Models for Simulating the Seismic Response of Concrete Structures - Dynamic Behavior of Concrete and Seismic Engineering - page 234

between the materials themselves or between the structure and its support. We
should endeavor to deal with both aspects consistently to achieve relevant results.
We present below a few examples of the opportunities afforded by the literature
to deal with analysis of the seismic operation of concrete structures. Generally, non-
linear models are divided into two large families, depending on the scale
represented: on the one hand, global and semi-local simplified models (fiber and
multilayer models), based on bar or beam elements, and on the other hand, more
comprehensive models that rely on volume or surface finite element meshing.
Each has advantages and drawbacks shown revealed by applications, implying
different types of structures tested in the laboratory on a shaking table or with a
reaction wall owing to a pseudo-dynamic method.
7.2. Different discretization families
7.2.1. Global modeling
Such models reproduce the behavior of a whole structure element, such as a
beam, column, concrete wall or masonry wall, a whole storey or even a whole
building. The laws of behavior are generally uniaxial and link a global strain-
curvature, shear, strain, extension, relative displacement with its associated global
stress: moment, shear load or normal load.
Multilinear curves are often used to represent the behavior of reinforced concrete
elements: concrete cracking follows the elastic behavior; it brings about lower
stiffness then steel plastification and sometimes concrete crushing or steel failure.
Simplified laws allow us to reproduce the main phenomena observed with cyclic or
seismic loading (decrease of the overall stiffness, strength degradation under cyclic
loading, recovered stiffness when cracks close).
Figure 7.1 shows a shear law for the study of not very slender reinforced
concrete walls, as well as the modeling of a masonry in-filled wall owing to two
diagonal connecting rods. These global laws generally apply to beams or diagonal
beams.