NZ Structures Group Ken Elwood (Group Leader) 1 Roberto Leon 2 - - PDF document

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

NZ Structures Group

Ken Elwood (Group Leader) Roberto Leon Arturo Schultz Henri Gavin Jose Restrepo Amit Kanvinde

• G. Kumar Venayagamoorthy

with input from several New Zealand colleagues:

• D. Bull; D. Brunsdon; D. Hopkins; J. Ingham; W. Kam; S. Oliver; S. Pampanin; E. Seville

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Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

Performance of Retrofitted Wood Diaphragms

Jazalyn Dukes and Stephanie German , Ph.D. Students (field reconnaissance), Julie Dykas, M.S. (data processing) and Roberto T. Leon, Professor (*) CEE, Georgia Tech, Atlanta, GA

(*) Collaborators: J. Ingham, Professor, U. of Auckland, NZ; L. Moon, Ph.D. Student, U. of Adelaide, AU; A. Schultz, Professor, U. of Minnesota, and D.Biggs, Consultant, Troy, New York

Objective: collect data on the performance of diaphragms, and reevaluate/propose changes to current US strengthening practices

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Key Findings

• Most damage due to inadequate anchorage of roof and floor

diaphragms to walls due to improper installation or selection of anchor.

• Many partial retrofits (either in terms of overall base shear or

local diaphragm forces) did not work well

Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

The Malthouse – successful retrofit by The Holmes Group (J. Hare, SE)

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NSF-EERI Rapid Workshop 9-10 Feb. 2012

Data collection on the field performance of adhesive anchors

GOALS AND OBJECTIVES 1) Investigate performance of adhesive anchors in existing buildings with masonry of various grades. 2) Field loading of anchors in tension 3) Record loads and displacements 4) Observe failure modes University of Minnesota: PI Art Schultz, Chris Nobach. University of Auckland: Jason Ingham, Dmytro Dizhur and Najif Ismail. Georgia Tech University: Stephanie German and Jazalyn Dukes.

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NSF-EERI Rapid Workshop 9-10 Feb. 2012

Key Findings

Lower strength adhesives anchor failure usually by pullout with good deformation capacity. Higher strength adhesive anchor failure was transitions to ductile fracture of the anchor. 22.5° anchor inclination improved performance Foil tubes no marked effect on anchor capacity. Best practices make installation time-consuming and labor-intensive.

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Restrepo et al. RAPID

• July-September 2011
• Damaged 5-level Parking Structure
• Damaged 8-story hotel in CBD
• Extensive ambient vibration data for both
• Triggered earthquakes for both
• Demolition vibrations (nearby) for hotel
• NEES personnel brought equipment and worked

with UC and UCSD researchers

Gavin RAPID

• September 2011 - present
• Base isolated hospital building
• Connected conventional building
• Extensive ambient vibration data for both
• Triggered earthquakes for both
• 100’s of aftershocks
• NEES personnel installed equipment in collaboration

with UC and Duke researchers

• Remote operation of instrumentation via hospital VPN

NEES@UCLA AS A RESOURCE FOR RAPID PROJECTS IN CHRISTCHURCH

Bob Nigbor, Erica Eskes, Steve Keowen, Alberto Salamanca, John Wallace (NEES@UCLA)

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Seismic Behavior of the Christchurch Women's Hospital

• Henri Gavin (Duke), Bob Nigbor (UCLA),
• Wayne Lawson (CDHB NZ),
• Greg MacRae, Geoff Chase, Geoff Rodgers, Stefanie Gutschmidt (Canterbury NZ)
• The objective of this project is to collect perishable seismic response data from the base-isolated

Christchurch Women's Hospital. The strong and continuing sequence of aftershocks presents a unique

• pportunity to capture high-fidelity data from a modern base-isolated facility. These measurements

will provide quantitative information required to assess the mechanisms at play in this and in many

• ther seismically-isolated structures.

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Key Findings

The deformations within the isolation system (2-5 cm) were generally smaller than would have been anticipated. Free-field records from Dec 23 events had PGA ~ 0.2g and PGV ~ 15 cm/s (comparable to the Feb 22 2011 M6.3 motions at the site). Measured accelerations below the isolation system were half of the free-field levels (0.1 g). Accelerations at the top level of the adjacent fixed- base structure were on the order of 0.4 g. Long period accelerations and liquefaction debris observed in the isolation galley suggest that soft soils may have contributed to this behavior. M6 @10 km, Dec 23 2011

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2/13/2012 5 Mapping of Earthquake Damage in Precast Buildings in Christchurch, New Zealand

Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

US Researchers

José Restrepo, UCSD (P.I.) Robert Fleischman, Univ. of Arizona (Co-P.I.) Matthew Schoettler, UC Berkeley Robert Nigbor, UCLA David Deutsch, USC (PEER intern)

The project objective was to gather perishable data on two precast concrete buildings damaged by the events in Christchurch, New Zealand. Damage patterns were collected and archived for future numerical model verification. This information is bolstered by the concurrent deployment of high quality sensors to record data for system identification.

International collaborators

Stefano Pampanin, Univ. of Canterbury Sahin Tasligedik, Univ. of Canterbury Umut Akguzel, Univ. of Canterbury Patricio Quintana Gallo, Univ. of Canterbury John Marshall, Precast NZ Hannah Clarke, Powell Fenwick Consultants

9-story Hotel Precast concrete moment frame 5-story Parking Garage Partially precast concrete helical ramp structure

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Key Findings

• Damage patterns were consistent with current NZ

seismic design philosophy.

• Plastic deformations concentrated in regions

especially detailed for seismic energy dissipation.

• But both structures had regions that experienced

excessive damage.

• Deployed sensors identified significant soil-

structure interaction. Damping ratios of the damaged structures ranged between 1 and 4%.

Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

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Forensic Analysis of Eccentrically Braced Frame Fracture during the 2/22/11, Christchurch, NZ, Earthquake

Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

US Researcher: Amit Kanvinde, UC Davis NZ Counterpart: Chris Allington, Holmes Consulting, New Zealand; Thanks to, Wayne Lawson, Canterbury Health Board Objective: Examine factors influencing first ever fractures of EBF links

• bserved in the field, by conducting material tests and 3-d scans on failed

frames

Field Fractures FE Simulations Material tests + 3d scans

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Key Findings

• Material weakness, or overall deformation

demand does not appear responsible for fracture, as evidenced by material (CVN and fracture) tests, and by 3-d scans, indicating very large local deformation prior to fracture

• Poor stiffener detailing appears to be the major

factor, and enhancement of provisions to preclude such details (and rigorous inspection) will mitigate similar issues in future earthquakes

Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

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Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

IMPACTS OF EARTHQUAKES ON THE ELECTRICITY INFRASTRUCTURE

Ganesh Kumar Venayagamoorthy, PhD Clemson University Clemson, SC, USA gkumar@ieee.org Neville Watson, PhD University of Canterbury, Christchurch, New Zealand neville.watson@canterbury.ac.nz Research on the effects of the February 21, 2011 magnitude 6.3 South Island of New Zealand (Christchurch) earthquake on the electricity infrastructure, and project the impacts to scenario if smart grid technologies were integrated to existing power network, what would the impacts look like. Will it be worse or better? Or a combination?

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Key Findings

• Underground electric power distribution system and substations

were seriously damaged. A significant portion of Christchurch lost power.

• 630 millions of customer minutes not met. The longest in the

history of major natural events in Christchurch.

• Off-grid electricity customers did not face power cuts

e.g. solar panels powered homes.

• Communication infrastructure did not shut down.

Japan and NZ Earthquakes RAPID and Research Needs Workshop Arlington, VA Feb 9 and 10, 2012

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

• What new questions raised by these events require basic research?
• What new data are available as a result of these events?
• What unique aspects of these events require the development of a

focused research program?

• What are the important lessons from these larger than expected

events?

Opportunities for Future Research

Structure-type specific Seismic demands Broader impacts

Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Masonry Buildings

• Partial retrofit strategies not sufficient

for “larger-than-expected-events”.

• Above what shaking intensity

will partial retrofits not work?

• Selective retrofit of diaphragms

requires careful consideration of

• verloading of other critical elements.
• Impact of in-plane wall damage and

flexible diaphragms on out-of-plane wall response.

• Reconsider HAZUS damage models

for URM structures.

• Vulnerability of cities such as

Memphis and St. Louis.

Ingham and Griffith, 2011

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Concrete Buildings

• Need focused study on performance of

concrete wall buildings to better understand observed failure modes:

• Web buckling
• Bar fracture in lightly reinforced walls
• Out-of-plane shear
• Crushing with high axial loads
• Need to better define post-earthquake

capacity and repairability of RC buildings.

41% 44% 15%

Before 1980 (27)

58% 32% 10%

1980s (19)

50% 21% 29%

After 1990 (28)

Tagging statistics for RC wall buildings (12 June 2011)

Dunning and Thornton

Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Site Effects

• Correlation between level of damage and local ground motions/soil

conditions? Systematic study needed.

• How do interactions between locally soft/weak soils and adjacent/coupled

structures affect the performance of (isolated) structures?

• Need development of more refined (holistic) analysis tools that incorporate

soil-structure interaction (SSI) and integrate into PBSD.

CBD Ground settlement and liquefaction (Misko Cubrinovski) CBD Building Assessment Placards (Christchurch City Council)

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Ground motions

• Are the hazards from

unknown faults adequately represented in our design ground motions?

• Are vertical accelerations

appropriately considered in seismic design?

Component UP Peak values: acceleration 5008.9 mm/s/s, Acceleration mm/s/s

• 6000

6000 Component S89W Peak values: acceleration 3521.3 mm/s/s, v Acceleration mm/s/s

• 6000

6000

(Stirling et al., 2002)

Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012 3/10/2010 25/03/2011 14/06/2011

Aftershocks

• How to consider cumulative damage from

several earthquakes?

• How to consider local seismic environment

during post-earthquake assessments?

• How rare was this pattern?
• How do aftershocks impact recovery?

Particular concern for urban earthquakes.

• J. Ingham

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Data

• Structural response data from over 200 triggered events

(and counting) from M 3.5 to a M6 event (@10 km).

• Performance of structures based on detailed

engineering reports for verification/evaluation of PBSD.

• Building drawings available for model

development/validation. Damage documentation needed.

• Potential extraction and testing of samples from

buildings being demolished.

• New data on failures of electric power distribution

system assets and system.

• Reconnaissance data – improve collection and usability.

Challenge How to manage the voluminous data?

Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Broader Impacts

Resiliency at what cost?

• Is the seismic performance currently

provided by building codes adequate for societal needs?

• How can the consequences of “larger-than-

expected” catastrophic events be reduced?

• If operability is to be become a

performance target in the code, what hazard level should be considered?

• How to encourage free market to adopt

damage-resilient structural systems?

• How to achieve higher resilience of

heritage structures? How much importance does society place on protection of heritage structures?

Ross Becker Ross Becker

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Japan and NZ RAPID and Research Needs Workshop February 9 and 10, 2012

Why is Christchurch important (for US/NSF)?

• Unknown fault – although low probability event, could
• ccur in any seismic active region.
• Similar historical and modern construction practices.
• The BIG small urban earthquake – scalable?
• Challenges focus on life-safety objectives of our codes.
• Correlation of site conditions and damage.
• Unprecedented access to information/data.
• Information being demolished as we speak…
• Ongoing aftershocks… never ending data (lessons).