Fatigue Assessment of Steel-UHPC Lightweight Composite Deck Based on Multiscale FE Analysis: Case Study

Abstract

A lightweight steel–ultrahigh performance concrete (UHPC) composite deck (LWCD) was developed for alleviating deterioration issues in orthotropic steel decks (OSDs). In recent years, the LWCD has been increasingly applied to steel bridges in China. This paper focuses on the fatigue assessment of the LWCD on the basis of a pilot project on the 310-m cable-stayed Haihe Bridge. A multiscale finite-element (FE) model was built to integrate the global and local responses of the bridge without significantly increasing the computing cost. In the study, a parametric analysis was conducted to reveal the influences of the longitudinal position of the girder segment and the transverse position of the fatigue load on the stresses of the LWCD. In addition, a detailed fatigue assessment was performed that covered the following fatigue-prone details: the rib-to-deck connection and the rib-to-diaphragm connection in the OSD, the headed studs, and the UHPC layer. The analysis results show that for the OSD details, the values of the vehicle-induced stress ranges were significantly reduced when a thin UHPC layer was added, indicating that the fatigue-cracking risks in the details could be basically eliminated. In addition, the results also reveal that both the headed studs and the UHPC layer, generated by the application of the LWCD, can meet the design requirements in terms of fatigue.