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Structural Steel Design

Tension Members

Dr. Seshu Adluri

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Stell Tension -Dr. Seshu Adluri

Tension in

Nature Tension members are the most

efficient and economical of allstructural elements

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Stell Tension -Dr. Seshu Adluri

Tension Members Used From

Primitive Times

If you wantyour grandkids to playTarzanand theTensionMember,

save theforests!

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Stell Tension -Dr. Seshu Adluri

(Wo)Man-made Tension Structures

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Stell Tension -Dr. Seshu Adluri

Typical

tensionmembers

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Steel and Tension

Steel in TensionExcellent in Tension (and compression)

Very ductile (highly desirable structuralproperty for stress redistribution and safety)

Connections induce loss of effective area Bolt holes, etc.

Shear lag in outstanding parts (of both bolted andwelded connections)

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Typical

cross-sections

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Material behaviour

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Material behaviour

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Stresses in tension members

(gross-section)

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Stresses innet-section

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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/s in the

connection zone

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Plate in Tensionwith Bolts

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Plate in Tension with Bolts

b b

aa

8 x in. bar

Gusset plate

7/8 in. diameter hole

Section a-a

Section b-bb b

aa

8 x in. bar

Gusset plate

7/8 in. diameter hole

b b

aa

8 x in. bar

Gusset plate

7/8 in. diameter hole

Section a-a

Section b-b

Section a-a

Section b-b

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Angle in Tension with Bolts

L 4 x 4 x 3/8

db = 5/8 in.

Gusset plate

a

a

Section a-a

L 4 x 4 x 3/8

db = 5/8 in.

Gusset plate

a

a

L 4 x 4 x 3/8

db = 5/8 in.

Gusset plate

L 4 x 4 x 3/8

db = 5/8 in.

Gusset plate

a

a

Section a-aSection a-a

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Rupture

of net

section

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Typical Truss Connection

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Typical Frame Connection

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Shear lag

Out-standing parts of rolled sectionsLegs 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)

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Shear lag

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Shear lag

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Shear lag effect

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Length of connection (for shear lag)

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Eccentricity of elements

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Staggered bolts

Tear out paths can be inclineds2/4g rule (Cl. 12)

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Gauge Length

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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

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Block Shear Tear-out Cl. 13.11

Paths parallel & perpendicular to load