Page 24 - Riem-Vol6_nº3

376 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 3
Numerical and experimental study of a waffle slab designed to serve as a tennis court floor
1. Introduction
Sophisticated and rational structural solutions are on increasing
demand in the daily work of structure designers due to the evolu-
tion of architectural designs and new construction management
concepts. Therefore, it is necessary to evaluate a variety of struc-
tural systems, seeking to find the solution that can best deliver
economic viability, speed and versatility of application.
According to Dias R.[1], in multi-storied reinforced concrete struc-
tures, the slabs are responsible for a significant share of the con-
crete consumption. In the case of solid slabs, this share reaches
almost two thirds of the total volume of the structure. Therefore, it
is important to study different types of slab to be used in multi-story
buildings to find solutions that are both technically viable and less
expensive.
From this perspective, the use of waffle slabs is proving to be an
interesting option. This structural system can be defined as a set
of ribs distributed in two directions, spaced at regular intervals and
connected by a top concrete slab.
The waffle slab structure was conceived with the reduction of con-
crete below the neutral axis, creating voids in a rhythmic pattern.
This leads to a reduction in the weight of the structure and to a
more efficient use of materials.
However, the behavior of reinforced concrete waffle slabs still
raises some questions due to their complexity, which has led
some researchers to undertake numerical and experimental stud-
ies (Ajdukiewicz & Kliszczewicz, 1986 [2]; Selistre, 2000 [3]; Ab-
dul-Wahab & Khalil, 2000 [4]; Dias, 2003 [1]; Soares, 2003 [5];
Schwetz, 2005 [6]; Schwetz, 2011 [7]).
In Brazil, there has been a gradual increase in the use of waffle
slabs, but conventional structural arrangements made of solid
slabs and concrete frames remain the preferred model for rein-
forced concrete structures. However, it is necessary to develop
procedures and standards to guide the use of waffle slabs con-
structive system. In fact, as the development of numerical algo-
rithms that allow the design of this type of structure is quite recent,
many questions still remain with regards to the quantification of the
slab stresses and their adequate modeling by the design methods
and the mathematical models currently used.
This study, which is part of an ongoing research project [7], seeks
to improve the knowledge about reinforced concrete waffle slabs
Figure 1 – Formwork developed for waffle slabs
Figure 2 – Position of top and bottom reinforcement
Figure 3 – Geometry of the waffle slab