Browsing by Author "van de Lindt, John W., advisor"
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Item Open Access A multi-objective community-level sesimic retrofit optimization combining social vulnerability with an engineering framework for community resiliency(Colorado State University. Libraries, 2015) Jennings, Elaina N., author; van de Lindt, John W., advisor; Atadero, Rebecca, committee member; Mahmoud, Hussam, committee member; Peek, Lori, committee memberThis dissertation presents a multi-objective optimization framework for community resiliency by providing decision maker(s) at the local, state, or other government level(s) with an optimal seismic retrofit plan for their community's woodframe building stock. A genetic algorithm was selected to perform the optimization due to its robustness in multi-objective problem solving. In the present framework, the algorithm provides a set of optimal community-level retrofit plans for the woodframe building inventory based on the socio-demographic characteristics of the focal community, Los Angeles, California. The woodframe building inventory was modeled using 37 archetypes designed to several historical and state-of-the-art seismic design provisions and methodologies. The performance of the archetypes was quantified in an extensive numerical study using nonlinear time history analysis. Experimental testing was conducted at full scale on a three-story soft-story woodframe building. The experimental testing investigated the seismic performance of several retrofit strategies for use in the framework, and the results were used in development of a metric correlating inter-story drift limits with damage states used in the framework. A performance-based retrofit design is presented in detail, and the experimental testing results of four retrofits are provided as well. The algorithm uses each archetype's seismic performance to identify the set of optimal community-level retrofit plans to enhance resiliency by minimizing four objectives: initial cost, economic loss, number of morbidities, and recovery time. In the model, initial cost sums the cost of each new retrofit, economic loss incorporates direct and indirect costs; the number of morbidities includes injuries, fatalities, and persons diagnosed with post-traumatic stress disorder (PTSD); and a recovery time is estimated and may be used to represent the loss in quality of life for the affected population. The framework was calibrated to the estimated losses from the 1994 Northridge earthquake. An application of the framework is presented using Los Angeles County as the community. Two forecasted populations are also examined using the census data for Daly City, California and East Los Angeles to further exemplify the framework. Analyses were conducted at six seismic intensities. In all illustrative examples, the total financial loss (e.g., initial cost + economic loss) was higher for the initial population (i.e. un-retrofitted community). When combining this financial savings with the reduced number of morbidities, it is clear that the higher initial cost associated with retrofitting the woodframe building stock greatly outweighs the risks and losses associated with not retrofitting. The results also demonstrated how retrofitting the existing woodframe building stock greatly reduces estimated losses, especially for very large earthquakes. The resulting losses were further investigated to demonstrate the important role that the mental health of the population plays in a community's economy and recovery following disastrous events such as earthquakes. Overall, the results clearly demonstrate the necessity in including social vulnerability when assessing or designing for community-level resiliency for a seismic hazard.Item Open Access A resilience-based decision framework to determine performance targets for the built environment(Colorado State University. Libraries, 2018) Masoomi, Hassan, author; van de Lindt, John W., advisor; Ellingwood, Bruce R., committee member; Mahmoud, Hussam N., committee member; Senior, Bolivar, committee memberCurrent design codes and standards focus on the design of individual facilities. A typical building is designed with the objective of the life safety of occupants. Even performance-based design approaches assess the required physical performance of an individual structure in order to satisfy prescribed criteria for that structure individually. Thus, even these performance objectives are likely not sufficient for a broad view of community-resilience goals. A modern community is made up of highly coupled networks, and disruptions within one or more networks may lead to disruptions to other networks. If a large number of buildings within a community become non-functional for a long time following an event, either because of physical damage or loss of utilities such as electric power and/or water, the consequences may affect other parts of the community such that, eventually, significant socioeconomic losses occur. Therefore, the current approach for designing individual physical components within a community can be reimagined such that it not only takes into account the performance of a component individually after a catastrophic event but also considers the consequences its design has on a community. The main purpose of this dissertation is to develop a methodology that links the performance of components within the built environment to community-level resilience goals by considering the dependencies and cross-dependencies between components and networks. Therefore, ultimately, this methodology enables disaggregation of the community-level objectives into a set of performance targets for the components of the built environment, which leads itself to the needs of policymakers and community leaders in order to make long-term planning decisions for a community.Item Open Access Damage analysis and mitigation for wood-frame structures subjected to tornado loading(Colorado State University. Libraries, 2016) Standohar-Alfano, Christine Diane, author; van de Lindt, John W., advisor; Ellingwood, Bruce R., committee member; Heyliger, Paul R., committee member; Schumacher, Russ S., committee memberTornadoes are one of the most devastating natural hazards that occur in the United States. While there is an average of approximately 1200 tornadoes per year across the country, the annual likelihood of experiencing a tornado at a particular location is quite small due to their relatively small size. However, the high consequence of a tornado strike necessitates the determination of geographic tornado hazard. A methodology to estimate the annualized probabilistic tornado hazard over the contiguous U.S. was developed and used the most recent 38 years of climatological tornado data. Furthermore, with the use of detailed damage surveys after the April 3-4, 1974 and April-May, 2011 tornado outbreaks, an empirical method was developed and applied to account for the gradient of wind speed along a tornado’s path length and path width. From this, a probabilistic tornado hazard index was developed across the United States which quantified the annual probability of experiencing a tornado of any strength on the Enhanced Fujita scale. Tornado hazard curves were developed from the tornado hazard analysis at six illustrative locations which varied as a function of location-specific occurrence rates. Five different residential wood-frame building archetypes were designed at each of the locations based on current residential building code and/or practice. Fragilities for the roof sheathing, truss to wall top-plate, and wall-to-foundation connections were developed for each archetype. At each of the six locations, the fragility curves for the locally adopted residential building code were convolved with the tornado hazard curve at that specific location in order to compute annual failure probabilities for select components along the vertical load path. This was one of the first times unconditional risk of component failure due to tornadoes has been computed since the tornado hazard curve was convolved with the fragility curves. These probabilities quantify failure probabilities of residential wood-frame construction components to tornado winds. In addition, the more wind-resistant Florida residential building code is applied to other locations in the U.S., fragilities are developed and convolved, and failure probabilities for these modified buildings are computed. This resulted in a quantitative measure of risk reduction from tornadoes by using strengthened construction at various locations across the country. The convolved failure probabilities were first developed for individual components. The system level behavior of the entire structure was also assessed and included the correlated dependencies between individual components. Results indicate that stricter building codes may be beneficial in areas with a high annual tornado risk, such as Tornado Alley. The final portion of this work used a simplified property loss model applied to the April 25-28, 2011 tornado outbreak. This was one of the largest tornado outbreaks in U.S. history and resulted in over $5B in property loss. In order to determine property loss over a broad area, census data regarding household income and home market value was utilized. The performance of manufactured homes had to be considered in conjunction with wood-frame residential construction since the tornado outbreak impacted the southern U.S. which has a high number of manufactured homes. Using the system level fragility analysis, property loss was estimated based on both locally adopted residential codes and the stricter guidelines described in the Florida Residential Building Code. Results indicate that using strengthened construction methodologies would reduce property loss up to 40% as compared to current design guidelines.Item Open Access Determination of seismic performance factors for cross laminated timber shear wall system based on FEMA P695 methodology(Colorado State University. Libraries, 2018) Amini, Mohammad Omar, author; van de Lindt, John W., advisor; Mahmoud, Hussam, committee member; Heyliger, Paul, committee member; Senior, Bolivar, committee memberCross Laminated Timber (CLT) was initially introduced in Europe and has recently gained popularity in North America where it is seen as a sustainable alternative to steel and concrete in midrise construction. Although most CLT structures to date have been constructed in low seismic regions, recent tests have indicated that CLT based lateral force resisting systems can successfully be utilized in regions of higher seismicity. Despite the many advantages that CLT offers, the lack of a design code and systematic design procedure is one of many challenges inhibiting widespread adoption of CLT in the US. The purpose of this study was to investigate the seismic behavior of CLT based shear wall systems and determine seismic performance factors, namely, the response modification factor (R-factor), the system overstrength factor (Ω), and the deflection amplification factor (Cd), using the FEMA P695 procedure. The methodology is an iterative process that includes establishing design requirements, developing archetypes, performing a series of tests, developing and validating nonlinear models, nonlinear static and dynamic analysis, and evaluating performance; all in conjunction with a peer panel to provide input. Nine index buildings that include, single-family dwellings, multi-family dwellings, and commercial (including mixed-use) mid-rise buildings were developed. Archetypes were then extracted from these index buildings. Testing performed at the component and subassembly levels include connector tests and isolated shear wall tests. A subsequent full-scale shake table test was performed for system level demonstration. A critical aspect of this study is use of generic connectors whose properties are already addressed by a design specification to facilitate building code recognition. Test-based performance for these generic connectors is reported as part of this study to facilitate evaluation of proprietary alternatives for seismic equivalence. Connector tests were performed on angle brackets, used for attachment of the wall to the supporting element, and inter-panel connectors. These tests showed connector thickness to be important in achieving the desired ductile behavior with lesser thickness (12 gauge) being the more favorable. Quasi-static cyclic tests were conducted for a portfolio of CLT shear walls to systematically investigate the effects of various parameters. CLT demonstrated rigid behavior with energy dissipation concentrated in the connectors. Boundary constraints and gravity loading were both found to have a beneficial effect on the wall performance, i.e. higher strength and deformation capacity. Specific gravity also had a significant effect on wall behavior while CLT thickness was less influential. Higher aspect ratio panels (4:1) demonstrated lower stiffness and substantially larger deformation capacity compared to moderate aspect ratio panels (2:1). However, based on the test results there is likely a lower bound for aspect ratio (at 2:1) where it ceases to benefit deformation capacity of the wall. Multi-panel configuration comprised of high aspect ratio panels connected through vertical joint demonstrated considerably larger deformation capacity. Shake table tests showed the proposed system's potential to meet life-safety code requirements and its applicability in US seismic regions. A CLT shear wall design method was developed and refined based on the test results. Phenomenological models were used in modeling CLT shear walls. The archetypes were designed based on the proposed design method and were numerically evaluated by assessing their performance using nonlinear static and dynamic analyses. Based on the rigorous process, an R factor of 3 is proposed for the CLT shear wall systems and an R factor of 4 is proposed for the cases with high aspect ratio panels only. Results from the study will be proposed for implementation in the seismic design codes and standards in the US.Item Open Access Evaluation of new reactive FRP reinforcement assemblies for reinforced concrete transportation structures(Colorado State University. Libraries, 2014) Bright, Christopher, author; van de Lindt, John W., advisor; Atadero, Rebecca, advisor; Radford, Donald, committee memberThis thesis evaluates two new glass-fiber reinforced polymer concrete reinforcement systems which have been designed to serve as a non-corrosive alternative to steel reinforcement in reinforced concrete bridge girders. Due to the nature of the reinforcement geometry, these systems react in a way to introduce compressive confinement into the concrete in the inner regions of the system units. The introduction of this compressive confinement zone will increase particle interaction effects which results in increased shear and tensile force resistance contributed by the affected concrete. The system is also well integrated into the surrounding concrete matrix, therefore eliminating the potential for debonding failures. A proof of concept is conducted in order to evaluate a set of alternative reinforcement system prototypes. Before the reinforcement systems are evaluated, technical literature pertaining to alternative reinforcements is reviewed. Select specimens provided evidence of sufficient mechanically constrictive behavior. Indications of good bond strength and shear strength contribution from the flexural reinforcement systems were also found. Parameters which control the structural behavior of the reinforcement system were identified.Item Open Access Fragility approach for performance-based design in fluid-structure interaction problems, Part I: Wind and wind turbines, Part II: Waves and elevated coastal structures(Colorado State University. Libraries, 2016) Do, Trung Quang, author; van de Lindt, John W., advisor; Heyliger, Paul R., committee member; Mahmoud, Hussam N., committee member; Zahran, Sammy, committee memberThis dissertation focuses on a methodology for performance-based design using fragilities in fluid-structures interaction problems. Two types of fluid-structure interaction problems are investigated in this dissertation: Part I: wind-structure interaction (for wind turbine tower-base fatigue), and Part II: wave-structure interaction (for elevated coastal structures subjected to shear and uplift loading). The first problem type focuses on performance-based design of a wind turbine tower base connection subjected to wind loading using a fatigue limit state. A finite element model for wind turbines is subjected to nonlinear wind loading in the time domain. The relative motion of the actual wind speed and velocity of the moving blades in the along-wind direction creates force nonlinearity for the applied wind load, and hence, necessitates a fluid-structure interaction model. Then, a model for fatigue assessment including crack propagation was developed for the tower base connection. The inclusion of crack propagation is expected to extend the service life of the tower compared to conventional fatigue life analysis using the characteristic S-N approach. By varying the tower thickness, diameter, and considering predefined levels of crack propagation, fragility curves based on a fatigue life limit state are developed for the application of performance-based design. The desired fatigue life of a wind turbine tower for different wind sites can be obtained based on the fragilities. Finally, an illustrative example of performance-based design for a typical 5-MW wind turbine throughout Colorado is used as an illustrative example in this study. The second type of problem focuses on development of a performance-based design methodology for elevated coastal structures such as bridges and buildings. Initial numerical results are compared to existing data from a large-scale bridge section test and a full-scale transverse wood wall tested previously at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. These validations provide the foundation for developing a method of wave generation for interaction with bridge and building models. By introducing fragility modeling, a variety of design options can be considered consisting of either raising the elevation of the bridge or strengthening the structure itself in order to obtain the desired probability of failure for a specified of hurricane surge and wave intensity.Item Open Access High-resolution multi-hazard approach to quantify hurricane-induced risk for coastal and inland communities(Colorado State University. Libraries, 2021) Nofal, Omar M., author; van de Lindt, John W., advisor; Cutler, Harvey, committee member; Mahmoud, Hussam N., committee member; Guo, Yanlin, committee memberHurricanes are devastating natural hazards that often cause damage to coastal and in-land communities as a result of their loadings which include storm surge, waves, wind, and rainfall and riverine flooding, often in combination. Modeling these hazards individually and their effects on buildings is a complex process in that each loading component within the hazard behaves differently affecting either the building envelope, the structural system, or the interior contents. For coastal communities, realistic modeling of hurricane effects requires a multi-hazard approach that considers the combined effects of wind, surge, and waves. Previous studies have focused primarily on modeling these hazards individually with less focus on the multi-hazard impact on the whole building system made up of the combination of structure and its interior contents. For inland communities, high-resolution hydrologic and hydrodynamic models are required to develop high-fidelity flood hazard maps that account for the different hazard characteristics (e.g., flood depth, velocity, duration, etc.). The current flood damage assessment standards are still using stage-damage functions to account for flood damage to buildings. These functions include inherent uncertainties in the damage assessment with significant limitations on their applications. Additionally, the analysis resolution used in these previous studies did not allow hurricane risk assessment through at the building component level (e.g., interior content, structural, and non-structural components). To address these research gaps, a high-resolution flood risk model was developed for inland communities using robust probabilistic flood fragility functions developed for a portfolio of 15 building archetypes that can model the flood vulnerability at the community-level. For coastal communities, a regional-level multi-hazard hurricane risk analysis methodology is proposed to account for the combined impacts of wind-surge-wave loadings driven by hurricanes for both the building system and its interior contents. Fragility functions are used to describe building vulnerability to the multiple loadings driven by hurricanes, and a new convolutional vulnerability approach was developed to combine wind and wave/surge fragilities. The models developed in this dissertation were included in an open-source Interdependent Networked Community Resilience Modeling Environment (IN-CORE) to allow researchers/users to systematically use these models in different types of engineering, social, and economic analyses. The analysis resolution used in the hazard, exposure, and vulnerability models allowed investigation of different levels of mitigation measures including component-, building-, and community-level mitigation strategies. The proposed hurricane risk models for coastal and in-land communities were then applied to a number of case studies to demonstrate the ability of the developed methods to predict damage at the building level across a large spatial domain of small and large communities. The main contribution of these efforts is the development of generalized fragility-based flood vulnerability functions that were applied to a suit of building archetypes and are extendable to be used for other buildings/facilities. These fragilities were then combined with another suite of existing wind fragilities and other storm surge-wave fragility functions to account for the impact of the hurricane-induced hazards on coastal communities. These models enable a better understanding of the damages caused by hurricanes for coastal and in-land communities, thereby setting initial post-impact conditions for community resilience assessment and investigation of recovery policy alternatives.Item Unknown Optimizing resilience decision-support for natural gas networks under uncertainty(Colorado State University. Libraries, 2019) Ameri, Mohammad Reza, author; van de Lindt, John W., advisor; Chen, Suren, committee member; Jia, Gaofeng, committee member; Shields, Martin, committee memberCommunity resilience in the aftermath of a hazard requires the functionality of complex, interdependent infrastructure systems become operational in a timely manner to support social and economic institutions. In the context of risk management and community resilience, critical decisions should be made not only in the aftermath of a disaster in order to immediately respond to the destructive event and properly repair the damage, but preventive decisions should to be made in order to mitigate the adverse impacts of hazards prior to their occurrence. This involves significant uncertainty about the basic notion of the hazard itself, and usually involves mitigation strategies such as strengthening components or preparing required resources for post-event repairs. In essence, instances of risk management problems that encourage a framework for coupled decisions before and after events include modeling how to allocate resources before the disruptive event so as to maximize the efficiency for their distribution to repair in the aftermath of the event, and how to determine which network components require preventive investments in order to enhance their performance in case of an event. In this dissertation, a methodology is presented for optimal decision making for resilience assessment, seismic risk mitigation, and recovery of natural gas networks, taking into account their interdependency with some of the other systems within the community. In this regard, the natural gas and electric power networks of a virtual community were modeled with enough detail such that it enables assessment of natural gas network supply at the community level. The effect of the industrial makeup of a community on its natural gas recovery following an earthquake, as well as the effect of replacing conventional steel pipes with ductile HDPE pipelines as an effective mitigation strategy against seismic hazard are investigated. In addition, a multi objective optimization framework that integrates probabilistic seismic risk assessment of coupled infrastructure systems and evolutionary algorithms is proposed in order to determine cost-optimal decisions before and after a seismic event, with the objective of making the natural gas network recover more rapidly, and thus the community more resilient. Including bi-directional interdependencies between the natural gas and electric power network, strategic decisions are pursued regarding which distribution pipelines in the gas network should be retrofitted under budget constraints, with the objectives to minimizing the number of people without natural gas in the residential sector and business losses due to the lack of natural gas in non-residential sectors. Monte Carlo Simulation (MCS) is used in order to propagate uncertainties and Probabilistic Seismic Hazard Assessment (PSHA) is adopted in order to capture uncertainties in the seismic hazard with an approach to preserve spatial correlation. A non-dominated sorting genetic algorithm (NSGA-II) approach is utilized to solve the multi-objective optimization problem under study. The results prove the potential of the developed methodology to provide risk-informed decision support, while being able to deal with large-scale, interdependent complex infrastructure considering probabilistic seismic hazard scenarios.Item Unknown Performance based design of woodframe structures for flooding(Colorado State University. Libraries, 2007) Taggart, Mason, author; van de Lindt, John W., advisor; Johnson, Bradly Thomas, committee member; Chen, Suren, 1973-, committee memberIn 2005 Hurricane Katrina demonstrated how devastating flood waters can be to residential structures. Obviously, life safety of the inhabitants is the most critical issue for residential buildings followed by financial (property) loss due to water damage. This paper presents a methodology, software, and several examples for the design of wood frame residential structures for for flood. The methodology is based on probabilistic flood hazard and provides the owner and engineer with a fragility for annualized loss or for loss over the anticipated/expected lifetime of the building. The primary purpose of this information is to aid in decision making during the planning, construction or retrofit/repair process. The approach is based on known properties of wood and housing products, and when not available, reasonable interpretations/assumptions were used based on discussion with colleagues in the wood and/or housing industry.Item Unknown Performance-base seismic design of woodframe buildings using non-linear time history analysis(Colorado State University. Libraries, 2010) Liu, Hongyan, author; van de Lindt, John W., advisor; Criswell, Marvin E., committee member; Heyliger, Paul R., committee member; Senior, Bolivar, committee memberPerformance-based seismic design (PBSD) is a developing design methodology in the modern seismic design and research community and has already been applied to concrete and steel structures. However, the application to woodframe buildings, which represents the vast majority of the residential building stock in North America, is still under early stage of development. The total economic loss directly connected with woodframe structures was more than $20 billion after the 1994 Northridge earthquake in California. This lesson provided the impetus for both engineers and researchers to realize that seismic design should focus on system behavior during an earthquake event instead of just at the component behavior, in other words, explicitly considering system behavior and performance of a structure. The current focus in force-based design philosophy for wood looks at the component level and then makes the assumption that system performance is ensured by the component design. Because of the limitations in current design methodology and concerns of system level performance, the concept of PBSD is being adapted and applied to woodframe buildings. The ultimate goal of this study is to develop a generalized PBSD procedure that can provide a specific level of performance for woodframe buildings under prescribed earthquake loading levels. In order to achieve this goal, this study focuses on four objectives. The first objective is to develop a conceptual PBSD procedure suitable for woodframe buildings. This includes defining the performance expectations at system level with explicit probability measures, choosing an appropriate format for the design requirements, deciding on the numerical tools and steps to determine the design that satisfies these design requirements. The second objective is to improve the existing numerical model and include base isolation device as an option to woodframe buildings for the PBSD. This task involves numerical modeling and experimental testing of friction pendulum sliding bearing base isolation devices on the shake table at CSU. The third objective is to apply the proposed design procedure to realistic building designs. This includes several design examples in this study having different floor plans from low-rise to mid-rise buildings. The examples included in this study cover several typical floor plans in the U.S. for residential buildings. The design example also includes the use of FP base isolation on a mid-rise woodframe structure. Finally, the last objective of this study is to develop a simplified design procedure that can be used by average engineers without using advanced structural models and non-linear time history analysis. This was accomplished by developing the design tables that are generated through simplified models using non-linear time history analysis. The results are checked with full simulation thereby validating the approach. The most significant anticipated contribution of this study to the woodframe design and research communities will be the development of a generalized PBSD and is only applied to a limited number of examples in this dissertation, the format of this procedure was based on and improved from the current state-of-the-research and can be extended to many different situations including base isolation as demonstrated herein. The simplified design procedure and the format of the design table is a good candidate for incorporation of PBSD into design practice because of the prescriptive approach.Item Unknown Performance-based seismic retrofit (PBSR) methodology for multi-story buildings with full-scale experimental validation(Colorado State University. Libraries, 2015) Bahmani, Pouria, author; van de Lindt, John W., advisor; Heyliger, Paul R., committee member; Mahmoud, Hussam N., committee member; Radford, Donald W., committee memberRecent earthquakes such as Loma Prieta (1989) and Northridge (1994) in California have highlighted the poor performance of one class of existing buildings. Many older buildings were designed prior to the implementation of modern seismic design codes. Although building codes have clearly evolved, the problem is still unresolved for older buildings that are code-deficient such as soft-story wood-frame buildings. Many retrofit procedures have been proposed by the research and structural engineering communities including force-based and performance-based retrofit methodologies. A performance-based seismic retrofit (PBSR) methodology is developed and validated in this dissertation and is a method that seeks to meet or exceed minimum performance criteria specified by building stakeholders when the building is subjected to a predefined seismic intensity level. Unlike traditional force-based design methods, the PBSR method enables engineers to design and retrofit buildings based on the performance level expected by the stakeholders; and eventually, results in a more comprehensive method of retrofitting multi-story buildings. The objective of this study was twofold. The first objective was to develop a new displacement-based design (DBD) method with the ability to account for torsion (DBDT), thereby, generalizing the displacement-based design to be applied to linear and non-linear structures with vertical and torsional (horizontal) irregularities without the need for time-history analysis. This first objective involves the decoupling of translational and torsional mode shapes of the structure, standardizing the global stiffness and mass matrices, and finally combining the decoupled translational and torsional mode shapes to meet the designated performance criteria. The second objective was to develop a new performance-based seismic retrofit (PBSR) methodology for retrofitting existing multi-story buildings with torsional (horizontal) and vertical irregularities. The PBSR method was developed using the proposed DBDT method and was validated numerically to retrofit a three-story soft-story building with excessive torsion at all stories. The PBSR method was then modified to eliminate the torsion in the building and satisfy the designated performance criteria. This enables the design to use only the dominant translational mode shape (i.e., first mode shape) for the retrofit. This also eliminates the need for modal analysis and the decoupling of translational and torsional mode shapes makes it more straightforward for practice. The new simplified PBSR method for retrofitting multi-story buildings was then applied to a four-story soft-story wood-frame building with torsional irregularities at all stories and assessed numerically using non-linear time-history (NLTH) analysis. The method developed in this dissertation was validated experimentally by conducting a series of full-scale tests on a four-story 370 m² (4,000 ft²) soft-story wood-frame building at the outdoor uni-axial shake table at the University of California - San Diego's Network for Earthquake Engineering Simulation (NEES) laboratory. The test provided the first-of-its-kind (landmark) dataset for use by researchers and practitioners for retrofitting soft-story wood-frame buildings. The experimental test results showed that the retrofitted building met the designated performance criteria and essentially validated the PBSR method developed in this dissertation. It should be noted that although the PBSR method was only validated experimentally for the asymmetric soft-story wood-frame building, the method can be used for any type of structure provided the necessary details of design and material properties are addressed. Finally, in order to investigate the collapse mechanism of soft-story wood-frame buildings the un-retrofitted building was subjected to series of ground motion with increasing intensities until it collapsed. These series of tests are the first full-scale collapse tests of a full-size building.Item Unknown Physical-socio-economic systems integration for community resilience-informed decision-making and policy selection(Colorado State University. Libraries, 2022) Wang, Wanting, author; van de Lindt, John W., advisor; Mahmoud, Hussam, committee member; Guo, Yanlin, committee member; Cutler, Harvey, committee memberNatural hazards are damaging communities with cascading catastrophic economic and social consequences at an increasing rate due to climate change and land use policies. Comprehensive community resilience assessment and improvement requires the analyst to develop a model of interacting physical infrastructure systems with socio-economic systems to measure outcomes that result from specific decisions (policies) made. There is limited research in this area currently because of the complexity associated with combining physics-based and data-driven socio-economic models. This dissertation proposes a series of multi-disciplinary community resilience assessment models (e.g., multi-disciplinary disruption assessment and multi-disciplinary recovery assessment) subjected to an illustrative natural hazard across physical infrastructure and socio-economic systems. As illustrative examples, all the proposed methodologies were applied to the Joplin, Missouri, testbed subjected to tornado hazard but are generalizable. The goal is to enable community leaders and stakeholders to better understand the community-wide impacts of a scenario beyond physical damage and further empower them to develop and support short-term and long-term policies and strategies that improve community resilience prior to events. Advancements in multi-disciplinary community resilience modeling can help accelerate the development of building codes and standards to meet the requirements of community-wide resilience goals of the broader built environment, consistent with the performance objectives of individual buildings throughout their service lives.Item Unknown Seismic fragility analysis of reinforced masonry buildings(Colorado State University. Libraries, 2013) Zamora, José EfraÃn Mazariegos, author; van de Lindt, John W., advisor; Atadero, Rebecca, committee member; Strong, Kelly, committee memberReinforced masonry walls are a widely used lateral force resisting system for buildings around the world. These structures, if not correctly detailed to resist earthquake loads, are a main cause of casualties and economic losses, particularly in developing countries. This thesis presents the result of a study whose objective was to apply the seismic fragility methodology to both in-plane (shear) and out-of-plane (transverse) reinforced masonry shear walls to quantify probabilities of exceedance for ASCE 41-06 drifts associated with continued occupancy, life safety, and collapse prevention, performance states. The load-displacement curves (hysteresis) were obtained from quasi-static out-of-plane and in-plane experimental testing by Klingner et al. (2010). In this thesis, that data was applied to obtain the parameters for a widely used ten-parameter hysteretic model. The software SAPWood Version 2.0 was selected for use in this thesis to enable nonlinear modeling of the shear wall and out-of-plane components. An analytical model of the reinforced masonry walls was developed in SAPWood and subjected to each earthquake within a well-known suite of 22 earthquakes. The peak of drifts for each ground motion record was recorded and each earthquake intensity increased over the range interest, i.e. an incremental dynamic analysis (IDA) was performed. Finally, as mentioned the information obtained from the IDA was used to develop fragility curves for the in-plane and out-of-plane walls based on peak story drift limits defined in ASCE 41 for continued occupancy, life safety, and collapse prevention.Item Unknown Shake table testing of concrete portal frame with high spray dryer ash (SDA) content(Colorado State University. Libraries, 2010) Rudraprasad, Karthic Rechan, author; van de Lindt, John W., advisor; Atadero, Rebecca, committee member; Senior, Bolivar, committee memberSignificant research has been conducted in replacing part of the cement content in concrete by fly ash. This thesis presents the method and results of an experiment to study the seismic behavior of a concrete portal frame with fifty percent of its cement content replaced by a spray dryer ash (SDA), which is similar to fly ash, obtained from the Platte River Power Authority’s Rawhide power plant in Northern Colorado. The behavior of the SDA portal frame under dynamic earthquake load is compared to the results obtained for the seismic behavior of ordinary Portland cement concrete. The portal frame is designed to represent the bottom story of a three-story office building in a high seismic region, e.g. Los Angeles, California. A mid bay portal frame is selected as a prototype frame and four similar 1/3 scaled down models of this frame were constructed. Two frames were constructed with fifty percent SDA concrete and the other two frames were constructed with ordinary Portland cement concrete. The frames were tested on the uniaxial shake table at the Colorado State University (CSU), Engineering Research Center (ERC), by placing two frames of the same mix type parallel to each other for stability. The scaled seismic mass is then placed on the frame and the instrumentation is installed. The concrete frames were tested first and then the SDA frames were tested using the same successive ground motions. Damage levels, and displacement response were recorded for each earthquake for both the tests and the results were compared. The basic premise of this thesis is to determine if a high SDA content frame sustains approximately the same amount of damage as a conventional concrete frame. By the results obtained from this study it has been shown that SDA frame may be considered to perform well, but not as good as conventional concrete frame. There was no significant damage or structural failure such as a collapse exhibited by the SDA frame when compared to that of conventional concrete frame. Hence about fifty percent of cement in concrete mix could be replaced by SDA for the construction of structural members in high seismic zones which leads to more economical buildings that help sustain the environment by redirecting spray dryer ash away from landfills.Item Unknown Testing of a full-scale mass timber diaphragm(Colorado State University. Libraries, 2018) Kode, Anirudh, author; van de Lindt, John W., advisor; Mahmoud, Hussam, committee member; Shuler, Scott, committee memberCross Laminated Timber (CLT) has only recently garnered attention as a new building material in the United States. Despite being introduced in Europe nearly 20 years ago, CLT is still not used widely in North America. One primarily reason is because CLT is not yet recognized as a structural system for seismically active regions of the U.S. One sub-assembly that has not been fully investigated are horizontal diaphragms for floors, roofs, or bridge decks. This thesis aims to test a single large scale CLT cantilever diaphragm subjected to a simulated seismic load. Data was collected and the behavior of the diaphragm documented to help begin to reduce this dearth of CLT data in the U.S. This data will also assist in refining CLT diaphragm design procedures that have recently been developed. Ten CLT panels were used to build the diaphragm, which was setup as a cantilever beam according to ASTM specifications. A 110-kip actuator was used to apply a concentrated load at one end of the diaphragm while a steel base serving as a fixed boundary condition was at the other end. The CUREE test protocol with a reference displacement of 75.6 mm (3 inches) was applied to the floor diaphragm specimen, which included a number of string potentiometers to collect displacement data. The diaphragm behaved in a predictable manner and the connectors failed in tension first even with a chord designed per the National Design Specification (NDS) for wood. Then the CLT panels separated resulting in a total failure. This data set will be made available to those working on CLT diaphragm provisions for refinement of on-going revisions.Item Unknown Understanding and mitigating tsunami risk for coastal structures and communities(Colorado State University. Libraries, 2011) Park, Sangki, author; Atadero, Rebecca A., advisor; van de Lindt, John W., advisor; Heyliger, Paul R., committee member; Senior, Bolivar A., committee memberTsunamis have attracted the world's attention over the last decade due to their destructive power and the vast areas they can affect. The 2004 Indian Ocean Tsunami, killed more than 200,000 people, and the 2011 Great Tohoku Japan Earthquake and Tsunami, resulted in 15,000 deaths and an estimated US $300B in damage, are recent examples. An improved understanding of tsunamis and their interactive effects on the built environment will significantly reduce loss of life in tsunamis. In addition, it is important to consider both the effect of the earthquake ground motion and the tsunami it creates for certain coastal regions. A numerical model to predict structural behavior of buildings subjected to successive earthquakes and the tsunamis was developed. Collapse fragilities for structures were obtained by subjecting a structure to a suite of earthquake ground motions. After each motion the numerically damaged structural model was subjected to tsunami wave loading as defined by FEMA P646. This approach was then extended to the community level; a methodology to determine the probability of fatalities for a community as a function of the number of vertical evacuation shelters was computed. Such an approach also considered the location and number of vertical evacuation sites as an optimization problem. Both the single structure cases and the community analyses were presented in terms of fragilities as a function of the earthquake intensity level and evacuation time available. It is envisioned that the approach may be extended to any type of structure as they are typically modeled nonlinearly with strength and stiffness degradation. A logical fragility-based, or performance-based, procedure for vertical evacuation for coastal buildings and for whole communities was developed. A mechanism to obtain a reduction in the collapse risk of structure and more critically maximize the survival rate for a community was a major outcome of this dissertation. The proposed tsunami vertical evacuation methodology was intended to provide key information to better understand and mitigate risk caused by earthquakes and tsunamis, thus it is possible to mitigate hazard for a community with only several large vertical evacuation shelters. It is able to provide a framework for a vertical evacuation plan and for the mitigation of collapse risk and fatalities of structures and a community based on a limited amount of information.