steel frames and precast buildings have
a lot of similar benefits that's why
it's a debate between which one to
choose so this is a battle royale
between steel frames and precast
buildings so which one will win my name
is brendan your structural engineer now
let's get into it let's go with the
first comment of why people want to
choose either between a steel frame or a
precast building what's really to do
with reliability you see the problem
with on-site construction is you're
delayed by how the weather is it's a hot
day you may be delayed it's raining or
other effects may slow down your
construction where if you go with a
steel frame structure or a precast
building you can do a lot of the
fabrication offside for example for
precast buildings you can have rigged
inside a building where you can pour
concrete doesn't matter what the weather
is so it allows you have a more
controlled environment have a better
product in the end that is not affected
by weather similar still framed
buildings you can fabricate parts of the
building together having stings already
installed before it's coming to site so
allows you to a lot of that fabrication
before coming to site as opposed to
in-situ design so there's better
reliability between choosing one or the
other so
what is the drawbacks here though with a
steel frame building you can just bolt
it up and it can be stable straight away
where precast you need to have joining
connections such as grout beds and
dowels which need to be grouted up so
sometimes you need to temporarily pop
the precast building as opposed to the
steel frame building where if it's a
steel frame building you may need to
clad over it where a precast building
can be finished as soon as it's put down
now you may be thinking of things like
floors however both in the precast and
the steel framing you still need to pour
a concrete slab to make that floor
integral so there's no real benefit
between doing that steel framing or
precast design so which one wins this
one reliability it's a draw as there's
benefits and drawbacks of choosing
either of them but they're both
definitely more reliable than an
institute or stick frame solution how
about the next factor that typically
drives our decision now that is cost
cost has a high factor of which one to
choose over the other now depending on
which element you're choosing there's
definitely benefits for using one or the
other sometimes if you're doing a
precast wall it'd be cheaper to have the
walls and columns things like floors can
sometimes be cheaper underneath the
steel solution due to the reduced size
so for cost so the precast becomes more
finished however there's a little bit
more work of lifting and putting in
place where the steel needs a little bit
more additional work to have it finished
off so for this case again it's a draw
there's benefits of drawbacks for either
but depending on where you are in the
world sometimes precast will be the
chosen solution but other times steel
will be construction time is also
something that's a big driver of these
different type of solutions sometimes
even more so than cost as the quicker
you can get it finished the quicker you
can sell it and the quicker you get the
money back in your pocket if there's a
lot of changes within your design
precast can be quite expensive however
most of the time if you've got a
symmetrical structure going up you've
got walls positioned on top of each
other you don't have many transitions or
transfer floors means that you've got a
lot of replication and a lot of
repetition that's really where you get
the benefit of precast design so we get
a building with a lot of repetition you
can build it really quickly most of the
time it's better to have mostly designed
as precast to reduce that construction
time so the winner here is precast
design environmental sustainability is
going to become more and more relevant
as we move into the next century so
which one is more environmentally
suitable is it the steel solution or is
it the precast for example precast is
heavier so it takes more time for it to
get to site and overall there's a little
bit more embodied carbon in your precast
solution both due to the weight and the
way it needs to be installed so
typically steel will win out here
wherever it's only just and by a
marginal basis and it really depends on
where you're getting energy from and
what type of steel you're using because
you don't necessarily need to always
mill it out of the ground to get it in
place however you can reuse and melt
down and reuse steel sections so the
winner here ding ding ding
is steel
how about aesthetic appeal this can be
also another factor that helps drives
your decisions where steel it just goes
into place it doesn't really have that
cladding involved with it so it's only
the steel frame although you can make
connections look nice it still needs
another features to make it look more
appealing the precast is not just a
structural element you can put designs
in your precast building to make it look
more appealing as soon as this goes down
it has a more aesthetic appeal so the
winner here for aesthetics is definitely
precast how about on-site construction
as this can increase the cost which
one's going to be easy to install and
build really depends on where you're
putting it in and what aspects you have
typically steel is a lot more accessible
you can move it into places you can
stick it up in different areas you don't
need heavy machinery to lift up pieces
into place it also means you're not
restricted by the access to the side or
the crane that's lifting up your
elements as you can build it in stick
framing and put it together on site so
it makes it more versatile in this
situation whereas precast is heavy you
need big trucks to bring into place you
typically need big cranes to lift them
up to the top of the building and put
them into place so it's really unlimited
based on what crane you have access to
and side access to allow that trucks to
come up into place there's also
additional complications of having to
prop it so after you put it up in place
it's not always stable until the other
elements are around it so definitely the
winner here for constructability is
steel following on to constructability
and you probably know the answer here
transportation transportation that
definitely winner is steel due to its
lightweight nature and being smaller
it's a lot easier to transport to the
site you're not limited by what access
you have or the access to the site as
you can build it in small parts but
precast needs to become in big sl
elements to make it efficient so it
means that you're limited based on the
trucks that you have side access and how
it can get from the precast yard to the
side so the winner 100 here is steel for
transportation durability for both fire
and long-term aging is definitely
something you need to consider when
you're choosing between your steel or
your pre-cast solutions as typically
when you put a steel frame building
together you need to treat it for either
external use or the environment that's
around it as it's not untreated it can
rust and degrade over time for example
steel to put into place you need to
treat it for fire with either a
protection layer around the outside or
intermediate paint or sometimes you may
need to hot dip galway to give it the
characteristic age that it needs to
achieve whereas precast it pretty much
becomes as durable as you need it to be
you just increase the covers of the
reinforcement and you increase the
durability of your structure so the
winner here is definitely precast design
as it already comes with the durability
required and doesn't need additional
treatment how versatile is either the
steel framing or the precast see precast
can be used in a lot of situations and
it can just be finished as is you can
have it as a floor
roof walls or columns
where a steel frame typically needs
additional elements attached to it to
make those work as a specific function
for example if you've got a roof you
need to have rafters purlins and a roof
sheet on top with precast you can just
put the precast down on top and it's
already stable provided within the given
range similar to walls you may have a
steel frame in there that's really
efficient but it still needs cladding on
top of it to finish if it's a steel
frame building where precast can have
its finished solution as soon as it goes
down so for versatility precast is
definitely the winner here so which one
has the better space saving flexibility
is it either the steel framing or the
precast receiver precast is typically a
solid block so you can't cast services
in it you can't put services through
them so typically you'll need a ceiling
space and have the services run beneath
them whereas steel is normally more
flexible you can put holes through it
allowing you to achieve the penetrations
needed for the services so typically you
have the steel framing and the services
within the same zone so definitely the
winner here is still framing as it
allows to have the services
and the structural elements within the
same zone as opposed to beneath it so
typically you can have a shorter
structure or thinner structure using a
steel frame building the other one that
may make a decision between one or the
other is its ability to resist sound or
transmit sound through the floors a lot
of time people complain especially in
high-rise buildings that floor
transmission of sound is really annoying
people living above you transmitting the
sound through that can be really
irritating for example walls if you've
got a wall between two areas you may not
want the sound to go through that
element now with steel frame buildings
you typically need to put another
element in between it as it's really
thin it doesn't have enough mass or
density to resist the sounds between
them where precast wall or precast floor
already has that density within it and
if it's thick enough will help prevent
the sound transmit through the
structural element for sound
absorbability
the winner is definitely precast in this
situation and lastly about design
flexibility we're always talking about
trying to make buildings architectural
so which one's going to give you the
biggest design flexibility example
precast design is very rigid as it's
heavy and typically means things need to
be aligned you don't really want to have
offsets as it creates transfer
structures that make it really expensive
there's also limitations on how thick a
structure needs to be as concrete is
normally not as efficient it needs to
have thicker designs so for design
flexibility steel allows you to have a
lot more greater flexibility have those
bigger spans have that more ornate
structure so for design flexibility a
steel frame solution is definitely the
winner it allows you to have that out of
facade it allows you to have a thinner
structure it allows you to come up with
those really thin elements candle
everything out making it look like it's
almost floating into nothing
now i'm sure you can see off to the side
of which one's the winner either that
still framed building or the precast
design i didn't keep track where it's
never just one or the other a lot of
times a combination of both steel
framing and precast to get to the right
solution
maybe depending on site access
transportation and other factors
depending on which element to choose
it's about choosing the right element
for the right situation
so despite them having one winner both
will potentially be the best solution
for your chosen design if you're
interested in learning about more of the
rules of thumb would be the concrete
design or steel design i'll link to the
videos here to give you more insight
about which one to choose if you're
interested on this channel there's two
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possible as always stay safe keep
learning and i'll see you next week bye