Cold stiffening of the plate of Orthotropic Steel Deck (OSD) of bridges can be achieved by adding a layer of Ultra-High Performance Fiber Reinforced Cementitious Composite material (UHPFRC) on top of the deck plate by composite design, thus expecting to reduce stresses in fatigue critical details of OSD and avoid fatigue vulnerable welded details at composite interface. This paper focuses on experimental and analytical study for the bending behavior of UHPFRC - steel composite specimens in elastic domain, corresponding to the stress levels of deck plate for in-service steel bridge with OSD. In the total 11 UHPFRC - steel composite test specimens, it was considered UHPFRC with thicknesses ranging from 25 mm to 50 mm, loading configurations simulating sagging or hogging moment region, and different composite designs including materials natural bonding, epoxy-glued interface and epoxy-glued corrugated steel plate shear connector. Epoxy-glued interface was effective composite method leading to stiffness improvement for sagging moment region of OSD and thus decreased stresses in the OSD deck plate. The proposed corrugated steel plate shear connector turned out to be effective for stiffness improvement especially for specimens simulating hogging moment region, indicating that this mechanical connector acted as both shear connector and confined steel bar. The bending processes were analyzed for UHPFRC - steel composite specimens simulating sagging and hogging moment region respectively, especially for the loading stage before attaining 0.5 epsilon(sy) at mid-span section. Based on test and analytical results, design recommendations were given for OSD stiffening by means of UHPFRC. (C) 2020 Elsevier Ltd. All rights reserved.