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ATC/MCEER Joint Venture Publishes Liquefaction Study Report and Design Examples
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The ATC/MCEER Joint Venture, a partnership of the Applied Technology Council (ATC) and MCEER, is pleased to announce the availability of Liquefaction Study Report, MCEER/ATC 49-1 and Design Examples, MCEER/ATC 49-2.
The Liquefaction Study Report presents the results of a study of the effects of liquefaction and associated hazards, lateral spreading and flow. It is part of a series of reports that comprise these recommended guidelines.
The study investigated liquefaction hazard implications for the design of bridges from the perspective of real sites and real structures. The scope was limited to two sites in relatively high seismic locations, one in Washington State and the other in Missouri. Actual site profile data and bridge configurations were used. The study included:
Simplified, conventional liquefaction analyses
Development of both 475-year and 2,475-year acceleration time histories
Nonlinear assessment of the site response to these accelerations, including the time history of pore water increases
Assessment of stability of abutment end slopes
Estimates of lateral spreading and/or flow conditions
Design of structural systems to withstand predicted response and flow conditions
Evaluation of geotechnical mitigation of liquefaction-related ground displacement
Evaluation of cost impacts of the structural and geotechnical mitigation strategies
The results for the 475-year and 2,475-year events were compared to assess the implications of using the larger event for design. Additionally, the conduct of the study helped synthesize an overall approach for handling liquefaction-induced movements in the recommended design provisions.
The report includes a CD-ROM containing detailed information for each study site.
The Design Examples illustrate use of the recommended LRFD guidelines. The two examples are the eighth and ninth in a series originally developed for FHWA to illustrate the use of the AASHTO Division 1-A Standard Specifications for Highway Bridges. The eighth design example was performed on a five-span continuous cast-in-place concrete box girder bridge and the ninth design example was performed on a three-span continuous steel girder bridge. Each example emphasizes different features that must be considered in the seismic analysis and design process.
For additional information or to order reports, visit http://mceer.buffalo.edu/publications/sp_pubs/03-SP03/default.asp.
Tri-Center Report on Seismic Safety
Promoting
Seismic Safety: Guidance for Advocates, by Daniel Alesch, Peter May,
Robert Olshansky, William Petak and Kathleen Tierney, is a 200-plus page report
that distills the findings of previous social science and policy research
to provide guidance to seismic safety advocates.
It has two parts. Part 1 is a collection of concise tips for advocates organized into the following topics: successful seismic safety advocacy, earthquake basics, ABCs of seismic building codes, policies and legislation, appearing before committees, informing and persuading, partnerships for seismic safety, working with experts, effective risk communication, and using the media.
Part 2 is a collection of background papers, developed by the authors, to support and amplify the advice to advocates in the guidance document.
The report is authored by social science and policy researchers at the three earthquake engineering research centers, MAE, MCEER and PEER, and was funded by the Federal Emergency Management Agency.
It is available on MCEER's website at http://mceer.buffalo.edu/publications/sp_pubs/04-SP02/default.asp or can be ordered from MCEER Publications for $35.00.
Experimental Study of Seismic Isolation Systems with Emphasis on Secondary System Response and Verification of Accuracy of Dynamic Response History Analysis Methods
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This combined experimental and analytical study provides an assessment of the validity and accuracy of analysis methods commonly used for seismically isolated structures, emphasizing secondary system response, contemporary seismic isolation systems, and strong and/or near-fault seismic excitation. A six-story steel model was used in three configurations: flexible moment-frame, asymmetrically braced-frame and stiff braced-frame. Eight isolation systems were studied, namely, low damping elastomeric bearings with and without linear and nonlinear viscous dampers, Friction Pendulum (FP) bearings with and without linear and nonlinear viscous dampers, low damping elastomeric bearings with lead cores, and low damping elastomeric bearings in conjunction with flat sliding bearings. Over 300 experiments were conducted. The various experimental results were compared with analytical results obtained using the SAP2000 and 3D-BASIS-ME computer programs. The vast database of experimental results on secondary system response provided the opportunity to assess the performance of various seismic isolation systems.
Tension, Compression and Cyclic Testing of Engineered Cementitious Composite Materials
The
study described in this report describes the testing performed to examine
the potential use and behavior of engineered cementitious composite (ECC)
materials in lieu of traditional materials. The materials are proposed for
use in seismic strengthening and retrofit applications. Specifically, an infill
panel system was developed that uses the pseudo-strain hardening properties
of the ECC materials. Laboratory studies examined the effect of different
curing and drying times, the tensile response of different specimen geometries,
and the response of ECC materials to reversed cyclic loadings. The ECC materials
investigated showed a wide range of tensile properties as a function of specimen
geometry and constituent materials. Other key findings are summarized in the
Conclusions section of the report. This study is the first to investigate
the response of the ECC materials to reversed cyclic loadings.
Cyclic Testing of Braces Laterally Restrained by Steel Studs to Enhance Performance During Earthquakes
This
report describes an experimental investigation into the seismic behavior and
efficiency of using braced steel infills for steel framed buildings. Cold
formed steel studs (CFSS), typically used in nonstructural partition walls,
were studied to determine if they could be used to laterally restrain braces
against buckling and thus enhance their seismic performance. Four specimens
were designed and cyclically tested: single square tube braces with and without
vertical CFSS and rectangular solid bar X braces with and without CFSS members.
The effects of KL/r ratio, bracing configuration and cross-sectional type
of braces were studied, as well as behavior characteristics of the specimens
with an emphasis on hysteretic energy dissipation. As a result, the CFSS members
showed promise for use in new buildings or as a retrofitting technique in
buildings that lack strength, lateral stiffness and ductility.
Methodologies for Post-Earthquake Building Damage Detection Using SAR and Optical Remote Sensing: Application to the August 17, 1999 Marmara, Turkey Earthquake
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The study described in this report explores how remote sensing technology can bring significant benefits to post-earthquake response and recovery activities, through improved urban damage detection. The Marmara, Turkey earthquake of August 17, 1999 is used as a testbed, as one of the first earthquakes where a temporal sequence of Ôbefore' and Ôafter' optical and radar imagery was available. The authors present a series of qualitative and quantitative methodological procedures and algorithms, which can be used to characterize the location, severity and extent of building damage. This study paves the way for subsequent research, employing very high-resolution imagery acquired by the new generation of optical satellites. Finally, since many of the illustrations rely on color to convey meaning, and the report is printed in black and white, a full-color version is included on a CD-ROM.
Nonlinear Structural Analysis Towards Collapse Simulation: A Dynamical Systems Approach
In
this study, the authors have developed structural models and numerical techniques
to analyze structures in damage states up to collapse. These are needed to
determine functional limit states required for performance and fragility based
seismic design methodologies. The authors explored alternatives to the widely
used displacement-based incremental iterative algorithms. They developed a
framework, termed a dynamical system, where displacements, internal forces
and other state variables can be treated uniformly. Two methods have been
formulated: State Space and Lagrangian. Both methods clearly distinguish the
modeling of components from the numerical solution. Thus, phenomenological
models of components such as steel connections, reinforced concrete elements,
semi-active devices, shock absorbers, etc. can be incorporated into the analysis
without having to implement element-specific incremental state determination
algorithms.
Proceedings of the Second PRC-US Workshop on Seismic Analysis and Design of Special Bridges
The
Proceedings are the result of the second in a series of international workshops
on seismic analysis and design of special bridges collaboratively arranged
by MCEER and the State Key Laboratory for Disaster Reduction in Civil Engineering,
Tongji University, Shanghai, China. The workshop themes include seismic design
and retrofit of long span bridges, performance based design, seismic safety
evaluation, soil-pile-structure interaction and pseudo-dynamic and hydrodynamic
experimental study. This volume contains 23 papers addressing a wide range
of these research fields, and includes a summary of research needs and workshop
recommendations. The workshop agenda and list of participants is also included.
For more information, visit the MCEER website at: http://mceer.buffalo.edu/publications/workshop/04-0006/default.asp.
Seismic Vulnerability Evaluation of Axially Loaded Steel Built-up Laced Members
The
objective of this research is to provide better knowledge on the seismic behavior
of laced members, which can be broadly applicable to many steel truss bridges
that share similar structural characteristics and details. Commonly encountered
built-up brace details and configurations were collected from actual bridges
that have laced members. Using this information, an experimental program was
conducted to investigate the hysteretic behavior of typical built-up compression
members. Strength capacity of the specimens, obtained from the testing, was
correlated with the predicted strength in the AISC LRFD Specifications. Assessments
of hysteretic properties such as ductility capacity, energy dissipation capacity,
and strength degradation after buckling of the specimen were performed. Nonlinear
pushover analyses were also conducted and correlated with test results. The
observed cyclic inelastic behavior of the specimens showed that these latticed
members can exhibit variable seismic performance and could often fail to meet
the displacement demands for typical braced frames in seismic regions.
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