And, then you come to the last which is the proof load test.
Proof load basically is the safety test let us say sample mock up is designed for 2
2 kPa windloads.
So, what happens the is that nowadays we find unexpected you know levels of activity
in winds the cyclonic pattern is different weather patterns are changing and the windloads
are increasing in certain areas.
So, this is the safety test basically which is to put 1.5 times or 100 and 50 percent
the design load pressure on the curtain wall on the positive and the negative.
There are no measurements, it is again a visual just to see if all the elements in the curtain
wall are there and the integrity of that entire structure is there physically.
So, it is very important to ensure that in the worst combust scenario the glass does
not fly off or the system does not buckle or the the hardware does not give up.
So, the proof load is a very critical test to put it on worst combust scenario and then
if that passes then you are absolutely sure that whatever happens this thing is not going
to fall down.
And, then you have you know the building maintenance unit BMU you must have seen
people hanging coming down in a building to clean it of on the using a gondola.
So, you also have a BMU pull out because these tall buildings when the gondola comes down
from the roof it because of the winds it is start to sway and in order to avoid the sway
they put in pins every 20 feet and the wire the the the the steel wire is actually locked
into that BMU pin so that does not sway.
So, that is exerting certain loads on that pin and then then in turn getting transferred
to the curtain wall of the façade.
So, what we do is actually physically you know the pin is fixed in the sample and
you do a load test on all the five directions - left, right, top, bottom and outwards to
ensure that the same amount of load which which is actually transferring itself from
the gondola we replicated by adding certain safety factors to that.
So, around 2.5 kilo Newton of load is added and pulled in all directions, the pin should
not give wave neither should the curtain wall move too much and it should not be able to
they should not be any damage to the curtain wall.
Then, we do an impact an impact and I just to simulate let us say there are you have
the vision panel if you look at the curtain wall or a facade from inside the building
you have up to the seal level you may have a opaque structure I mean I can have a glass
which is which is not visible, but from here till the wall sealing you will have a vision
panel.
So, or some of the buildings right from the floor to the top you have vision panel that
is the glass is clear glass or reflective glass.
So, what happens if somebody walking on the corridor tips and falls on the glass.
The impact of the person falling how much of joules of load is energy is getting impacted
and whether the glass panel is able to take that load.
So, we simulate by adding by dropping a weight which is hanging from the roof we pull
it back and then let it fall and that creates a certain amount of kilo Newtons of impact
and with that impact the glass should not shatter.
So, that is the pass-fail criteria again Thermal cyclic test is also becoming very
important in a country like India where in certain areas say up north in Delhi and up
and all these Punjab in those areas where the temperature difference in during the winters
and the high temperatures during the summer is quite very very extreme .
So, what happens is because of this the wind the climatic conditions there are certain
amount of linear expansion and contraction.
So, because the curtain wall or a facade has glass, it has aluminium, it has rubber, it
has gaskets, it has silicone and all these things are expanding and contracting because
of the temperature.
So, we we need to create a similar such kind of conditions.
So, what we do is to have a curtain wall sample and we have an insulated box let say one
and half floors high or two floors high and this box is the actual outside in a real
life situation and we create an atmospheric condition in side that box and that is in
turn affecting the curtain wall from the outside So, we come down you know chill it chill the
box and bring the temperature down to let say 5 degrees or 3 degrees and then you increase
it to 50 degrees hold it for 6 hours come back to normal temperature atmospheric chill
it down to 2 degrees hold it for 6 hours and then come back to normal.
Like this you continue over a period of 3 or 4 days you have 3 cycles or 6 cycles and
then after you do this you do a repeat of air and water just to check whether with all
these expansion and contraction whether there are any holes which are appeared in the curtain
wall and if so, why and what is to be done to correct it?
Of course, acoustics you all know we have huge high rise buildings on main roads and
the noise outside is pretty high and in generally an office or a house needs certain amount
of low audio I mean sound noise inside.
So, you actually can measure how much of noise is coming through the facade and what can
be done to reduce that sound.
So, using the right kind of a glass, the right kind of a system and gaskets you can cut
down quite drastically the amount of noise that is coming into the building.
So, that is also a you know you can simulate it by creating noise outside have a sample
and measure the noise from the inside.
So, acoustic testing is slowly gaining popularity in India .
Now, on site; now once this offsite is done at the lab and everything is passed the architect
in the consultants says, ok, the sample is good to go, start production and then start
installations.
So, in order to ensure that the same kind of a care is taken at the site and to ensure
the quality we do there are specifications again for checking the water and air at
the site.
So, for water you have a specific nozzle as per AAMA 501.2 and there is a pressure
gauge which is a calculated pressure gauge and we we have a high pressure of water sprayed
in a particular pattern through this specified nozzle on the vertical and horizontal grooves
and this is a random sample that will be selected by the architect nobody knows which area is
going to be tested, it could be any area.
So, this testing starts and then only the vertical all the grooves are tested and typical
sample is 3 meter by 3 meter and it takes about an hour and half to check all the vertical
and horizontal joints of that particular sample and the people are standing inside the building
and observing it.
Obviously, the pass-fail criterias that no water should come inside.
And, for an air leakage in order to maintain do the air testing at site we need to build
a small temporary chamber using a plywood very thin plywood and then have a blowers
connected there have a manometer to measure the differential pressure and have the spray
of array of nozzles from outside just like we do it in the lab for 15 minutes and check
for water if it is a window and you have a airflow meter on the blower and that will
measure the leak through the sample at the site.
So, these two things are again done just to counter check whether it is matching with
what has happened when the lab test was completed.
Ah This is very essential specially the water test is very essential for skylights which
are used in public spaces because even a small hole on the top can lead to a lot of leakage
in water and cause accidents on you know people slipping and falling or you know damage to
property or the interiors of the building.
So, onsite water tests are very important to ensure that consistency of delivery at
the site can be ensured by the fabricator .
Then, load test basically you have the you know expansion bolts which are anchored
into the concrete and those of the anchors which are holding the brackets and the entire
facade is mounted onto these brackets.
So, these lot of load on the particular anchor bolts.
So, there are test to pull out and see whether the tests are able to the anchor bolts are
able to take the load.
So, those bolts are tested on even those channels which are casting channels.
Nowadays people are casting the channels into the concrete whereas, when the concrete is
cast and then the bolts are you know slit into the channel and then the bracket is installed
on that particular channel.
So, we do a pull out test and see whether channel is able to take that design load and
there is no you know failure over there.
And, also the shearing of that you push the thing on the side and ensure that the
bloat does not shear off because of the load vertical dead load.
Now, which are the standards to apply now the most prominent standards in the world
now being used by consultants is the American standard which is the ASTM or AAMA or the
Australian New Zealand standard ASNZ or the British European standard BS EN.
Now, which standards are good which is bad I would say all of them are equally good
and they have evolved over a period of time based on the requirements and based on the
experience of these people had and they have improved constantly and upgraded constantly.
So, in that sense every test whichever standards you follow you follow any standard and you
get a product which is pass the standards you can be assured that you know there is
going to be you are getting a good value for that product
Now, advantages in the cyclical test that we explained earlier is that the test pressure
is on the entire mock up the every square inch of that mock up is got the uniform pressure
which is created in the chamber unlike dynamic where the pressure is high in the
periphery and then as you go away at a distance it is drop because it is an open open to sky.
So, here you have a uniform pressure on the entire sample and you can go up to much higher
pressures to test it and the it is gusts actually the 3 to 5 seconds is almost like a natural
low wind frequency which being repeated and it is a very effective for mock ups it is
a very difficult specification and if the water passes in cyclic test it is actually
a very good you know result for the you know for the designer and commendable because it
is very stringent.
Dynamic is you know water is wind driven.
So, it simulates the cyclonic kind of it creates a turbulence and fluctuating window which
is a close to the natural conditions and it is effective for mock ups which have slope
proofs and external features and lot of corners where it is very difficult to have a uniform
spray of water in uniform pressure.
It will be better to have a dynamic which is you know covering the wind and you have
wind going through this corners and creating their own you know turbulence and that
in turn tests how good the sample is in terms of water resistance.
So, there are videos which are attached to show you the static water, the dynamic
water, the seismic movement and the structural you I mean you will be able to understand
better when you see the pictures.
Ah, Which standards to use some of them are lenient in one particular area and, but there
are very stringent in the next.
So, in the in essence you know you pass any standard it does not matter which standard
it is, you will end the end up with the very structurally sound a watertight and a highly
efficient air efficient energy efficient façade .
Now, coming to the mock up size what should be the mock up size
These specifications is the minimum of three panels three panels width and two floor height.
So, that is the minimum size that should be tested and sometimes the consultants also
asked for a corner because the corner is the very critical joint is three panel width with
two panels in the corner.
So, this becomes the minimum size for a mock up sample.
There are some pictures of mock up samples just to show you how it look in the this is
at the laboratory it is not the real building the sample is at the lab.
This is constructed at the lab to test it and it is exact replica of what is happening
in the site.
The same design, the same profiles, the same element, the same screw bolt, nut, gaskets,
glass which is used in the building which going to be tested.
So, this is how it look as a sample.
So, for the windows and doors the largest window in that particular project using the
same profile if you have small windows big windows and all of them are using the same
profile the same glass thickness when test the largest.
So, that all the smaller windows are automatically passed along with that.
So, this is the typical sample of a of a building with the aluminuim composite panel, the window,
the external elements everything fixed this is the mock up for testing as a sample.
This is another sample where you have a fixed glazing curtain wall with the window and aluminuim
composite panel and people are standing inside the sample and there is a water test going
on in there seeing if there is any leak through the window.
And, for balustrades and handrails at least three vertical posts the sample should be
having three vertical posts.
If there are vertical posts, nowadays you have a lot of windows I mean the handrails
where you just have just glass held in the bottom with aluminium clamping system.
So, in that so, in that you need only with the largest aluminium glass panel to be tested,
one panel.
When there are so, handrails or balustrades with vertical stainless steel vertical hole
or you know balustrades and then there is a handrail then you need to have at least
three verticals on that sample.
So, what are the common failures that we see during the test.
Now, typical failures will be water leakage where you see here waters leaking through
the openables, droplets coming in through the joints . So, these are typical fabrication
issues which can be addressed either because there is not cut it properly or uh sometimes
it is a design problem for example, over here there probably not enough drain holes on the
window shutter on the outside.
So, the waters overflowing into the inside of the building.
So, water leakages are very dangerous and totally avoidable if the design is good and
the fabrication is good you can avoid any kind of water coming into the building because
it is very difficult to identify where it is coming in from.
For example, you see the small screw which has been put into the aluminium frame now
whenever there is a screw to be put they usually use silicone on the screw and then tighten
it so that the silicon close the little holes which are created over there.
Now, here the screw has been put without that silicone and this water dripping in through
that little hole.
So, this is again an example of bad fabrication.
And, then you have structural failures here.
The glass entire glass is blown out it is not able to hold tight.
So, the wind loads this will really happen in the building if suppose this is the 30
storied or 50 storied building can you imagine what will happen when the glass shatters and
even a small piece of 2 square inches of glass falls from a thirty or forty storage building
it comes down like a bullet and if treats somebody on the head it is going to for sure
break is skull.
Here you see the aluminium given way because of the structural load it is not able to take
the load.
Panel is come out out of the mock up sample.
These are typical failures that we see and then corrective action needs to be taken to
ensure that this does not happen in the real building.
Reinforcements are done, the aluminuim itself is buckled because of the wind loads.
Or you have typical situation where the glass panel is delaminated come out the composite
the back pan which is there in the curtain wall is come off, not been anchored the aluminium
sheared off from the bracket by just thrown out because the thickness of the aluminium
is not adequate.
At the point where it is anchored the bracket is come out of this hole lock because the
whole system is moved out the it is deal I am taken the here you see the bracket is you
know totally gone, distorted and the lock which is supposed to be here hooked in here
it is actually slipped out and come out.
So, this is the this is the slab.
So, this whole curtain wall is come out by so much here the glass is blown out because
these are typical structural failures that you see.
The pin is sheared or locking pin.
So, these are some of the failures that we see and at the end of the day any product
that we use in our lives we use it after it is been tested.
So, that is how these products become iconic, you know the what is the difference between
successful product, iconic brand, cheap one it is the consistency with it performs
and how do you achieve the consistency it is by putting it through a rigorous test so
that under normal conditions it performs beautifully.
So, at the end of the day facade is like any other product it is designed to do certain
things and there are clear established parameters.
All we need to do is to measure that and see whether the performance of that particular
facade is matching the parameters that are been specified and if it is then you get a
good product. .