Instrumented pile tests are vital to establish the performance of a pile and validate the assumptions made during initial design. Conventional instrumentation includes vibrating wire strain gauges and extensometers to measure the change in strain or displacements within a pile. While these strain and displacement gauges are very accurate, they only provide strain/displacement readings at discrete locations at which they are installed. It is therefore common to interpolate between two consecutive points to obtain the values corresponding to the data gaps in between; in practice, these discrete instrumented points could be tens of Manuscript Click here to download Manuscript Pelecanos_et_al_Manuscript_7.2.docx 2 meters apart, at depths corresponding to different soil layers, and hence simple interpolation between the measurement points remains questionable. The Brillouin Optical Time Domain Reflectometry fibre optic strain sensing system however is able to provide distributed strain sensing along the entire length of the cable, enabling the full strain profile to be measured during a maintained pile load test. The strain data can also be integrated to obtain the displacement profile. In this paper, three case studies are presented where the performance of three concrete bored piles in London is investigated using both conventional vibrating wire strain gauges and distributed fibre optic strain sensing during maintained pile load tests which enabled comparisons to be made between the two instrumentation systems. In addition, finite element analyses were conducted for the three piles and it was found that the ability to measure the full strain profiles for each pile is highly advantageous in understanding the performance of the pile and in detecting any abnormalities in the pile behaviour.

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Suspension Bridge using a wireless sensor networkA study on the thermal performance of the Tamar Suspension Bridge deck in Plymouth, U.K., is presented in this paper. Ambient air, suspension cable, deck and truss temperatures were acquired using a wired sensor system. Deck extension data were acquired using a two-hop wireless sensor network. Empirical models relating the deck extension to various combinations of temperatures were derived and compared. The most accurate model, which used all the four temperature variables, predicted the deck extension with an accuracy of 99.4%.Time delays ranging from 10 minutes to 66 minutes were identified between the daily cycles of the air temperature and of the structural temperatures and deck extension. However, accounting for these delays in the temperature -extension models did not improve the models' prediction accuracy. The results of this study suggest that bridge design recommendations are based on overly-simplistic assumptions which could result in significant errors in the estimated deck movement, especially for temperature extremes. These findings aim to help engineers better understand the important aspect of thermal performance of steel bridges. This paper also presents a concise study on the effective use of off the shelf wireless technology to support structural health monitoring of bridges.