Download (PPT, 533KB)

shrubflattenUrban and Civil

Nov 25, 2013 (4 years and 7 months ago)




No role till 19 century

in a
structural cap.

First all metal structure

cast iron
bridge built in the late 18 century in
England. Still in use today.

Cast iron was first

but is very

1850’s still came available
inexpensively with introduction of
the Bessemer process.

Bessemer process

air blown into
vess4el of molten iron to burn of the


open hearth method was
developed which further reduced
the cost.

Material Steel

Steel is any range of alloys of
iron and carbon

that contains
less than 2 % carbon.

Ordinary structural steel called
mild steel contains less then
3/10 of 1% carbon

Ordinary cast iron contains 3
to 4% carbon

To much carbon makes a hard
but brittle metal

While to little produces a soft
weak material

Thus mild steel is iron whose
properties have been
optimized for structural

Iron is produced in a blast
furnace charged with
alternating layers of iron ore,
coal without its volatile
combustibility leaving only
carbon, and limestone.

Uwe R. Zimmer



Coke burned by large quantity of air forced in
from the bottom

produces a gas of carbon

which reacts with the ore to
reduce it to elemental iron.

Limestone forms a slag which reduces the
impurities of the iron

Molten iron is drawn off the bottom of the

One ton of iron requires

1 ¾ tons of iron ore

¾ ton of coke

¼ ton of limestone

4 tons of air

Today most steel is produced by basic oxygen

other methods can be used

In which a water cooled lance is lowered into a
constancy of molten iron.

Stream of pure oxygen at very high pressure is
blown from the lance into the metal to burn off
carbon and other impurities.

Molten steel from the furnace is cast into
molds to produce ingots

Production of structural shapes

Rolling process begins at the blooming

The hot ingots is reduced in size by
squeezing it between rollers

Then brought to structural mill with temp
still above 2200 f

Here it passes through a succession of

That press the metal into progressively
more refined shapes and sizes

Typically wide flange shapes passes
through set of rollers around 40 times

Then it is allowed to cool

After cooling a straightening machine
takes out minor crookedness

And a saw cuts the lengths of steel into
shorter pieces.

Sizes and Shapes

By varying the space of the
rollers you can obtain a varied of
shapes and sizes

Wide flange uses for most
column and beams

American Standard I beam

less efficient structurally then
wide flange

because roller
arrangement that produces
them is incapable of increasing
the amount of steel to the
flanges without also adding
steel to the web

where it does
little to increase the load
carrying capacity.


Wide flange W21 x 83

Sizes range from 4 to 18” in 2 in. increments

18 to 36” in 3” increments

American Standard S18 x 70

Sizes 3,4,5,6,7,8, 10,12, 15,18,20,24

Wide flange measurements

W12 x 24 used as a beam or girder

Depth actual 12.22 inches flanges 6.49 in.

W12 x 336 intended for columns

Depth actual 17 in.

Steel angles

extremely versatile

L4 x 3 x 3/8

Uses as lintels spanning doors and windows in masonry construction

Steel buildings cut into short pieces and used to connect wide flange shapes

Diagonal to braces steel frames

Members of steel trusses


C9 x 13.4

Used as truss members and bracing

Tees, plates and bars

WT13 x 47

Open Web Steel Joists

One of the many structural
steel products fabricated

A mass produced truss
used in closely spaced
arrays to support floors
and roof decks

Comes in three sizes

K series span 60 ft

Depth 8 to 30 inches

LH series (long span) 96 ft

Depth 18 to 48 inches

DLH series (deep long span)
144 ft

Depth 52 to 72 inches

Cold work steel

Sheets of steel can be
bent into c shaped, z
shaped sections

Channel stud

Cee stud

Double Stud

Cee Joist

Double Joist

Joining Steel Members


a fastener
consisting of a cylinder
body and a formed head

Heated to a white color

Inserted through the holes in
the member

With a pneumatic hammer to
produce a second head
opposite the first

As the rivet cools its shrinks
and clamping the joined
pieces together tightly

Joining Steel Members


Two categories

Carbon steel bolts

Also known as unfinished or common bolts

Similar to ordinary machine bolts that can be purchase at
hardware store

Not very strong

Highest strength bolts

Heat treated to develop necessary strength

Their connecting ability either is a shear connect

which stems
from their shear resistance

Or from being tighten to the point that the members join are kept
from slipping by the friction between the producing a fiction

Joining Steel Members


Offers a unique and
valuable capability

Can join members of
steel together as if they
were one

Joining Steel Members

Shear Connections and Moment

In order to understand the respective
roles of shear connections and moment
connections necessary to understand the
means by which a building may be made
stable against the lateral forces of wind
and earthquakes

Three basic mechanisms

Diagonal bracing

Sheer panels

Moment connections

Diagonal bracing works by creating stable
trim angles within the unstable geometry
of a steel building

The connections within a diagonally brace
frame do not transfer moments

They behave like pins which is another
way of calling them shear connections

Shear panels

rectangle panels made of
steel or concrete

shear connections

Sheer connection

Moment connection

Metal Decking

Sheets of steel that
have been corrugated
to increase its stiffness

Span determined by


Building fires are not hot enough to melt steel

but many are able to weaken it to cause structural


encasing steel in brick or concrete

but the weight added is considerably to the load
and cost

Metal lath and plaster

Boards or slabs of gypsum or other fire resistance

can serve as a finished surface

Spray on materials #1 today

general consists of