Page 26 - Riem-Vol6_nº3

378 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
3. Numerical analysis
The numerical analysis was done with two computer programs
traditionally used in the design and analysis of reinforced con-
crete waffle slabs. The results were compared to the experimen-
tal data obtained by Schwetz [7] in the actual structure, with the
aim of verifying how close the mathematical models are to the
actual behavior of the slab. The tested slab was numerically
analyzed considering the values obtained experimentally from
the test specimens for the parameters compressive strength (fck,
estimated) and modulus of elasticity (E28).
3.1 SAP2000
The first numerical analysis was done using SAP2000 software
with finite elements. The SAP2000 is a structural engineering
software for linear and nonlinear static and dynamic analyses
of several types of structures, simulating their behavior when
submitted to a wide range of demands [8].
The software has a library of finite elements. Among the existing
options, the elements that were used in the numerical models
proposed in this study are described below.
3.1.1 The Shell Element
The Shell element is an area element used to model shells, mem-
branes and plates in structures in two and three dimensions. The
SAP2000 software defines two types of Shell element. They are
denominated as Homogeneous Shell, used for homogenous ma-
terials, and as Layered Shell, used when the element is formed
by heterogeneous materials or by more than one material. How-
ever, the software only allows nonlinear analyses when the ele-
ment is a Layered Shell. Each element has its local coordinate
system for the definition of material properties, loads and output
of results. Tensions, internal forces and moments are determined
by the Gauss quadrature method and extrapolated to the nodes.
Figure 5 – Vertical displacements measurement
A B
Figure 6 – Location of instrumentation