Impact of NEES Research on Building Design Practice

Bill HolmesRutherford + Chekene

San Francisco

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Special thanks to:Barbara FossumKelly CobeenJim MalleyS.K. GhoshJim HarrisBenson Shing

• 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.

• Comprehensive review of research results from a practical application standpoint has not been done (by me or anybody else to my knowledge).– Many project titles are intriguing but results could be less so– Project participants have sometimes pushed for adoption into codes or

practice.– All the results--singular and combined-- should be systematically mined

to identify potential improvements in current practice.• Examples given here are not based on comprehensive review of

every NEES project, but known examples of current input into codes, standards or practice.

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Disclaimer

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• What “NEES Research” have I considered?– Considered here: NEES research solicitations and major co funding– Not considered here: Non-NSF funded projects at NEES sites,

workshops, educational advancement, RAPIDs, equipment installation or upgrades.

• What’s in a name?– 10 years of NEES– 197 total projects considered– Key words used in project names

Overview

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0 5 10 15 20 25 30 35 40

Structure/structuralBuilding

Concrete/RCBridgeSteel

TsunamiDamage

FoundationsInnovative

Performance‐basedIsolation/isolator

LiquefactionCollapse

PileDamping/damped

MasonryWood/timber

ResilienceNonstructural

Soft storyInfill

Key Word frequency for197 unique NEES  projects

Building Design Practice  is obviously related to only a portion of NEES research

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• Simulation (analysis) methods in practice in all materials are gradually improving due to NEES laboratory results of testing and researcher improvements to nonlinear modeling

• Improved availability of data enabling development of performance databases.– Concrete column performance database used to significantly improve

ASCE 41 in 2007. Ongoing enlarged database currently used in development of collapse evaluation for older concrete buildings.

– Similar databases for other components and materials also under development. Systematic review of this aspect is needed.

– Many fragilities used in loss analyses —particularly the FEMA P58 methodology--have been developed or improved for both structural systems and nonstructural components.

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Overarching Improvements

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Concrete (1)• 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 Slab-

Column 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.

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Concrete (2)• NEESR-SG: Seismic Behavior, Analysis and Design of Complex Wall Systems

– The products of this research were a valuable resource to the ATC-94 projectstudying 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.

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Steel (1)

• NEESR: Collaborative Developments for Rehabilitation of Vulnerable Braced Frames; Berkeley NEES site, in conjunction with the University of Washington is making great advances in better understanding the response of these systems.

• UC Davis researchers at Berkeley NEES Site Shared use award) will result in an improvement understanding of column splices—seldom previously tested.

• International Hybrid Simulation of Tomorrow's Steel Braced Frames:Includes researchers from the US, Japan and Taiwan, as well as affiliated researchers from Canada. NEES@Berkeley, NEES @Minnesota and the NCREE Laboratory in Taiwan. Advanced hybrid simulation research methods and international, cooperative investigation to develop performance-based tools and techniques for advanced seismic engineering of steel braced frame systems. It is expected to generate changes in both AISC 341-16 and AISC 360-16.

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Steel (2)

• Hybrid Simulation of Steel Moment Frame to Collapse (Shared Use project) Shake table hybrid testing to collapse of a moment frame structure at SUNY-NEES 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 NEES-Lehigh. These system will likely be widely used in the future, as demand by owners for performance beyond code minimum values increases.– Controlled Rocking of Steel-Framed Buildings With Replaceable Energy

Dissipating Devices– Inertial Force Limiting Floor Anchorage Systems for Seismic-Resistant

Building Structures

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• NEESWood and NEESoft projects: Software for nonlinear seismic analysis of wood light-frame construction was advanced. Secondary effects include– Used in FEMA P-695 and P-795 (Equivalency) Analysis– RWFD studies (FEMA/BSSC)– SEAOC “Corridor Only” bracing studies led to change in AWC’s Special

Design Provisions for Wind and Seismic (SDPWS), 2015 edition.– Nonlinear analysis of timber now being considered by engineering firms

• NEES-Soft: Seismic Risk Reduction for Soft-Story Woodframe Buildings is a five-university multi-industry collaboration and has the objectives of developing better understanding of the capacity of, and developing a methodology to retrofit soft-story woodframe buildings.– Videos of collapse on shake table has generated public interest– Any new information will feed directly into retrofit programs currently in place

or under consideration.

Wood (1)

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Wood (2)

• NEESWood: Seismic Design of Wood Buildings. Also buffalo Research resulted in development of new wood frame structures up to 6 stories tall successfully tested on Miki Table, Japan

• Engineered Timber Structural Systems for Seismically Resilient Tall Buildings (Cross-Laminated Timber): Wood structures 8-14 stories are being investigated using CLT and various energy absorption techniques. Sustainability of such systems has generated exposure for CLT construction and it is starting to be considered as a viable design alternate.

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Masonry

• NEESR-SG: Seismic Performance Assessment and Retrofit of Non-Ductile RC Frames with Infill Walls: Used to update infill provisions of ASCE 41

• “NEESR-SG: Performance-Based Design of New Masonry Section 12.2.2.10 in 2013 MSJC is based on findings. Results of shaking table tests show that ring-shank nails or screws are required to anchor masonry veneer to wood backing for SDC D, E, and F.

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• A recently completed project supported by NIST/NEES with shaking table tests conducted at NEES@UCSD has confirmed the detailing requirements and the validity of the Limit-Design Method (Appendix C of 2013 MSJC). In the future, it may lead to the implementation of a displacement-based design method in MSJC and ASCE 7 for masonry structures.– Quasi-static test data from the same project mentioned above

are being used to develop shear-friction design provisions for masonry shear walls for 2016 MSJC. Currently, a ballot proposal is under development.

Masonry

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Miscellaneous

• 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 NEES Buffalo/Reno– 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 many insights.– Immediately, change in ASCE 7 egress stair requirements are in ballot

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