Punching of slurry infiltrated fiber concrete (sifcon)‎ flat slabs

الملخص EN

The addition of steel fibers to reinforced concrete slabs has been proven to enhance the punching strength and reduce the brittle nature of punching.

However, those advantages are not fully utilized due to the limitations of fiber contents in the concrete mixture.

To overcome this drawback, Slurry Infiltrated Fiber Concrete (SIFCON), in which high volume of fraction, up to 27 %, could be obtained has been introduced and extensively investigated in the early nineties of last century.

SIFCON showed a great enhancement in the matrix properties such as ductility, strength, and energy absorption.

In the current research, the behavior of SIFCON flat slabs in punching is investigated.

An experimental program consisting of thirteen one-third scale slabcolumn connections has been carried out (seven for interior columns, three for edge columns and three for corner columns).

The investigated parameters in this study are the volume fraction of fibers ; the column location with respect to the slab and the fiber location along the slab thickness.

The obtained experimental results showed a distinguished behavior of SIFCON slabs.

An increase in punching strength, ductility and strain energy up to 115 %, 72 %, and 518%, respectively, was achieved for SIFCON slabs compared to conventional RC slabs.

The volume fraction of fibers showed a direct relation to both strength and ductility.

The behavior enhancement is attributed to the ability of high volume of fibers to bridge cracks and transfer stresses developing multiple cracks, thus spreading strain energy.

The main contribution of the fibers was proven to arise from their existence in the tension side of slab rather than the compression one.

Nonlinear FEM analysis proved the conceptual role of SIFCON in enhancing the punching behavior of flat slabs.