Experimental Methods in Earthquake Engineering - Dynamic Behavior of Concrete and Seismic Engineering - page 165

Chapter 5
Experimental Methods
in Earthquake Engineering
Introduction
Considering the vast size of most civil engineering structures, direct structure
experimentation cannot generally be considered. Apart from a few particular cases
of structure instrumentation on high-risk sites in which earthquakes are anticipated,
model experimentation in the laboratory has been preferred . The most natural
approach uses the shaking table, which involves reproducing the motion of the soil
on which the model has been laid. By imposing acceleration on the table
identical, for example, to the one measured on the ground surface during an
earthquake owing to jacks, we can reproduce the behavior of actual structures. That
behavior results from the properties of stiffness (evaluative in the case of concrete
cracking and steel plasticity), of damping and of the distributed mass of the
structure.
Nevertheless, directly transposing the results of model laboratory tests to actual
structures encounters several difficulties, which include the need to use laws of
similarity which are often ill-adapted to concrete material, the piloting of the table,
and the accuracy of the accelerogram representation at the model level (considering
the filtering carried out by the table itself).