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ICUSOnlineNewsDecember28th,2016,Number3

Interna.onalCenterforUrbanSafetyEngineering,Ins.tuteofIndustrialScience,TheUniversityofTokyo

During 10th-12th December, 2016, Infrastructure Management Group, SATREPS ANZEN Project conducted bridge investigations in Yangon. The investigations consisted of two objectives. One is to evaluate the quality of concrete structures (conducted on 10th and 11th) and the other is to capture the deformations in a suspension bridge (conducted on 12th).

(1) Investigations for Evaluating Quality of Concrete Bridges

BridgeInves/ga/onsConductedinYangon,asapartoftheSATREPSANZENProjectinDecember2016

Location of the bridges investigated

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Dr.KojiMatsumoto,ProjectLecturer,IIS,TheUniversityofTokyoMs.NunAkornKitratporn,MasterCourseStudent,IIS,TheUniversityofTokyo

Target bridges are Nga Moe Yeik Bridge and Thaktut Bridge located in Yangon area (please see the map). Nga Moe Yeik Bridge is a new structure which was opened to traffic in the last March. Thaktut Bridge was opened to traffic in 1991 and after several years, severe corrosion of steel reinforcements were found in the slabs. A part of the slabs of Thaktut Bridge had been replaced by new slabs. We selected these bridges to investigate differences of material quality and construction quality affected by construction years and repairs. In both bridges, we conducted (a) steel bar detection tests to measure the position and depth of cover thickness by using Ground Penetrating Radar (GPR), (b) surface electric resistivity measurement, (c) surface moisture measurement, and (d) air permeability tests. As for Thaktut bridge, both old slabs and new slabs were tested. During the two-days investigation, several dozen locations on the surface of concrete of the bridges were successfully tested. We will analyze the measurement data and report the state of these bridges soon.

Air permeability test in Nga Moe Yeik Bridge Detected steel bar positions in a slab of Thaktut Bridge

Nga Moe Yeik Bridge

Thaktut Bridge

Twantay Bridge

Yangon Technological University

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(2) 3D Scanning for Capturing Deformations in Suspension Bridge Twantay Bridge is a suspension bridge whose span length is

263 m constructed in 2007. After it was opened to traffic, it was noticed that the main towers inclined toward the main span and significant camber deflection occurred. To ensure the safety of this bridge, we are conducting various investigations on this bridge.

One of the investigation is to obtain current geometric information of the complete structure. In this December visit, we aimed to collect data of not only the towers, but also main cable and hangers. Takeuchi laboratory and Remote Sensing/GIS group of SATREPS demonstrated and used 3D Terrestrial Laser Scanner (TLS) to retrieve high accuracy information. 16 scan locations were selected with the consideration to optimize scan quality and available resource, 12 scans at the ground level and 4 scans on the bridge deck near each tower. This data will be compared with previously obtained geometric reconstructed from multiple 2D images. In addition, direct measurement using handheld digital level was also completed on each hanger.

The collected data is now being processed and further analysis will be shared.

Toward to concrete anchorage

Tower inclined

Inclination of the main tower of Twantay Bridge (Dala side, Sep. 2015)

3D scanning conducted at Twantay Bridge with scan location on the ground (left) and on the deck (right)

Terrestrial Laser Scanner

3D point cloud of Twantay Bridge from terrestrial laser scanner