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High Rise Buildings and Large fires Structural loads & thermal strain What can happen? As presented to the Northern California-Nevada Chapter of the Society of Fire Protection Engineers On April 21, 2006 in Walnut Creek, California. by Edward Munyak, P.E. email@example.com
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As presented to the Northern California-Nevada Chapter of the Society of Fire Protection Engineers
On April 21, 2006 in Walnut Creek, California.
by Edward Munyak, P.E.firstname.lastname@example.org
Performance based approach deleted fire proofing on most secondary steel.
Catenary action on beams and
Tensile membrane action of floor slabs compensated for the reduction of strength at higher temperatures
After the initial fireball
1050 C for 2min.
Fuel burns off in 10 minutes
4 lbs/ ft fire load equates
To 30-40 min duration.
Strain energy that must be overcome before limit collapse is complete is proportional to all forces squared and inversely proportional to high strength modulus of elasticity.
Integration of area under the stress-strain curve represents a massive amount of strain energy that must be overcome before collapse is complete in the case WTC 1, 2 & 7.
The only available source of energy of that magnitude is the potential energy of at least 10 floors and it had to be released in a sudden impulse.
Chemical energy in jet fuel(2 planes)=6.9.e+10 metric joules
(applied over 5 -10 minute time duration)
Kinetic energy (2 planes) = 1.9 e+9 metric joules
(less than one second)
Potential energy (2 towers) =6.8 e=11 metric joules
(controlled demolition can release this in less than one second)
Reimbursement of any loss must be contingent upon access to and analysis of fire damaged structure:
Department of Physics and Astronomy
“WTC 7 collapsed rapidly and symmetrically-even though fires were randomly scattered in the building”
“Where is the delay that must be expected due to conservation of momentum-one of the foundational laws of physics”