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Cantilever Beams and Continuous Beams

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Cantilever beams are subjected to negative moment through the whole length, therefore tensile reinforcement placed on the top of the beam, a maximum negative moment occurs at the point of fixity (face of fix support), therefore more reinforcement will be provided near the support and this reinforcing steel should be extended and anchored in concrete beyond the support, the extended or anchored length named as development length. the development length has not to be straight, bars may bend and hooked to concrete to provide better bonding. figure 1 showing reinforcing bar hooked at 90, 180 angle, figure 2 showing shear and moment diagram for cantilever, figure 3 showing reinforcement location for a cantilever beam. a home balcony is an example of a cantilever beam.




                                                                        Figure 1







Figure 2


Figure 3




usually, beams and slab are continuous over different support as shown in figure 4-a, using equilibrium equations for analyzing of continuous beam or slab is insufficient, Continuous beam subjected to the positive and negative moment at the same time, reinforcing steel will be placed at the bottom of beam for a positive moment, for negative moment, reinforcement will be placed at the top of the beam as shown in figure 4-b.

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