Projects

NEESR: Collaborative Developments for Rehabilitation of Vulnerable Braced Frames

Funding: NEESR Award Number: NSF - 1208002

PIs: Charles W. Roeder (University of Washington), Jeffrey Berman (University of Washington), Dawn Lehman (University of Washington), Stephen Mahin (UC Berkeley)

Students: Barbara Simpson (UC Berkeley)

Test Time: Scheduled for FY13-FY14

Test Laboratories: nees@berkeley Laboratory

Participants: University of Washington, National Taiwan University

Data Repository: NEES Project Warehouse

This research project will advance the knowledge about non-seismic concentrically braced frames (NCBF) evaluation and rehabilitation. In high seismic regions, thousands of NCBFs remain in service. In low and moderate regions, these systems are still being constructed. NCBFs exhibit complex behaviors, including frame member failure, weld and bolt fracture and prying action in connections, which impact their damage and collapse potential. The capacities of the individual components are inter-related. As such, evaluation or retrofit cannot be considered component by component; an integrated, holistic approach is needed. This project will take such an approach and use an international team with renowned expertise on (concentrically braced frames) CBFs and state of the art facilities to improve NCBFs.

NEESR: Performance of Conventional and Innovative Special Structural Walls

Funding: NEESR Award Number: NSF - 1208192

PIs: John W. Wallace (UC Los Angeles), Jack P. Moehle (UC Berkeley), Claudia P. Ostertag (UC Berkeley)

Students: Carlos Arteta (UC Berkeley), Nick Hardisty (UC Berkeley), Panos Galanis (UC Berkeley), and Christopher Segura (UCLA)

Test Time: Scheduled for FY13-FY14

Test Laboratories: nees@berkeley Laboratory

Participants: UC Los Angeles, E-Defense

Data Repository: NEES Project Warehouse

This project is exploring design and performance limits for structural walls, considering both conventional wall construction practices and innovative construction practices. A principal finding of recent earthquakes and tests is that wall performance is limited by stability and ductility capacity of the flexural compression zone. For conventional walls, the objective of this project is to establish, through tests and analyses, the minimum requirements for wall thickness and confinement reinforcement. Recognizing conflicts between these minimum seismic performance requirements and programmatic requirements for modern buildings, the project is also exploring use of innovative designs to achieve target performance through use of innovative materials and wall configurations. Tests are designed to acquire knowledge, improve construction practices, and advance simulation tools. The research is a collaborative effort among researchers at UCLA and UC Berkeley. Collaboration with Japanese partners conducting full-scale shaking table tests on the E-Defense shaking table is also one of the objectives of the project.

NEESR: Development and Simulation of Seismically Isolated Unibody Residential Buildings for Enhanced Life-Cycle Performance (Phase 1 and Phase 2)

Funding: NEESR Award Number: NSF - 1135029

PIs: Gregory Deierlein (Stanford University), Benjamin Fell (California State University, Sacramento), and Eduardo Miranda (Stanford University)

Students: Ezra Jampole (Stanford University) and Cristian Enmanuel Acevedo (Stanford University)

Test Time: Scheduled for FY13-FY14

Test Laboratories: nees@berkeley Laboratory, nees@sandiego Laboratory

Participants: Stanford University and California State University, Sacramento

Data Repository: NEES Project Warehouse

Publications

While modern building codes and construction practices in the United States generally provide an adequate level of life safety, observed earthquake damage and the resulting economic losses and disruption are neither acceptable to the public nor cost-effective from a life-cycle viewpoint. This is of particular concern in low-rise residential construction, where deformations, resulting from reduced design strengths lead to relative flexible structures that lead to larger lateral displacement demands that can cause extensive damage to architectural partitions, cladding and other finishes. The resulting damage and repair costs for light-frame residential construction are major contributors to earthquake losses. For example, in the 1994 Northridge Earthquake about $20 billion dollars in losses, more than half of the total earthquake losses were associated with damage to residential construction. The objectives of this project are to address this issue by developing: (a) a new strength-and-stiffness enhanced unibody light-frame construction methods, whereby efficient strength and stiffness to earthquake effects is achieved by integrating structural and architectural building walls, floor and ceiling systems; and (b) economical seismic base isolation systems for light-frame residential construction which, when combined with the enhanced light-frame construction, provides superior damage protection in regions of severe ground shaking hazards. Testing at NEES@Berkeley consisted of two phases. In Phase 1 three different low cost sliding isolation systems were tested under harmonic loading at increasing levels of velocities and then under various ground motions with velocities up to 40 in/s. The objective of these tests was to obtain a mechanical characterization of each of the sliding isolation systems and to develop models to predict their seismic response. In Phase 2 full-scale room assemblies with interior walls with gypsum wallboard on both sides and exterior walls with paperless gypsum wallboards and stucco using enhanced connector were tested to quasi-static loading protocols up to drifts of 10%. The objective is to gain insight into the behavior of full-scale walls with innovative detailing and develop data for validating the computational models and to understand the levels of deformation triggering damage.

Hybrid Simulation of Multi Story Structural Systems through Collapse

Funding: NEES (NEESR Award Number: TBD)

PIs: Eduardo Miranda (Stanford University)

Students: Konstantinos Balafas (Stanford University)

Test Time: Scheduled for FY12-FY13

Test Laboratories: nees@berkeley Laboratory

Participants: Stanford University

Data Repository: NEES Project Warehouse

Collapse of buildings is one of the main sources of monetary losses and loss of human lives in a large earthquake. Estimation and mitigation of the collapse risk of a structure is, therefore, one of the main goals of earthquake engineering. In this project, a series of 1:2 scale beam-column specimens with Enhanced Gravity Connections will be tested using hybrid simulation through collapse. The tests will help further understanding and prediction of collapse and hybrid simulation methods, as well as evaluate the performance of the proposed gravity connections, whose aim is to significantly increase the collapse capacity of a building.

NEESR-II: Toward Rapid Return to Occupancy in Unbraced Steel Frames

Funding: NSF (Award Number: 0830414)

PIs: Peter Dusicka (Portland State University), Jeffrey Berman (University of Washington), Rupa Purasinghe (California State University, Los Angeles)

Test Time: Scheduled for FY12-FY13

Test Laboratories: nees@berkeley Laboratory

Participants: Portland State University

Data Repository: NEES Project Warehouse

The large scale experimental phase of this NEESR-II project focuses on validating the system response of the linked column frame system, developed as a braced free structural steel lateral system capable of returning rapidly to functionality via replacement of key components. Hybrid tests will be conducted on 2 different frames, each with different structural characteristics as governed by the replaceable components and the contributions of the remainder of the system. The experimental frames will be a single bay two story subsystem of a three story 6 bay structure modeled in OpenSees.


Seismic Performance of Column Splices

Funding: American Institute of Steel Construction (AISC) and NSF Shared-use Award #0825155

PIs: Amit Kanvinde (UC Davis)

Students: Sean Shaw (UC Davis)

Test Time: Scheduled for FY12

Test Laboratories: nees@berkeley Laboratory

Participants: UC Davis

Data Repository: NEES Project Warehouse

Column splices are used in all types of steel framing systems for several reasons. The most prominent of these reasons include the impracticality of transporting very long rolled sections to the construction site, OSHA overhead height limits on unfastened steel framing, and to implement cost saving. Research in this area occurred prior to the Northridge earthquake of 1994, and suggested that partial joint penetration (PJP) welds were prone to brittle failure. Since the Northridge quakes, weld quality has improved measurably and the objective of the project is to determine the feasibility of using PJP welds in modern steel SMRF’s. In this project, five full scale test will be performed on splices W14 and W24 specimens. Studies have suggested that significant bending moment may be felt at the column splices when the column are bent in single curvature (due to higher mode effects). For this reason single point bending tests will be performed on each specimen to access the capacity and ductility of the PJP welded splices.

EAGER: Next Generation Hybrid Simulation - Evaluation and Theory

Funding: NSF (Award Number: CMMI-1153665)

PIs: Khalid M. Mosalam (UC Berkeley), Sanjay Govindjee (UC Berkeley)

Test Time: February 2012 – April 2013

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley

Data Repository: NEES Project Warehouse

Publications

The objective of this Early-Concept Grant for Exploratory Research (EAGER) award is to explore new ideas to overcome the heuristic approaches of hybrid simulation research of the past decade. In hybrid simulation, the structure is typically idealized into several substructures, where some of the substructures are modeled analytically and the remaining substructures are physically tested and their measured responses are used in the computational algorithm for the numerical integration. This research aims at establishing the fundamentals of hybrid simulation to allow it to become a reliable method for simulation of structures and structural systems. Recent advances in computational mechanics will be used to create algorithms for hybrid simulation through an integrated approach involving both theory and experiments. In that regard, modified variational principles will be used to change the geometric structure of the governing equations for the purposes of time stepping. The research will be conducted using a verification and validation paradigm in which experiments, conducted in the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) and the Civil and Environmental Engineering Structural laboratories at the University of California, Berkeley, will be used to identify the correct theoretical models and algorithms for hybrid simulation by means of different test structures and a tailored experimental program. This exploratory approach brings together the two fields of hybrid testing and computational mechanics, in a synergistic fashion, aiming at the interdisciplinary advancement of the field. If successful, this work will represent a major conceptual shift from the present hybrid simulation techniques and will establish a thorough basis for hybrid simulations rooted on sound experimentation coupled with theoretical and applied multi-scale mechanics.

The structural safety of the built environment is critical to all citizens. When faced with the challenges of constructing bridges, buildings, power plants, and other infrastructure to withstand the extreme forces from earthquakes, hurricanes, and other natural disasters, engineers need to be able to test new ideas in a safe and reliable manner without having to construct full-scale prototypes. The research aims at providing engineers a robust methodology to reliably test components for new designs without having to build complete structural systems solely for test purposes, leading to safer and more reliable structures for everyone. This award also aims to train a new generation of engineers to be knowledgeable in both the theory and practice of hybrid simulation.

Pathways Project: Experimental Determination of Performance of Drift-Sensitive Nonstructural Systems under Seismic Loading

Funding: NEES (NEESR Award Number: 0619157)

PIs: Kurt McMullin (San Jose State University), Winncy Du (San Jose State University), Thuy Le (San Jose State University), Bozidar Stojidinovic (UC Berkeley), Kathi Rai (SensiBuild)

Test Time: July 2011 – April 2012

Test Laboratories: nees@berkeley Laboratory

Participants: San Jose State University, UC Berkeley

Data Repository: NEES Project Warehouse

Detailed Information: website “http://www.engr.sjsu.edu/~pathway/”

Publications

This project investigates the damage events of nonstructural building components due to lateral story movement due to an earthquake. The project is led by Professor Kurt McMullin (San Jose State University) and explores seismic damage to three different nonstructural systems: precast concrete cladding, inset windows, and vertical plumbing risers. A series of six full-scale experiments are to be conducted. The primary experimental test objectives include defining component and system force-deformation relationships, quantifying damage events with applied drift, evaluation of a robotic plumbing inspection system, and qualitative understanding of the behavior of façade systems. The testing involved several students including doctoral candidates from U.C. Berkeley, masters-level students from both San Jose State University and U.C. Berkeley, and undergraduate students from San Jose State University. Experimental test results will be correlated with both pre-test and post-test analytical models.

Performance-Based Design of Squat Reinforced Concrete Shear Walls

Funding: NEES (NEESR Award Number: CMMI-0829978)

PIs: Andrew Whittaker (University at Buffalo), Bozidar Stojadinovic (University of California, Berkeley), Laura Lowes (University of Washington), Abraham Lynn (California Polytechnic State University, San Luis Obispo)

Students: Catherine Whyte (University of California, Berkeley), Joshua Rocks (University at Buffalo), Bismarck Luna (University at Buffalo), Joshua Pugh (University of Washington)

Test Time: July 2011 – December 2011

Test Laboratories: UB-NEES (Buffalo), nees@berkeley Laboratory

Participants: University at Buffalo, University of California, Berkeley, University of Washington, California Polytechnic State University, San Luis Obispo

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

This project will investigate the earthquake response of large-scale reinforced concrete walls through hybrid simulation tests conducted at the nees@Berkeley laboratory site. Squat structural walls with aspect ratio (wall height/wall length) of approximately 0.5 are often the primary seismic lateral-force-resisting components in nuclear and industrial facilities. In nuclear structures, the walls are very thick for radiation shielding and blast and fire protection. Similarly thick walls are also found in industrial structures. This combination of a thick and squat wall results in a high wall stiffness. The goals of this project are to develop hybrid testing methods suited to this problem of a very stiff specimen and to better understand the earthquake response behavior. With a very stiff specimen, a small increment in displacement causes a large increment in force. This is difficult to manage in a typical displacement control hybrid simulation since very small displacements must be commanded to the specimen to achieve reasonable size force increments. We are considering using either a high precision displacement encoder in displacement control or force control. These types of walls have not been previously studied dynamically in large scale because of the difficult nature of performing these tests. Most previous studies have used predefined monotonic or cyclic loading patterns. The relatively few dynamic tests were performed on small scale models on a shaking table.

TIPS: Tools to Facilitate Widespread Use of Isolation and Protective Systems

Funding: NEES (NEESR Award Number: 1113275)

PIs: Stephen Mahin (UC Berkeley), Keri Ryan (University of Nevada, Reno)

Students: Tracy Becker (UC Berkeley), Brian Olson (UC Berkeley)

Test Time: January 2011 – June 2012

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley

Data Repository: NEES Project Warehouse

In the design of seismically isolated buildings in the US, response modification factors (R-values) greater than one are permitted in the design of the superstructures of non-critical facilities. These R-values may lead to yielding under the Design Basis Earthquake, and will certainly result in yielding in structures designed to be compliant with minimum code provisions during the Maximum Considered Earthquake. Using the NEES Reconfigurable Platform for Earthquake Testing (REPEAT) frame, we are testing multiple superstructure configurations to determine, in the event of superstructure yielding, what is the best design approach to achieve acceptable post-yield performance. The experimental setup consists of a 1/3-scale two-story, two-bay by one-bay frame supported on six triple friction pendulum bearings. At critical plastic hinge locations, the frame uses pinned clevis connections with steel coupons installed to resist moment. The coupons will yield during testing to produce plastic hinge action, but can easily be replaced to test a new configuration. The experimental goal is to better understand the behavior of isolated buildings when yielding occurs in the superstructure, and to find a recommendation for equivalent linear design procedures that will avoid concentrated yielding in the story immediately above the isolation plane. To test the frame, we assembled a 19x7 ft one-dimensional hybrid shake platform with +/- 20 in displacement capacity in the NEES lab at UC Berkeley. The shake platform can perform a wide variety of tests, including ones where the isolation plane is located at the top of columns or over several stories to eliminate the need for a moat at a the base of a building. The portion of the building below the isolation plane is numerically simulated during these hybrid shaking table tests.

NSF RAPID RESPONSE: Laser Scanning Technology for Damage Assessment after the January, 12, 2010 Haiti Earthquake

Funding: NSF (Award Number: 1034808)

PIs: Khalid Mosalam (UC Berkeley)

Students: Steven Liu (UC Berkeley)

Test Time: March 2010 – July 2010

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley

Data Repository: NEES Project Warehouse

The project focuses on using laser scanners capable of measuring large objects in space, an important attribute for structural assessment. The use of such high definition laser scans has many advantages and has been successfully applied to assess and document structural damage in earthquake engineering. Several of these earthquake engineering applications were conducted in laboratories and this project attempts to demonstrate the use of this technology in the field. While collapse is obvious to the naked eye, it is often difficult to discriminate between lesser damage states. The main goals of the projects are: 1) to geo-reference all laser scans and create a combined database of photo images and the laser scans, 2) to document structural damage, 3) to develop quantitated approach of structural damage assessment, and 4) compare structural damage assessment from conventional on-the-ground surveillance to that of laser scans. The team plans to scan close to 50 structures including the buildings in two city blocks previously surveyed by both the World Bank from the aerial photos and by two members of the team (Mr. Fierro and Dr. Miranda) using on-the-ground surveillance. All information is planned to be analyzed and organized in a searchable database and will be made available to the engineering community via the Internet by means of utilizing Google Earth.

Seismic Performance of Reinforced Concrete Corner Beam-Column Joints without Transverse Reinforcement — Phase II (Axial Collapse)

Funding: NEES Grand Challenge

PIs: Jack P. Moehle (UC Berkeley)

Students: Wael Hassan (UC Berkeley)

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

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

Testing of four full scale corner beam-column joint subassemblies, including floor slabs, is under way. The goal is to evaluate non-ductile corner joints shear strength and axial residual capacity under high axial load reversals varying with lateral loads; and 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).

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 in 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.

Design, Evaluation and Testing of a Ductile Fiber-Reinforced Concrete Infill Panel System for Seismic Retrofitting of Existing Steel Structures

Funding: NEESR-SG

PIs: Professor James Wight (University of Michigan), Sarah L. Billington (Stanford University)

Postdoctoral Researcher: Dimitrios G. Lignos (Stanford University, Kyoto University)

Students: Daniel Mauricio Moreno-Luna (Stanford University)

Test Laboratories: nees@berkeley Laboratory

Participants: University of Michigan, Stanford University

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

This project is part of a larger project titled “NEESR-SG: Innovative Applications of Damage Tolerant Fiber-Reinforced Cementitious Materials for New Earthquake-Resistant Structural Systems and Retrofit of Existing Structures” funded by the National Science Foundation under award number CMS-0530383 to Prof. James Wight (PI) at The University of Michigan Ann Arbor.

Large-scale hybrid testing will be conducted at the NEES facility at the University of California at Berkeley (UCB) to evaluate the performance of full-bay and partial bay infills in steel frame structures. Two testing phases are scheduled of a 2/3 scale of a 2-story steel moment frame designed in 1980s in United States. Global performance (e.g. building energy dissipation, story drift ratios) as well as local performance, such as the response of the existing frame at its own connections and where the panels connect to the existing frame, will be evaluated. The main objectives of the experimental program are as follows:

  • Develop and evaluate an easily-installed and rapidly-repairable system for steel frames that can be used for both retrofits and new design

  • Evaluate the hysteretic response and connection performance of precast HPFRC panels connected to each other and to steel frame components, subjected to cyclic loading

Seismic Performance of Reinforced Concrete Corner Beam-Column Joints without Transverse Reinforcement — Phase I

Funding: NEES Grand Challenge

PIs: Jack P. Moehle (UC Berkeley)
and Khalid M. Mosalam (UC Berkeley)

Students: Sangjoon Park (UC Berkeley)

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

Four full-scale reinforced concrete corner beam-column joints without transverse reinforcement are constructed with floor slabs between two orthogonal beams to assess the vulnerability of old existing reinforced concrete buildings. The specimens are designed by two main parameters: (1) beam longitudinal reinforcement ratio and (2) joint aspect ratio expressed by beam depth to column depth. Testing is conducted under quasi-static reverse cyclic alternating uni-directional loading. During test, column axial load varies linearly with respect to beam shear by the pre-defined relationship in order to consider the fluctuation of column axial load due to overturning moment within reasonable range. The objectives are to assess the seismic performance of corner joints in old existing reinforced concrete buildings, and to provide the information for analytical joint shear strength model and progressive collapse analysis of old existing RC buildings.

International Hybrid Simulation
of Tomorrow's Steel Braced Frames

Funding: NEESR

PIs: Charles Roeder (University of Washington)
and Dawn Lehman (University of Washington)

NEES-ES Investigator: Stephen Mahin (UC Berkeley)

Students: Jiun-Wei Lai (UC Berkeley)

Test Time: ongoing since July 2008 (test preparation)

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; University of Minnesota; University of Washington; NCREE Taiwan

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

These experimental research tests at Berkeley are part of the NEES small group project “International Hybrid Simulation of Tomorrow's Steel Braced Frames.” The overall project team includes researchers from the US, Japan and Taiwan, as well as affiliated researchers from Canada. The research utilizes the NEES facilities at the University of California, Berkeley, the University of Minnesota and the NCREE Laboratory in Taiwan. The major objective is to use 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. The research work at the Berkeley site is directly supervised by Professor Stephen Mahin. The test program consists of:

  1. Testing nearly full-scale planar specimens of steel concentrically braced frames (including SCBF, BRBF, and innovative braced frame systems). At least five experiments are planned.

  2. Testing full-scale bracing components.

  3. Developing and validating hybrid simulation techniques for geographically distributed hybrid simulations of steel braced frame building structures.

Seismic Response of Column Base Connections:
Flexural Limit States

Funding: AISC, NEESR

PIs: Amit M. Kanvinde (UC Davis) and
Gregory G. Deierlein (Stanford University)

Students: Ivan R. Gomez (UC Davis)

Test Time: December, 2008 - March, 2009

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; UC Davis; Stanford University

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Notes. This project corresponds to Phase 4 of the overarching ULCF project (Large Scale Tests and Micromechanics-Based Simulation of Ultra-Low Cycle Fatigue and Fracture in Steel Structures).

This NEESR-SG project will run its AISC-NEES Phase 2 tests on a number of column base plate specimens. The research team is led by Professor Amit Kanvinde (UC Davis). The main objective of this phase of testing is to develop an improved understanding of flexural limit states in base plate details under seismic loading. The emphasis is on the force and deformation patterns and on the capacities of various components (i.e. base plate, anchor rods, concrete and grout) to resist the imposed force and deformation demands. The work is being carried out collaboratively between UC Davis and Stanford with students from each University participating. The key issues examined during the testing (which will include a total of 7 tests), will be the effects of anchor rod placement and strength, base plate thickness as well as gravity loads. The test data will be complemented by an extensive simulation component to inform and improve design considerations.

Fundamentals of Column Bases
and Exposed Seismic Base Design

click here for panorama movie of the setup

Funding: NEESR (CMS 0421492)

PIs: Amit M. Kanvinde (UC Davis) and
Gregory G. Deierlein (Stanford University)

Students: Ivan R. Gomez (UC Davis)

Test Time: December, 2007 - January, 2008

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; UC Davis; Stanford University

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

Notes. This project corresponds to Phase 3 of the overarching ULCF project (Large Scale Tests and Micromechanics-Based Simulation of Ultra-Low Cycle Fatigue and Fracture in Steel Structures).

The main aim of this phase of testing is to develop a better understanding and design considerations for shear transfer in base plate connections. A number of issues regarding shear transfer mechanisms will be addressed:

  1. friction as an initial load bearing mechanism,
  2. anchor rod shear as the limit mechanism, and
  3. use of shear keys for larger shear loads.

Hybrid Simulation of Base Isolated Structures

click here for web camera

click here for wmv movie of a shaking table run

Funding: NEES

PI: Stephen Mahin (UC Berkeley)

Students: Andreas Schellenberg (UC Berkeley)

Test Time: December, 2006 - May, 2007

Test Laboratories: nees@berkeley Laboratory; PEER Shaking Table Laboratory

Participants: UC Berkeley

Data Repository: NEES Project Warehouse

The goal of this Equipment Enhancement and Improvement (EEI) project is to develop a hybrid simulation algorithm for a 6 degrees of freedom system that produces results well correlated to shaking table tests.

International Distributed Hybrid Experiments
on Bridge Systems

Funding: NEES/E-Defense

PIs: Yoshikazu Takahashi (Kyoto University), Stephen Mahin (UC Berkeley) and Gregory L. Fenves (UC Berkeley)

Students: Andreas Schellenberg (UC Berkeley), Hong Kim (UC Berkeley) and Yosuke Nakano (Kyoto University)

Test Time: February-March, 2007

Test Laboratories: nees@berkeley Laboratory, Kyoto University

Participants: nees@berkeley Laboratory, Kyoto University

Data Repository: local

Detailed Information: presentation

This project investigates the seismic response of a continuous bridge planned to be tested at the E-Defense shaking table by a distiributed hybrid simulation with OpenFresco and OpenSees. The bridge consists of a RC C-bent column, a RC single column, a steel single column, a steel girder and elastomeric bearings. The C-bent RC column and the steel column were tested at Kyoto University and nees@berkeley Laboratory, respectively.

NEES TITech and UCB Joint Research on Seismic Performance of Bridge Columns Based on NEES and E-Defense Collaboration

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Funding: NEES, Tokyo Institute of Technology (TITech)

PIs: Stephen Mahin (UC Berkeley) and Kazuhiko Kawashima (TITech)

Students: Erik Okstad (UC Berkeley), Gakuho Watanabe (TITech), Seiji Nagata (TITech), Takashi Matsumoto (TITech)

Test Time: September-October, 2006

Test Laboratories: nees@berkeley Laboratory; PEER Shaking Table Laboratory

Participants: UC Berkeley; E-Defense; Tokyo Institute of Technology

Data Repository: NEES Project Warehouse

Detailed Information: webpage

This project performed a series of shaking table experiments on reinforced concrete bridge columns. Four columns were tested, comparing bridge construction details commonly used in Japan and California.

Large Scale Tests and Micromechanics-Based Simulation of Ultra-Low Cycle Fatigue (ULCF) and Fracture in Steel Structures — Phase II

click here for wmv movie

Funding: NEESR (CMS 0421492)

PIs: Amit M. Kanvinde (UC Davis) and Gregory G. Deierlein (Stanford University)

Students: Andy T. Myers (Stanford University)

Test Time: August-September, 2006

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; UC Davis; Stanford University

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

This project investigate Ultra-Low Cycle Fatigue (ULCF) in large-scale welded steel columns. The extensive experimental study was complemented by detailed continuum-based FEM and micromechanics-based models that capture the fundamental processes of void growth, collapse, and damage responsible for ULCF

Investigation of Welded Reinforcement Grids
in Compression

Funding: PEER (REU), NEES

PI: Jack P. Moehle (UC Berkeley)

Student: Matthew Rood (University of Florida)

Test Time: August 2006

Test Laboratories: nees@berkeley Laboratory

Data Repository: local

Detailed Information: report

A monotonic uniaxial compression test was performed on a high-strength concrete (7.5 ksi) column with welded grids for transverse reinforcement. The column reached design compressive strength around 2100 kips, but failed prematurely (strain in test region = 0.01) owing to fracture of the welds in the welded grids. Axial load dropped effectively instantly from 2100 kips to 100 kips, suggesting complete failure.

2006 National Student Leadership Conference (NSLC)
Engineering Program at UC Berkeley

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Funding: NEES

PIs: Khalid Mosalam (UC Berkeley)

Students: Tran Ngoc Le, Timmy Siauw, Matias Hube, Tarek Elkhoraibi (all UC Berkeley)

Test Time: June-July, 2006

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley, National Student Leadership Conference (NSLC)

Data Repository: local

The nees@berkeley experimental facility hosted an engineering program for the National Student Leadership Conference (NSLC). High school students from across the US particiated in a hands-on introduction to earthquake engineering. The program included in numerous full-scale hybrid simulations and conventional tests of wood frame panels.

Large Scale Tests and Micromechanics-Based Simulation of Ultra-Low Cycle Fatigue (ULCF) and Fracture in Steel Structures — Phase I

click here for mpeg movie

Funding: NEESR (CMS 0421492)

PIs: Amit M. Kanvinde (UC Davis)
and Gregory G. Deierlein (Stanford University)

Students: Benjamin V. Fell (UC Davis)

Test Time: October-December, 2005

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; UC Davis; Stanford University

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

This project investigates Ultra-Low Cycle Fatigue (ULCF) in large-scale steel bracing members. The experimental findings are complemented by detailed continuum-based FEM and micromechanics-based models that capture the fundamental processes of void growth, collapse, and damage responsible for ULCF.

Collaborative Research Behavior of Braced Steel Frames with Innovative Bracing Schemes – A NEES Collaboratory Project

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Funding: pre-NEESR (CMS 032462)

PIs: B. Stojadinovic and J. Moehle (UC Berkeley); B. Shing (UC San Diego); A. Reinhorn and M. Bruneau (University at Buffalo, SUNY); R. Leon and R. DesRoches (Georgia Institute of Technology)

Students: T. Y. Yang (UC Berkeley); A. Stavridis (UC San Diego); M. Chachter (University at Buffalo); W. Yang (Georgia Institute of Technology)

Test Time: April-May, 2005

Test Laboratories: nees@berkeley Laboratory; University of Colorado, Boulder (distributed hybrid simulation); University at Buffalo, SUNY (shaking table tests); Georgia Institute of Technology (quasi-static tests)

Participants: UC Berkeley; UC San Diego; University at Buffalo, SUNY; Georgia Institute of Technology; University of Colorado, Boulder

Data Repository: NEES Project Warehouse

Detailed Information: webpage

Publications

The project studied the behavior of braced steel frames under seismic loading with emphasis on a novel configuration called a zipper frame. In addition to its innovative technical content, the project was a successful showcase of the capabilities and potential of some of the newly installed NEES facilities to demonstrate the advantages of integrating new advanced control algorithms for testing and analysis.

Hybrid On-Line Experiments and Monitoring of Structural Systems

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Funding: pre-NEESR (CMS 0115006)

PIs: Khalid M. Mosalam (UC Berkeley)

Students: Alidad Hashemi and Tarek Elkhoraibi (UC Berkeley)

Test Time: February-March, 2005

Test Laboratories: nees@berkeley Laboratory; PEER Shaking Table Laboratory

Participants: UC Berkeley

Data Repository: NEES Project Warehouse

Publications

An extensive experimental research of reinforced concrete frames infilled with masonry walls was conducted. Both shaking table and hybrid simulation tests were conducted to study the complex behavior of the test models with the quasi-brittle component. A hybrid simulation methodology based on mixed-variable control of a structure with multiple physical and computational substructures was developed.

Grand Opening of nees@berkeley Facility

click here for mov movie

Funding: NEES (outreach)

Test Time: November, 2004

Test Laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; SEAONC

Data Repository: local

Detailed Information: webpage

The grand opening of nees@berkeley was coordinated with the Structural Engineers Association of Northern California (SEAONC) Dinner Program. The evening featured brief statements by invited dignitaries, a laboratory tour including exciting demonstration experiments, refreshments and a catered dinner. This was followed by a presentation by Professors Mahin, Stojadinovic, and Moehle, who were responsible for the development of the new facility. The presentation introduced NEES, described the special capabilities of nees@berkeley, including the new hybrid simulation capability, and through an open dialogue with attendees, explored ways that SEAONC engineers can join in to utilize this unique new facility to advance earthquake engineering practice.

 

nees@berkeley Laboratory • UC Berkeley — Richmond Field Station • 1301 South 46th Street, Building 484 • Richmond, CA 94804 • nees@berkeley.edu