Thermostatic shrinkage effect monitoring and analysis of novel Post-Combination Steel-UHPC composite decks

Abstract

Combining Ultra-High-Performance Concrete(UHPC) layers to orthotropic steel decks through connectors has been increasingly applied to improve the latter’s fatigue resistance. However, a low water-binder ratio resulting in rapid and large UHPC shrinkage becomes a challenge since the constraint of connectors may cause shrinkage-induced stress and even cracks. To this end, a novel post-combination steel-UHPC composite deck was proposed to induce a low shrinkage constraint effect. It mainly refers to a relatively free shrinkage process due to absence of interlayer connectors in the early construction period. Particularly, 3 full-scale segmental steel-UHPC composite decks were prepared for 120 days shrinkage effect monitoring in a constant 18.5℃ space. Meanwhile, simulation and parametric analysis with shrinkage and damage plasticity constitutions were also conducted. The monitoring results showed that the shrinkage-induced UHPC strain in a post-combination specimen was 43% larger than a normal specimen, while the strain on a steel deck and rib became 60% and 79% lower. It tells an obvious lower-shrinkage constraint feature. Moreover, the lower shrinkage constraint of post-combination also resulted in a nearly 15% larger reinforcement compressive strain. Furthermore, the parametric analysis showed a detailed relationship between the low shrinkage constraint extent and the shrinkage-induced effect. Finally, a simplified theoretical shrinkage effect evaluation method was proposed. The research results provide fundamental knowledge for the shrinkage mechanism understanding of such a novel post-combination operation.