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Evaluation of lateral strength and deflection for unreinforced masonry cracked walls
No full textAn evaluation methodology for lateral strength and deflection of unreinforced masonry cracked walls is developed in this study. With this approach, the post cracked behavior is considered by neglecting the shear transfer across the cracked masonry. Based on the developed shear and normal stress distributions with cracking, the possible failure modes in an unreinforced masonry wall are examined. Some failure criteria are directly related to the results of nondestructive measurements. To consider effects of cracking, the conventional expression for lateral deflection is modified with shear and flexural deformation amplifying factors. The feasibility of the evaluation procedure is verified through correlation with the results of experimental work done by others. Based on the proposed procedure for lateral strength, the tabulated lateral strengths corresponding to the different material parameters and different wall length-to-height aspect ratios are presented, which provide the possibility for using current research results in engineering practice.Made available in DSpace on 2011-05-07T13:07:58Z (GMT). No. of bitstreams: 2
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Previous issue date: 1992Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:50:37Z
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Behavior of reinforced concrete frames with masonry infill walls
No full textOut-of-plane behavior and strength of cracked masonry panels cannot be accurately predicted. This report increases the knowledge and understanding of the behavior observed in masonry panels, and provides tools to estimate their ultimate capacities.An analytical model was developed to predict the out-of-plane behavior and strength of masonry panels with and without previous in-plane damage. The analytical model was based on an arching action theory. Analytical model parameters included the masonry compressive strength, the infill slenderness ratio, and the extent of in-plane damage experienced by the panel prior to the out-of-plane testing.Experimental testing of a series of specimens was done to verify predictions by the analytical model. Horizontal forces were applied (a) parallel to the plane of an infill and (b) normal to the plane of an infill. Specimens consisted of full-scale reinforced concrete frames with clay brick or concrete block masonry infills. Test specimens were first loaded statically in the in-plane direction up to an arbitrary relative deflection which produced a shear-cracked infill. Specimens were then loaded monotonically with uniform pressures normal to their plane using an air bag. After loading to failure, specimens were repaired and retested.Based on the analytical model and on the supporting experimental results, this research resulted in the development of a seismic evaluation and rehabilitation procedure for unreinforced masonry infill panels loaded normal to their plane.Made available in DSpace on 2011-05-07T14:11:28Z (GMT). No. of bitstreams: 2
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Previous issue date: 1994Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T15:03:57Z
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Out-of-Plane Seismic Response of Unreinforced Masonry Walls: Conceptual Discussion, Research Needs, and Modeling Issues
Get PDFModeling unreinforced masonry walls, subjected to seismic loads applied normal to their plane,
has received much attention in the past. Yet, there is a general lack of conformance with regard to
what aspects of seismic response a computational model should reflect. Boundary conditions are
certainly an important aspect, as the response can involve two-way bending or just one-way
bending and, in the second case, along vertical or horizontal directions. In this respect, flexural
restraint of wall intersections can be significant in addition to size and placement of openings.
Moreover, in-plane damage can modify the boundary conditions and the overall out-of-plane
performance. Proper modeling of actions is also relevant, as they can be a result of distortions
imposed upon wall elements and/or inertial forces along the span of a wall. Axial forces can
markedly affect the out-of-plane response of the wall, particularly vertical compressive forces,
which can enhance out-of-plane strength. The outcome of static verifications can be more
conservative than that of dynamic analyses, but the latter are much more complex to carry out.
These topics are discussed with reference to previous research, observations in the field and in the
laboratory, as well as numerical analyses on three-dimensional models
An experimental study of the response of reinforced masonry building systems to earthquake motions
No full textExperiments were performed to study the dynamic response of reinforced concrete masonry building structures. Two reduced-scale reinforced masonry perforated shear wall structures were subjected to simulated earthquake motions on a shaking table. A third was tested using conventional static methods to provide insight into differences in behavior of systems that are subjected to artificial static forces and those allowed to develop natural inertial forces.Experimental data were studied to determine trends in nonlinear dynamic response and to evaluate current practice for seismic design and analysis. Analysis of measured response identified simplified procedures for evaluating lateral strength and seismic drift of reinforced masonry structures. It was suggested that sufficient lateral strength could be provided in the piers of a perforated wall structure by placement of minimum amounts of vertical reinforcement and selection of horizontal reinforcement by a capacity design approach. The use of a substitute linear method was suggested for assessing the stiffness (based on lateral drift) of a trial structural configuration.Made available in DSpace on 2011-05-07T13:12:10Z (GMT). No. of bitstreams: 2
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Previous issue date: 1991Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:51:35Z
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Dynamic response of URM buildings with flexible diaphragms
No full textAs 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.Made available in DSpace on 2011-05-07T12:10:17Z (GMT). No. of bitstreams: 2
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Previous issue date: 1995Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:37:38Z
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Response of an unreinforced masonry building during the Loma Prieta earthquake
No full textThe subject structure of this study is a two-story historic building and former firehouse located in downtown Gilroy, California. The structure was built in 1890 and it is one of the first URM buildings that has been both instrumented and subjected to a moderate earthquake in U.S. history. Recorded peak ground accelerations were as high as 0.29g and peak roof accelerations as high as 0.79g. Considerable amplifications of the peak accelerations between the ground and the roof were observed. The former firehouse withstood the Loma Prieta Earthquake with little damage.Unreinforced masonry construction used in Northern California at the turn of this century was similar throughout the United States. Because moderate earthquakes are expected east of the Rocky Mountains, the response of the firehouse can help foretell the earthquake hazard in the eastern and midwestern United States. The ground motions recorded at the firehouse represent an upper bound for assessing possible hazards associated with similarly constructed buildings in the eastern United States. Since the firehouse was not appreciably damaged, even with these high accelerations, there is hope that similar historic buildings across the nation may survive a future earthquake. However, such extrapolation is not warranted unless a detailed investigation is done to examine the reasons for the superior performance.The objectives of this study are the following: (1) Investigate the reasons of the survival of the firehouse of Gilroy with the use of both simplified and state-of-the-art methods. (2) Present a simplified discrete MDOF dynamic model developed for the seismic evaluation of the firehouse and similar URM buildings with flexible diaphragms. (3) Correlate the recorded, observed and computed response of the firehouse with estimates of dynamic response and prescribed allowable stress limits by state-of-the-art masonry and seismic codes.Made available in DSpace on 2011-05-07T12:41:37Z (GMT). No. of bitstreams: 2
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Previous issue date: 1992Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:44:27Z
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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