Interface Shear Stresses

Assuming elastic analysis, the distribution of the actual interface shear stresses between a hollowcore slab and its concrete topping due to the interface shear force can be estimated using the interface shear stresses tool given below. It will follow a non-linear distribution, similar to that shown in the figure.

Interface Shear Stresses Tool (Modeling of Interface Behaviour)

Modeling of Interface Behaviour in Composite Hollowcore Slabs

Interface Shear Stresses Tool (Actual Interface Shear Stresses)

Nonlinear Shear Stress Distribution at the Interface between Hollowcore Slab and its Topping

For more information, please refer to:

Adawi A, Youssef MA, Meshaly ME, 2015, “Analytical Modeling of the Interface between Lightly Roughened Hollowcore Slabs and Cast-In-Place Concrete Topping”, ASCE Journal of Structural Engineering, 141(4): 04014119. 

Hollowcore slabs are commonly used in different types of structures. They are usually topped with a 50 mm concrete topping. Structural engineers can use this topping to increase the slab load carrying capacity. North American design standards relate the horizontal shear strength at the interface between hollowcore slabs and the concrete topping to the slab surface roughness. This paper presents results of four push-off tests on hollowcore slabs supplied by two manufacturers and roughened using a conventional steel broom. The tested slabs sustained higher horizontal shear stresses than those specified by the design standards. Utilizing the data from the push-off tests, an analytical model was applied to evaluate the shear and peel stiffnesses, ks and kp, of the interface between hollowcore slabs and concrete topping. Structural engineers can utilize ks and kp values to model the composite action between hollowcore slabs from the two manufacturers and concrete topping. The analytical model was also used to evaluate the actual distribution of shear and peel stresses.


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