1
CVE312: Structural Steel
Design:
Beams
Mohammad AlHamaydeh, Ph.D., P.E.
American University of Sharjah, UAE
Chapter 4: Beams
Introduction
Bending Stress and Plastic Moment
Flexural Stability
Classification of Shapes
Bending Strength of Compact Shapes
Bending Strength of Noncompact Shapes
Summary of Moment Strength
CVE312
Dr. Mohammad AlHamaydeh
Shear
Deflection
Design of Beams
Miscellaneous Topics

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2
Types of Beams
Beams are members that support transverse loads. Among the many types
of beams are
joists lintels spandrels stringers
and
floor beams
of beams are
joists
,
lintels
,
spandrels
,
stringers
, and
.
Joists
are the closely spaced beams supporting the floors and roofs of
buildings, while
lintels
are the beams over openings in masonry walls
such as windows and doors.
A
spandrel
beam supports the exterior walls of buildings and perhaps
part of the floor and hallway loads.
Stringers
are the beams in bridge floors running parallel to the roadway
Floor beams
are the larger beams in many bridge floors which are
di
l
h
d
f h
b id
d
hi h
d
f
CVE312
Dr. Mohammad AlHamaydeh
perpendicular to the roadway of the bridge and which are used to transfer
the floor loads from the stringers to the supporting girders or trusses.
A
Girder
is a large beam and perhaps one into which smaller beams are
framed.
Sections Used as Beams
The
W-shapes
will normally prove to be the most economical
beam sections and they have largely replaced channels and S
beam sections and they have largely replaced channels and S
sections for beam usage.
The
W-shapes
have more steel concentrated in their flanges than
do S beams and thus have larger moments of inertia and resisting
moments for the same weights. They are relatively wide and
have appreciable lateral stiffness.
CVE312
Dr. Mohammad AlHamaydeh
Channels
are sometimes used for beams subjected to light loads,
such as
purlins
, and in places where clearances available require
narrow flanges. They have very little resistance to lateral forces
and need to be braced by sag rods.

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Strain Due to Bending
Consider a beam segment of length
L
.
After deformation, the length of the neutral
surface remains
L
.
At other sections,
linearly)
ries
(strain va
y
y
L
y
y
L
L
y
L
x
CVE312
Dr. Mohammad AlHamaydeh
max
max
max
1
or
c
y
c
ρ
c
x
Strain Due to Bending
•
Deformation due to bending moment
M
is
tifi d b
th
t
f th
t
l
f
quantified by the curvature of the neutral surface
M
I
Mc
Ec
Ec
c
m
1
1
1
max
CVE312
Dr. Mohammad AlHamaydeh
EI
Curvature
)
(

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