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Evaluation, Modeling, and Retrofit of Flat-Slab Buildings subjected to Seismic LoadingJanuary 1995 (has links)
Flat-slab buildings designed and detailed for gravity loads only typically do not have
the ability to resist moderate earthquakes without experiencing severe damage. The
damage potential of such seismically deficient buildings therefore needs to be
assessed and strategies developed to improve their seismic resistance. Punching
failure at slab-column connections in non-ductile flat-slab buildings during
earthquakes can trigger progressive collapse of floor slabs. Based on the test results
of a large number of interior and exterior connections, a methodology is developed
to predict shear and unbalanced moment-transfer capacities of connections under
combined gravity and lateral loads. Furthermore, a frame analysis procedure is
developed based on the equivalent frame concept which targets both the moment-transfer
capacity as well as stiffness of the interior and exterior slab-column
connections. The approach employs a parametric hysteretic model and is based on
the effective slab-width concept. The proposed procedure for evaluating the seismic
capacity of flat-slab connections and frames is verified by comparing the calculated
and measured responses of two-bay flat-slab subassemblies tested under earthquake-type
loading. Seismic reliability against punching failure of slab-column connections
in flat-slab buildings designed for gravity loads was investigated using the proposed
equivalent frame approach. The reliability analysis indicated that the flat-slab
buildings constructed prior to the 1960's could experience significant damage during moderate intensity earthquakes. By limiting the gravity load on floor slabs and by
controlling the lateral drift, the potential for punching failure in flat-slab buildings
can be minimized. The seismic resistance of older flat-slab buildings can be
improved by retrofitting interior connections to protect against progressive collapse
and by utilizing infill walls to control lateral drift. An economical connection retrofit
scheme is proposed and verified experimentally. The equivalent strut concept is used
to model masonry infills whose effectiveness in controlling the lateral drift is
demonstrated through theoretical analysis of typical flat-slab frames.
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Soil-structure interaction under multi-directional earthquake loadingYan, Xiaorong., 閆晓荣. January 2012 (has links)
The dynamic interaction between the soil and the structure resting on it during
earthquakes can alter the response characteristics both of the structure and the soil.
Despite significant efforts over the past decades, the interaction effect is not yet
fully understood and is sometimes misunderstood. In the context of performance
based design, there remain a number of uncertainties to be addressed seriously.
Current practice of seismic soil-structure response analysis has tended to focus on
the effect of horizontal motion although actual ground motions are comprised of
both horizontal and vertical components. In several recent earthquakes, very
strong vertical ground motions have been recorded, raising great concern over the
potential effect of vertical motion on engineering structures. To address this
emerging problem, seismic response considering the soil-structure interaction
effect to both vertical and horizontal earthquake motions needs to be investigated.
This thesis presents a simple and practical framework for the analysis of site
response and soil-structure interaction to both horizontal and vertical earthquake
motions, which can take into account the soil nonlinearity and material damping
effect. The analysis procedure involves the use of the dynamic stiffness matrix
method and equivalent-linear approach and is built in the modern MATLAB
environment to take the full advantages of the matrix operations in MATLAB.
The input motions can be specified at the soil–bedrock interface or a rock
outcropping. A detailed assessment of the procedure is provided to illustrate that
the procedure is able to produce acceptable predictions of both vertical and
horizontal response of soil-structure systems. It is shown that soil nonlinearity
plays an important role in altering the response of the structure and soil, and the
methods of analysis for soil-structure interaction adopted in current engineering
practice may not be able to adequately account for soil nonlinearity. Furthermore,
effects of a number of influencing factors, such as material damping ratio,
Poisson’s ratio of soil, intensity and location of input motion and the embedment
ratio of the foundation are examined, leading to several useful implications for
seismic engineering practice. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy
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Complete design of a three-story reinforced concrete warehouse frame for a seismic locationDotis, John Constantine, 1927- January 1956 (has links)
No description available.
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Spatial assessment of earthquake induced geotechnical hazardsRockaway, Thomas D. 08 1900 (has links)
No description available.
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Incentives for earthquake hazard mitigation /Teakle, Geraldine Mary Reid. January 1998 (has links) (PDF)
Thesis (M. Env. Sc.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1999? / Includes bibliographical references (leaves 94-99).
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A study of the seismic performance of early multi-story steel frame structures with unreinforced masonry infill a thesis /Potterton, Kristin. Nuttall, Brent. January 1900 (has links)
Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on March 11, 2009. "January 2009." "In partial fulfillment of the requirements for the degree [of] Master of Science in Architecture with a Specialization in Architectural Engineering." "Presented to the faculty of California Polytechnic State University, San Luis Obispo." Major professor: Brent Nuttall, M.S. Includes bibliographical references (p. 82-84). Also available on microfiche.
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FRP confined reinforced concrete circular cross section seismic applications a thesis /Lyon, Jeffrey Gordon. Chadwell, Charles Brian. January 1900 (has links)
Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on Sept. 16, 2009. "August 2009." "In partial fulfillment of the requirements for the degree [of] Master of Science in Civil and Environmental Engineering." "Presented to the faculty of California Polytechnic State University, San Luis Obispo." Major professor: Charles B. Chadwell, Ph.D. Includes bibliographical references (p. 67-71).
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A Methodology for Regional Seismic Damage Assessment and Retrofit Planning for Existing BuildingsMcCormack, Thomas C. 01 January 1996 (has links)
Recent geologic research has shown that earthquakes more destructive than formerly expected are likely to occur in the Pacific Northwest. To mitigate catastrophic loss, planners are gathering information to make decision on implementing regional seismic retrofit programs. This research develops a model to estimate regional earthquake losses for existing buildings, and determine optimal retrofit priorities and budgets. Fragility curves are developed to provide earthquake damage estimates for a range of seismic intensities. The published earthquake damage estimates of a large group of prominent earthquake engineering experts are extended to include the combined effect of structure type, earthquake-sensitive variations in building design, site-specific soil conditions, and local seismic design practice. Building inventory data from a rapid visual screening survey of individual buildings form the basis for modeling structural variations. Earthquake Hazard Maps are the basis of modeling the effect on building damage of ground motion amplification, soil liquefaction, and slope instability. Published retrofit effectiveness estimates and retrofit cost data are used to estimate post-retrofit damage avoided, lives saved, and retrofit cost. A Building Classification System is formulated to aggregate buildings with similar retrofit benefit magnitudes. A cost-benefit analysis is used as the basis for a retrofit prioritization and efficiency analysis, to establish the cut-off point for an optimal retrofit program. Results from an Expected Value and a Scenario Earthquake Event are compared. Regional Earthquake Loss and Retrofit Analysis Program (REAL-RAP) software was developed, and used to make a loss estimate for more than 7,500 buildings inventoried in the 1993 Portland Seismic Hazards Survey. One hundred percent of the loss of life is attributed to only 10-percent of the buildings. A retrofit analysis is made for a Design Basis Earthquake. Twelve-percent of the building inventory was identified for the optimal retrofit program, wherein 98-percent of the loss of life is avoided at less than one-quarter the cost of retrofitting all the buildings. An alternate optimal retrofit program was determined using an Expected Value Analysis. Most of the buildings in the Design Basis Earthquake optimal retrofit program are also contained in the alternate program.
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Nonlinear effects in ground motion simulations: modeling variability, parametric uncertainty and implications in structural performance predictionsLi, Wei 08 July 2010 (has links)
While site effects are accounted for in most modern U.S. seismic design codes for building structures, there exist no standardized procedures for the computationally efficient integration of nonlinear ground response analyses in broadband ground motion simulations. In turn, the lack of a unified methodology affects the prediction accuracy of site-specific ground motion intensity measures, the evaluation of site amplification factors when broadband simulations are used for the development of hybrid attenuation relations and the estimation of inelastic structural performance when strong motion records are used as input in aseismic structural design procedures.
In this study, a set of criteria is established, which quantifies how strong nonlinear effects are anticipated to manifest at a site by investigating the empirical relation between nonlinear soil response, soil properties, and ground motion characteristics. More specifically, the modeling variability and parametric uncertainty of nonlinear soil response predictions are studied, along with the uncertainty propagation of site response analyses to the estimation of inelastic structural performance. Due to the scarcity of design level ground motion recording, the geotechnical information at 24 downhole arrays is used and the profiles are subjected to broadband ground motion synthetics.
For the modeling variability study, the site response models are validated against available downhole array observations. The site and ground motion parameters that govern the intensity of nonlinear effects are next identified, and an empirical relationship is established, which may be used to estimate to a first approximation the error introduced in ground motion predictions if nonlinear effects are not accounted for.
The soil parameter uncertainty in site response predictions is next evaluated as a function of the same measures of soil properties and ground motion characteristics. It is shown that the effects of nonlinear soil property uncertainties on the ground-motion variability strongly depend on the seismic motion intensity, and this dependency is more pronounced for soft soil profiles. By contrast, the effects of velocity profile uncertainties are less intensity dependent and more sensitive to the velocity impedance in the near surface that governs the maximum site amplification.
Finally, a series of bilinear single degree of freedom oscillators are subjected to the synthetic ground motions computed using the alternative soil models, and evaluate the consequent variability in structural response. Results show high bias and uncertainty of the inelastic structural displacement ratio predicted using the linear site response model for periods close to the fundamental period of the soil profile. The amount of bias and the period range where the structural performance uncertainty manifests are shown to be a function of both input motion and site parameters.
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The response of silt-clay mixtures to cyclic loadingRaybould, Matthew James January 1991 (has links)
No description available.
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