Question

What is the load capacity of a beam in bending and define the internal bending moment from which this capacity depends. (draw e sketch to illustrate this relationship)

Answer 1

Load capacity of a beam in bending is the maximum load that can be applied to the without failure in bending.

Now when beam fails in bending; at any section there is tensile force and compressive forces are generated at bottom and top. When these forces exeeds the ultimate strength of material of beam; the beam fails.

The stress generated at section can be calculated using very famous pure bending equation.

M/I = f/y = E/R

where M = internal bending moment at that section

I = moment of area of that section

f = stress generated

y = distance at which we are calculating stress from nuetral axis

E = modulas of elasticity of material

R = radius of curvature

Except M; all quantities are material properties and shape properties.

thus maximum load capacity will occur at point of maximum internal bending moment.

Now internal bending moment is the bending moment inthe material due to external load in beam.