Application of Fibre Optical Sensors in Push‐out Tests on Composite Steel Truss and Concrete Beams

Abstract

AbstractExperimental push‐out tests have been playing an essential role for the evaluation of the structural behaviour of shear connectors in steel‐concrete composite beams along with the development of analytical design guidelines for predicting the respective longitudinal shear capacity. Although standard push‐out tests allow to quantify the global response of the specimen in terms of load‐slip behaviour, numerical simulations are usually needed to broaden the mechanical insight with a special focus to the areas involved in the mechanical failure. This holds in particular for composite steel truss and concrete beams, where a dedicated shear connection does not exist. The shear connection relies instead on a mechanical interlock between the steel parts and the concrete.Modern measurement devices allow expanding the experimental insight to internal mechanisms of combined concrete‐steel failure. This paper reports on the instrumentation of push‐out tests on composite steel truss and concrete (CSTC) beams with the support of a distributed fibre optical sensing (DFOS) system and evaluates the experimental results. The content presents different concepts of fibre installation and discusses the respective rate of success and the measurement ranges along the global load‐slip curves of the push‐out specimens. The results from the DFOS system provide the strain field histories along essential structural elements embedded in concrete within a crucial range of the load‐slip curves. Hereby it was possible to gain more insight into the load‐bearing mechanisms and identify the material component most likely involved in the stiffness degradation of the push‐out specimens.