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

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Contact:

Eva Lantsoght

E.O.L.Lantsoght@tudelft.nl // elantsoght@usfq.edu.ec

+31(0)152787449