Structural Steel Design Tension Members

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29 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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Structural Steel Design
Tension Members
Dr. Seshu Adluri
Stell Tension -Dr. Seshu Adluri
Tension in
Nature

Tension members are the most
efficient and economical of all
structural elements
Stell Tension -Dr. Seshu Adluri
Tension Members Used From
Primitive Times

If you want
your grand
kids to play
“Tarzan
and the
Tension
Member,”
save the
forests!
Stell Tension -Dr. Seshu Adluri
(Wo)Man-made Tension Structures

Stell Tension -Dr. Seshu Adluri
Typical
tension
members

Stell Tension -Dr. Seshu Adluri
Steel and Tension

Steel in Tension

Excellent in Tension (and compression)

Very ductile (highly desirable structural
property for stress redistribution and safety)

Connections induce loss of effective area

Bolt holes, etc.

Shear lag in outstanding parts (of both bolted and
welded connections)
Stell Tension -Dr. Seshu Adluri
Typical
cross-
sections

Stell Tension -Dr. Seshu Adluri
Material behaviour

Stell Tension -Dr. Seshu Adluri
Material behaviour

Stell Tension -Dr. Seshu Adluri
Stresses in tension members
(gross-section)

Stell Tension -Dr. Seshu Adluri

Stresses in
net-section
Stell Tension -Dr. Seshu Adluri
Basic Failure modes

Yielding of gross c/s

Limiting the capacity to yield prevents very large
deformations (before strain hardening kicks in)

Rupture (fracture) of net c/s

Localized yielding and strain hardening is permitted

Ultimate stress is the limit for the local c/sin the
connection zone
Stell Tension -Dr. Seshu Adluri
Plate in Tension
with Bolts

Stell Tension -Dr. Seshu Adluri
Plate in Tension with Bolts
b
b
a
a
8 x ½ in. bar
Gusset plate
7/8 in. diameter hole
Section a-a
Section b-b
b
b
a
a
8 x ½ in. bar
Gusset plate
7/8 in. diameter hole
b
b
a
a
8 x ½ in. bar
Gusset plate
7/8 in. diameter hole
Section a-a
Section b-b
Section a-a
Section b-b
Stell Tension -Dr. Seshu Adluri
Angle in Tension with Bolts
L4 x 4 x 3/8
db
= 5/8 in.
Gusset plate
a
a
Section a-a
L4 x 4 x 3/8
db
= 5/8 in.
Gusset plate
a
a
L4 x 4 x 3/8
db
= 5/8 in.
Gusset plate
L4 x 4 x 3/8
db
= 5/8 in.
Gusset plate
a
a
Section a-a
Section a-a
Stell Tension -Dr. Seshu Adluri
Rupture
of net
section

Stell Tension -Dr. Seshu Adluri
Typical Truss Connection

Stell Tension -Dr. Seshu Adluri
Typical Frame Connection
Stell Tension -Dr. Seshu Adluri
Shear lag

Out-standing parts of rolled sections

Legs of angles, flanges, etc.

Connected parts due to insufficient load
transfer in the connection zone

Single side welds

Two side welds of insufficient lengths

Cl.12 (effective net areas)
Stell Tension -Dr. Seshu Adluri
Shear lag

Stell Tension -Dr. Seshu Adluri
Shear lag

Stell Tension -Dr. Seshu Adluri
Shear lag effect

Stell Tension -Dr. Seshu Adluri
Length of connection (for shear lag)

Stell Tension -Dr. Seshu Adluri
Eccentricity of elements

Stell Tension -Dr. Seshu Adluri
Staggered bolts

Tear out paths can be inclined

s2/4g rule(Cl. 12)
Stell Tension -Dr. Seshu Adluri
Gauge Length
Stell Tension -Dr. Seshu Adluri
T
T
Shear failure
Tension failure
(a)
(b)
(c)
T
T
Shear failure
Tension failure
Shear failure
Tension failure
(a)
(b)
(c)
Block Shear Tear-out

Cl. 13.11

Paths parallel
to load
Stell Tension -Dr. Seshu Adluri
Block Shear Tear-out

Cl. 13.11

Paths parallel & perpendicular to load