Title : Shear Force and Bending Moment

Objective : To determine the shear force and bending moment when concentrated load, symmetrical load and non symmetrical load are applied

Introduction

The shear force (F) in a beam at any section, X, is the force transverse to the beam tending cause it to shear across the section. The shear force at any section is taken as positive if the right-hand side tends to slide downwards relative to the left hand portion. The negative force tends to cause the right hand portion to slide upwards relative to the left. X

W

F

Shear force F = Load W but in opposite directions

W

The bending effect at any section X of a concentrated load W is measured by the applied moment Wx, where x is the perpendicular distance of the line of action of W from section X. This moment is called the bending moment M. x

X

M = Wx

The bending moment is balanced by an equal and opposite moment exerted by the material of the beam at X, called the moment of resistance. The bending moment is positive if its effect makes the beam to sag at the section considered. If the moment tends to make the beam bend upward or hog at the section, it is negative.

For any value of x, the relationship between load W and shearing force F is :- W = dF / dx

And the relationship between shearing force and bending moment M is :- F = dM / dx

Apparatus and Materials

1. Shear forces apparatus :- 1 set of 80mm x 50mm x 38mm aluminium section with 2 adjustable span support. 2. 1 unit of shear force dynamometer.

3. 2 sets of weight hangers.

4. 1 set of weights.

5. 2m measuring tape.

Procedure

Shear force and bending moment experiment for concentrated load. 1. The 2 edge supports is set up on the base of the structural test frame at a distance of 800mm from edge to edge. 2. The shear force apparatus is placed on...

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