Abstract
Distributed Optical Fiber Sensors (DOFS) are strain measuring tools whose potential related to the civil engineering field has been discovered in the latest years only. A unique utility lies in the possibility of bonding these extremely thin sensors to steel reinforcement bars which will later be embedded in concrete elements (RC) in order to monitor its mechanical strains. The present paper presents the results of an experimental campaign that saw the tensing of two RC tensile members (ties) with DOFS-instrumented steel rebars providing strain readings every 7.5mm. Their cracking behavior allows to gain insight on the steel rebar’s strain profile when surrounded by cracking concrete. The described results are novel as measurements that are accurate, completely distributed, experimentally extracted, both before and after concrete cracking, have been impossible up until now. The internal strain measurements are additionally integrated with an external Digital Image Correlation (DIC) monitoring which provides data on the displacements and strains of the members’ surfaces. The present research represents the beginning of an in-depth experimental campaign aimed at providing reinforcement strain data for multiple loaded RC ties encompassing different geometrical features (concrete cover, reinforcement ratio, bar diameter).
Highlights
The most pivotal point behind the behavior of RC structures is the concrete-steel reinforcement bars interaction
A unique utility lies in the possibility of bonding these extremely thin sensors to steel reinforcement bars which will later be embedded in concrete elements (RC) in order to monitor its mechanical strains
The present paper presents the results of an experimental campaign that saw the tensing of two RC tensile members with Distributed Optical Fiber Sensors (DOFS)-instrumented steel rebars providing strain readings every 7.5mm
Summary
The most pivotal point behind the behavior of RC structures is the concrete-steel reinforcement bars (rebar) interaction. Modern research decided to set aside the commonly assumed theory of perfect interaction between the two materials or simplified constant bond relations [1] in favor of a stresstransfer approach. The latter suggests a continuous interaction between the two materials in the form of a force transfer along their contact surface (bond stress τb) which varies according to the slip (wherever the absolute displacements of concrete and steel are dissimilar).
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