Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design (2020) / Chapter Skim
Currently Skimming:
Pages 4-36
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 4... ...
4 Literature Review and Synthesis Literature Review Purpose of Literature Review Performance-based seismic design (PBSD) for infrastructure in the United States is a developing field, with new research, design, and repair technologies; definitions; and methodologies being advanced every year.
|
From page 5... ...
Literature Review and Synthesis 5 The following e-mail was sent to the owners and researchers. Dear (individual)
|
From page 6... ...
6 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design • Seismic hazard analysis • Structural analysis and design • Damage analysis • Loss analysis • Organization-specific criteria for bridges • Project-specific criteria Where new or updated information is available for these areas, a summary is included. Marsh and Stringer (2013)
|
From page 7... ...
Literature Review and Synthesis 7 The State of Washington The State of Washington's resiliency plan, outlined in Washington State Emergency Management Council–Seismic Safety Committee (2012) , works to identify actions and policies before, during, and after an earthquake event that can leverage existing policies, plans, and initiatives to realize disaster resilience within a 50-year life cycle.
|
From page 8... ...
8 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design volume of traffic, to give the public as much access as possible while damaged roads and bridges are repaired. For major and minor arterials, which encompass arterial roadways (including bridges)
|
From page 9... ...
Literature Review and Synthesis 9 The document is one of the only references that addresses a system to develop probabilistic methods to estimate downtime. The overall intent is to provide a roadmap to resilience.
|
From page 10... ...
10 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Source: Adapted from FHWA by CEMP (2015)
|
From page 11... ...
Literature Review and Synthesis 11 defines an acceleration used in design that would be exceeded during a given window of time (e.g., a 7% chance of exceedance in 75 years)
|
From page 12... ...
12 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design DOT to include the 2014 U.S. Geological Survey hazard model; however, most state DOTs are still using the out-of-date hazard model.
|
From page 13... ...
Literature Review and Synthesis 13 consistent with the median, 0 is the minimum, and 100 is the maximum)
|
From page 14... ...
14 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design response at any given period (period-dependent rotation angle.) Figure 7 shows an example of the two orthogonal horizontal components, as well as the RotD50 and RotD100 spectra for the as-recorded ground motion from the 2011 Christchurch, New Zealand, earthquake at Kaiapoi North School station.
|
From page 15... ...
Literature Review and Synthesis 15 reasonably well, while designing to the RotD50 spectrum results in displacements that are much greater than expected. This is, of course, only one result of an axisymmetric system.
|
From page 16... ...
16 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Boore et al.
|
From page 17... ...
Literature Review and Synthesis 17 Another approach to developing the appropriate seismic hazard comes out of Europe. Delavaud et al.
|
From page 18... ...
18 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design FEMA-440 (FEMA 2005)
|
From page 19... ...
Literature Review and Synthesis 19 Accelerated bridge construction is also a fast-developing field in bridge engineering, with draft guide specifications for design and construction currently being developed for adoption by AASHTO for AASHTO LRFD Bridge Design Specifications (AASHTO 2014)
|
From page 20... ...
20 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design require additional length to adequately develop the energy-dissipating or capacity-protecting system that was intended by the designer for performance of the bridge in a high seismic event. Tazarv and Saiidi (2014)
|
From page 21... ...
Literature Review and Synthesis 21 polymer confinement -- and compared them to a conventional reinforced column. The research and properties of the material are provided; incorporating laboratory tests and calibration, design examples are created to help engineers understand how to use these advanced materials in a linear elastic seismic demand model and to determine performance using a pushover analysis.
|
From page 22... ...
22 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design is required: the two assemblies are placed together and the annular space between the column and cap filled with grout. Figure 10 shows the details of this connection, and Figure 11 shows a test of the system.
|
From page 23... ...
Literature Review and Synthesis 23 such as fuse capacity, shear response, and sliding response, which can be used to account for more standard bearing configurations in seismic analysis, especially lower seismic hazard regions. A variation on the use of bearings in order to improve seismic performance of a pier wall configuration was outlined in Bignell et al.
|
From page 24... ...
24 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Damage Analysis As stated in NCHRP Synthesis 440, it is a fundamental need for the PBSD methodology to determine the type of damage and the likelihood that such damage will occur in the particular components of the structural system. This determination is of vital importance, as the damage sustained by a structure (and its nonstructural components)
|
From page 25... ...
Literature Review and Synthesis 25 where rs = reinforcement ratio, fyhe = expected yield strength of the steel tube (ksi) , Es = elastic modulus of steel (ksi)
|
From page 26... ...
26 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design has occurred; and Pr(B) is the marginal probability of Event B
|
From page 27... ...
Literature Review and Synthesis 27 The seismic risk associated with exceeding different damage states in the columns, including yielding, cover spalling, bar buckling, and structural collapse (i.e., dynamic instability) was predicted.
|
From page 28... ...
28 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design serviceability, and durability of bridges. Based on those lessons, design earthquake ground motions corresponding to the subduction-type earthquake were revised, and the requirements for easy and secure maintenance (inspection and repair works)
|
From page 29... ...
Literature Review and Synthesis 29 The probabilistic damage control approach uses the extent of lateral displacement nonlinearity defined by Damage Index (DI) to measure the performance of bridge columns.
|
From page 30... ...
30 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Figure 14. Fragility curve.
|
From page 31... ...
Literature Review and Synthesis 31 Research has shown that the next great (magnitude 9.0) Cascadia subduction zone earthquake is pending, as shown in Figure 16.
|
From page 32... ...
32 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design The South Carolina DOT South Carolina Department of Transportation (South Carolina DOT) has updated its geotechnical design manual (South Carolina DOT 2019)
|
From page 33... ...
Literature Review and Synthesis 33 are referenced in FEMA (2012a, 2012b, 2012c)
|
From page 34... ...
34 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Identification of Knowledge Gaps The resources to develop guide specifications for PBSD are improving with examples such as the upcoming Seismic Design Criteria, Version 2 from Caltrans, which will address aspects of PBSD and the building industry's efforts to develop practices in PBSD and tools for engineers and owners to collaborate on solutions based on performance criteria and expectations. There is still a perception that the bridge industry could better predict likely performance in large, damaging earthquakes than is being done at the present, and there are still gaps in that knowledge base that need to be closed.
|
From page 35... ...
Literature Review and Synthesis 35 Gaps related to structural analysis can include minimum and expected properties for reinforcing greater than Grade 80, stainless steel, and other materials that can improve serviceability and in some conditions performance. Oregon DOT has been using stainless steel in their bridges located along the coastline and other highly corrosive environments to extend the service life of the bridge; however, many of these locations are also prone to large CSZE and the use of these materials in earthquake resisting elements is still being developed.
|
From page 36... ...
36 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design While the seismic hazard definition was once thought to be relatively well understood, there is a growing knowledge gap related to the effect of rotation angle on intensity of ground motions and how the use of a geometric mean of the motions, or other methods of including the effect of rotation angle (RotDxx) , should be incorporated into seismic design.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.