Experiments on Large Structures - Dynamic Behavior of Concrete and Seismic Engineering - page 221

station juxtaposed downstream. The latter consists of concrete foundation, including
the turbines and alternators, and a metallic superstructure.
A dynamic test campaign was carried out in collaboration with the owners,
Hydro-Quebec, in order to determine the response spectrum on the dam's crown.
Important works had been planned on the site and a building was to be erected on
the crown to shelter the numerous transformers and other electrical equipment. It
was therefore expedient to estimate the response spectrum on the crown, and this
was assessed using data regarding the dynamic properties of the works.
Figure 6.16. Sectional drawing of the dam with test instrumentation
As the Beauharnois dam produces a large amount of the total energy supply to
the City of Montreal, stopping a group during the test period was out of the question.
However, as repair work was underway on one of the alternators, the necessary
measurements were made on an inoperative system, without contamination from
noise due to the operation of the alternator and the water flowing through turbines.
Nonetheless, some noise from the neighboring groups was measured.
An unbalanced mass exciter used to generate a horizontal harmonic force on the
crown was placed inside the water intake valve shelters. Figure 6.16 is a sectional
drawing showing the location of the accelerometers. As the test results were used to
calibrate a two-dimensional finite element model, it was necessary to place
instruments on the water intakes (upstream), the concrete power station and its
metallic superstructure.