더욱 오래 견디는 다리를 만들기 위한 데이터 수집

Minho 대학은 영구적으로 삽입 된 센서의 모니터링를 위해 HBM의 장비를 사용하여 포르투갈의 다리의 내구성을 향상 시키기 위한 장기적인 프로젝트를 수행하고 있습니다. 정보는 장기 모니터링과 계획의 유지를 위해 사용 될 것이며, 미래 다리의 설계의 통항을 위해 유용하게 사용 될 것 입니다.

The 120 m long bridge is on a gentle curve of the highway as it crosses the Ave River on the A11 between the cities of Braga and Guimarães in the hilly northern Portuguese region of Minho. The recently opened bridge is constructed from pre-stressed, pre-cast, high performance concrete girders. The cast-in-place, concrete deck slab is reinforced with mild steel. Eight V piers, made of ordinary concrete, support the bridge.

Notes Professor Paulo Jorge de Sousa Cruz, Director of Minho University’s Civil Engineering Department: “The bridge over Ave River is probably the most innovative bridge in Portugal constructed using this method. This is because of the pre-stress construction system and the complexity of the construction sequence”. The bridge has one of the longest spans constructed from pre-cast girders in Portugal.

Using pre-cast girders is quite common in Portugal and there are many other bridges, underpasses and overpasses made with this method. To help prolong their service life it was decided to monitor the Ave River bridge during construction and while in service to evaluate its durability.

Minho University gathers the data needed for monitoring the bridge using HBM’s MGCplus fitted with ML801 cards and catman® software. A total of 256 sensors are installed in the bridge comprising 74 full-bridge strain gages on the reinforcement, 42 embedded strain gages in the concrete, and 88 temperature sensors. An additional 52 corrosion sensors are checked separately.

The bridge is fitted with five access boxes holding the cable ends terminating in connectors that can be easily plugged into the portable MGCplus at any time. Notes Professor Paulo Jorge de Sousa Cruz: “The data is used principally to determine deformations of the structure under imposed loads. It is also possible to examine the sectional load distribution and how these are affected both by time and temperature”.

HBM’s equipment was also used during the initial construction to monitor the bridge’s behaviour by taking measurements during the proof load test before entering service. These tests were related to the program of durability monitoring and were not needed to verify the structural solution.

Deflection measurements taken during the proof load test on the bridge showed absolute deflections of between 0.5 mm and 5 mm with the maximum deflection recorded under a load of about 112 tonnes. Only a few readings have been taken so far as the structure is new and future readings will be taken at periodic intervals during the structure’s life.

Comments Professor Paulo Jorge de Sousa Cruz: “We chose HBM’s equipment because it is highly versatile and allows users to select the correct cards needed for different types of sensors. The electrical connections between the sensors and the cards are quite easy to prepare and the catman® software is a consistent way of measuring. Most important of all, this equipment guarantees proper measuring. In practical terms I think that the ease with which the sensors can be connected to the MGCplus and the catman® software makes our work much easier”.