Fundamentals of Column Bases and Exposed Seismic Base Design (continuation of Large Scale Tests and Micromechanics-Based Simulation of Ultra-Low Cycle Fatigue (ULCF) and Fracture in Steel Structures project): Phase 3

Funding: NEESR

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

Students: Ivan R. Gomez (UC Davis)

Description: 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.

Test time: December, 2007 - January, 2008

Test laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; UC Davis; Stanford University

Data repository: NEEScentral, CMS - 0421492

Detailed information: report or/and web-page

Fragility Testing of 230-kV Porcelain Insulators under Cyclic Loading

Funding: PEER
PI: Yousef Bozorgnia (UC Berkeley)
Staff Researcher : Shakhzod Takhirov (UC Berkeley)
Description: The project aims to study degradation and fragility of porcelain insulator sections commonly used by utilities in installation of 230-kV disconnect switches. The experimental program is intended to investigate common failure modes of the insulator posts and to determine ultimate loads under cyclic loading. Free-vibration and pull-back tests are conducted after each increment of cyclic loading amplitude to detect a degradation of the insulator sections if any.
Test time: August, 2007 - January, 2008

Test laboratories: nees@berkeley Laboratory

Data repository: local
Detailed information: report or/and web-page

Hybrid Simulation of Base Isolated Structures

Funding: NEES

PIs: Stephen Mahin (UC Berkeley)

Students: Andreas Schellenberg (UC Berkeley)

Description: 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 would produce results well correlated to shaking table tests.

Test time: December, 2006 - May, 2007

Test laboratories: nees@berkeley Laboratory; EERC Shaking Table Laboratory

Participants: UC Berkeley

Data repository: NEEScentral

Detailed information: report or/and web-page

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)

Description: The aim of the project was to investigate the seismic
response of a continuous bridge planned to be tested at E-Defense shake
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.

Test time: February-March, 2007

Test laboratories: nees@berkeley Laboratory, Kyoto University

Participants: nees@berkeley Laboratory, Kyoto University

Data repository: local

Detailed information: presentation or/and web-page

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

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)

Description: A series of shaking table experiments on reinforced concrete bridge columns was performed. Four columns were tested, comparing bridge construction details commonly used in Japan and California.

Test time: September-October, 2006

Test laboratories: nees@berkeley Laboratory; EERC Shaking Table Laboratory

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

Data repository: NEEScentral

Detailed information: report or/and web-page

Large Scale Tests and Micromechanics-Based Simulation of Ultra-Low Cycle Fatigue (ULCF) and Fracture in Steel Structures: Phase 2

Funding: NEESR

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

Students: Andy T. Myers (Stanford University)

Description: The aim of the project was to 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

Test time: August-September, 2006

Test laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; UC Davis; Stanford University

Data repository: NEEScentral, CMS - 0421492

Detailed information: report or/and web-page

Investigation of Welded Reinforcement Grids in Compression

Funding: PEER (REU)
PI: Jack P. Moehle (UC Berkeley)
Student: Matthew Rood (University of Florida)
Description: 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.
Test time: August 2006

Test laboratories: nees@berkeley Laboratory

Data repository: RRW's local
Detailed information: report or/and web-page

Test of Two Column Viaduct with Re-Centering System

Funding: PEER

PI: Stephen Mahin (UC Berkeley)
Student: Hyungil Jeong (UC Berkeley)
Description: As part of on-going research program and based on the previous research results, a series of shaking table test was conducted to assess the ability of partially prestressed reinforced concrete columns with unbonded post-tensioning tendons to reduce residual displacements resulting from strong earthquake ground motions.
Test time: July-August, 2006

Test laboratories: EERC Shaking Table Laboratory

Data repository: RRW's local
Detailed information: report or/and web-page

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

Funding: NEES

PIs: Khalid Mosalam (UC Berkeley)

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

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

Test time: June-July, 2006

Test laboratories: nees@berkeley Laboratory

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

Data repository: RRW's local

Detailed information: report or/and web-page

Shake Table Testing of Friction Pendulum System

Funding: Gift

PI: Stephen Mahin (UC Berkeley)
Student: Troy Morgan (UC Berkeley)
Description: The objectives of this research program center around the verification of anticipated seismic performance of double- and triple-concave Friction Pendulum (FP) bearings and the validation of nonlinear analytical models and solution algorithms employed by commercially available structural analysis software to predict observable response quantities.
Test time: June-July, 2006

Test laboratories: EERC Shaking Table Laboratory

Data repository: RRW's local
Detailed information: report or/and web-page

Two Story Wood Frame Building Shake Table Test

Funding: Service to Industry

PI: Khalid Mosalam(UC Berkeley)
Student: Alidad Hashemi and Tarek Elkhoraibi (UC Berkeley)
Description: A 13.5'×19.5' two-story wood frame house representing San Francisco 1940’s design of residential house a garage space on the first level was tested on the shaking table. The structure was subjected to scaled ground motion based on Los Gatos record from Loma Prieta 1989 earthquake. The strong motion time history was scaled to match design spectra of a site in Richmond district of San Francisco. The testing was aired as MSNBC Datelines on May 21, 2006.
Test time: May, 2006

Test laboratories: EERC Shaking Table Laboratory

Data repository: RRW's local
Detailed information: report or/and web-page

Reinforced Concrete Frame Validation Tests: Frame
Funding: PEER
PI: Jack P. Moehle (UC Berkeley)
Student: Wassim M. Ghannoum (UC Berkeley)
Description: The goal of the project was to develop validation data and nonlinear models for nonlinear response, component failure mechanisms, and internal force redistribution as collapse occurs in a building frame representative of older concrete construction.
Test time: February 2006

Test laboratories: EERC Shaking Table Laboratory

Data repository: RRW's local
Detailed information: report or/and web-page

Large Scale Tests and Micromechanics-Based Simulation of Ultra-Low Cycle Fatigue (ULCF) and Fracture in Steel Structures: Phase 1

Funding: NEESR

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

Students: Benjamin V. Fell (UC Davis)

Description: The aim of this project is investigate 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.

Test time: October-December, 2005

Test laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; UC Davis; Stanford University

Data repository: NEEScentral, CMS - 0421492

Detailed information: report or/and web-page

Reinforced Concrete Frame Validation Tests: Single Columns

Funding: PEER

PI: Jack P. Moehle (UC Berkeley)
Student: Yoon Bong Shin (UC Berkeley)
Description: The goal of the project was to develop validation data and nonlinear models for nonlinear response, component failure mechanisms, and internal force redistribution as collapse occurs in a building frame representative of older concrete construction.
Test time: October 2005

Test laboratories: EERC Shaking Table Laboratory

Data repository: RRW's local
Detailed information: report or/and web-page

The Developments of Details of New Methods for Reducing Residual Displacements of Reinforced Concrete Bridge Columns

Funding: PEER
PI: Stephen Mahin (UC Berkeley)
Student: Hyungil Jeong (UC Berkeley)
Description: A series of shaking table test was conducted to assess the ability of partially prestressed reinforced concrete columns with unbonded post-tensioning tendons to reduce residual displacements. The specific objectives of this research were to study the effect of debonding the mild reinforcing bars in the area of the expected plastic hinge, to study the effect of incorporating steel jacketing combined with locally unbonding of the mild reinforcement, and to investigate the effects of the magnitude on the prestressing force.
Test time: July- August, 2005
Test laboratories: EERC Shaking Table Laboratory
Data repository: RRW's local
Detailed information: report or/and web-page

Shaking Table Tests of Concrete Columns with Rocking Freedom

Funding: Caltrans, FHWA
PI: Stephen Mahin (UC Berkeley)
Student: Andy Espinosa (UC Berkeley)
Description: Several reinforced concrete columns with thick rubber pads under the foundations were tested on the shaking table. The rubber pads were used to simulate a rocking freedom of the columns.
Test time: June, 2005
Test laboratories: EERC Shaking Table Laboratory
Data repository: RRW's local
Detailed information: report or/and web-page

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

Funding: pre-NEESR

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)

Description: 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.

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: NEEScentral, CMS - 032462

Detailed information: report or/and web-page

Hybrid On-Line Experiments and Monitoring of Structural Systems

Funding: pre-NEESR

PIs: Khalid M. Mosalam (UC Berkeley)

Students: Alidad Hashemi and Tarek Elkhoraibi (UC Berkeley)

Description: 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.

Test time: February-March, 2005

Test laboratories: nees@berkeley Laboratory; EERC Shaking Table Laboratory

Participants: UC Berkeley

Data repository: NEEScentral, CMS - 0115006

Detailed information: report or/and web-page

Grand Opening of nees@berkeley Facility

Funding: NEES (outreach)

PIs: Nicholas Sitar (UC Berkeley)

Description: The grand opening of nees@berkeley had been 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 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 the unique new facility to advance earthquake engineering practice.

Test time: November, 2004

Test laboratories: nees@berkeley Laboratory

Participants: UC Berkeley; SEAONC

Data repository: RRW's local

Detailed information: report or/and web-page

Earthquake Simulation Tests on Reducing Residual Displacements of Reinforced Concrete Bridge Columns
Funding: PEER
PI: Stephen Mahin (UC Berkeley)
Student: Junichi Sakai (UC Berkeley)
Description: The goal of the project was to validate the new system to reduce the residual displacement using the partially unbonded post-tensioning tendon. Two 1/4.5-scaled circular columns were designed and constructed for the tests: a model of a conventionally designed reinforced concrete bridge column and a model of the proposed design.
Test time: May-June, 2004

Test laboratories: EERC Shaking Table Laboratory

Data repository: RRW's local
Detailed information: report or/and web-page