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SHEAR FORCE AND BENDING MOMENT

INTRODUCTION

Shearing forces are not placed in straight line forces which pushing one part of a body

in one direction, and another part of the body in the opposite direction. When the

forces are placed in straight line into each other, they are called compression forces.

Bending moment is the reaction occur in a structural element when an external force

is applied to the element causing the element to bend. For equilibrium, the moment

created by external forces with distance must be balanced.

OBJECTIVES

To understand the reaction between the shear force and bending moment for a

beam under various loads.

To determine the type and sie of a structural member.

To handle the structural member designing easily.

To avoid any unexpected damage in future.

Shear Bending

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THEORY

Relationship beteen shea! "o!#e an$ ben$in% &o&ent

'( The maximum bending moment occurs at a section, where the sheaf force is

either ero or changes sign from !ve to "ve. This is an important relation

which helps us in obtaining the maximum values of bending moment.

#. The rate of change of bending moment at any section, is equal to the shear

force at that section.

Shea! "o!#e si%n #on)ention

Ben$in% &o&ent si%n #on)ention

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$f cloc%wise bending moments are ta%en as negative, then a positive bending moment

within an element will cause &sa%%in%&, and a negative moment will cause &ho%%in%&.

Appli#ation in !eal li"e

Bending moment and shear diagrams are used all the time by engineers designbridges, buildings, boats, cars, planes and any type of structure that has to resist

forces.'sing these diagrams the type and sie of a member of a given material can be

easily determined.

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RESU*T

(oad ) *++gram

Distan#e *oa$ applie$ to balan#e bea&

+%!a&,

-' -.

/'0 1('2& + *+

/. 0 1('1& + *++

/30 1(12& *-+ +

(oad ) +gram

Distan#e *oa$ applie$ to balan#e bea&

+%!a&,

-' -.

/'0 1('2& + +

/.0 1('1& + +

/30 1(12& **+ #+

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(oad ) *++gram

Distan#e Fo!#e +N,

/ mass x 0.1*2

-'+N, -.+N&,

/ Force x distance2

/' 0 1('2& +.01* *.-* +.*-#

/.0 1('1& +.01* +.01* +.+01*

/3 0 1(12& +.01* +.-0+ +.+-0*

(oad ) +gram

Distan#e Fo!#e +N,

/ mass x 0.1*2

-' +N, -.+N&,

/ Force x distance2

/' 0 1('2& +.-0+ +.31 +.+34

/.0 1('1& +.-0+ +.-0+ +.+-0*

/3 0 1(12& +.-0+ +.#-3 +.+#-

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Sa"et4

$. When doing experiment you must wear a fastened lab coat.

$$. (ong treasures or 5eans must be wear that cover all your legs.

$$$. 6eep your wor% area tidy and clean up any water spills on the floor.

$7. 8eport all accidents and all incidents to lecturer.

Health

$. 9our health must be in good condition.

$$. :ust be ready to carrying out the experiment.

$$$. Foods and drin%s are prohibited.

5!e#a6tion

$. ;void disturbance from the surroundings.

$$. :a%e sure that your hands must not disturb the balance level of the beam.$$$. $t is good practice to see the balance level of the beam from a certain distance.

$7. ;void reading error.

7. :a%e sure that the beam is in the balanced position then ta%e the readings.

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DISCUSSION

We can see that the difference of the load weight is quite large in balancing the beam.

The difference of the load weight is caused due to the shifting the loads /front portion2

to other line in every sub"reading. When we shift a %nown load weight /front portion2

from one line to another, the un%nown load weight are added to the two suspensions

lines until the beam is equilibrium.

CONC*USION

From the result obtained, we can conclude that the bending moment is at maximum

when the shear force is ero. force

http)==en.wi%ipedia.org=wi%i=Bending>moment

http://en.wikipedia.org/wiki/Shear_forcehttp://en.wikipedia.org/wiki/Shear_force

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5ROCEDURE

*. Set up all the equipment properly.

#. There have different metal weights which is useful to ma%e the beam balance.

*++g, +g, #+g, ? *+g.3. There have three different portions in this experiment. First have three beam

lines in the front portion which is use for hanging loads. Secondly have a

suspension beam line in the middle portion and lastly have a suspension beam

line in last portion.

-. Ta%e three load hangers and put in each portion.

. :a%e sure the load hanger is placed in first beam line of the front portion in

first reading.

4. $n this experiment, have two reading sets. $n the first reading set, the front load

weight must be maintained which is *++g. $n the second reading set, the front

load weight also must be maintained which is +g.

. @ow balances the beam by apply loads to the both suspension beam lines.

1. ;fter balancing, record the weight of all the three load hangers.

0. 8emove all the loads from the middle and last load hangers.

*+. @ow move the load hanger /front portion2 from first beam line to second beam

line. 8emember the weight of the load must be maintained.

**.

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A55ARATUS

Beam

(oad hanger

; set of metal weights

Beam lines

/ *, #,3 2

Suspension beam lines

/ W*, W#2

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A55ENDI/