Name of the experiment: Bending Moment in a simply supported beam.Objectives:

1) To comprehend the action of moment of resistance in a beam.

2) To measure the bending moment at a normal section of a loaded beam and to check its agreement with the theory.

3) To draw the bending moment diagram.

Apparatus:

1) Bending Moment Assembly.

2) Load Hangers.

3) Weights.

Theory: A bending moment exists in a structural element when a moment is applied to the element so that the element bends. Moments and torques are measured as a force multiplied by a distance so they have as unit newton-metres (Nm), or foot-pounds force (ftlbf). The Bending Moment at the cut is equal to the algebraic sum of the moments caused by the forces acting to the left or right of the cut.

The forces and moments on either side of the section must be equal in order to counteract each other and maintain a state of equilibrium so the same bending moment will result from summing the moments, regardless of which side of the section is selected.

Description of the experimental set-up: Figure 1 shows the Bending Moment in a Beam experiment. It consists of a beam, which is cut by a pivot. To stop the beam collapsing a moment arm bridges the cut onto a load cell thus reacting (and measuring) the bending moment force. A digital display shows the force from the load cell. A diagram on the left-hand support of the beam shows the beam geometry and hanger positions. Hanger supports are 20 mm apart, and have a centre slot which positions the hangers. The moment arm is 125 mm long.

Procedure: 1) Check the Digital Force Display meter reads zero with no load.

2) Carefully load the beam with the hangers in a position away from the cut, using the loads indicated Record the Digital Force Display reading in a table as in Table 2. Convert the force reading into a bending moment by the following equation,Bending moment at the cut (in Nm) = Displayed force 0.1253) Calculate the support reactions (RA and RB) and calculate the theoretical bending moment at the cut.

4) Repeat the procedure with the beam in different loading condition. Comment on how the results of the experiments compare with those calculated using the theory.Data Sheet:

No. of observation Load Force Reading(N) Experimental Bending Moment (Nm)RA (N) RB (N) Theoretical Bending Moment

W1

(N)W2

(N)W3

(N)

Results: For each loading arrangement calculate the Bending Moment at the section, draw the bending moment diagram and compare the measured value with it.