Title: Reinforced concrete waffle flat slabs under shearing

Author(s): Shirley do Socorro Melo de Souza, Dênio Ramam Carvalho de Oliveira

Publication: IBRACON

Volume: 4

Issue: 4

Appears on pages(s): 610 625

Keywords: reinforced concrete, waffle slab, flat slab, shearing, punching.

DOI:

Date: 10/10/2011

Abstract:
The structural systems with waffle flat slabs are the most used in Brazil when the main exigency are flexible "layouts" and long spans with reasonable economy. However, few studies have been developed in Brazil regarding the behavior of these slabs when the flexural resistance is satisfactory and the shear in the ribs and punching resistances become competitive. This work shows the experimental analyses of 8 two-way reinforced concrete waffle flat slabs under centered load. The dimensions of the slabs were constant and same the 1,800 mm x 1.800 mm x 140 mm. The ribs presented 80 mm (height) for 50 mm (width) and the compression resistance of the concrete was of approximately 40 MPa. The experimental results were compared to the observed ones with those estimated by the Brazilian code NBR 6118:2003. It was verified that the resistance of the ribs is not satisfactorily estimated by the code, underestimating the results too much for the ribs with and without shear reinforcement.