STUDY OF PARAMETERS THAT INFLUENCE I-GIRDER BRIDGE BEHAVIOR DURING FIRE EVENTS

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G. Peris-Sayol, I. Payá-Zaforteza
Euroestudios S.L
Universidad Politécnica de Valencia

Bridge fires

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MacArthur Maze Collapse, USA, 2007

collapse

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22 min until collapse
1 month closed
Repair Cost: 9 million USD
Indirect Cost: 180 million USD (6M USD/day)

9 mile, Detroit, USA, 2009

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Bridge near Hazel Park
Detroit, USA - July 15th, 2009

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Standards

Eurocode 1: Actions on Structures

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Standards

NFPA 502: Road Tunnels, Bridges and Other Limited Access Highway

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OBJECTIVE

To improve bridge resilience against fires

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Tanker truck

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I-Girder Bridges

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I-Girder bridge construction

https://erkrishneelram.wordpress.com

Very Common Type of Bridge

Approaches to Port Authority Bus Station, NYC

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Very vulnerable structural system

Peris-Sayol et al. 2016, Garlock et al., 2012

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Importance of several parameters on the maximum gas temperatures

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Four Geometric Parameters
Two Fire Scenario Parameters

PARAMETERS

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Geometric Parameters

geometric1 Vertical Clearance (6 and 9 meters)

Geometric Parameters

Span (16 and 24 meters)

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Geometric Parameters

Width (13 and 23.4 meters)

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Geometric Parameters

Bridge Substructure (Piers or Abutments)

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Geometric Parameters

Bridge Substructure (Piers or Abutments)

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Fire Scenario Parameters

Position of the Fuel Load
(2 Positions, Center and close to the Abutment)

Heat Release Rate
(Type of Fuel)

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Fire Scenario Parameters

Vertical Substructure Heat
Clearance Bridge Span Release Position Width
Configuration Rate
6 m Piers 16 m 1800 kW/m2 (diesel) Mid-span 13 m
9 m Abutment 24 m 2400 kW/m2 (gasoline) Abutment or Pier 23.4 m

Table 1. Table of Scenario Parameters

26=64 different cases

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Taguchi design of
experiments technique

26-1 = 32 cases

Design of Experiments

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Temperatures?

CFD Simulations

Fire Model using FDS title1

CFD Simulations

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Alós Moya et Al. “Analysis of a Bridge Failure due to fire using Computational Fluid Dynamics and Finite Element Models.” Engineering Structures, 68, pp 96-110, 2014.

CFD Simulations

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Control Volume: Varies according to the scenario.

  • X-direction: 28 to 58 m
  • Y-direction: 27 to 30 m
  • Z-direction: 12 to 15 m

Mesh: 0.20 x 0.20 x 0.20 m.

  • Total amount of cells: 1,134,000 to 3,262,500 cells

CFD Simulations

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Fire Load:

  • Tanker truck: 30 m2 (12 x 2.5 m) at one meter above road level.
  • HRR is a parameter
  • CO yield and Soot Yield according to SFPE Handbook
  • CO yield = 0.019 g/g
  • Soot yield = 0.059 g/g

CFD Simulations

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Adiabatic Temperatures

  • Sensors every 20 cm
  • 3 sensors per section
  • Most exposed girder

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CFD Simulations

Adiabatic temperatures along the most exposed girder

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ANOVA ANALYSIS

Maximum Adiabatic Temperatures Imagen1
What parameters are responsible for these values?
Imagen1b
ANOVA
(Analysis of Variance)

ANOVA ANALYSIS

Bottom Flange Temperatures

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p-values below 0.05 indicate significance influence

ANOVA ANALYSIS

Web Temperatures

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Imagen6 Imagen7

p-values below 0.05 indicate significance influence

ANOVA ANALYSIS

Web Temperatures
1 vano
3 vanos

Smoke Accumulation

ANOVA ANALYSIS

Interactions (synergies)

clearance - position - bridge substructure Imagen10
Coandâ Effect

STRUCTURAL ANALYSIS

STRUCTURAL ANALYSIS

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CASE STUDY

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  • 21 meters span
  • 5 girders
  • 2 fire scenarios

BOUNDARIES

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RESULTS AND CONCLUSIONS

Bridges fail by yielding of the steel girder when steel reaches its ultimate strain

Imagen15 Different times and modes of failure

CONCLUSIONS AND FUTURE WORK

  1. Vertical Clearance, HRR and fire position have an influence in flange temperatures
  2. Web temperatures are also influenced by the bridge substructure configuration
  3. Interactions have to be taken into account (Coandâ Effect)
  4. Position of the fire load also influence the structural behavior

THESE CONCLUSIONS SHOULD BE CONSIDERED IN FUTURE PROPOSALS OF FIRE CURVES SPECIFIC FOR BRIDGES Imagen16

EUROESTUDIOS

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Thanks for looking :-)