BENDING MOMENT (1)
1.0 OBJECTIVE
To show that the bending moment at a cut section of a beam is equal to the algebraic sum of the moments acting to the left or right of the section.
2.0 THEORY
L_{x} L_{2}
W_{1}
L_{1} X
R_{A} X R_{B}
Bending moment at section xx is :
B.M xx = W_{1} (L_{x}L_{1} ) – R_{A} L_{x}
OR B.M xx = R_{B} L_{2}
When the load is to the right of xx :
B.M xx = R_{A} L_{x}
3.0 APPARATUS

A pair of simple supports.

Special beam with a cut section.

A set of weights with several load hangers.
4.0 PROCEDURE

Connect the load cell to the digital indicator.

Switch on the indicator. For stability of the reading, the indicator must be switch on for 10 minutes before taking readings.

Fixed the two simple supports to the aluminum base at a distance equal to the span of the beam tested. Screw the support tightly to the base.

Hang the load hanger to the beam.

Place the beam on the supports.

Place the load hanger at the desired location.

Note the indicator reading. If it is not zero, press the tare button on the indicator.

Place a load on each load hanger.

Record the indicator reading. This represents the shear force at the cut section.

Remove all loads from the load hangers and apply a different set of loading and at different set of locations.

Repeat step 6 to 11 for another 5 sets of readings.
5.0 RESULTS
Beam span = ………………….mm
Distance of the bending section from the left support, LX = ………………….mm
Distance of the load from the left support, L1 = …………………..mm
Distance of load cell from the centre of the beam cross section = 175 mm
Table 1
Load (N)

L_{1} (mm)

Load cell reading F (N)

Bending Moment at xx

Experimental (F x 175)(Nmm)

Theory (Nmm)


























6.0 QUESTIONS

Using the data in Table 2, plot of the bending moment versus load.

Determine the slope of the graph.

Calculate the theoretical slope, L1 x ( L1/L)

From the slopes, calculate the average percentages error for the experiment.
Percentage error = [ (slope theory – slope exp.)/ (slope theory)] x 100%

Comment on the accuracy of the experiment.

State the probable factors that affect the accuracy of the experiment.
BENDING MOMENT (2)
1.0 OBJECTIVE
To show that the bending moment at a cut section of a beam is equal to the algebraic sum of the moments acting to the left or right of the section.
2.0 THEORY
L_{X }L_{4}
L_{3}
L_{2}
L_{1}
W_{1} W_{2 } W_{3} X
R_{A} X R_{B}
Bending moment at section xx is :
B.M xx = W_{1} (L_{x} – L_{1}) + W_{2} (L_{x} – L_{2}) + W_{3} (L_{x} – L_{3}) – R_{A} L_{x}
OR B.M xx = R_{B} L_{4}
3.0 APPARATUS

A pair of simple supports.

Special beam with a cut section.

A set of weights with several load hangers.
4.0 PROCEDURE

Connect the load cell to the digital indicator.

Switch on the indicator. For stability of the reading, the indicator must be switch on for 10 minutes before taking readings.

Fixed the two simple supports to the aluminum base at a distance equal to the span of the beam tested. Screw the support tightly to the base.

Hang the load hanger to the beam.

Place the beam on the supports.

Place the load hanger at the desired location.

Note the indicator reading. If it is not zero, press the tare button on the indicator.

Place a load on each load hanger.

Record the indicator reading. This represents the shear force at the cut section.

Remove all loads from the load hangers and apply a different set of loading and at different set of locations.

Repeat step 6 to 11 for another 5 sets of readings.
5.0 RESULTS
Beam span = ………………….mm
Distance of the shear section from the right support , L_{4} = ………………….mm
Table (a)
Load case

Load and its distance from the left support

Load cell reading F (N)

W_{1 }(N)

L_{1}(mm)

W_{2} (N)

L_{2}(mm)

W_{3} (N)

L_{3}(mm)

Case 1








Case 2








Case 3








Case 4








Case 5








Table (b)
Load Case Number

Bending Moment (Nmm)

Experimental ( F x 175)Nmm

Theory (Nmm)

1



2



3



4



5



6.0 QUESTIONS

Using the data in Table (a), plot the bar chart for the bending moment for the theoretical and experimental case for each load case.

Calculate the percentage error for each load case and hence determine the overall percentage error.

Comment on the accuracy of the experiment.

State the probable factors that affect the accuracy of the experiment.

What is the importance of bending moment in civil engineering area?
CIVIL ENGINEERING DEPARTMENT
BENDING MOMENT
No.

I/C No.

Name

1.



2.



3.



Section / Group


Lecturer’s Name


Item

Mark

Mark

Mark

Introduction

25

2


Objective

5


Equipment

5


Theory

5


Procedures

8


Data / Table

35

10


Data Analysis / C.P / Graph

15


Results of Experiment

10


Discussions

35

20


Conclusion

10


Suggestions / Comments

5


Reference / Attachment

5

5


Total

100

100


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