A New Process to Improve Tall
Buildings Heat Resistance and Security
B. Bastita
Free-Lance Researcher
98, rue Jean-Renaud Dandicolle - 33 000 Bordeaux, France
This important engineering
paper was first called to our attention by the author,
who has kindly allowed it to be published in The Citizen
Scientist. Editor.
Abstract
The proposed concept is a combination of
a load-bearing metal frame and a fire-fighting system. The
principle is based on the use of the metal frame to convey
the fire suppression liquid to the sprinklers. In this way,
the system ensures the liquid supply of the fire-fighting
system and the cooling of the frame that provides its mechanical
properties. The proposed system is suitable for buildings
built with two-core metal section, such as IPE, IPN, HPE,
HPN or others. The metal section are upgraded by plugging,
and drills are positioned at the interconnection. The liquid
supply is provided through the usual ground reserves and conveyed
by means of pumps, or, in case of very high buildings, by
gravity from the roof. In order to provide maintenance of
the system, a draining device can be fitted on the base of
the building. Apart from technical and economical aspects,
one of the most important improvements is the possibility
for rescuers, in case of a blaze, to intervene with more security
and for a longer period.
Figure 1. The Conference on Tall Buildings announcement
where this research was presented by the author.
Introduction
September 11, 2001, highlighted the weakness
of load-bearing metal frames when subjected to very high temperatures.
According to the expert appraisal report
drawn up by the American Society of Civil Engineers, two determining
factors must be taken into consideration in the collapsing
process of the Twin Towers:
1. Heat. Concentrated heat weakened the load-bearing
metal frame. The continuous overheating of several spots of
the frame led to different distortions on the metal sections
(expansion, contraction and endothermic reactions) and altered
the mechanical properties of the load-bearing metal frame.
2. Load factor and massive bulk. This extensively
contributed to the collapse process. Despite having been struck
by the second aircraft, Tower 2 fell down first. The impact
was lower down than on Tower 1. Therefore, the load above
the point of impact was much heavier, hence, the re-heating
time needed to distort the metal frame was much shorter.
The goal of this work is to ensure the fire
resistance of buildings and to allow rescue teams to reach
the scene of an incident without running into risks such as
those brought to light by the World Trade Center disaster.
The process is very straightforward. It is
based on the use of the load-bearing metal frame to convey
the spraying liquid to the fire-fighting outlets. In this
way the system ensures the liquid supply to the sprinklers
and the cooling of the frame that maintains its mechanical
properties.
The proposed system is compact and easy to
implement. Its components exist already or are easy to manufacture.
The whole system is less expensive than buildings
equipped with standard fire-fighting systems. The elimination
of the main fittings supplying the sprinklers and the supply
lines themselves, leads to savings in materials and manpower,
which can be used to finance the alterations brought about
by the implementation of the new system. In addition to increased
safety, the process also provides lighter and more compact
construction, while saving space.
Figure 2. Overall sketch of the system.
The proposed system comprises three main
components:
1. The load-bearing metal frame.
2. The automatic fire-fighting system.
3. The storage of spraying liquid.
These will next be considered in order.
1. The load-bearing
metal frame.
Framework is made up of standard two-core
metal sections, or metal sections specially designed for the
implementation of the process. According to the type of construction,
metal sections can be fitted together by simple arc or MIG
welding.
Slight alterations are necessary to ensure
the flow of fire-fighting fluid. Mainly, the two-core metal
sections need to be preplugged at their extremities and drilled
when being interconnected.
The connections can be achieved in two different
ways. One way is to employ a direct connection with drilled
plugs welded end to end (it is also possible to use drilled
plates). Plugs or plates must be, at least, as thick as metal
sections, and made of the same material, so as to make the
welding easier on production lines or on building site and
to avoid an inherent weakness. A second way is to provide
external connections through rigid or flexible conduits on
core, flange or any other position on the metal sections.
Such external connections can be welded or bolted. Whichever
method is used, platens need to be fitted to compensate for
the weakness due to the drilling.
Figure 3. Methods for connecting the system using
drilled plug (left) or external tubing (right).
2. The automatic fire-fighting
system.
The current automatic fire-fighting systems
(sprinkler type) allow the implementation of the process.
In fact, they will have to ensure the automation of the whole
system. If a blaze occurs, the fire-fighting system is activated
by a thermocouple, bimetallic or other heat sensing system.
Spraying fluid on the fire causes the flow of cooling liquid
within the framework, ensuring the cooling of the framework.
Should the blaze spread, additional sprinklers would be activated.
Therefore, the liquid flow would increase and ensure effective
cooling of the load-bearing metal frame.
There is no risk of metal section exploding.
In the theoretical event that intense heat would cause the
fire-suppression fluid to boil, the resulting steam would
be evacuated through the active sprinkling outlets. The fact
that the sprinkling liquid could possibly reach high temperatures
does not alter its cooling function.
The fire suppression liquid could be water,
with or without an additive, or a specific fluid according
to the builder’s preference.
3. The storage of
sprinkling liquid.
The storage of fire suppression liquid can
be provided in various ways. The most common is ground storage.
A swimming pool and pumps can supply the source for the fire-fighting
system. Alternatively, the liquid can be stored in a roof
reserve and delivered to the fire using gravity. Roof storage
of fire suppression liquid might also provide an anti-seismic
counterweight, an idea currently under experimentation.
Figure 4. Storage of the spraying liquid.
The combination of the two systems described
above can be anticipated, in order to make the fluid supply
more secure and make easier the pressurization of the load-bearing
metal frame.
Now, we are going to take up some issues raised by the process.
Pressure of the water
column.
As we are talking about tall buildings, a
problem arises related to the pressure exerted by the liquid
column on the internal bases of metal sections. Faced with
this issue, two solutions can be imagined:
1. The use of large metal sections with an
internal core. This passive mass would replace a large part
of the liquid without preventing it from flowing. In this
way, the pressure would be significantly reduced.
The passive mass could be of different materials, according
to the builder's preference. As for its installation, it is
possible to fix it on a central axis, welded on the inner
side of the plugs. Its placement could also be ensured by
the shape of the passive mass (grooved surface or chocking).
2. The pressure exerted by the water column
can also be decreased by aligning thinner metal sections together
and connecting them to allow the flow of spraying liquid.
As a result, the inner surface has increased, which automatically
reduces the pressure per cm2.
Figure 5. Axial column construction using a passive
mass (left) or bundling (right).
It is possible to combine these different
systems (bundles, passive mass or simple metal section), depending
on the characteristics of the construction. It is obvious
that all these metal sections could be adapted in the plant
or on site, regardless of their shape, since their adjustment
would involve standard techniques.
As regards their size, the sections can
be mass-produced. They can also be modified at the construction
site, which can be easily achieved by professionals.
Corrosion risks are minor, since the metal
frame is permanently filled, like most of the current fire-fighting
systems. For maintaining the system, simple draining plugs
can be fitted at the base of each metal section or series
of sections.
To summarize the process, we can say:
1. Robustness and safety. This system can
prevent buildings from collapsing, allowing rescue teams to
intervene on the spot in greater security, thus, saving lives.
2. Cost-effectiveness. Substantial savings
can be made when compared with current fire fighting systems
(supply pipes, manpower, materials and surface), thus, allowing
the implementation of this new system without any additional
costs.
Figure 6. Current system (left) and proposed system
(right).
Conclusion
In conclusion, the implementation of this
process is possible with current technologies. The process
integrates systems commonly used in current construction (such
as fire-fighting systems) and avoids additional security systems,
especially for emergency evacuation. Therefore, the proposed
new system avoids redundancy of materials and subsidiary security
systems.
With such an upstream approach to the design
of secure buildings, the proposed system allows us to protect
the building itself, and, even more importantly, to save the
lives of the occupants, which, at the end of the day, is the
ultimate goal. Buildings can be reconstructed, not human lives.
Acknowledgments
Bernard Bastita, Inventor
Virginie Bastita, Teacher
Jean-Pierre Petorin, Engineering consultant
Bruno Jacq, Architect, Computer graphics designer
Didier Quemener, Consulting Architect
This project did not receive any subsidy
or development assistance. 
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