Bridges: Lutrive

Case study: SOFO System

Box-girder concrete bridge
Spatial deformation monitoring under thermal loading
Curvature analysis

Project Description

Summary: Spatial deformation monitoring under thermal loading, curvature analysis, long-term monitoring, load test, traffic loading patterns

Clients: Vaud Canton

Place: Vaud Canton (Switzerland)

Period: 1996 - 2000

Installation: IMAC-EPFL

Structure's short description: The Lutrive bridges are two parallel twin bridges built in 1972 by the corbelling method with central articulations, the two bridges are gently curved and each bridge is approximately 395 m long on four spans. The bridges cross-section consists of a box girder of variable height and two overhangs.

Aim of monitoring: Six 10 m long SOFO sensors were installed inside the box girder to monitor the curvature variations of one bridge span. By double-integration of the curvature it is possible to calculate the vertical displacements of the bridge and compare them to simulations of the healthy bridge to asses its condition

Number of sensor: 26

Main Results: The curvature variations of the bridge under thermal loading were measured during 24 hours. The figure shows the temporal comparison between the vertical displacements calculated from the fiber optic sensors (solid line) and an hydrostatic leveling system (dashed line) for a point placed at quarter span. The hydrostatic leveling precision can be estimated to about +/- 0.5 mm. The one of the fiber optic system (including the mathematical analysis) can be shown to be of better than +/- 0.1mm. This example shows the possibility of obtaining precise information about the vertical displacement of a bridge using only a reduced number of displacement sensors. Because of the integrating nature of the SOFO measurements, local effects like concrete inhomogeneities or cracks have a minor influence on the results compared to more localized measurement systems (e.g. inclinometers, strain gauges,?).

Sensor layout

Deformations under thermal loading during one day and comparison witht measurements from hydrostatic leveling system

Bibliography:

Structural monitoring by curvature analysis using interferometric fiber optic sensors , D. Inaudi, S. Vurpillot, N. Casanova, P. Kronenberg, Smart Materials and Structures, Vol 7, p.199-208, 1998

Vertical deflection of a pre-stressed concrete bridge obtained using deformation sensors and inclinometer measurements , S. Vurpillot, G. Krueger, D. Benouaich, D. Cl?ent, D. Inaudi, ACI Structural Journal, Vol 95, No 5, p 518 - 526, 1998

Bridge monitoring by interferometric deformation sensors , D. Inaudi, S. Vurpillot, N. Casanova, Conference on Laser Optoelectronics and Microphotonics: Fiber Optic Sensors, Beijing, invited paper, SPIE, Vol 2895, p 34-45, 1996

Statistical analysis of under-sampled dynamic displacement measurement , D. Inaudi, J. P. Conte, N. Perregaux, S. Vurpillot , SPIE, Symposium on Smart Structures and Materials, San Diego, USA, Vol 3325, p 105-110, 1998

Vertical displacement of bridges using the SOFO? system: a fiber optic monitoring method for structures , N. Perregaux, S. Vurpillot, J.-S. Tosco, D. Inaudi, O. Burdet, 12th Engineering Mechanical Conference, La Jolla, USA, p 833 - 836, 1998

SOFO?: Monitoring of concrete structures with fiber optic sensors, D. Inaudi, N. Casanova, P. Kronenberg, S. Vurpillot, 5th int. Workshop on Material Properties and Design, Weimar, Germany, Aedificatio Publishers, p 495 - 514, 1998

Long-gage structural monitoring for civil structures , D. Inaudi, S. Vurpillot, E. Udd, Pacific Nordwestern Conference on Fiber optic Sensors, p 1-8, 1998

Bridge deformation monitoring with fiber optic sensors , D. Inaudi, N. Casanova, S. Vurpillot, B. Glisic, S. Lloret , IABSE Symposium, Structures of the future - The search for quality, Rio de Janeiro, Brazil, Vol 83, p 132, 1999

SOFO?: Structural monitoring with fiber optic sensors , D. Inaudi, S. Vurpillot, G. Martinola, G. Steinmann, Fib Commission Meeting, Institute or structural engineering, University of applied sciences, Vienna, Austria, Vol 40, 9, 1999

Fiber optic sensors for evaluation and monitoring of civil structures, D.R. Huston, P.L. Fuhr, E. Udd, D. Inaudi, SPIE, Fiber optic sensor technology and applications, Boston, USA, Vol 3860, p 2-11, 1999

Pont de la Lutrive - N9 - Autoroute du L?an, Rapport d'installation et r?ultats pr?iminaires, S. Vurpillot, L. Pflug, Rapport ISS-IMAC IM-01-1997-FO-SV 001, 25.09.1997, p 1-7 + annexes, 1997

Deformation monitoring during bridge refurbishment under traffic , D. Inaudi, N. Casanova, S. Vurpillot, B. Glisic, P. Kronenberg, S. Lloret, 16th Congress of IABSE, Luzern, Switzerland, on CD, 2000

Load-Displacment Correlation form Continuous Monitoring Systems , Andrea Del Grosso, Daniele Inaudi, Samuel Vurpillot, First International conference on Bridge Maintenance, Safety and Managment, IABMAS'02, CIMNE, Barcellona, 2002

Fibre Optic Methods for Structural Health Monitoring , Branko Glisic and Daniele Inaudi, Johh Wiley & Sons, Ltd, 2007