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Seismic Performance Assessment of Wood-Frame Shear Wall StructuresJayamon, Jeena Rachel 01 March 2017 (has links)
Wood-frame shear wall structures are widely used for residential and commercial buildings. These buildings are lightweight, have very ductile connections and includes multiple load paths. The main objective of this dissertation is to evaluate the seismic performance of a wide range of wood-frame shear wall building designs under the influence of modeling and analysis parameter variations.
The first step towards the broad objective of seismic performance evaluation is to identify the different modeling and analysis parameters that can have a potential influence in the seismic response variations. The major variations considered in this study include level of critical damping, analytical modeling of damping, hysteresis model shape variations, ground motion characteristics, level of gravity loads, and floor acceleration variations. A subset of building model designs that were originally designed for the development of FEMA P-695 methodology is adapted for the numerical evaluations and a baseline for the variations is established.
To study the sensitivity of inherent damping in wood-frame shear wall structures, an extensive literature survey is completed to find the experimentally observed damping levels in these buildings. Later, nonlinear dynamic analysis is performed for the range of damping levels using different Rayleigh damping models. Ground motion scaling methods, source-to-site distance, and peak intensity levels are the selected variations in ground characteristic group. To assist with the ground motion scaling procedures, a computational toolkit is created to produce amplitude and spectrum matched ground motions for response history analysis. The particular hysteresis model CASHEW that is used for the wood-frame shear wall system has a specific load-displacement shape which is a function of the shear wall design. Three key parameters of this model are varied in a range of values that were observed during experimental tests and seismic performance responses are computed for this variations.
From the performance evaluations it is observed that the seismic response is quite sensitive to several of the modeling parameter variations and analysis variations mentioned above and has a unique response based on the design of the building. The range of performance variations for the different models are outlined in the chapters included in this dissertation. / Ph. D. / Wood-frame shear wall structures are widely used for residential and non-residential buildings worldwide. These buildings have several structural elements which can help the building to resist different load scenarios including wind effects, constant weights, and earthquake hazards. The primary aim of this dissertation is to identify the behavior of different designs of wood-frame shear wall buildings to earthquakes of different intensities through numerical modeling methods.
Analytical prediction of the response of a building to seismic hazards is influenced by several numerical modeling and analysis assumptions and specific characteristics of earthquakes that can occur at the building location. For a reliable prediction of the building response to earthquakes, it is important to study the sensitivity of various modeling assumptions that are considered in the development of numerical models of the buildings. With this objective, a wide range of woodframe building designs and configurations are selected in this dissertation. These building designs are converted to suitable numerical models using computational tools.
For evaluating the sensitivity of the modeling assumptions on the predicted behavior to potential earthquakes, a performance evaluation methodology – FEMA P-695 methodology is selected. This methodology outlines several computational methods which can be used to express the seismic response in terms of certain performance evaluation factors and probability distributions. The seismic responses that can be used in the development of the performance evaluation factors includes the displacement of the building from the original configuration, accelerations felt on the different floor levels, damage occurred on different components attached to the floors and walls of the building.
This dissertation identified the several possible sources of the modeling variations for a wide range of building designs and computed the FEMA P-695 performance evaluation factors. These factors are in turn used to access the sensitivity of the building performance to each of the modeling assumptions.
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An Evaluation of Coastal Community Response to Sea Level Rise on the Delmarva PeninsulaVillanueva, Timothy 27 July 2000 (has links)
The purpose of this project is to evaluate the response of coastal community comprehensive plans to the threats posed by sea level rise. The communities evaluated are Chincoteague, VA, Ocean City, MD, and Rehoboth Beach, DE. The results of the evaluations illustrate to what extent these communities are prepared to deal with sea level rise and provide a basis for recommendations to improve plan quality. The level of community risk and the components of the individual comprehensive plans are evaluated using new models created for this project. Risk level is measured using computer disaster simulations, topographic and demographic data. The plan evaluation criteria include standard plan quality benchmarks and hazard mitigation and adaptation elements suggested by numerous agencies and resources. The plan evaluations range in quality from “poor” to “excellent”. These evaluations will be used to create policy strategies and recommendations for addressing the threat of sea level rise.
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Seismic fragility and retrofitting for a reinforced concrete flat-slab structureBai, Jong-Wha 30 September 2004 (has links)
The effectiveness of seismic retrofitting applied to enhance seismic performance was assessed for a five-story reinforced concrete (RC) flat-slab building structure in the central United States. In addition to this, an assessment of seismic fragility that relates the probability of exceeding a performance level to the earthquake intensity was conducted. The response of the structure was predicted using nonlinear static and dynamic analyses with synthetic ground motion records for the central U.S. region. In addition, two analytical approaches for nonlinear response analysis were compared. FEMA 356 (ASCE 2000) criteria were used to evaluate the seismic performance of the case study building. Two approaches of FEMA 356 were used for seismic evaluation: global-level and member-level using three performance levels (Immediate Occupancy, Life Safety and Collapse Prevention). In addition to these limit states, punching shear drift limits were also considered to establish an upper bound drift capacity limit for collapse prevention. Based on the seismic evaluation results, three possible retrofit techniques were applied to improve the seismic performance of the structure, including addition of shear walls, addition of RC column jackets, and confinement of the column plastic hinge zones using externally bonded steel plates. Finally, fragility relationships were developed for the existing and retrofitted structure using several performance levels. Fragility curves for the retrofitted structure were compared with those for the unretrofitted structure. For various performance levels to assess the fragility curves, FEMA global drift limits were compared with the drift limits based on the FEMA member-level criteria. In addition to this, performance levels which were based on additional quantitative limits were also considered and compared with FEMA drift limits.
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Seismic fragility and retrofitting for a reinforced concrete flat-slab structureBai, Jong-Wha 30 September 2004 (has links)
The effectiveness of seismic retrofitting applied to enhance seismic performance was assessed for a five-story reinforced concrete (RC) flat-slab building structure in the central United States. In addition to this, an assessment of seismic fragility that relates the probability of exceeding a performance level to the earthquake intensity was conducted. The response of the structure was predicted using nonlinear static and dynamic analyses with synthetic ground motion records for the central U.S. region. In addition, two analytical approaches for nonlinear response analysis were compared. FEMA 356 (ASCE 2000) criteria were used to evaluate the seismic performance of the case study building. Two approaches of FEMA 356 were used for seismic evaluation: global-level and member-level using three performance levels (Immediate Occupancy, Life Safety and Collapse Prevention). In addition to these limit states, punching shear drift limits were also considered to establish an upper bound drift capacity limit for collapse prevention. Based on the seismic evaluation results, three possible retrofit techniques were applied to improve the seismic performance of the structure, including addition of shear walls, addition of RC column jackets, and confinement of the column plastic hinge zones using externally bonded steel plates. Finally, fragility relationships were developed for the existing and retrofitted structure using several performance levels. Fragility curves for the retrofitted structure were compared with those for the unretrofitted structure. For various performance levels to assess the fragility curves, FEMA global drift limits were compared with the drift limits based on the FEMA member-level criteria. In addition to this, performance levels which were based on additional quantitative limits were also considered and compared with FEMA drift limits.
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Emergency communications management : analysis and applicationSherbert, Nicole Elizabeth 24 November 2010 (has links)
Adopted in 2003, the National Incident Management System is the nation’s first standardized management system unifying the actions of all levels of governments during a large-scale emergency response. It sets the standard for interagency coordination and communication in the event of an emergency.
This professional report seeks to produce a working, NIMS-compliant emergency communication plan for the City of Austin, Texas.
The report begins with an explanation of NIMS, focusing on the national protocols for interagency communication and public information. It then presents a case study of emergency communications in practice, examining two firestorms in San Diego County, California that occurred four years apart – prior to and after the County’s implementation of NIMS communications protocols.
The report synthesizes best practices in emergency communications – from both NIMS research and the San Diego case study – to create the City of Austin Public Information and Emergency Communication Plan, an operational guide that fully utilizes the tools and organizational structure of all City departments, including the City’s Communications and Public Information Office. / text
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Spaces of uneventful disaster : tracking emergency housing and domestic chemical exposures from New Orleans to national crisesShapiro, Nicholas Edward January 2014 (has links)
In this thesis, I examine the politics, poetics, and logics of uneventful human harm in the United States by tracking the life and afterlife of a chemically contaminated emergency housing unit. In 2005, the Federal Emergency Management Agency (FEMA) deployed 120,000 trailers to the US Gulf Coast to house those displaced by Hurricanes Katrina and Rita. Chemical testing, spurred by reports of inhabitant illness, revealed elevated levels of formaldehyde emanating from the plywood walls of the trailers. After being reclaimed by the federal government and beginning in 2010, the FEMA trailers were resold at auction to every corner of the country. Resold trailers gravitated to precarious populations at the poles of rural capital accumulation—from oil patches in North Dakota to reservations in Washington. These trailers serve as an exceptional substrate for an investigation into the anatomy of the uneventful as they once approached the apex of eventfulness as a national controversy and now reside in the shadows of the everyday. This thesis apprehends and theorizes these dispersed and ordinary instruments of domestic harm across multiple registers: epistemological, material, spatial, and affective. I examine how failures of matter and meaning shaped and patterned the lives of those who inhabited the FEMA trailers as their lives became framed by chemical off-gassing, architectural insufficiency, material deterioration, and electrical short-circuiting. Crossing scales and venues, I interrogate the modalities of scientific incomprehension that erode the perception, admittance, or substantiation of mass chemical exposure. These technical processes, along with cultural horizons of eventfulness and the chronicity of disaster, foreclosed avenues of toxic harm accountability. These ‘economies of abandonment’ bring into relief the contemporary biopolitical priorities in which the FEMA trailer—an ostensible protection from harm that fosters illness—becomes possible. FEMA trailer residents attend to the minute, gradual, and ongoing symptoms of exposure to discern the reality and magnitude of residential contamination. The body of the exposed becomes both an epistemic instrument and, across time, the means of making low-level, chronic, and cruddy chemical exposures into eventful instances that drive individuals to action.
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Understanding the Floodplain Administrator: Measuring and Analyzing Perceived Competence with Implications for TrainingKeys, Chad A 08 1900 (has links)
Utilizing survey data gathered from local local level floodplain administrators (FPAs) operating within Federal Emergency Management Agency Region 6, this study provides a more nuanced understanding of perceived competency among FPAs across key floodplain management topics through the use of a principal component analysis (PCA). PCA identified six distinct components related to perceived competency among FPAs including; Modification and Update Process, General Knowledge, Grants and Programs, Analysis, Development and Real Estate, and Administration and Outreach. The study then employed regression analyses to identify organizational and individual level characteristics that predict perceived competency. Data analyses identified several organizational variables as significant positive predictors of perceived competency including working within an urban community, full-time job status and overall workload percentage dedicated to floodplain management. Additionally, several individual characteristics such as educational attainment, professional certification, previous disaster experience, and years of experience working as an FPA were also identified as significant positive predictors of perceived competency. Based on these findings the study makes several recommendations about improvements to training and educational materials for practitioners and students.
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Influence of the Gravity System on the Seismic Performance of Special Steel Moment FramesFlores Solano, Francisco Xavier 09 April 2015 (has links)
This study investigates the influence of the gravity load resisting system on the collapse performance of Special Steel Moment Frames (SMFs). The influence was quantified using the FEMA P-695 methodology. The buildings used for this study were a 2-, 4- and 8-story SMFs taken from the ATC76-1 project where their collapse performance was already evaluated without the gravity system. The main work of this dissertation has been divided in two parts. The first part studies the influence of the gravity system when it is incorporated explicitly as part of the lateral resisting system. Aspects of the gravity frame that were investigated include the contribution of stiffness and strength of beam to column connections, and the location of splices in the gravity columns. Moreover, this research investigates the potential for the development of inelastic deformations in the gravity columns, and the effect of such deformations on structural response. The results show that gravity connections and gravity column's continuity profoundly affect the computed response and collapse probability. The inelastic behavior in gravity columns has a less important effect but should be included in the analysis.
The second part of the investigation looks more in depth at the role of the gravity columns on the collapse performance of SMFs. Using the 2-, 4- and 8-story SMFs, the gravity columns are incorporated using the approach where all the gravity columns are lumped into one elastic, pinned at the base and continuous element. The approach is first validated by checking different aspects such as: strength of gravity connections to induce yielding into gravity columns, difference between the explicit and lumping column approach, and required gravity column's splices to provide continuity. The stiffness of the element representing the gravity columns was varied in order to find the influence of the gravity columns. At the end of the study it was found that they have a significant influence on the collapse performance of SMFs, especially on taller structures like the 8-story model. Moreover it was concluded that an adequate stiffness of the gravity columns could be found by performing nonlinear static pushover analysis. / Ph. D.
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Seismic Design of Composite Plate Shear Walls -- Concrete-FilledMorgan Renee Broberg (14210369) 07 December 2022 (has links)
<p>Composite plate shear walls – concrete-filled (C-PSW/CF) are a new innovative lateral force resisting system intended for high-rise buildings. The walls consist of parallel steel faceplates connected with tie bars and filled with concrete. This dissertation introduces the C-PSW/CF </p>
<p>system and coupled C-PSW/CFs consisting of C-PSW/CF walls and composite coupling beams. Three studies are presented herein covering seismic design parameters for C-PSW/CFs, non-linear modeling techniques for composite coupling beams, and the design philosophy for coupled C-PSW/CFs.</p>
<p> </p>
<p>The first study summarizes the results of a recent FEMA P695 study completed to verify seismic design parameters for uncoupled C-PSW/CFs with rectangular flange plate boundary elements. Seven archetype structures were: (i) designed, (ii) modeled using a benchmarked fiber-based finite element analysis approach, (iii) subjected to nonlinear pushover analysis, (iv) subjected to incremental nonlinear dynamic analysis to failure for 22-sets of scaled ground motions, and (v) the results were statistically analyzed to assess performance. These structures ranged from three (3) to twenty-two (22) stories and included both planar and C-shaped wall configurations. As part of this design process, recommendations for stiffness approximations for linear analysis of C-PSW/CFs</p>
<p>were developed. Additionally, these nonlinear incremental dynamic analysis results were post-processed to determine the rotation and strain demands at the base of these structures at the design basis, maximum considered, and failure level earthquakes. These results showed that the rotation and strain demand at failure level earthquakes were comparable regardless of the ground motion. Ultimately, this FEMA P695 approach verified the R factor of 6.5, C<sub>d</sub> factor of 5.5, and Ω<sub>0</sub> of 2.5 for C-PSW/CFs with boundary elements. </p>
<p><br></p>
<p>The second study proposes modeling approaches for composite coupling beams used in combination with C-PSW/CFs. Capturing the behavior of these components is critical to understanding the system behavior of coupled C-PSW/CFs, as the coupling beam components undergo yielding, plastification, and fracture prior to collapse of coupled C-PSW/CF walls. Although steel-concrete composite walls have been a known structural system for decades, only recently have coupled C-PSW/CF systems been investigated and implemented as a seismic force resisting system. As the interest in coupled C-PSW/CF systems increases, the necessity of reliable nonlinear modeling techniques for pushover, cyclic, and seismic analysis has become apparent. This paper presents fiber-based options for modeling composite coupling beam components of coupled C-PSW/CF walls for use in nonlinear and seismic response analyses. Recommendations include effective steel and concrete stress-strain curves, modeling parameters for fiber-based </p>
<p>materials, and concentrated plasticity options for additional computational efficiency. These recommendations are then implemented for a full-scale coupling beam section. </p>
<p><br></p>
<p>In the final study, a capacity design principle is used to establish a basis for the seismic design of coupled composite plate shear walls – concrete filled (CC-PSW/CF) systems. This design philosophy implements a strong wall-weak coupling beam approach, where flexural yielding in coupling beams occurs before flexural yielding at the base of walls. The coupling beams are sized </p>
<p>to resist the calculated seismic lateral force level. The walls are sized to resist an amplified seismic lateral force corresponding to the overall plastic mechanism for the structure, while accounting for the capacity-limited forces from the coupling beams and the coupling action between the walls. Based on this philosophy, recommendations and requirements for appropriate sizing of coupling beams and C-PSW/CFs are presented. These recommendations are used to design four example (8-22 story) structures and evaluate their seismic behavior. The structures were modeled using 2D finite element models and fiber-based models subjected to monotonic and time history analysis. </p>
<p>The nonlinear inelastic behavior and seismic responses of the example structures were in accordance with the capacity limited design philosophy (strong wall-weak beam), thus confirming the philosophy’s efficacy. </p>
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Evaluating the unequal impacts of Hurricane Harvey: A critical GIS analysis in systems of governmental risk assessment and mitigationMonk, Mustafa Ansari 07 August 2020 (has links)
This thesis uses flooding driven by Hurricane Harvey in 2017 and a history of inundation in Houston, Texas to critique the systems of floodplain mapping through the National Flood Insurance Program (NFIP). The role of Geographic Information Systems becomes a subject of interest in the context of U.S governance and the role of property as a driving force in urban development. The shortcomings of existing systems of mitigation are examined through mappings that bring measures of risk, damage, and recovery into contrast with each other. Racial and economic inequality are integrated into the analysis through a deeper consideration of the NFIP as the main form of federal protection against losses. Seeing that the NFIP has not protected the true status quo of urban life, it is argued that public perceptions of risk are formed contrary to the logic of home insurance, leading to observable inequalities in preparation and recovery
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