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Field Monitoring of Reinforced Concrete Closure Strip Behavior with Wireless Sensors



The control of cracking due to shrinkage in reinforced concrete floor slabs has traditionally been achieved through various approaches including the use of closure strips. A closure strip is a gap that divides a concrete floor slab into smaller areas during the pouring of the concrete. This, in theory, allows each smaller area to undergo initial shrinkage of the concrete as an isolated region in an effort to control cracking and displacements of the whole structure. The closure strip is then filled with concrete at a later time creating a continuous floor slab. Because the closure strip has to be constructed separately at a later date, it adds to the overall cost and schedule of the project. The effectiveness of these strips in controlling shrinkage and the duration over which the majority of the shrinkage cracks actually occur is not clearly understood. To the knowledge of the authors, there has not been enough field data gathered regarding the behavior of closure strips. In this monitoring program, field measurements were obtained from closure strips on multiple floors of a reinforced concrete building during the construction process using wireless sensors. Displacement readings of the closure strips were taken every 10 minutes over a period of 6 days in order to capture initial effects of concrete shrinkage on the width of the closure strip. Temperature readings were also taken within the strips in order to perform thermal compensation on the displacement measurements. The field monitoring results from one of the building’s three monitored floors are presented and discussed. The conclusions drawn from the study and the reliability of the results are discussed and suggestions for future research are presented.

doi: 10.12783/SHM2015/46

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