Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 1: Research Overview and Volume 2: Guidelines (2017) / Chapter Skim
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Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms Volume 2: Guidelines NCHRP RESEARCH REPORT 864 NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
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TRANSPORTATION RESEARCH BOARD 2017 EXECUTIVE COMMITTEE* OFFICERS Chair: Malcolm Dougherty, Director, California Department of Transportation, Sacramento ViCe Chair: Katherine F
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2017 N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP RESEARCH REPORT 864 Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms Volume 2: Guidelines M Saiid Saiidi Mostafa Tazarv Sebastian Varela Infrastructure InnovatIon, LLc Reno, NV Stuart Bennion M
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NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research is the most effective way to solve many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others.
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The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research.
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C O O P E R A T I V E R E S E A R C H P R O G R A M S AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 12-101 by Infrastructure Innovation, LLC in collaboration with BergerABAM and Modjeski and Masters, Inc. The principal investigator (PI)
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This report describes the evaluation of new materials and techniques for design and construction of novel bridge columns meant to improve seismic performance. These techniques include shape memory alloy (SMA)
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FRP wrapping) and analytical techniques (e.g., current design practice, direct displacement based design, and substitute structure design method)
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Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org)
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1 Standard reinforced concrete bridge columns are generally designed to dissipate earthquake energy through the yielding of longitudinal reinforcing steel and spalling of concrete that collectively causes large plastic deformations in columns. Even though bridge collapse is expected to be prevented using current design specifications, excessive plastic hinge damage and large post-earthquake permanent lateral deformations may cause the decommissioning of bridges for repair or replacement.
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2 Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 2: Guidelines any existing or emerging novel columns, evaluation guidelines were developed in this document using 14 parameters to determine suitability and performance of the columns. The parameters included in the evaluation guidelines were (1)
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3 A conventional reinforced concrete (RC) bridge column is generally designed to dissipate earthquake energy through yielding of longitudinal reinforcing steel combined with cracking and spalling of concrete that leads to large plastic deformations in columns.
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4A variety of resilient novel columns are emerging. Uniform assessment tools are needed to assist bridge owners and designers in selecting the columns that meet various constraints.
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5 Treatment of specific novel column concepts are avoided in these guidelines, as they are intended to apply to a broad range of concepts, both existing and those yet to be developed. This has led to certain modifications of existing seismic design provisions, such as the use of drift ratios in place of ductility.
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6Definitions of the terms that may not be commonly understood as they pertain to novel column design, construction, behavior, and evaluation are presented herein. Advanced Material: An existing or emerging material that is not commonly used in bridge construction but is used in the design of a novel column.
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Definitions 7 Rubber: A natural or fabricated material that can undergo large deformations without failure. Shape Memory Alloy (SMA)
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8A general definition of novel columns was presented in the previous section. For seismic applications, any novel column should minimize plastic hinge damage and residual lateral displacements, while having sufficient lateral displacement capacity.
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Characteristics of Novel Columns 9 considered to be "low." When the plastic hinge of a novel column is composed entirely of highperformance, low-damage materials (e.g., FRP jackets or rubber with SMA or FRP bars) , seismic damage can be essentially eliminated, which is categorized as the "no-damage" level (the top layer in the pyramid in Fig.
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10 Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 2: Guidelines ratios that may be utilized in novel column design. An extensive parametric study on conventional RC columns was conducted to establish a relationship between the displacement ductility and drift ratio for these columns.
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Characteristics of Novel Columns 11 5.3 Residual Displacements Excessive lateral residual displacements after a severe earthquake can result in delays in reopening the bridge to traffic or even the need to replace the bridge. Currently, there is no limit on the residual displacement in the U.S.
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12 Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 2: Guidelines between 1.0% to 1.5%. A residual drift exceeding 1.5% may lead to bridge closure and replacement after a severe earthquake and must be treated as "high." Conventional columns are usually susceptible to high residual drifts even for design level earthquakes when they are near an active fault.
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13 Many parameters need to be considered for each novel column before field deployment. These parameters can be categorized as (1)
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14 Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 2: Guidelines Linear-elastic analysis is usually conducted to calculate the demand in the force-based design method. In the displacement-based design, the displacement is the target (e.g., AASHTO SGS)
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15 In addition to the seismic performance and design considerations, many other parameters may affect an owner's decision in selecting a novel column for field deployment. These parameters include: (1)
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16 Figure 8-1 illustrates a flowchart for comprehensive evaluation of existing or emerging novel columns. A quantitative evaluation technique developed to compare different alternatives to facilitate the decision-making process in choosing among novel column concepts is presented in Table 8-1.
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Evaluation and Selection Criteria 17 A score of 1.0 is given to the "Proof Test" parameter if the concept has been experimentally evaluated with sufficient test data. "Analysis Tools" are given a score of 1.0 if existing modeling methods can estimate the overall behavior with reasonable accuracy.
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18 Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 2: Guidelines Parameter Quantification (deduction(a) form unity unless stated otherwise)
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Evaluation and Selection Criteria 19 measures than conventional columns to ensure their functionality during earthquakes. A novel column may incorporate a material or mechanism that affects inspectability by limiting access to the column components.
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20 Analysis and design of novel columns is based on the provisions of the AASHTO SGS. Force-based design procedures such as those presented in AASHTO LRFD should not be used for the design of novel columns since these methods are not intended for advanced materials: the seismic force modification factors (R-factors)
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Analysis and Design Procedure Development 21 9.2 Design Procedure Requirements The application of capacity design principles for novel columns is the same as that for conventional columns. Once the displacement demands have been determined through an analysis, the column displacement capacity must be checked, as well as minimum and maximum drift limits.
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22 Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 2: Guidelines ratio in percent. This equation relates displacement ductility to drift ratio in conventional RC columns.
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23 With the new paradigm of requiring infrastructure to be resilient to serve the public effectively, new novel bridge columns utilizing unconventional construction material are likely to emerge. The proposed AASHTO guidelines identified 14 parameters to consider in assessing any novel column.
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Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America's Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012)
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