Fatigue Design, Assessment, and Retrofit of Bridges

Abstract

The special collection on Fatigue Design, Assessment, and Retrofit of Bridges is available in the ASCE Library (https://ascelibrary.org /page/jbenf2/fatigue_assessment_retrofit_bridges). Fatigue deterioration due to the cyclic nature of the loads to which bridges are subjected has long been a concern of bridge designers. As materials and design methods have advanced and bridges have become lighter, traffic loads have increased and fatigue is increasingly a governing limit state in the design of new structures. In the assessment of existing bridges, engineers are increasingly faced with challenges associated with the early detection of fatigue damage and retrofitting of the poor fatigue details commonly found in older structures. While much knowledge and experience has accumulated in recent decades concerning the fatigue behavior of bridges, research on this subject has shifted during this time from fundamental research on the fatigue design and performance of conventional welded structures to research addressing issues such as the fatigue behavior of bridge components made out of emerging materials such as fiber-reinforced polymers (FRPs), ultrahigh performance concrete (UHPC), and high-strength steel; how to exploit new materials in the fatigue retrofitting of existing bridges; fatigue of new connection concepts for accelerated bridge construction (ABC); how to exploit structural health monitoring (SHM) technologies for assessing fatigue damage, fatigue uncertainty quantification, and reliability estimation; how to assess fatigue damage due to environmental loads, coupled fatigue, and environmental damage (e.g., corrosion); and the fatigue design of multiuse bridge structures. This special collection is aimed at synthesizing the state of the art in the area of fatigue design, assessment, and retrofitting of bridges. It includes 16 articles, received in response to a related call for papers, which were published online between July 2017 and April 2018. In general, the included papers offer a diverse, international perspective from research groups based around the world. The papers cover a broad range of topics that can generally be grouped into three subject areas: fatigue evaluation and strengthening of existing bridges; improving our understanding of the fatigue behavior and design of new bridges; and the fatigue assessment, ret-rofit, and design of lightweight, orthotropic steel bridge decks. On the subject of fatigue evaluation and strengthening of existing bridges, Wang, Zhai, Duan, and Wang discuss various retrofitting approaches applicable to steel bridges, including cold bonding of steel plates or bonding and bolting of steel angles, in their paper titled "Cold Reinforcement and Evaluation of Steel Bridges with Fatigue Cracks" (Wang et al. 2018). In their paper, "Fatigue Strength Upgrading of Cover Plate Ends by Welded Extensions in Existing Steel Bridge Girders," Grigoriou, Nussbaumer, and Lignos investigate the fatigue upgrading of typical cover plate joint connections in existing steel bridge girders through the use of an innovative cover plate extension approach (Grigoriou et al. 2018). Also investigating the fatigue retrofitting of steel bridges in their paper titled "Novel Method for Retrofitting Superstructures and Piers in Aged Steel Railway Bridges," Lin, Taniguchi, and Yoda discuss the retro-fit of steel bridge piers using a technique employing rubber-latex mortar, glass-fiber-reinforced polymer plates, lightweight rapid-hardening concrete, and reinforcement bars (Lin et al. 2017). Several papers in this special collection look at fatigue issues related to retrofitted reinforced concrete structures. In their paper titled "Performance of FRCM-Strengthened RC Beams Subject to Fatigue," Pino, Hadad, De Caso y Basalo, Nanni, Ali Ebead, and El Refai investigate the fatigue performance of reinforced concrete (RC) beams strengthened with fabric-reinforced cementitious matrix (FRCM) materials (Pino et al. 2017). In their paper "Predicting Flexural Fatigue Performance of RC Beams Strengthened with Externally Bonded FRP due to FRP Debonding," Chen and Cheng investigate the fatigue performance of RC beams reinforced with externally bonded FRP laminates (Chen and Cheng 2017). On the subject of improving our understanding of the fatigue behavior and design of new bridge structures, Sjaarda, Porter, West, and Walbridge investigate the fatigue performance of welded shear studs either in cast-in-place decks or concentrated in precast deck pockets to enable ABC in their paper "Fatigue Behavior of Welded Shear Studs in Precast Composite Beams" (Sjaarda et al. 2017). In their paper titled "Coupled Fatigue-Corrosion Failure Analysis and Performance Assessment of RC Bridge Deck Slabs," Yang, Yi, and Li investigate the interaction between chloride-induced rebar corrosion and the fatigue cracking of concrete deck slabs (Yang et al. 2017). In their paper "Performance of Composite Twin I-Girder Bridges with Fatigue-Induced Cracks," Lam, Lin, and Yoda study the system performance and safety of a twin I-girder bridge with simulated fatigue cracks in one of the girders (Lam et al. 2017). In their paper titled "Fatigue Stress Spectra and Reliability Evaluation of Short-to Medium-Span Bridges under Stochastic and Dynamic Traffic Loads," Yan, Luo, Lu, Yuan, and Beer investigate stochastic and dynamic effects associated with vehicular traffic on the applied stress spectrum for fatigue design (Yan et al. 2017). While much of the work presented in this special collection focuses on vehicular or generic bridge applications, Lou, Nassif, and Su, in their paper on the "Impact of Heavy Freight Railcar on the Remaining Fatigue Life of Centenarian Railway Bridges" (Lou et al. 2017), present an interesting investigation of the effects of increased railcar weights on the remaining fatigue lives of railway bridges located on transit lines in New Jersey. A significant number of the papers received for this special collection focused on the subject of the fatigue assessment, retrofit, and design of lightweight, orthotropic steel bridge decks. In their paper titled "Fatigue Assessment of Full-Scale Retrofitted Orthotropic Bridge Decks," Teixeira de Freitas, Kolstein, and Bijlaard investigate the strengthening of orthotropic bridge decks through the addition of a second steel plate on top of the existing deck (Teixeira de Freitas et al. 2017). In their paper "Fatigue Performance of Rib-to-Deck Joints in Orthotropic Steel Decks with Thickened Edge U-Ribs," Heng, Zheng, © ASCE 02018001-1 J. Bridge Eng.