Example Effects of NEES Research
on Structural Design Practice
Bill Holmes
Rutherford + Chekene
San Francisco
March 3, 2014
NEES Governance Board Workshop
1
Discussion
• Building code change cycle is, at the least, 5 years. After research
results are recognized, it takes a while to get into codes and longer
to get into common practice.
• Examples given here are not based on comprehensive review of
every NEES project, but known examples of current input into codes
and standards.
– Some concrete examples suggested by SK Ghosh.
– Some steel examples suggested by Jim Malley
– Some wood example suggested by Kelly Cobeen
March 3, 2014
NEES Governance Board Workshop
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Overarching
• Simulation (analysis) methods in practice in all materials are
gradually improving due to NEES laboratory results of testing and
researcher improvements to nonlinear modeling
• Fragilities used in loss analyses—particularly the FEMA P58
methodolog--have been improved for several structural systems and
nonstructural components.
• Several projects contributed to development of concrete column
performance database that significantly improved ASCE 41 in 2007.
– Same database with improvements currently being used to develop
practical evaluation of older concrete buildings to identify significant
collapse risks.
March 3, 2014
NEES Governance Board Workshop
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Concrete
• NEESR-GC: Mitigation of Collapse Risk in Vulnerable Concrete
Buildings
– Improved understanding of joint behavior in older concrete frames for
use in evaluation
– Significant risk awareness effect due to LA inventory of older concrete
buildings. Probable future mitigation effect.
•
NEESR-CR: Assessment of Punching Shear Vulnerability of SlabColumn Connections
– Presented to ACI 318; future provisions concerning headed stud
reinforcement will be influenced.
• NEESR-SG: Performance-Based Design of Squat Reinforced
Concrete Shear Walls
– results of these tests were used to establish a diaphragm design force
reduction factor for cast-in-place reinforced concrete diaphragms.
March 3, 2014
NEES Governance Board Workshop
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Concrete
•
NEESR-SG: Seismic Behavior, Analysis and Design of Complex Wall
Systems
– The products of this research were a valuable resource to the ATC-94
project studying the 2010 Chile Earthquake. The ATC-94 project, in turn,
had an influence on the revision of special shear wall design provisions for
ACI 318-14.
•
NEESR: Seismic Performance of Conventional and Innovative Special
Structural Walls; NEESR-SG: Seismic Behavior, Analysis and Design of
Complex Wall Systems
– This research has had an impact on the revision of special shear wall
design provisions for ACI 318-14.
•
The NEES DSDM (Diaphragm Seismic Design Methodology) research
carried out by Rob Fleischman et al.
– Influenced several code changes in NEHRP Provisions
– Research interacted with IT 06 of the PUC to make more applicable
– Has large effect on diaphragm white paper to be published in NEHRP
Provisions, 2014.
March 3, 2014
NEES Governance Board Workshop
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Steel
•
•
•
•
For older construction, the work on older braced frames that is ongoing
at the Berkeley NEES site, in conjunction with the University of
Washington, is making great advances in better understanding the
response of these systems.
For present construction, the work by UC Davis researchers at Berkeley
NEES will result in an improvement to the AISC 341-16 document. In
addition, work at Berkeley and Minnesota as part of the braced frame
project with U of Washington and NCREE in Taiwan has provided
information that will cause changes to both AISC 341-16 and AISC 36016.
Shaking table testing to collapse of a moment frame structure at SUNYNEES demonstrated large displacement capacity, confirming that
present design approaches are adequate for collapse response.
The next generation of systems that provide high performance including
the ability to self-center are being studied at NEES-UIUC and NEESLehigh. These system will likely be widely used in the future, as
demand by owners for performance beyond code minimum values
increases.
March 3, 2014
NEES Governance Board Workshop
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Timber
• Research contributed to understanding of behavior of soft story
wood framed buildings, now being mitigated in several communities
due to mandatory retrofit ordinances
• Research resulted in development of new wood frame structures up
to 6 stories tall
March 3, 2014
NEES Governance Board Workshop
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Miscellaneous
• NEESR-SG: Seismic Performance Assessment and Retrofit of NonDuctile RC Frames with Infill Walls
– Used to update infill provisions of ASCE 41
• All projects related to Tsunami, but particularly, NEESR-SG:
Development of Performance Based Tsunami Engineering
– Provided input into the FEMA funded document on vertical evacuation
structures.
– Resulted in completely new chapter on Tsunami Loading in ASCE 7.
• NEESR-GC: Simulation of the Seismic Performance of
Nonstructural Systems
– Contributed to development of fragilities in FEMA P-58 methodology
– Provided insight into performance of suspended ceilings in large
spaces—never tested before; will result in refinement of installation
standards.
• Dynamic testing of 5-story concrete building with nonstructural
contents in San Diego resulted in several insights.
– Immediately, change in ASCE 7 egress stair requirements are in ballot
March 3, 2014
NEES Governance Board Workshop
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