ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/296646
10 | ASPIRE , Winter 2014 A worker inspects under the State Highway 3 Bridge over Childs Creek in northern Idaho. All Photos: Idaho Department of Transportation P E R S P E C T I V E The need of bridge owners to effectively assess the condition of their bridge assets in order to efficiently manage their preservation, repair, rehabilitation, and replacement has been ever present. With the introduction of the 2013 AASHTO Manual for Bridge Element Inspection (AASHTO MBEI), 1 st Edition, the American Association of State Highway and Transportation Officials (AASHTO) has developed a state-of-the- art tool for assessment of the nation's bridges. Background I n t h e e a r l y 1 9 9 0 s t h e F e d e r a l Highway Administration (FHWA)— working collaboratively with several states—introduced the concept of more accurately assessing individual components or elements of bridges and how they deteriorate. This information is essential to bridge management. Subsequently, AASHTO created the concept of bridge elements with the AASHTO Guide for Commonly Recognized (CoRe) Structural Elements, First Edition (1998). This inspection approach improves upon that required by the National Bridge Inspection Standards (NBIS) in that individual bridge elements are quantified and their condition assessed. For example, individual components of a concrete arch bridge—such as beams or stringers, floor beams, spandrel columns, arches, their concrete protective coatings, and concrete reinforcing steel protective systems—are quantified and their conditions are assessed rather than simply giving one condition assessment to the entire superstructure of an arch- type bridge as would be done with the NBIS. As the use of element-level inspection techniques proliferated, the need for improvements became identified. In 2011, AASHTO created the AASHTO Guide Manual for Bridge Element Inspection (GMBEI), 1 st Edition. This manual contained many improvements and enhancements, such as: • changes in the measurement units of decks and slabs, • development of the wearing surface element, • standardization of the number of element states, • development of the protective coating element, and • incorporation of expanded element smart flags. The goal of the AASHTO GMBEI was to completely capture the condition of bridges in a simple way that could be standardized across the nation while providing the flexibility to be adapted to both large and small agency settings. Michael B. Johnson of the California Department of Transportation and Paul Jensen (retired) of the Montana Department of Transportation were fundamental to the development of the GMBEI. After the introduction of the AASHTO GMBEI, bridge inspectors and bridge asset managers from bridge owner a g e n c i e s , t h e F H WA , c o n s u l t a n t inspection firms, and training instructors suggested improvements. The result is now presented as the 2013 AASHTO MBEI. AASHTO MBEI The AASHTO MBEI comprises 245 pages and has been divided into three sections and five appendices. Section 1, Background, discusses the philosophy b e h i n d e l e m e n t l e v e l c o n d i t i o n assessment and multiple distress paths within the defined condition states. T h e m u l t i - p a t h d i s t re s s l a n g u a g e provides the means to fully incorporate all possible defects within the overall condition assessment of the element. The overall condition of the element can be utilized in this aggregate form, or broken down into specific defects as desired by the agency for bridge management system (BMS) use. In Sections 2 and 3, the AASHTO MBEI provides a comprehensive set of bridge elements that are designed to satisfy the needs of all agencies. The element set presented includes two element types identified as national bridge elements ( N B E s ) a n d b r i d g e m a n a g e m e n t elements (BMEs). Also a framework for agency developed elements has been created to provide an agency with the ability to define custom sub-elements in accordance with the NBEs or BMEs or for agency elements not defined in the AASHTO MBEI. All elements a re a s s i g n e d a s t a n d a rd n u m b e r representing one of four condition states: good, fair, poor, and severe. NBEs represent the primary structural components of bridges necessary to determine the overall condition and safety of the primary load carrying members. NBEs are a refinement of the deck, superstructure, substructure, and culvert condition ratings defined in the FHWA's Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation's Bridges. Additional elements included in this section are bridge rail and bearings. NBEs are designed to remain consistent from The AASHTO Manual for Bridge Element Inspection by Matthew M. Farrar, Idaho Transportation Department and Barton Newton, California Department of Transportation AspireBook_Win14.indb 10 12/10/13 12:53 PM