Seismic Analysis Of Multi Story Unreinforced Masonry Buildings With Flexible Diaphragms
DOWNLOAD
Download Seismic Analysis Of Multi Story Unreinforced Masonry Buildings With Flexible Diaphragms PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get Seismic Analysis Of Multi Story Unreinforced Masonry Buildings With Flexible Diaphragms book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
Seismic Analysis Of Multi Story Unreinforced Masonry Buildings With Flexible Diaphragms
DOWNLOAD
Author : Juan Aleman Hernandez
language : en
Publisher:
Release Date : 2014
Seismic Analysis Of Multi Story Unreinforced Masonry Buildings With Flexible Diaphragms written by Juan Aleman Hernandez and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
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 building 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 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.
Tri Directional Seismic Analysis Of An Unreinforced Masonry Building With Flexible Diaphragms
DOWNLOAD
Author : Steven C. Sweeney
language : en
Publisher:
Release Date : 2004
Tri Directional Seismic Analysis Of An Unreinforced Masonry Building With Flexible Diaphragms written by Steven C. Sweeney and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Buildings categories.
Dynamic Response Of Urm Buildings With Flexible Diaphragms
DOWNLOAD
Author : Andrew Christopher Costley
language : en
Publisher:
Release Date : 1995
Dynamic Response Of Urm Buildings With Flexible Diaphragms written by Andrew Christopher Costley and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
As seismic awareness increases, especially in traditionally non-seismic regions, there is an ever-increasing need to evaluate the lateral resistance of existing structures. Unreinforced masonry (URM) structures are perceived to be seismically unsafe due to dramatic media coverage of these structures following earthquakes. However, well-built URM structures can possess substantial seismic resistance, although quantifying this strength can be difficult. Through a combination of experimental and analytical investigations, the overall objective of the study is to provide recommendations for the evaluation and rehabilitation of URM buildings. To accomplish this objective, the study was broken down into three primary tasks: (1) an experimental investigation, (2) the development of a simple dynamic model, and (3) a review of current analysis methods. The experimental investigation consisted primarily of the construction and dynamic testing of two, two-story, URM buildings with flexible floor and roof diaphragms on the University of Illinois shaking table. The two buildings were subjected to a total of nine simulated earthquakes. Experimental results indicated that (first-story) pier rocking was a ductile mode of response. Based on experimental results, a simple (3-DOF), nonlinear elastic model was developed. This model, in conjunction with a nonlinear time-step integration program, was used to estimate peak displacements during the rocking portions of the later earthquake simulations. The third task was a review of existing static and dynamic methods for analyzing URM structures. The static methods studied included two design codes, two rehabilitation codes, finite element modeling, and a pushover analysis. Dynamic methods included an elastic time-step integration, response spectra analysis, equivalent frame modeling, and finite element modeling. After a thorough examination of the measured results from the dynamic testing and a comparison between these results with those calculated during the analytical studies, a number of recommendations for the evaluation and rehabilitation of unreinforced masonry buildings with flexible diaphragms were made.
Seismic Strengthening Of Low Rise Unreinforced Masonry Structures With Flexible Diaphragms
DOWNLOAD
Author : Franklin Lehr Moon
language : en
Publisher:
Release Date : 2003
Seismic Strengthening Of Low Rise Unreinforced Masonry Structures With Flexible Diaphragms written by Franklin Lehr Moon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Composite materials categories.
As a capstone to several Mid-America Earthquake Center (MAE Center) projects, a full-scale two story unreinforced masonry (URM) building was tested following the application of several retrofit techniques, which included the use of fiber reinforced polymer (FRP) overlays, near surface mounted (NSM) rods, vertical unbonded post-tensioning, and joist anchors. The test structure was composed of four URM walls, flexible timber diaphragms and interior stud walls, and was designed and built following construction practices consistent with those used in Mid-America prior to 1950. Initial testing subjected both the roof diaphragm and in-plane walls to slowly applied lateral load reversals in an unreinforced sate. Following this series of tests, each in-plane wall was retrofit and retested. Experimental results indicated that global issues such as flange participation and the effects of overturning moment substantially impacted the response of primary components both before and after retrofit. FRP retrofit techniques resulted in strength increases up to 32% and displayed a pseudo-ductile response caused by progressive debonding. For cases where such retrofits forced sliding failures, large increases in energy dissipation resulted. The use of vertical unbonded post-tensioning resulted in strength increases between 40%-60%; however, piers displayed a tendency to switch from a ductile rocking/sliding mode to a more brittle diagonal tension mode. In addition, results highlighted the need for retrofit schemes to employ both horizontal and vertical reinforcement to prevent progressive crack opening that can decrease wall displacement capacity. Based on the experimental results, the model implied by the "Prestandard for the Rehabilitation of Existing Structures," FEMA 356, for the analysis of in-plane URM walls was modified and extended to (1) include the effect of FRP pier retrofits and (2) consider the global effects of URM structures. The resulting model displayed reasonable estimates of measured response both before and after retrofit, with an average error of 14%. In addition, the proposed model displayed improvements over the current model from 14% to 66%. Based on the results of sensitivity analyses this improved accuracy was primarily attributed to the consideration of global effects.
Seismic Assessment Of Timber Floor Diaphragms In Unreinforced Masonry Buildings
DOWNLOAD
Author : Aaron W. Wilson
language : en
Publisher:
Release Date : 2012
Seismic Assessment Of Timber Floor Diaphragms In Unreinforced Masonry Buildings written by Aaron W. Wilson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Diaphragms (Structural engineering) categories.
An integrated experimental and analytical study investigating the in-plane performance of timber floor diaphragms in URM buildings is presented. The research presented in this thesis was conducted with the primary aim of developing a revised procedure for the detailed seismic assessment of timber floor diaphragms in URM buildings. The deformation mechanics of timber floor diaphragms are presented and were used to develop an analytical model that can be used to predict diaphragm nonlinear performance. The analytical model was used to update the current idealisation of diaphragm behaviour in current seismic assessment documents. A three-phase experimental testing program is presented. Nail connection testing results indicated that connections in diaphragms contained within existing URM buildings have substantially lower initial stiffness, strength, and displacement capacity than do new connections. Small-scale diaphragm testing results proved that friction resistance between straight-edge or tongue and groove floorboards is negligible. Full-scale diaphragm testing results confirmed the highly flexible and orthotropic behaviour of timber floor diaphragms, and that a small stairwell penetration or the presence of discontinuous joists having a reliable mechanical connection do not significantly influence diaphragm performance. A finite element (FE) modelling method for timber floor diaphragms using the structural analysis software SAP2000 was appropriately validated using analytical modelling results and experimental data. Salvaged nail connection load-slip test data was used to program a diaphragm FE model to establish the representative performance of diaphragms in ~100 year old URM buildings in New Zealand. A comprehensive parametric analysis of diaphragm behaviour was subsequently undertaken. Finally, a revised assessment procedure for timber floor diaphragms was developed, which incorporates representative performance parameters, and provides suitable provisions to account for diaphragm orthotropic behaviour and for variations in key diaphragm configuration characteristics.
Seismic Response Of Low Rise Masonry Buildings With Flexible Roof Diaphragms
DOWNLOAD
Author : Gregory L. Cohen
language : en
Publisher:
Release Date : 2001
Seismic Response Of Low Rise Masonry Buildings With Flexible Roof Diaphragms written by Gregory L. Cohen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
This study compares the responses from shaking-table testing and analytical predictions evaluated in the context of geometric scaling, to provide a coherent description of the seismic response of low-rise masonry buildings with flexible roof diaphragms. Two half-scale, low-rise reinforced masonry buildings with flexible roof diaphragms are subjected to carefully selected earthquake ground motion on the Tri-axial Earthquake and Shock Simulator at the Construction Engineering Research Laboratory. Damage to the half-scale specimens is assessed using published protocols. Geometric scaling analysis relates response and damage of the half-scale specimens to those of the full-scale prototype structures. Linear elastic modeling is simplified to a generalized two-degrees-of-freedom idealization. Response-spectrum analysis of such an idealization is accurate and justified for prediction of dynamic response of the half-scale specimens and the corresponding full-scale prototype. It is shown that low-rise masonry buildings with flexible roof diaphragms can be designed for seismic loads as single-degree-of- freedom systems, using the degree of freedom associated with the in-plane response of the diaphragm in the building's transverse direction, rather than the degree of freedom associated with the in-plane responses of the shear walls.
Seismic Evaluation Of Low Rise Reinforced Masonry Buildings With Flexible Diaphragms
DOWNLOAD
Author : Steven C. Sweeney
language : en
Publisher:
Release Date : 2008
Seismic Evaluation Of Low Rise Reinforced Masonry Buildings With Flexible Diaphragms written by Steven C. Sweeney and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Flexible diaphragm categories.
This paper provides an integrated approach to the seismic evaluation of low-rise reinforced masonry buildings with flexible roof diaphragms. The paper is divided into four phases. In Phase 1 (Behavior), results from shaking-table testing, quasi-static testing, and analytical predictions are integrated to provide a coherent description of the seismic response of low-rise reinforced masonry buildings with flexible roof diaphragms. Two half-scale, low-rise reinforced masonry buildings with flexible roof diaphragms are subjected to earthquake ground motions on the Tri-axial Earthquake and Shock Simulator at the United States Army Construction Engineering Research Laboratory, Engineer Research and Development Center. Following the shaking-table tests, diaphragms and top four courses of attached masonry walls are salvaged from the half-scale structures and tested quasi-statically in their own plane. A new index, the diaphragm drift ratio, is introduced to describe the potential for diaphragm damage. In Phase 2 (Analysis), coordinated analytical modeling is developed and implemented to corroborate and extend the results of that experimental work, and to examine the efficacy and accuracy of different analytical modeling approaches. Linear elastic finite-element models, simplified two-degree-of-freedom models, and nonlinear lumped-parameter models are developed; all agree well with measured responses. In Phase 3 (Seismic Evaluation), the first two phases are used to develop and verify a simple extension to FEMA 310, the predominant seismic evaluation methodology for low-rise reinforced masonry buildings with flexible diaphragms. In Phase 4 (Application and Verification), the proposed extension, applied to four existing buildings, is shown to be simple, useful, and necessary.
Seismic Assessment Of Out Of Plane Loaded Unreinforced Masonry Walls
DOWNLOAD
Author : Hossein Derakhshan
language : en
Publisher:
Release Date : 2011
Seismic Assessment Of Out Of Plane Loaded Unreinforced Masonry Walls written by Hossein Derakhshan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Buildings categories.
This thesis investigates the behaviour of URM walls subjected to out-of-plane seismic forces, and the study is focused primarily on single-storey and two-storey one-way spanning walls connected to flexible diaphragms. Expressions that describe the intermediate-height cracking of out-of-plane loaded one-way spanning URM walls were formulated, and wall force-displacement behaviour and the sensitivity to various parameters were studied. Crack height was identified to be particularly sensitive to low values of masonry bond strength and/or to low values of applied overburden. Crack height was found to have significant effects on both wall instability displacement and lateral resistance. A comprehensive quasi-static testing programme was developed by subjecting full-scale two-leaf and three-leaf URM walls to out-of-plane uniform forces. The objective of the tests was to develop an idealised predictive model for the out-of-plane behaviour of URM walls, by accounting the effects of different mortar mixes, multi-leaf construction and overburden loads. An in-field out-of-plane pushover testing programme was next completed, and some of the key questions about actual wall performance were answered. Wall support types and characteristics and their effect on wall behaviour were investigated by testing multiple walls having different support configurations, which included timber diaphragms, concrete ring beam, and grouted steel anchorage bars. The effect of plaster and wall finishings was investigated, and the conditions upon which the previously developed idealised predictive model had acceptable results were determined. A simplified reduced-degree-of-freedom numerical model was developed to study the dynamic behaviour of URM walls, with critical requirements of the model being an ability to account for the effects of flexible supports and an ability to predict the behaviour of two-storey walls. An existing assessment procedure for seismic assessment of out-of-plane loaded URM walls was reviewed in detail, an alternative methodology for wall assessment was introduced, and seismic assessment charts were presented for single-storey and two-storey walls.
Assessment Of Perforated Unreinforced Masonry Walls Responding In Plane
DOWNLOAD
Author : Charlotte Louise Knox
language : en
Publisher:
Release Date : 2012
Assessment Of Perforated Unreinforced Masonry Walls Responding In Plane written by Charlotte Louise Knox and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Buildings categories.
The research presented in this thesis describes the seismic assessment of perforated unreinforced masonry (URM) walls subjected to in-plane loading through accurate analysis of the wall lateral capacity and seismic demand. Current assessment methods for determining the capacity of perforated URM walls loaded in-plane, as outlined in the New Zealand guideline document (NZSEE 2006), are based on the assumption of infinitely rigid spandrel elements. From observations of damage after the 2010/2011 Canterbury earthquake sequence, this assumption has been proven to be invalid for certain perforated wall geometries. The research reported in this thesis was conducted with the primary aim of developing a practitioner focused assessment tool that accurately captured the global and local response of a perforated URM wall, with an emphasis placed on defining the influence of the spandrel geometry on the system level response of perforated URM walls responding in-plane. Pseudo-static cyclic testing of six full-scale pier-spandrel substructures and a two storey half-scale isolated perforated URM wall was conducted to investigate the variables which control spandrel failure mode and the influence of spandrel failure on the lateral capacity of multi-storey URM walls. Testing showed that the behaviour of the spandrel has a significant effect on the failure mode of the piers and hence the strength, stiffness and energy dissipation capacity of the system. A non-linear Equivalent Frame modelling method for perforated URM walls using the structural analysis software SAP2000 was appropriately validated using modelling results and experimental data. Spandrel behaviour was included within the modelling through the use of a moment-axial failure domain and a shear-axial relationship. Finally, a modified linear elastic procedure for assessing the demand on the in_ plane loaded walls of URM buildings with flexible diaphragms was developed and validated through the use of non-linear time history modelling.
Dynamic Response Of Unreinforced Masonry Buildings With Flexible Diaphragms
DOWNLOAD
Author : A. C. Costley
language : en
Publisher:
Release Date : 1996
Dynamic Response Of Unreinforced Masonry Buildings With Flexible Diaphragms written by A. C. Costley and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Building, Brick categories.