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Frontiers of Structural and Civil Engineering

Front. Struct. Civ. Eng.    2014, Vol. 8 Issue (3) : 282-291
Energy absorption potential of concrete floors containing secondary (shrinkage and temperature) reinforcements
Department of Civil Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada
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This paper experimentally investigates the energy absorption potential of two types of concrete floors, namely, normal density concrete and structural low-density concrete, containing secondary (shrinkage and temperature) reinforcements. The test program considered the following secondary reinforcements: 1) traditional welded-wire steel mesh, 2) steel fiber and 3) poly composite fiber. To estimate the extent to which crushing of floor slab materials would help absorb energy, a series of concrete penetration tests employing patch loading was undertaken on scaled down model slabs. Each concrete-secondary reinforcement combination considered slabs of 50 mm in depth with square plan dimensions ranging from 50 to 500 mm, resulting in a total of 30 test specimens. The first part of the paper discusses the test specimens, the test setup, and the test procedure. The second part of the paper presents the experimental results and establishes the energy absorption of different concrete- secondary reinforcement combinations. Sieve analysis results of the crushed specimens were used to derive a “work index” value that relates the pulverized particle size distributions to energy inputs. The work index values of concrete-secondary reinforcement systems can be used to assess the energy dissipation potential associated with such floor slabs in buildings undergoing progressive collapse. The results indicate that floors with secondary reinforcements could play an important role in helping arrest global progressive collapse.

Keywords concrete floors      structural low-density concrete      shrinkage and temperature reinforcements      energy absorption      penetration tests      sieve analysis     
Corresponding Authors: K. S. SIVAKUMARAN   
Issue Date: 19 August 2014
 Cite this article:   
K. S. SIVAKUMARAN,R. M. KOROL,Xiao FAN. Energy absorption potential of concrete floors containing secondary (shrinkage and temperature) reinforcements[J]. Front. Struct. Civ. Eng., 2014, 8(3): 282-291.
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Fig.1  Secondary (shrinkage and temperature) reinforcements; steel mesh, steel fiber, and polypropylene fiber
Fig.2  Test specimens made of normal density concrete (NC) and structural low-density concrete (LC)
Fig.3  The test set-up with test specimen LC-SM20
Fig.4  Specimens after tests – Representative failure modes
specimen sizeconcrete - reinforcement combinations and the corresponding peak loads/kN
50 mm (2″)1089054512125
75 mm (3″)207171140937677
125 mm (5″)307269289148131115
250 mm (10″)385319181209120100
500 mm (20″)471430301358169207
Tab.1  Experimental peak loads for normal density concrete specimens (NC) and structural low-density concrete specimens (LC) having secondary (shrinkage and temperature) reinforcements
specimen sizeconcrete - reinforcement combinations and corresponding energy values/J
50 mm (2″)526636540291140243
75 mm (3″)7626001128462454619
125 mm (5″)10801136136465412291335
250 mm (10″)359723802112318712441614
500 mm (20″)421044114463641628283757
Tab.2  Energy absorption potential for normal density concrete specimens (NC) and structural low-density concrete specimens (LC) having secondary (shrinkage and temperature) reinforcements
Fig.5  Load penetration relations for normal density concrete (NC) and structural low-density concrete (LC) having secondary (shrinkage and temperature) reinforcements
slab IDslab weight/gNsieve size (% of crushed specimen larger than 20mm and % retained in sieves)
> 20 mm20 mm10 mm5 mm2.5 mm1.25 mm610 μm315 μm160 μm60 μm (dust)
Tab.3  Sample sieve analysis results (% retained) of failed specimens
specimenpatch to area, a/Anormal density concrete (NC)structural low-density concrete specimens (LC)
test energy (Joules)work index Wi (kWh/t)test energy (Joules)work index Wi (kWh/t)
SM 200.0142105.0564169.50
SM 100.0435975.1531879.71
SM 50.1610801.416541.05
SM 30.447620.934620.68
SM 21.005260.722910.51
NC-SM Wi (avg) = 2.65LC-SM Wi (avg) = 4.29
SF 200.0144116.4728285.28
SF 100.0423803.2112442.29
SF 50.1611361.9012291.98
SF 30.446000.954540.68
SF 21.006360.931400.32
NC-SF Wi (avg) = 2.69LC-SF Wi (avg) = 2.11
PF 200.0144636.3237577.20
PF 100.0421123.5116142.21
PF 50.1613642.2813351.96
PF 30.4411281.756190.99
PF 21.005400.862430.47
NC-PF Wi (avg) = 2.94LC-PF Wi (avg) = 2.57
Tab.4  Bond Work Index values for normal density concrete specimens (NC) and structural low-density concrete specimens (LC), both having secondary (shrinkage and temperature) reinforcements
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