Kalymnos island power station instrumentation, Hellenic P.P.C.

Kalymnos island power station instrumentation

The power station's main building was constructed in the mid 70s from reinforced concrete. It is of rectangular shape 42.0 by 35.5 meters. There is also a 15 meter long crane carrier across the building's main span. In 2013, three columns were reinforced with shotcrete (gunite).

To cover the needs of the buildings reinforced bearing skeleton static and dynamic analysis, CRD Group installed a structural monitoring system consisting of 31 strain FBG (Fiber Bragg Grating) optical sensors.

inside view of Kalymnos power station: crane carrier beam (axis C)
inside view of Kalymnos power station: crane carrier beam (axis C)
inside view of Kalymnos power station: crane carrier beam (axis B)
inside view of Kalymnos power station: crane carrier beam (axis B)
CRD-patch FBG sensor layout along C axis
CRD-patch FBG sensor layout along C axis

The sensors were installed on the structure's most critical points (maximum stress or strain). These positions were chosen on three main structural frames, in order for the main columns', beams' and crane carrier beams' measurements to be comparable and symmetrical. Sensors were placed both on the old concrete, inside the shotcrete and on top of it.

CRD-concrete FBG sensor installed on a column's foot before shotcrete works
CRD-concrete FBG sensor installed on a column's foot before shotcrete works
CRD-patch FBG sensor installed on a column before shotcrete works
CRD-patch FBG sensor installed on a column before shotcrete works
CRD-patch FBG sensor's installation under a column-beam joint after shotcrete works
CRD-patch FBG sensor's installation under a column-beam joint after shotcrete works

The sensors’ spectral response was completely satisfactory, even on those undergone the shotcrete work's stress. For the sensors layouts' data acquisition, CRD Group utilized its own sensor monitoring software.

FBG sensors' wavelength chart screenshot from CRD Group's interrogator software
FBG sensors' wavelength chart screenshot from CRD Group's interrogator software

Measurements were taken during several crane carrier's crossings (dead load only). A noteworthy change of strain was recorded from the crane carrier beam sensors. This fact is due to the old structural members' lesser stiffness, because of old material quality and richer crack network. The newly reinforced columns showed smaller strain, as expected. As a conclusion, the structure's monitoring indicates the good quality of the structural reinforcing (shotcrete works).

FBG sensor strain diagram from the bottom side in the middle of a crane carrier beam during a crane carrier crossing
FBG sensor strain diagram from the bottom side in the middle of a crane carrier beam during a crane carrier crossing
FBG sensor strain diagram from the bottom side in the middle of a crane carrier beam during a crane carrier crossing
FBG sensor strain diagrams from the bottom side in the middle of a crane carrier beam during a crane carrier crossing

Contact Information

Mobile: +30 6944846519
Email: crd@crd.gr

Office Hours

9:00 to 17:00
Monday to Friday

Postal Adress

Currently relocating

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