Maintenance management monitoring

We have engaged in many bridge monitoring projects utilizing optical fiber and been accumulating a great deal of know-how since our company was established.
TTES will make a suggestion on maintenance monitoring from a structural engineer’s point of view cooperating with sensor engineers and system engineers.

Monitoring techniques utilizing optical fiber (Main work list)

2004-2008

We engaged in monitoring project of 3 bridges (Tamagawa Viadict, Oosaka bridge, Arakawa bridge). Sensors were installed to these bridges to modify the monitoring system, analyze the monitoring data and plan specification change.
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〈Tamagawa Viadict〉
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〈Oosaka bridge〉
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〈Arakawa bridge〉

2005-2010

We engaged in monitoring of Yokohama Bay Bridge utilizing optical fiber for 6 years since its lower part had opened.
Optical fiber was installed to monitor performance of the part where new construction method was applied.
We carried out design for the improvement of performance, installation of the sensors and data analysis.

We have considerable knowledge of on-site durability of optical fiber sensors.
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〈Yokohama Bay Bridge〉

2009-

With various type of bridges (RC bridge, pre-beam bridge and steel plate deck bridge) in Okinawa as a target, we have been conducting bridge monitoring utilizing optical fiber (FBG) to check soundness of the structure.
Development for building wide area monitoring network is advancing.
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〈A bridge in Okinawa, No.1〉
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〈A bridge in Okinawa, No.2〉

2010-2012

We engaged in investigation and design of the monitoring system of Tokyo Gate Bridge.
We propose a long-term maintenance management method for structures based on a high performance system utilizing optical fiber (e.g. FBG strain gauge, accelerometer, displacement gauge).
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〈Tokyo Gate Bridge〉

Examples of monitoring system :

We have a skill to estimate soundness of bridges by installing various sensors on a bridge and analyzing the data obtained.
For example, a technique called Weigh-In-Motion and a data processing program we originally developed are used to figure out traffic volume of large-sized vehicles, weight of the vehicles and their travel speed.

Monitoring items can be classified into two cases.

Normal period monitoring

Soundness of a bridge can be evaluated from its behavior caused by passing vehicles or temperature deformation and so on.
One of the items to be used to estimate the soundness is cumulative fatigue damage degree, by which we extract bridges with need of inspection and help you to draw up an appropriate inspection plan.

To calculate cumulative fatigue damage degree, number and weight of passing vehicles are used. These information can be calculated by our original program and the data measured by the sensors installed.
Moreover, abnormality of the bridge girder is detected by monitoring displacement of the bearing.
Various information of superstructure work of the bridge is reflected on the bearing supporting it. Therefore, information from the bearing can be a barometer of health of the bridge.

What is Weigh-In-Motion?


Weigh-In-Motion (W.I.M.) is a method to calculate weight of travelling vehicles from strain on a bridge caused by them passing on it. In other word, regarding a bridge as a scale, weight is calculate from stain generated on the bridge.

TTES has a skill to estimate not only weight of vehicles but travelling speed and which lane they are travelling on with high accuracy. The traffic flow is not disturbed during the monitoring since the sensors are installed under the deck plate.

Abnormality occurrence period (earthquake-time) monitoring

When an earthquake occurs, a change of behavior of the bridge girder before and after the event is monitored by sensors installed beforehand.
By the obtained data, we help with a quick judgment whether or not traffic can be opened after the earthquake.
The sensors installed detect a level difference generated on a girder, bridge collapse and so on, leading to a judgment whether traffic can be opened or closed.

Furthermore, the monitoring system utilizing optical fiber which does not need electricity has been developed and applied by assuming a case when the sensors do not work because of a power cut after an earthquake.

‹References›

LONG-TERM MONITORING OF TRAFFIC LOADS BY AUTOMATIC REAL-TIME WEIGH-IN-MOTION,
Proceedings of JSCE (773), 99-111, 2004-10-21
MONITORING SYSTEM OF BRIDGE PERFORMANCE WITH FIVER-OPTIC COMMUNICATIONS NET,
Proceedings of JSCE (686), 31-40, 2001-9
Deformation of composite girder bridge due to temperature for bridge health monitoring.
Journal of Structural Engineering,979-985,2002/3 Vol.48A