Bridges: Zhee Yen Bridge

Case study: SOFO, ADAM System

Thermal expansion coefficient
Early age
Prestressing
I girders

Project Description

Summary: Deformation monitoring of two I-beam type girders during on-site precast, prestress, errection and slab pouring. Prestress stage monitoring.

Clients: Hua-Lian County Government

Place: Hua-Lian (Taiwan)

Period: 2004 - N/A

Installation: RouteAero Tech. & Eng. Consultants

Structure's short description: Zhee Yen bridge is located on Hua-Lian county highway 64. Four 40 m long I-beam type girders were precast and prestressed on-site before erection. The formwork of girders with rebar cages and strands were aligned during the concrete pouring. After 28 days of storage time on-site, four I-beam girders were post-tensioned to transfer compression force to prefabricated concrete girders. The girders were erected in about one month after post-tensioned.

Aim of monitoring: The goal of this project is to monitor whole life of part of the bridge, including early age, prestressing, and transportation. In this project, two of four girders were monitored with 12 SOFO standard sensors embedded before pouring with thermocouples. The arrangement of sensors allowd monitoring of deformation and curvature, and thermal effect by ambient environment influence. Prestress stage was commonly considered most critical period of prefabrication, thus it was carefully monitored and recorded.

Number of sensor: 12

Main Results: Measurements, including thermocouples were recorded from the beginning of concrete pouring works. Continuous measurements were set for several hours after the pouring was finished. The girders were also monitored at 28 days age, after the storage time. During storage time, thermal coefficient was calculated using linear regression method and highly precise deformation data recorded by SOFO sensors, and reasonable thermal coefficient value were brought out for thermal effect estimation. Prestress load transfer was clearly identified by SOFO sensr. Afterthe the deck was completed, the dead load deformation was monitored.

Determination of Thermal Expansion Coefficient

Deformation vs. time during the prestressing

Bibliography:

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