Click for next page ( 15


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 14
14 Table 9. Definition of inspectability evaluation criteria. Definition Potential Relative to CIP Description +2 Much Better Damage of critical structural components is easily assessed by visual inspection or +1 Slightly Better nondestructive testing. 0 Equal No cracking indicates no damage, large cracks indicate yielding of reinforcement, and spalling of concrete indicates excessive deformations and potential bar failure. Damage of critical structural components can typically be assessed with nondestructive testing. 1 Slightly Worse The absence of visual signs of damage might not necessarily guarantee the integrity of all the critical structural components. Damage assessment of critical structural 2 Much Worse components is difficult and cannot be done without dismantling a portion of the connection. Can visual inspection recognize that there is a failure of a crit- Bridge Systems ical structural component that needs immediate mitigation? Can damage be assessed with nondestructive evaluation This report focuses primarily on individual connection or tools? pier system technologies and not directly on full bridge systems. Can damage be assessed with minimum need of decon- The nature of the ABC technologies, as they have been devel- oped to date, lend themselves to consideration on the element struction? (connection) or subsystem (column) levels. The seismic per- formance and efficacy of such elements or systems can be Note that the inspectability during construction is evalu- inferred through a building-block approach. Conceivably, dif- ated as part of the construction risk rating and is not consid- ferent connection types could be used within a single bridge and ered here. the overall seismic performance could be made to conform to the objectives of the AASHTO design specifications. The per- Definition of Durability Rating Criteria formance and success of the design depends on where, within the bridge, ABC technology is used; specifically, whether the The durability rating evaluates how the durability of an ABC technology is used within a region where inelastic response is connection would compare with a connection built of CIP or expected or within a region that is capacity protected. CIP-emulative precast concrete under similar typical envi- Where ABC connections or systems are used in the columns ronmental exposure. The criteria are defined in Table 10. The where inelastic action is expected, then adequate seismic per- following issues are considered: formance of the bridge will depend on the ability of the con- nections to tolerate cyclic inelastic deformations or on the Does the connection provide adequate protection of its ability to locate the connections where such inelastic action can structural components? be avoided. Where inelastic action is expected of the ABC con- Does the connection avoid ingress paths for contaminants nections, then proof testing must be conducted to demonstrate to structural components? that sufficient toughness is incorporated into the connections. Is the durability of the connection affected by the quality This type of connection is the focus of this report. of construction? In other parts of a bridge system, (for example, the super- How easy is it to detect deterioration during routine bridge structure), ABC connections may be designed as capacity- inspections? protected elements; thus, they do not need to be designed to accommodate inelastic cyclic actions, and non-seismic con- Table 10. Definition of nection technologies may be used. In abutments, typically the durability evaluation seismic loads are either carried elastically without damage or criteria. are transferred through shear keys or other fusible detailing to prevent damage to the superstructure and the abutment itself. Definition Technologies that lend themselves to inclusion of fusible ele- Potential Relative to CIP +2 Much Better ments between the superstructure and substructure may also +1 Slightly Better find application in ABC projects. For example, seismic isola- 0 Equal tion may be used to provide such fusing, while also providing 1 Slightly Worse an interface for assembling large prefabricated systems, such as 2 Much Worse complete superstructures.