Pre cast concrete hollow core slabs in fire
Transcript of Pre cast concrete hollow core slabs in fire
Pre cast concrete hollow core slabs in fireTom LennonPrincipal Consultant, Centre for Structural Engineering
BackgroundNatural Fire Safety Concept - adverse press reportsSpallingShear failure - European research Consultation with industryRevised experimental programme
Revised test schedule
Slab A All joints filled. Structural toppingconsisting of 50mm (minimum) depth ofconcrete and a mesh reinforcement (A98mesh with 300mm lap between sheets)
Slab B All joints filled. Hooked reinforcing barsplaced in the joints over the supports.
Fire design scenarioDesign fire load of 570MJ/m²thermal inertia of 945J/m²s½Kopening factor of 0.065m½ based on a single opening 3.6m wide by 2m highapplied static load of 3.66kN/m²floor and walls lined with a single layer of fire resistant plasterboard
Predicted time-temperature response for fire tests on hollowcore slabs (b=945, O=0.065)
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Test 1
Results from test 1 - slab AMaximum temperature in excess of 1200ºCmaximum vertical displacement of 100mmresidual deflection of 32mm
precast hollowcore fire test 17.9.01 - average compartment temperature
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comparison between average measured temperature and Eurocode prediction - test number 1
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precast hollowcore fire test 17.9.01
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Test 2
Results from test 2 - slab BMaximum vertical deflection of 115mmresidual displacement of 40mmMaximum temperature in excess of 1200ºC
precast hollowcore fire tests - average atmosphere temperatures
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precast hollowcore fire tests - comparison of central deflection
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ConclusionsNo evidence of significant spallingLimited cracking along the length of the slab for test 2No integrity failureNo insulation failureNo premature shear failure of the units