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Challenge the future
DelftUniversity ofTechnology
Predicting Shear Capacity of RC Slabs
subjected to Concentrated Loads close to
Supports with the Modified Bond Model
Eva Lantsoght, Cor van der Veen, Ane de Boer
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One-way vs. two-way shear (1)
Beam shear, one-way shear Punching shear, two-way shear
• Punching shear over perimeter• Beam shear over (effective) width
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One-way vs. two-way shear (2)
• 3D representation of failure modes
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Beam Shear Failure
• Since 1899 (Ritter)• 1955: collapse of warehouse
• Most experiments:• Beams
• Heavily reinforced
• Small size
• Slender (a/d ≥ 2,5)
• Basis for design codes
amount of shear experiments done
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Punching Shear Failure
Categories of methods for punching shear
Shear stress Beam analogy
Strut and tie Plate theory / FEM
The nature of shear failure is still not fully understood!
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Slab bridge under live loads
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Bond Model (1)
• Alexander and Simmonds, 1990
• For slabs with concentrated load in middle
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Bond Model (2)
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Modified Bond Model (1)
• Adapted for slabs with concentrated load close to support
• Geometry is governing as in experiments
• Determine factor that reduces capacity of “radial” strip
• Maximum load: based on sum capacity of 4 strips
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Modified Bond Model (2)
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Modified Bond Model: Quadrants
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Modified Bond Model: Load
redistribution
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Modified Bond Model: Strips
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Modified Bond Model: Effect of
continuous support
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Comparison to experiments
Experiments vs Eurocode shear2 load spreading methods
Experiments vs Modified Bond Model
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Summary & Conclusions
• Slabs under concentrated loads
• Transition between one-way and two-
way shear
• Bond Model for concentric punching
shear
• Modified Bond Model improvement as
compared to Eurocode