Flexural Capacity of a Cantilever RC Beam Planted on an Existing Column

摘要

The study is done to investigate the flexural capacity of reinforced cantilever beam planted on existing reinforced concrete column. The study is performed in two stages. The first stage is done to evaluate the tensile capacity of single adhesive steel planted bars in concrete block and are subjected to pull-out loading. The second stage is done to assess the flexural capacity of a planted reinforced concrete cantilever on an existing column. The investigations are done experimentally, theoretically and numerically in both stages. A nonlinear finite element software (ANSYS) is utilized for the numerical analysis. In stage I: pull out tests are done on eight specimens with varying parameters like the planted bars' diameters (d=12 mm and 16 mm) and the embedment length (h_(ef)=6d, 8d, 10d, and 12d). Additional four specimens are evaluated numerically only with additional parameters like the bar diameter (d=10 mm) and the effect of different configuration for fixing the specimens in the pull out testing (four configurations are investigated). All those specimens are evaluated also in according to ACI 318-14 recommendations. The results of stage I study showed that: (1) very good agreement for all the studying methods, (2) the bar diameter doesn't have a significant effect on the tensile capacity of the planted bars since they suffer concrete breakout failure at the same embedment length, (3) using embedment length of 12d achieve the target capacity, (4) the specimen fixation method has influence the testing results. In stage II: the studying parameters are the reinforcement ratio of the tensile planted bars (μ=0.24%, 0.36%, 0.48%, and 0.60%), the embedment lengths of (15d and 20d), and the orientation of the embedded bars. Those specimens are evaluated experimentally and numerically whereas two extra specimens are evaluated numerically only. The measured factors includes the tip cantilever deflection, the strains in the planted bars, the cracks pattern, and the failure modes. The results of stage I study showed that: (1) very good agreement between the experimental and the numerical methods, (2) increasing of the embedment length of the planted steel bars from 15d to 20d has a great effect on their flexural capacities, (3) using a reinforcement ratio doubled of those for the control specimen with embedment depth of 20d gives the best performance with respect to the load, deflection, and ductility.