Steel Construction Vol 40 No 2 - Tubular Steel Feature | Page 24

SAISC TECHNICAL
• It is going to be sharp (As in clever/
bright or as in a knife edge?)

• Do the extra part turn depending upon
the length of the bolt

• Makes stainless steel (That would surely
bring the price down!)
• Less crystals in the steel (So metallurgists,
why did we have to deal with those

The prize winning non-slip part 3 answer
was:
”…weld out to prevent slip”.

centre line laminations caused by
sulphide and chloride crystals???)
Composite construction issues

Hot dip galvanizing issues
Because it is an effective corrosion
protection method in the right applications

The question reads explain briefly why a

we cover the process. What always delights

composite concrete slab and steel beam

the students is the way in which I describe

is stronger than just the slab or the I-beam

the dangers of galvanising a closed box or

alone. The answers should make mention

Some of the student groups are just starting
their second years, others are halfway
through their second years. For any student
to understand what the 355 means in the
name of S355JR it is necessary to explain a
stress strain curve and how the stress in the
steel at the yield point defines the name of
the steel.

tube assembly. I emphasize the increase

that concrete is in the compression zone

in temperature can lead to an explosion

and steel is in the tension zone which

with showers of molten zinc raining on the

brings out the best attributes of both

workers with the possibility of death....!!!!!

Since this knowledge is basic to
understanding steel design concepts it is
a natural for exam purposes. I ask them to
name the steel (S355JR) and then ask them
what is the guaranteed minimum yield
strength of the steel.

S355JR the name of our commonly
available and used steel for structures

materials.
So imagine my surprise upon asking this as
I quote verbatim from 2 of the answers

an exam question when the answer came

“The slab is not stronger than the

back “it may burn up some of the stee l”

concrete slab since well there is

and there I was thinking galvanizing was

concrete in the concrete slab, then the

good for corrosion protection.

I-beam is not stronger than the one for
steel beam because steel has alloys it

Oh and by the way did you know that in

is galvanized.”

the galvanizing process we dip steel into

“Concrete when in tension is stronger
because it is bulky and steel when in
tension is weak, which will make them

For some reason not clear to the writer lots
of the students were confused by this part
of the work, see some of the answers that
follow
• Name: Aluminium
Yield: 3618 MPa. (Come on guys let’s get
that right, our future aircraft and space
ships could halve in mass!)
• Name: Stainless steel
Yield: 12 MPa (what a waste of good
money to buy such a weak material...)

to withstand gravity and not fall.”
Boy do I hope they were amongst the
handful who slept through most of the
course, otherwise have I done a really
lousy job!
Bolt issues especially those
troublesome HSFG bolts

Iron!
Some other did you knows…
Apparently we do not put vertical bracings
in the middle of the length of a shortish
building to allow for expansion and
contraction, but rather because “as long
as correct PPE is worn it is not too
dangerous”. He obviously did not think
of the danger that faces him in the case of
a building that may just fall over without
vertical bracings.

Anyone involved the major power station
or heavy steel projects will know there

One of our students has developed a

have been tremendous problems associated

new steel cutting process, pity he has

with the quality of grade 10.9 bolts, site

not patented it, “Cut with ultraviolet

abuse and tightening methods. As I recently

machine”. Now we do know that UV can

commented if I had just 1% of the money
The effect of carbon content on the
steel

cause burning of skin, I guess by extension

spent and/or wasted on the bolt issues,

we will just have to wait a long time to see

replacement of bolts and the like I would
retire a very wealthy man.

if it will ever burn steel. Maybe he knows

If you increase the carbon content you
can increase the strength (both yield and
tensile) dramatically but at the expense of
getting brittle.

• Name: Stainless steel
Yield: 200 MPa (slowly getting there!)

For this reason we teach the students about
non-slip connections and the turn of the
nut method of tightening pre-loaded and

about a new effect of the destruction of the
ozone layer!
In order to create adjustment for holding
down bolts that may be cast in the wrong

This was a new question that I dreamt
up... so did you know that increasing the
percentage of carbon alloy in steel:

HSFG bolts.

• Cracks concrete (The opposition better
watch out! We could end up putting mud
and wire out of business this way.)

• Snug tighten

be screwed in through the plate to

• Make a mark on the nut and the bolt

minimize shear force” – problemo

22 Steel Construction Vol. 40 No. 2 2016

In summary the three steps are

opposite each other

place, we do not need oversize holes,
grout or pockets in the concrete, when
all we need to do is “HSFG bolts must

solved!