Browsing by Author "Van de Lindt, John W., advisor"
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Item Open Access Correlated wind turbulence and aeroelastic instability modeling for 3-D time-domain analysis of slender structural systems(Colorado State University. Libraries, 2007) Goode, Jonathan S., author; Van de Lindt, John W., advisorSlender structural systems, such as high-mast lighting structural supports, are known to be sensitive to natural wind fluctuations. In particular, these systems are also prone to produce aeroelastic instabilities as a result of the structural motion and wind flow. This in turn can result in poor fatigue performance for these structures. In order to accurately estimate this fatigue performance, numerical time-domain solution techniques are needed. Time-domain solutions, however, require accurate modeling of the fluid/structure interaction and the structural system. Because these systems interact with the wind flow, this modeling problem is only exacerbated due to the modeling complexities associated with the wind flow and corresponding aeroelastic instabilities. This study seeks to incorporate existing models for wind flow and vortex shedding into a numerical time-domain analysis solution procedure. The objectives and contributions of this study are focused on three modeling techniques. First, the modeling of the approach wind flows to generate a simulated wind speed time history for use in the time-domain structural analysis algorithm is considered. The approach makes use of random field theory to model the spatial correlation of the approach flow based on an empirical relationship. The effects of varying the spatial correlation of the wind flow on the response of the slender structural system are determined. Second, the modeling of vortex shedding phenomenon into the time-domain structural analysis routine is implemented. Again, the model considered is empirical in nature and a numerical investigation is similarly conducted to determine the effects of varying parameters of the model on the response of the structure. Finally, the fatigue performance of a structural system with respect to a statistically described lifetime wind speed distribution that describes the natural wind fluctuations over the lifetime of the structure is modeled. The spatially correlated wind flow and vortex shedding models are subsequently included to determine their effects on the fatigue performance of the system. Recommendations for future study and improvement are made so that other studies can extend the work contained herein to obtain further understanding and potential improvements in design standards and mitigation techniques to improve performance.Item Open Access Development of performance-based wind engineering for residential structures: from concept to application(Colorado State University. Libraries, 2010) Dao, Thang Nguyen, author; Van de Lindt, John W., advisor; Chen, Suren, committee member; Bienkiewicz, Bogusz, committee member; Senior, Bolivar A., committee memberThe majority of buildings and approximately 90% of residential structures in North America are light-frame wood construction. Many of these structures are subjected to high winds along the eastern seaboard and Gulf Coast and as a result routinely suffer damage resulting in significant financial losses. Losses for residential wood construction during hurricanes occur for a variety of reasons, i.e. from different sources. These include sources such as (a) the failure of structure due to high wind loading; (b) water intrusion as a result of high uplift pressures on the roof system resulting in gaps or as a result of a loss of roof coverings and/or roof sheathing panels; and (c) debris impact from windborne debris. A relatively new paradigm in earthquake engineering is performance-based design (PBD). PBD is, by and large, felt by most to be a system-level philosophy that allows inclusion of system level behavior including the improvement in performance as a result of this assertion. However, in wind engineering most failures are understood to be at the component and sub-assembly level. This study outlines and demonstrates the development of performance-based wind engineering for residential structures based on losses to the owner. To date, this is the first time a mechanistic model has been used to develop fragilities for performance expectations related to all levels of performance: occupant comfort, continued occupancy, life safety, structural integrity, and manageable loss.Item Open Access Multi-criteria reliability-based optimization for evaluation and rehabilitation of concrete bridge structures(Colorado State University. Libraries, 2008) Buddhawanna, Saharat, author; Van de Lindt, John W., advisorThe American Society of Civil Engineers (ASCE) reported that approximately one-third of U.S. bridges are either in need of serious repair or functionally obsolete. Even as repairs are completed, the problem persists with more and more bridges being added to the list each year. In order to determine if repair is needed for a specific bridge, a condition evaluation is typically conducted. The selection of conditional evaluation method and the subsequent repair method has, to date, been based on the preference of the engineer and/or contractor and at times the equipment available.Item Open Access Quantifying sustainability metrics for trunkline bridges in the Mountain Plains region(Colorado State University. Libraries, 2016) Gopi, Vaishak, author; Van de Lindt, John W., advisor; Senior, Bolivar, advisor; Strong, Kelly, committee memberThe use of millions of cubic yards of concrete and steel to support the U.S infrastructure may result in a significant negative impact on the environment. CO2 released by the construction processes as well as the material production, is taking a toll on the environment. This study is aimed at developing a ranking system to determine the emission of CO2 for bridges and rank them based on their CO2 emission. Firstly, in order to accomplish this objective, rating systems for buildings from around the world were analyzed for common attributes applicable to bridges. Secondly, a sample of bridges from the state of Colorado was selected and analyzed for their sustainability by only considering their main materials and a ranking system based on the emission of CO2 was developed. This served as the first step in developing a rating system for bridges in Colorado where only the CO2 emission from the production and transport of concrete and steel were considered. This rating system can be further developed to include CO2 emissions from construction processes, demolition and disposal and other factors that contribute to sustainability, but its current version is intended only to provide an example of an approach for development of a ranking system.