Testing for the Nonductile Concrete Grand Challenge Project gets media attention

The final concrete beam-column joint in a series of eight, was tested at UC Berkeley on October 14th as a part of the PEER and NEES Grand Challenge project “Mitigation of Collapse Risk in Older Concrete Buildings.” The testing was coordinated by Wael Hassan, UC Berkeley PhD Candidate, under supervision of Jack Moehle, UC Berkeley Professor, former PEER director and project PI. Hassan is experimentally and analytically investigating the axial collapse likelihood following shear failure of unreinforced older-type construction concrete corner beam-column joints.

ABC 7 produced the following news story about the research testing.

Results of this testing will be released in the coming months.

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Successful NEES Grand Challenge Tests on Non-Ductile Beam-Column Joints Experiencing Axial Collapse under Simulated Seismic Loading

The axial collapse potential of existing gravity load designed RC buildings is a great concern during intense seismic events.

Wael Hassan, UC Berkeley PhD Candidate, under supervision of Jack Moehle, UC Berkeley Professor and former PEER director is experimentally and analytically investigating the axial collapse likelihood following shear failure of unreinforced older-type construction corner beam-column joints.

Testing of four full scale corner beam-column joint subassemblies, including floor slabs, is under way. The goal is to evaluate unreinforced corner joints shear strength and axial residual capacity under high axial load reversals varying with lateral loads; representing intense ground motion overturning moment effects. Gravity axial load is 0.20f ’c Ag , while the overturning axial loads vary with displacement reversals to range the joint axial load from tension to high compression (0.45f ’c Ag). A sophisticated test setup was constructed to simulate realistic boundary conditions of actual buildings. A drift based history is used to simulate lateral loading. The main test parameters are axial load level, joint aspect ratio, beam reinforcement ratio, and loading history (unidirectional vs. bidirectional displacement reversals).

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The results of this investigation will provide essential input to update strength and ductility provisions of existing buildings assessment documents (ASCE/SEI 41-06). Test results also will help quantify and prioritize the axial collapse vulnerability of shear damaged unreinforced beam-column joints. Throughout the analytical stage of the current research, a simplified shear strength model was developed and verified using test results. In addition, test and analytical model outcomes will be implemented into nonlinear dynamic analysis simulations of existing RC buildings aiming to assess collapse risk during seismic events.

Two specimens have been tested so far, while the remaining two specimens will be tested by the end of September 2010. Stay tuned to watch the interesting upcoming bi-directionally loaded joint test!

Axial collapse photos:

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Shear failure photos:

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Watch test videos

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Paper: Seismic Response of Older-Type Reinforced Concrete Corner Joints (PDF file – 521 KB)

More test videos

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KCET video report “Shake-Up Call” aired on November 13, 2008

Episode 108: Shake-Up Call
Correspondent Vince Gonzales
Produced by: Karen Foshay; Edited by: Alberto Arce; Associate Producer: Anne Lilburn
November 13, 2008 2:35 PM

Some experts are warning it could LA’s ‘Katrina.” There may be dozens, possibly hundreds of buildings in the city of Los Angeles capable of collapsing in a major earthquake and causing thousands of deaths. These buildings are part of a group called non ductile concrete structures. Built primarily before 1976, they have weak columns that can become brittle in a major quake, causing collapse. There are an estimated 2,000 of these buildings, but only a small amount – perhaps 5 to 10 percent – are possible killer buildings.

The city of Los Angeles has known about these vulnerable buildings for years and yet efforts to address them have gone nowhere. The threat is of such concern, UCLA professors are now conducting an inventory of these buildings and plans to hand it over to city officials who will then decide what to do next.

Watch the video.

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NEES-GC Researchers Receive 2007 SEAONC Award of Merit

BERKELEY, CA, May 2, 2007 — NEES-GC researchers have received a 2007 SEAONC Award of Merit for their work in developing revisions for the new ASCE/SEI 41 standard on seismic rehabilitation of buildings.

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Pacific Earthquake Engineering Research Center (PEER) Receives $3.6 Million NSF NEES Grand Challenge Grant

BERKELEY, CA, December 8, 2006—The Pacific Earthquake Engineering Research Center (PEER) has been awarded a five-year, $3.6 million NEES Grand Challenge grant from the National Science Foundation (NSF) to study the collapse potential of older nonductile concrete buildings during earthquakes. These buildings are pervasive throughout the U.S. and other countries, and are considered a high risk. The project will fully utilize the George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES).

Nonductile concrete buildings were a prevalent construction type in highly seismic zones of the U.S. prior to enforcement of codes for ductile concrete in the mid-1970s, and are widespread in many countries. In California, alone, it is estimated there are 40,000 of these buildings, including residential, commercial and critical service facilities. The poor seismic performance of nonductile concrete buildings was evident in recent earthquakes including Northridge (1994); Kobe, Japan (1995); Chi Chi, Taiwan (1999); Kocaeli, Duzce, and Bingol, Turkey (1999, 1999, 2003); Sumatra (2005); and Pakistan (2005).

For this project, PEER will study the vulnerability and toughening of nonductile concrete infrastructure against earthquake effects. Specifically, PEER’s research will develop procedures to identify the truly dangerous buildings from among the large building population, thereby turning an intractable problem into one that can be addressed with available resources. Mitigation strategies developed here also can inform strategies to mitigate for other natural and manmade hazards such as hurricanes and explosions.

“Existing vulnerable buildings are the number one seismic safety problem in the world, and nonductile reinforced concrete buildings are a noteworthy percentage of these that have yet to be addressed in a systematic way,” said Jack Moehle, PEER’s director. “This project will tackle this issue in a comprehensive way, leading to solutions that can save thousands of lives.”

According to Joy Pauschke, Program Director of NEES at NSF, “We have learned the lesson over and over again in past earthquakes in the U.S. and abroad – many of our nation’s older concrete buildings, where many of us live and work, are not safe during an earthquake. This project will use the NSF-funded NEES laboratories around the U.S. to provide building owners, occupants, and public officials with solutions to make these buildings safer.”

In order to improve understanding of earthquakes and their effects, the National Science Foundation created the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES), managed by NEES Consortium, Inc. in Davis, CA, under NSF award number CMMI-0402490. NEES is a shared network of fifteen experimental facilities, collaborative tools, a centralized data repository, and earthquake simulation software, all linked by the ultra high-speed Internet2 connections of NEESgrid. The University of California, Berkeley, is one of the NEES laboratories in this consortium. Altogether, these resources provide the means for collaboration and discovery in the form of more advanced research based on experimentation and computational simulations of the ways buildings, bridges, utility systems, coastal regions, and geomaterials perform during seismic events.

The PEER project team will include these institutions and their respective departments: University of California (UC) at Berkeley–Architecture Dept. and Civil Engineering Dept., UC Irvine–Civil Engineering Dept., UC Los Angeles–Civil Engineering Dept., San Jose State University–Civil Engineering Dept., University of Puerto Rico at Mayaguez–Civil Engineering Dept., University of Kansas at Lawrence–Civil Engineering Dept., University of Washington–Political Science Dept., Purdue University—Civil Engineering Dept., University of Southern California–School of Policy, Planning and Development.

The project team is partnering with the Earthquake Engineering Research Institute (EERI) to form the Concrete Coalition, an alliance of concerned engineers, planners, policy experts, and other stakeholders who will work with the project team to develop and implement effective mitigation strategies.

The research will consist of four areas: 1) Exposure—An inventory of older-type concrete buildings will be developed for one urban region to serve as a testbed for regional loss studies.; 2) Component and System Performance—Laboratory and field experiments will be conducted on concrete components and soil-foundation-structure systems to improve understanding of conditions that lead to collapse; 3) Building and Regional Simulation—Computer models and simulations will be developed and used to study regional distribution of building collapses in a major earthquake; and 4) Mitigation Strategies–Effective mitigation strategies will be developed to promote action for risk reduction.

Expected outcomes of PEER’s study include improved inventory, data and models for components and subsystems, single building simulation capabilities, improved fragilities/regional simulations, public policy, improved engineering assessment and retrofit tools, increased diversity in earthquake engineering, and active rehabilitation of truly vulnerable buildings nationwide initiated through public policy and professional encouragement.

The Pacific Earthquake Engineering Research Center (PEER) develops, validates and disseminates performance-based seismic design technologies for buildings and infrastructure to meet the diverse economic and safety needs of owners and society. PEER is supported by funds from the U.S. National Science Foundation, the State of California, participating universities, private industry and business partners. It is administered under the National Science Foundation’s Engineering Research Centers Program.

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EERI Announces Concrete Coalition: Major Initiative Aims to Find and Fix Earthquake-Dangerous Buildings

OAKLAND, CA, April 17, 2006 — The Earthquake Engineering Research Institute (EERI) is sponsoring a major collaborative effort to address the high earthquake risk posed by older concrete buildings in the western US. The effort will help engineers quickly distinguish truly dangerous, collapse-prone buildings within the large inventory of these buildings, retrofit the truly bad buildings, and avoid future casualties. The newly proposed Concrete Coalition would unite structural engineers, building officials, public policy interests, building owners, and managers in a long-term effort to meet the challenge.

According to Craig Comartin, President of EERI and a structural engineer, “Older concrete design procedures used prior to the 1970′s could result in brittle buildings that snap like a pencil when hit by an earthquake. Modern code provisions ensure that buildings have ductility – a property that allows them to distort like a coat hanger without breaking.” As a result, modern concrete buildings are safer against collapse than the older non-ductile ones by a factor of twenty or more. Recent estimates of the potential effects of a repeat of the 1906 San Francisco Earthquake indicate that the worst of the older buildings – including apartment houses, offices, schools, and hospitals – would be the greatest source of casualties.

The initiative grows out of planning sessions conducted recently in Seattle, San Francisco and Los Angeles. The meetings were held in conjunction with a technical seminar sponsored by EERI and the Pacific Earthquake Engineering Research Center (PEER), a consortium of universities working together to further improve earthquake design procedures.

Jack Moehle, Director of PEER and a University of California Professor of Civil and Environmental Engineering, says that significant recent advancements will help find the worst buildings. “There is no question that the new performance-based earthquake engineering procedures are the best framework for addressing the problem” he says.

Beyond these technical engineering issues, the Concrete Coalition intends to address related social and economic impacts. William Petak, Professor Emeritus at the University of Southern California and an expert in earthquake related public policy, notes that “The solution to the nonductile concrete building problem will require significant capital investment. This means that carefully planned programs to assist building owners and entire communities will be necessary to make the transition to safety a smooth process.”

According to Comartin, the group plans to share information on the vulnerability and inventory of buildings, as well as encourage funding for further research on innovative analysis and retrofit solutions. They will also coordinate a public outreach program to inform communities about the problem and solutions. Organization and communications will rely heavily on existing membership associations and institutions with a common interest in earthquake safety. Comartin adds that “Most importantly, the Concrete Coalition will help all stakeholders speak with a common voice to address all aspects of the problem”. The Earthquake Engineering Research Institute is an Oakland-based nonprofit with over 2500 academic and professional members throughout the world with a common interest in reducing the effects of earthquakes on society. EERI is a convener of the upcoming 100th Anniversary Earthquake Conference in San Francisco.

Additional contacts:

  • Craig Comartin, ccomartin@comartin.net
  • Jack Moehle, moehle@berkeley.edu
  • William Petak, petak@usc.edu
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Early Research on Nonductile Concrete by PEER

PEER began addressing the risk of nonductile response in the late 1990’s. Some of this work has lead to major advances in understanding seismic response of older hazardous concrete buildings, leading to engineering criteria for building assessment and retrofit, as well as advanced dynamic simulation capabilities.

PEER and the Earthquake Engineering Research Institute (EERI) unveiled findings from the PEER program in seminars conducted in San Francisco, Los Angeles, and Seattle in January and February 2006. The seminar proceedings is available for purchase from EERI. Visit the Publications and Reports page of this website for some of the seminar’s PowerPoint and video files.

PEER’s research formed a foundation for modeling and acceptance values in ASCE 41. PEER researchers also worked as part of an ad hoc committee to recommend revisions to ASCE 41 based on the results presented in the PEER/EERI seminar.

The PEER/EERI seminar series also served as the kickoff of the Concrete Coalition Site, which aims to organize a coalition of engineers, building officials, and other interested stakeholders to promote more proactive programs to identify and retrofit collapse-risk concrete buildings.

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