Seismic Analysis of Multi-story Unreinforced Masonry Buildings with Flexible Diaphragms

446 Pages·2015·20.06 MB·English

ISSN 1520-295X
Seismic Analysis of Multi-story
Unreinforced Masonry Buildings
with Flexible Diaphragms
by
Juan Aleman, Gilberto Mosqueda and Andrew Whittaker
Technical Report MCEER-15-0001
June 12, 2015
This research was conducted at the University at Buffalo, State University of New York,
and was supported by MCEER Thrust Area 2, Sustainable and Resilient Buidlings.
NOTICE
This report was prepared by the University at Buffalo, State University of New
York, as a result of research sponsored by MCEER. Neither MCEER, associates
of MCEER, its sponsors, the University at Buffalo, State University of New
Yao. rk,m naokr easn ya npye rwsoanr raacntitny,g eoxnp trheesisr obre himalpf:lied, with respect to the use of any
information, apparatus, method, or process disclosed in this report or that
such use may not infringe upon privately owned rights; or
b. assumes any liabilities of whatsoever kind with respect to the use of, or the
damage resulting from the use of, any information, apparatus, method, or
process disclosed in this report.
Any opinions, findings, and conclusions or recommendations expressed in this
publication are those of the author(s) and do not necessarily reflect the views
of MCEER, or other sponsors.
Seismic Analysis of Multi‐story Unreinforced  
Masonry Buildings with Flexible Diaphragms

by 

Juan Aleman,1 Gilberto Mosqueda2  andAndrew Whittaker3 

Publication Date: June 12, 2015 
Submittal Date: November 19, 2014 

Technical Report MCEER‐15‐0001 

MCEER Thrust Area 2, Sustainable and Resilient Buildings  

1 Engineer, Structures, Arup, Los Angeles and former Graduate Student, Department 
of Civil, Structural and Environmental Engineering, University at Buffalo, State 
University of New York  
2 Associate Professor, Department of Structural Engineering, University of 
California, San Diego 
3 Professor and Chair, Department of Civil, Structural and Environmental 
Engineering, University at Buffalo, State University of New York 

MCEER 
University at Buffalo, State University of New York 
212 Ketter Hall, Buffalo, NY 14260 
E‐mail: mceer@buffalo.edu; WWW Site: http://mceer.buffalo.edu

PREFACE

MCEER is a national center of excellence dedicated to the discovery and development of new
knowledge, tools and technologies that equip communities to become more disaster resilient in the face of
earthquakes and other extreme events. MCEER accomplishes this through a system of multidisciplinary,
multi-hazard research, education and outreach initiatives.
Headquartered at the University at Bu alo, State University of New York, MCEER was originally
established by the National Science Foundation (NSF) in 1986, as the first National Center for Earthquake
ff
Engineering Research (NCEER). In 1998, it became known as the Multidisciplinary Center for
Earthquake Engineering Research (MCEER), from which the current name, MCEER, evolved.
Comprising a consortium of researchers and industry partners from numerous disciplines and
institutions throughout the United States, MCEER’s mission has expanded from its original focus on
earthquake engineering to one which addresses the technical and socioeconomic impacts of a variety of
hazards, both natural and man-made, on critical infrastructure, facilities, and society.
MCEER investigators derive support from the State of New York, National Science Foundation,
Federal Highway Administration, National Institute of Standards and Technology, Department of
Homeland Security/Federal Emergency Management Agency, other state governments, academic
institutions, foreign governments and private industry.
The main goal of this study was to develop simulation capabilities supported by experimental testing
to evaluate the seismic performance of typical unreinforced masonry buildings with flexible diaphragms
located in NYC. Simplified nonlinear macro-models of wood diaphragms, masonry walls and floor-to-
wall connections were developed and validated individually using data from past experiments. The
models are implemented in both commercial and research software to demonstrate their practical use. In
particular, a new approach for modeling flexible diaphragms is proposed that is shown to provide similar
accuracy to detailed finite element models at a fraction of the computation cost. The models developed
were also validated at the system level, through shake table testing of two full-scale specimens conducted
as part of this study. The specimens were designed and constructed to represent the expected loading
conditions of a central portion of a one-story URM building and constructed of materials representative
of older masonry construction. The tests provide a unique data set that captures the interaction between
flexible floors, out-of-plane walls and their connections at full scale.

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ABSTRACT

Studies regarding the regional seismicity of New York City (NYC) indicate that earthquakes of
magnitude greater than or equal to 5 have a 20-40% probability of occurring in a 50 year period.
Considering that more than 50% of the large population of the region (19.1 million) is living in
an area where 80% of the buildings are of old Unreinforced Masonry (URM) construction, it is
likely that even a moderate earthquake could have critical consequences on public safety and the
economy of this area.
The main goal of this study was to develop simulation capabilities supported by experimental
testing to evaluate the seismic performance of typical unreinforced masonry buildings with
flexible diaphragms located in NYC. Simplified nonlinear macro-models of wood diaphragms,
masonry walls and floor-to-wall connections were developed and validated individually using
data from past experiments. The models are implemented in both commercial and research
software to demonstrate their practical use. In particular, a new approach for modeling flexible
diaphragms is proposed that is shown to provide similar accuracy to detailed finite element
models at a fraction of the computation cost. The models developed were also validated as at the
system level, through shake table testing of two full-scale specimens conducted as part of this
study. The specimens were designed and constructed to represent the expected loading
conditions of a central portion of a one-story URM building and constructed of materials
representative of older masonry construction. The tests provide a unique data set that captures
the interaction between flexible floors, out-of-plane walls and their connections at full scale.
The validated macro-models can be used for performance-based seismic assessment of
unreinforced masonry buildings in NYC and elsewhere. To demonstrate their use, preliminary
studies were conducted to develop out-of-plane URM fragility curves, a building-specific
collapse fragility function, and to estimate the seismic response of the building when subjected to
a ground shaking intensity similar to the 2011 Virginia Earthquake. The probabilistic framework
and new performance definitions provided by the FEMA P58 project were used to conduct a
performance-based seismic assessment for an archetype unreinforced masonry building in New
York City with an emphasis on out-of-plane behavior. This preliminary study served to
demonstrate the applicability of the proposed models for applications in performance-based
design.
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ACKNOWLEDGEMENTS

Financial support for this research was provided by the Multidisciplinary Center for Earthquake
Engineering Research, Buffalo, NY and partial funding to the first author was also provided by
the US Fulbright Scholarship Program. Their support is gratefully acknowledged. The
experimental portion of this research was benefited from donations of material and workmanship
by The International Masonry Institute, John H. Black Co. and Bricklayers of Local 3 Buffalo.
Their support is deeply appreciated. The authors also thank Dr. David Peralta and Mr. Michael
Schuller for providing experimental data for wood diaphragms and in-situ flatjack tests,
respectively.

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