Influence of Pressure and Thermal Loadings on Transverse ...
Beams and Loadings
-
Upload
royal-mechanical -
Category
Documents
-
view
234 -
download
1
Transcript of Beams and Loadings
-
8/22/2019 Beams and Loadings
1/13
LOADS
wrt TIME
STATIC DYNAMIC
wrt DIRECTION OFLOADS
NORMAL SHEAR
wrt AREA
CONCENTRATEDDISTRIBUTED
-
8/22/2019 Beams and Loadings
2/13
STATIC
DEAD LOAD
BEARING ON ASTATIONARY SHAFT
LOAD IS CONSTANT WRTTO TIME .
GRADUALLY APPLIEDLOAD
WHICH VARIES SLOWLYTO ITS MAXIMUMMAGNITUDE AND THENREMAIN CONSTANT.
GENERALLY LOAD VARIESTO ITS MAXIMUMMAGNITUDE IN 0 TO 1SEC THEN REMAIN
CONSTANT .
-
8/22/2019 Beams and Loadings
3/13
DYNAMIC
IMPACT/SHOCK LOAD
(QUICKLY) WHICH ARE ACTING IN SHORTINTERVAL OF TIME TOWARD MAXIMUM
MAGNITUDE.
WHEN ANY MASS IS DROPPED FROMSOME HEIGHT ON OTHER BODY , THEN
LOAD APPLIED ON OTHER BODY ISIMPACT LOAD .
FATIGUE/CYCLIC LOAD
WHOSE MAGNITUDE OR DIRECTION or BOTHMAGNITUDE AND DIRECTION CHANGE wrtTIME AND THESE LOADS ARE REPEATEDLY
APPLIED wrt TIME
SUDDENLYAPPLIED LOAD
IT IS ALSO SAME AS IMPACT LOAD , BUT THEDIFFERNCE IS THAT , THE LOAD APPLIED ON
OTHER BODY IS NOW FROM NEGLIGIBLE HEIGHT. ( STRESS = 2* STRESS IN CASE OF GRADUALLY
APPLIED LOAD i.e (W/A) )
WHEN THE CUTTING TOOL JUST TOUCHES
THE ROTATING WORKPIECE .
-
8/22/2019 Beams and Loadings
4/13
IMPACT LOAD = WHEN h (height of impact) has some value.
SUDDEN LOAD = WHEN h is very small or negligible.
-
8/22/2019 Beams and Loadings
5/13
a) Straight two-force member AB is in
equilibrium under application of F and -F.
b) Internal forces equivalent to F and -F are
required for equilibrium of free-bodies AC and
CB.
-
8/22/2019 Beams and Loadings
6/13
A to B UNIFORMLY DISTRIBUTED LOAD.
B to CUNIFORMLY VARYING LOAD.
-
8/22/2019 Beams and Loadings
7/13
BEAMS
-
8/22/2019 Beams and Loadings
8/13
CLASSIFICATION OF BEAMS TAKING OTHER FACTORS -
(a) STATICALLY DETERMINATE OR INDETERMINATE -
Statically determinate - Equilibrium conditions sufficient to compute reactions.
Statically indeterminate - Deflections (Compatibility conditions) along with equilibrium
equations should be used to find out reactions.
OR
STATICALLY DETERMINATE STRUCTURE
No. of unknowns
-
8/22/2019 Beams and Loadings
9/13
BEAMS SUPPORTS
SUPPORTS-Identified by the
resistance offered to forces .
(a) Rollers/Links:
Resists forces in a direction along the
line of action
(b) Pins/HINGES:
Resists forces in any direction of the
plane
(c) Fixed Support:
Resists forces in any direction
Resists moments.
-
8/22/2019 Beams and Loadings
10/13
SHEAR FORCE SIGN CONVENTION
HOW TO REMEMBER -
CLOCKWISE DIRECTION OF SHEAR FORCEWILL MAKE BEAM TO ROTATE IN
CLOCKWISE DIRECTION, HENCE TAKEN AS
POSITIVE.
-
8/22/2019 Beams and Loadings
11/13
BENDING MOMENT SIGN CONVENTION
POSITIVE MOMENT = SAGGING
NEGATIVE MOMENT = HOGGING
-
8/22/2019 Beams and Loadings
12/13
CALCULATION OF BEAMS -
When all the forces are applied in a single plane, the three equations of static equilibrium
are available for analysis.
Fx = 0, Fy = 0 and Mz = 0
Employing these, the reactions at supports could be found out
-
8/22/2019 Beams and Loadings
13/13
PLANE SECTIONS normal to the axis before
bending remain plane and normal after
bending also, as shown in Figure, ab, cd, ef
are sections which remain plane and
normal.
Beam is subjected to pure bending
(means no shear, only moments).
Longitudinal top fibers are in compression
and bottom fibres in tension.
Layer of fibres in between which is neither
in tension or compression, is called the
neutral surface.
Neutral axis is the intersection of such a
surface with the right section through thebeam.