Report 4 Structurennn

8/13/2019 Report 4 Structurennn

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1.0 INTRODUCTION

A beam having more than two supports is called as continuous beam. The supports at the ends

are called as the end supports, while all the other supports are called as intermediate support.

It may or may not have overhang. It is statically indeterminate beam.

A continuous beam is a structural component that provides resistance to bending when a load

or force is applied. These beams are commonly used in bridges. A beam of this type has more

than two points of support along its length. These are usually in the same horizontal plane, and

the spans between the supports are in one straight line.

In contrast to a simply supported beam, which has supports at each end and a load that is

distributed in some way along its length, a continuous beam is much stiffer and stronger. A

bridge that is made up of beams that span between only two supports is called a simply

supported beam bridge. If two or more beams are joined together rigidly over multiple

supports, the bridge becomes continuous.

The two main factors for consideration in the design of a continuous beam are the type of load

and the strength characteristics of the material used to construct the beam. The reactions that

occur at the supports of a simply supported beam can be determined by analyzing only the

forces applied to the beam.

2.0OBJECTIVEThe objective of the experiment is to determine the magnitude of fixing moment in a

continuous beam by experiment and to compare this value with the value obtained

theoretically.


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3.0 THEORYConsider the beam shown below ,

The fixing moment at B is given by,


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The three moment equation for a beam of constant cross-section is :

EQUATION 2

We know that MA = Mc = 0 and :


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4.0 APPARATUSThe following are required :

i. Two knife edge supportii. Test beamiii. Three stirrup

iv. Two double ended hook


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v. Two load hangers

vi.

Spring balance

vii. Adjuster and support


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viii. Dial gauge and small support

Let L1 = 400 mm and L2 = 600 mm


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5.0 PROCEDURE

i. The apparatus has been set up .

ii. First of all , we must adjust the dial gauge to zero by turning the hazel .

iii. After that , we applied the load of 10N to W1 and 5N to W2.


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iv. The spring balance has been adjusted by using the spring balance adjuster until the dialgauge reads zero .

v. Reading of spring balance has been recorded.

vi. Then, we increased w1 by 10N and W2 by 5N and the process has been repeated untilW1 = 50N


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6.0 RESULTS

W1 0 10 20 30 40 50

W2 0 5 10 15 20 25

Ro 0 3 3 3 3 3

Rf 0 5 8 13 16 18

R actual = Rf- Ro 0 2 3 10 13 15


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7.0CALCULATION

MB = W1L1

RL1

2

MB = W1L1RL1

2

i. MB = ()

()

MB = 0

MB = W1L1RL1

2

ii. Mb = ()

( )

= 2000800

= 1200

MB = W1L1RL1

2

iii. Mb = ( )

( )

= 40002000

= 2000

MB = W1L1RL1

2

iv. Mb = ( )

( )

= 60004000

= 2000

MB = W1L1RL1

2

v. Mb = ( )

( )

= 80005200

= 2800

MB = W1L1RL1

2

vi. Mb = ( )

( )

= 100006000

= 4000


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8.0 DISCUSSION

1. The comparison between the theoretical and actual results slightly differs due to certainfactors :

Observation error @ Parallax errors due to reading taken The dial gauge may not calibrated Small vibration and movement interferences which effects the reading on

dynamometers

Slightly inclined workbench which may cause vectored load into 2 axis components2. What we can see based on the graph that we plotted; we can see that the more

magnitude applied on the beam, the actual reading becomes higher. This is happened

because the load hanger has differences load.


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9.0 CONCLUSIONIt can be conclusively said that the reaction away from the cantilever displays much reaction

force compared to the one that is closer to it. Based on the observation the experiment has

shown that there will be more deflection at the other end of the beam as the beam gets longer

away from cantilever point. Even though there some errors or indifferences in the results

compared to theoretical, however the principal idea shows that both theoretical and

experimental shows the same concept of cantilever deflection which causes higher reaction

force as it moves away from the cantilever point.


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10.0 REFERENCES www.atapaje.blogspot.com http://www.wisegeek.com/what-is-a-continuous-beam.htm
http://www.atapaje.blogspot.com/http://www.atapaje.blogspot.com/http://www.wisegeek.com/what-is-a-continuous-beam.htmhttp://www.wisegeek.com/what-is-a-continuous-beam.htmhttp://www.wisegeek.com/what-is-a-continuous-beam.htmhttp://www.atapaje.blogspot.com/

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Report 4 Structurennn