What Is a Cantilever Beam?
A cantilever beam is a simplified model obtained in order to facilitate calculation and analysis in material mechanics. One end of the cantilever beam is a fixed support and the other end is a free end. Under the load, the bearing reaction force at the fixed end of the cantilever beam can be obtained according to the equilibrium condition of the force, including horizontal force, vertical force, and bending moment, and the axial force diagram, shear force diagram, and bending moment diagram can be drawn accordingly. Because the beam is generally subjected to a vertical concentrated load or a uniform load, the horizontal reaction force of the support is zero.
- When estimating the cross-section size, the cross-section height of a concrete cantilever beam is generally taken as 1/5 of the cantilever length.
- When calculating the reinforcement, there should be no less than 2 upper steel bars that extend to the outer end of the cantilever beam and bend down no less than 12d. The remaining steel bars should not be cut off at the upper part of the beam, but should be turned down according to the bending start position specified by the code Bend and anchor under the beam as required. The bending angle should be 45 ° or 60 °. There should be an anchor length parallel to the beam axis direction outside the bending end point, and it should not be less than 20d in the tension zone and not less than 10d in the compression zone.
- Under the assumption of small deformation of material mechanics, the deflection at any section of the cantilever beam can be obtained by the superposition principle based on the deflection of the free end, or it can be solved by integration using the method in structural mechanics. When the line bending moment diagram or actual When one of the load moment diagrams is a straight line graph, the deflection can also be directly solved by the graph multiplication. The following table is the formula for calculating the deflection of a cantilever beam under different loads.