Monitoring and analysis on shrinkage behavior of post-combined orthotropic steel-naturally cured UHPC composite deck

Abstract

Shrinkage of naturally cured Ultra-high Performance Concrete (UHPC) at an early age may induce considerable secondary stress on steel-UHPC composite decks and even UHPC cracks, which can result in durability and safety problems. A novel post-combined steel-UHPC composite bridge deck was presented in this paper. Particularly, UHPC at the parts with group-arranged stud connectors on the steel deck was not cast until the rest parts without studs shrunk to a certain extent. The secondary stress was expected to be reduced by this post-combination operation. Two full-scale segmental steel-UHPC composite decks were prepared for monitoring and simulation. According to the monitoring results of the initial 240 h, the shrinkage-induced UHPC strain developed much more rapidly in the specimen with the novel post-combination operation while the induced compressive steel strain was 20 % lower. It was consistent with the simulation analysis results works with assumed time-dependent material constitutions. Furthermore, parametric analysis work was conducted to investigate the effects of post-combination operation details on the low shrinkage constraint feature, which includes the free shrinkage extent at the part without studs and the stud configuration details in particular. The research outcome provides an efficient way of addressing the shrinkage-induced problems in steel-UHPC composite decks.