Monitoring and Simulation Study on Shrinkage Behaviour of Steel-UHPC Composite Deck

Abstract

Combining an Ultra-High Performance Concrete (UHPC) layer with an orthotropic steel bridge deck by stud connectors could enhance the fatigue performance of a deck system because of the improved system stiffness. However, UHPC is featured by significant early-term shrinkage owing to the material composition. Inappropriate constraints introduced by stud connectors may result in a high risk of UHPC cracking, leading to unexpected safety and durability issues. This study investigated the early-term shrinkage behaviour of a steel-UHPC composite bridge deck by conducting an 80-day shrinkage monitoring test at first. The monitoring results showed that the UHPC hardening process lasted for over 44 h, and the maximum UHPC shrinkage under constraint in the composite deck was only 120 μϵ, while the shrinkage induced compressive stress on the steel deck plate reached 36 MPa. Meanwhile, qualitative simulation and parametric analysis works were carried out to investigate structural dimension effects on shrinkage behaviour of the composite bridge deck in detail. According to the analysis results, the UHPC shrinkage and the induced stress on the steel deck plate had obvious uneven distribution feature. And stud spacing was found as a sensitive factor to shrinkage constraint extent compared with rebar spacing and stiffener thickness. Therefore, a rational stud spacing and design suggestions for practical applications were discussed in addition.