Fatigue damage in a conventional orthotropic steel bridge deck system poses a formidable challenge to bridge engineers all over the world because of ever-increasing heavy traffic volumes and higher wheel loads over the past decade. An effective solution may be to enhance the stiffness of the bridge deck to reduce the fatigue stress amplitude of its components. This paper proposes an innovative composite bridge deck system that consists of an orthotropic steel deck stiffened with a 45-mm reactive powder concrete (RPC) layer. Based on the analysis of HuMen Bridge in China (a suspension bridge with a conventional orthotropic steel bridge deck system with span length of 888 m) and two types of full-scale model tests, a comparison investigation is conducted between a conventional orthotropic deck system where the asphalt wearing course has been ignored and the proposed orthotropic deck system that includes an integral concrete wearing course, and the proposed composite bridge deck system proves to be c...

In recent years, ultrahigh-performance concrete (UHPC) has been increasingly applied to orthotropic steel deck (OSD) bridges. The UHPC layer and the OSD are connected through short-headed studs. This paper studies the static and fatigue behavior of short-headed studs embedded in UHPC. Seven specimens were fabricated for push-out tests, three of which were subjected to static tests, and the other four were subjected to fatigue tests. The headed studs in these specimens had a low height-to-diameter ratio of 2.7. Both the static and fatigue tests showed that the specimens failed because of the fracture of the headed studs, whereas the UHPC layer did not develop appreciable damage. These observations reflected the fact that the short-headed studs developed full strength when embedded in UHPC. Based on the fatigue test results, a design S-N curve with 95% survival probability was proposed.

An innovative lightweight composite deck (LWCD) is proposed for steel bridges to avoid premature fatigue cracking. The composite deck is composed of an open-ribbed orthotropic steel deck (OSD) and a thin ultrahigh-performance concrete (UHPC) layer. This study is based on a suspension steel bridge in China, namely, the Second Dongting Lake Bridge. The following investigations were performed: (1) preliminary finite-element analysis (FEA) was carried out to evaluate the vehicle-induced stress ranges (i.e., Δσ = σmax − σmin) of six typical fatigue-prone details; (2) parameter analyses were performed to investigate the effects of the shape of cutouts and the thickness of the floor beams; and (3) two fatigue tests, one that used a full-scale LWCD panel and another that used a LWCD beam specimen, were conducted to reveal fatigue performance of the OSD and the stud shear connectors, respectively. Results of the preliminary FEA show that, with the contribution of the UHPC layer, the vehicle-induced stress ...

The flexural behavioral properties of ultra high performance concrete (UHPC) low-profile T-beams reinforced with a combination of steel fibers and steel reinforcing bars were investigated in this paper. Five large scale T-beams were tested and analyzed regarding their deflection, ductility, strain, curvature, load capacity and crack development. The experimental variables include the reinforcement ratio, the slenderness (length to diameter ratio) of the fiber reinforcements, and the fiber type. The experiments showed that all specimens exhibit flexural failure with the yielding of steel bars and excessive expansion of flexural crack, and the compression zone in the reinforced UHPC low-profile T-beam is not crushed because of the ultra high compressive strength and area of UHPC. In addition, it was concluded that using hooked-end fibers can effectively increase the specimen’s durability-based cracking load in comparison to straight fibers of same slenderness, whereas the reinforcement ratio and the slenderness of the fibers have little influence on this. Increasing the reinforcement ratio and using hooked-end instead of straight fibers increase the load capacity and bending stiffness of the specimen, as well as reduces the crack width at comparable applied load. A model was established to compute the ultimate capacity of UHPC low-profile T-beams and the prediction agrees well with the experimental results in the present and published investigations.

Using field monitoring and finite-element analysis (FEA), this paper presents the results of an investigation on stress behavior and fatigue life estimation of fatigue-prone details on an orthotropic steel deck (OSD) with the ultrahigh-performance concrete (UHPC)-deck plate composite system. The work was performed on the Fochen West Bridge in southern China, a three-span-continuous OSD girder structure with a UHPC-deck plate composite system. The results of the study showed that welded details connected to the deck plate experienced one stress cycle for each passing individual axle, while other details away from the deck plate experienced one stress cycle for each passing axle group. Due to the significant contribution of the UHPC-deck plate composite system to deck stiffness, welded details connected to the deck plate experienced low stress ranges under direct wheel loads. However, local load effects under concentrated wheel loading still existed, and the magnitudes of stresses at fatigue-prone details were sensitive to the transverse position of individual wheel loads. Comparisons between FEA and field measurements indicated that the AASHTO fatigue truck may have underestimated stress ranges for fatigue evaluation of this bridge. The study concluded that all fatigue-susceptible details investigated on the Fochen West Bridge had sufficient resistance against fatigue cracking under the current traffic flows per AASHTO fatigue provisions. Finally, suggested guidance for the design of OSD with the UHPC-deck plate composite system was provided.