A strength and serviceability assessment of high performance steel Bridge 10462

High performance steels (HPS) were developed through the cooperative efforts of the American Iron and Steel Institute (AISI), the US Navy, and the Federal Highway Administration (FHWA). They offer several advantages over conventional bridge steels including greater yield strengths, improved ductility, increased toughness, and better welding characteristics. The three grades of HPS that are currently available in today\u27s bridge market are HPS 50W, 70W, and 100W. The current steel I-girder flexural capacity equations, however, were specifically developed for girders with nominal yield strengths less than or equal to 70 ksi. Because of this fact, the flexural capacities of I-girders incorporating HPS 100W have been restricted due to a lack of experimental and/or analytical evidence that supports the applicability of existing equations. In particular, the design flexural capacities of compact and noncompact sections in negative flexure are currently limited to their yield moment capacities (My) instead of their plastic moment capacities (Mp).;The focus of this research project was to experimentally and analytically evaluate the applicability of the current design specifications for I-girders fabricated with HPS 100W. In particular, the strength and serviceability of the Culloden Railroad Overpass (WVDOH Bridge No. 10462) was assessed by conducting static and dynamic load tests. The Culloden Bridge is a three-span-continuous bridge that utilizes HPS 100W in the compression flanges of sections in negative flexure at interior supports. The experimental natural frequency, lateral live load distribution factors, and live load ratings were calculated from field test data and compared with values obtained from an independent design assessment.;The results indicate that the Culloden Bridge performs with adequate strength and serviceability under the current 4th edition of the American Association of Safety and Highway Transportation Officials (AASHTO) specifications (2007 with 2008 interims). The live load deflections obtained from static load tests were found to be less than L/1000, as well as those determined analytically. Experimental live load deflection distribution factors were found to be larger than AASHTO factors. Conversely, experimental moment distribution factors were found to be less than AASHTO factors. Experimental and design live load ratings were calculated based on the HL-93 design vehicular live load. In all cases, the experimental and design live load rating factors were found to be greater than 1.0; which indicates that the Culloden Bridge has sufficient capacity

The stiffness of living tissues and its implications for tissue engineering

The past 20 years have witnessed ever- growing evidence that the mechanical properties of biological tissues, from nanoscale to macroscale dimensions, are fundamental for cellular behaviour and consequent tissue functionality. This knowledge, combined with previously known biochemical cues, has greatly advanced the field of biomaterial development, tissue engineering and regenerative medicine. It is now established that approaches to engineer biological tissues must integrate and approximate the mechanics, both static and dynamic, of native tissues. Nevertheless, the literature on the mechanical properties of biological tissues differs greatly in methodology, and the available data are widely dispersed. This Review gathers together the most important data on the stiffness of living tissues and discusses the intricacies of tissue stiffness from a materials perspective, highlighting the main challenges associated with engineering lifelike tissues and proposing a unified view of this as yet unreported topic. Emerging advances that might pave the way for the next decadeâ s take on bioengineered tissue stiffness are also presented, and differences and similarities between tissues in health and disease are discussed, along with various techniques for characterizing tissue stiffness at various dimensions from individual cells to organs.The authors would like to acknowledge financial support from the European Research Council, grant agreement ERC-2012-ADG 20120216-321266 (project ComplexiTE). C.F.G. acknowledges scholarship grant no. PD/BD/135253/2017 from Fundação para a Ciência e Tecnologia (FCT). The authors also thank the peer-reviewers for the constructive comments and suggestions that helped to shape this manuscript