Static and fatigue properties of the steel-UHPC lightweight composite bridge deck with large U ribs

A lightweight composite deck (LWCD) is a bridge deck system composed of an orthotropic steel deck and an ultra-high performance concrete (UHPC) layer. In this paper, the LWCD was refined with the concept of large U ribs. Based on an example bridge, the Sutong Bridge in China, the new LWCD scheme with large U ribs was proposed. Calculation showed that the steel consumption was basically the same as that of the original design, while the weld seam length in OSD was decreased by about 38.7%. Global and local finite-element (FE) models were built for the new LWCD scheme. The analysis results showed that for the LWCD with large U ribs, the stress reductions on fatigue-prone details were close to those of the LWCD with normal U ribs. The FE analyses also indicated that the maximum tensile stress of the UHPC layer was 10.9 MPa. Further, a full-scale longitudinal specimen was tested under negative bending moments. The test results showed that the nominal cracking stress of the UHPC layer was 24.1 MPa, implying that the UHPC layer could meet the design requirement. In addition, a nonlinear FE analysis was performed to make a comparison between the theoretical results and the test results.