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Engineered Cementitious Composites (ECC) is a family of high-performance fiber-reinforced cementitious composites with high tensile ductility and emerging in steel-concrete composite structures. In the composite structures, shear force transfer through shear connectors plays a critical role to integrate the steel and concrete. This study experimentally investigates the static and fatigue behaviors of short studs embedded in ECC through push-out tests of nine specimens. The test results of the shear strength, slip capacity, and fatigue resistance are compared with current design codes. The shear strength agrees well with that obtained from AASHTO LRFD, while the Eurocode 4 and Chinese code underestimate the shear strength. The slip capacity satisfies the ductility requirement in Eurocode 4. Based on the fatigue tests results, an S-N curve related to a survival probability of 95% is proposed. Empirical formulas are derived as a tool to help predict the load-slip behavior of the specimen under fatigue loading.

With increasing traffic volumes, fatigue of orthotropic steel decks (OSDs) has become a critical issue in recent years. In this study, an innovative composite deck composed of large-size U-ribs, a thin ultra-high-performance concrete (UHPC) layer and headed studs is proposed to enhance the fatigue properties of OSDs. Experimental and numerical approaches were combined to investigate the transverse fatigue behaviour of the proposed composite deck. A large-scale composite deck specimen was fabricated and tested under cyclic loading. The experimental results revealed the progressive failure process of the composite deck. The effects of damage accumulation in UHPC layer and headed studs on the mechanical behaviour of steel-UHPC composite deck were evaluated. The results indicated that the mechanical degradation in the composite deck system accelerated the damage accumulation in the fatigue-prone details of OSDs. It is necessary to consider the effects of mechanical degradation in fatigue resistance evaluation.

Fatigue damages in orthotropic steel deck have been a thorny problem that perplexed bridge engineers worldwide for decades. Two approaches have been applied to improve the fatigue performance of orthotropic steel decks: (1) to reduce the maximum stress range of structural components by enhancing the local stiffness through use of composite structural systems; (2) to reduce the quantity of fillet welded joints by enlarging the size of longitudinal U-shaped ribs. In this study, a full-scale model test and finite element analysis were conducted to investigate the fatigue performance of an innovative orthotropic steel-concrete composite deck (OSCD) with large longitudinal U-shaped ribs, which represents a combination of the two aforementioned strategies. Orthotropic steel deck and concrete layer are integrated through shear studs that are welded on the steel deck and embedded in concrete. The fatigue failure process of the OSCD structure was investigated, and the effects of damages in concrete and shear studs on the fatigue performance of OSCD were evaluated for the first time. The initiation and development of fatigue cracks were experimentally investigated. The interaction between the mechanical performance of OSCD and the damages caused by cyclic loadings was revealed. Concrete cracks and fracture of shear studs greatly accelerated the degradation of mechanical properties and the development of fatigue failure, and deteriorations of the mechanical properties accelerated the development of damages in concrete and shear studs.

Orthotropic steel decks offer many advantages in bridges, but they are prone to fatigue damage. One of the effective approaches to increase the fatigue resistance is to enhance the stiffness through applying a concrete layer, forming a composite section with the steel deck. However, once the concrete is cracked, the composite action is compromised. To improve the fatigue resistance, this study proposes a composite deck using engineered cementitious composite (ECC) and large U-ribs through experimentation and simulations. Two full-scale composite decks were tested to investigate the fatigue resistance and failure process, and validate a finite element model that was used to elucidate the effect of ECC on the fatigue performance. The test results showed that the composite deck had sufficient fatigue resistance, and the analysis results showed that the ECC overlay reduced the stress range by 90% at the rib-to-deck and diaphragm welded joints and 54% at the rib-to-diaphragm welded joints. One interesting finding is that the proposed deck has a robust fatigue resistance even after damages were caused in the deck system. This study is expected to advance the knowledge of the effect of ECC on the fatigue resistance, understand the underlying mechanisms, and promote further research and potential applications of the proposed composite deck.