New approach for evaluating Equivalent fire severity of Design fires Purushotham Pakala A40212649 11/20/2018 Purushotham Pakala

Outline Introduction Design Vs Standard fire Equivalent Fire Severity Equal energy method Simulations & Results Conclusions 11/20/2018 Purushotham Pakala

Introduction Most destructive natural calamity Damage varies (L, P, E) Proper knowledge of material properties, behavior required Concrete Vs Steel 11/20/2018 Purushotham Pakala

Design Vs Standard fire Real Vs Ideal Varies across scenarios Behavior of structural elements is entirely different Conditions different 11/20/2018 Purushotham Pakala

Equivalent Fire severity Means of comparison between Design and Real fire Resistance >= Severity Equivalent area method Areas are compared Maximum Temperature concept Peak Temperature compared Minimum load capacity concept ( Deflection) Max deflection or Min load capacity compared Empirical formulas 11/20/2018 Purushotham Pakala

Pros Vs Cons Equal area method good for correcting results of erroneous standard-fire resistance tests .No account of heat transfer (short hot vs long cold fire) Max. Temperature applicable for insulating elements. Inadequate if max temp is more or less than that of standard fire More realistic concept for load bearing elements 11/20/2018 Purushotham Pakala

Equal energy method Heat transfer mostly by radiation and convection. Technically strong to compare the amount of heat energy released than just comparing areas 11/20/2018 Purushotham Pakala

Problem at hand Loading = 16kips/ft L 11/20/2018 Purushotham Pakala 6  20 mm (a) Cross Section 150 mm 500 mm 300 mm  10 mm stirrups 40 mm Loading L Loading = 16kips/ft 11/20/2018 Purushotham Pakala

Fire Scenarios Fire Scenario Fuel Load (MJ/m2 floor area) Ventilation Factor (m0.5) Thermal capacity (Ws0.5/m2K ) 1 1600 0.02 488 2 1200 3 0.04 4 800 5 1900 6 7 400 0.026 8 1100 9 1300 0.03 10 900 11 1000 12 700 0.035 13 11/20/2018 Purushotham Pakala

Simulated Design fires (upto 7 hrs) 11/20/2018 Purushotham Pakala

Maximum Temperature (C) Results Fire Scenario Maximum Temperature (C) 1 1270.5 2 1229.6 3 1314 4 5 861.3 6 7 717.4 8 1306.4 9 890.4 10 1285.2 11 798.7 12 824.5 13 11/20/2018 Purushotham Pakala

Equal Energy concept 11/20/2018 Purushotham Pakala Standard Fire Design fires 11/20/2018 Purushotham Pakala

Results Time Equivalent (Minutes) Fire Scenario Maximum Temperature ( C) Energy Method Area Method Deflection method 1 1270.5 309.5 294.1 372.5 2 1229.6 235.6 223.3 280 3 1314 173.9 124.8 170 4 125.4 93.5 135 5 861.3 137.5 232.1 235 6 56.2 74.9 105 7 717.4 36.3 56.9 75 8 1306.4 162.1 117.1 162.5 9 890.4 93.1 132.6 10 1285.2 137.9 101.4 145 11 798.7 83.7 138.9 157.5 12 824.5 52 72.6 102.5 13 11/20/2018 Purushotham Pakala

Correlation 11/20/2018 Purushotham Pakala

Interpretation and Conclusions Energy Vs Deflection Works well for max temp above standard fire (~ 5,6,7,11,12) Modified Equal Energy Method = (3.5-0.0018*Tmax)* Teq (obtained from equal energy method) Should account for radiative effects in severe, simple fires (max temp) Compatible with equal area if max temp less than standard fire (5,6,7,11,12) 11/20/2018 Purushotham Pakala

Future Address the effect of radiation in fires where peak temperatures are less. Various support conditions Restraints 11/20/2018 Purushotham Pakala

Thank You  11/20/2018 Purushotham Pakala