Local Bond-Slip Monitoring in a Steel Plate-Ultra High Performance Concrete (S-UHPC) Beam Using Smart Aggregates

摘要

The structural performance of steel plate-concrete (SC) composite structure could be improved by incorporating ultra high performance concrete (UHPC). With its dense micro structure and 22 ksi compressive strength, UHPC is expected to facilitate rapid construction of structural elements with thinner and lighter modules that could withstand overload conditions and harsh environments. The bond condition between the steel plate and UHPC is critical for the structural integrity of the steel plate-ultra high performance concrete (S-UHPC) element since bond-slip could decrease the load-carrying capacity and ductility. Most of the structural damage of S-UHPC initiates with local cracks in concrete and local bond-slip between the steel-plate and concrete. The detection of the local bond-slip is vital for providing early warnings of a structurally compromised element. In this study, a reliable health monitoring technique utilizing embeddable lead zirconate titanate (PZT)-based smart aggregates (SAs) has been employed to detect the local bond-slip damage between steel plates and UHPC. By using the active sensing approach, the propagating stress wave attenuates when the local bond-slip occurs. To quantify the local-damage degree, the wavelet packet-based damage index was adopted. The results show that the SA-based active sensing approach and wavelet packet-based damage index can give a quantitative estimation of the local bond-slip initiation and development.