and-Tie model is used as a lower bound solution which contributes to the reliable and safe design.