http://hdl.handle.net/1957/22531 2013-05-22T08:20:36Z 2013-05-22T08:20:36Z White, William S. (William Schaffer) http://hdl.handle.net/1957/38540 2013-05-10T20:52:13Z 2013-04-30T00:00:00Z

Adjacent structure response sensitivity to seismic events using the direct differentiation method White, William S. (William Schaffer) The response of adjacent structural systems to earthquake motions is investigated using the finite element framework OpenSees. Results of sensitivity analyses demonstrate that structural response quantities can increase in either or both of the adjacent structures for specific configurations. The structural models used include steel moment-resisting frames and rigid shear walls. The soil that underlies both buildings is modeled with a "structure-soil- structure spring" that connects the structural models. Due to the variety of building heights in urban environments, all combinations of four-, eight-, and twenty-story buildings are analyzed. Six shallow crustal earthquake motions are selected to model the dynamic responses of structural models. Sensitivity analyses are carried out using the direct differentiation method (DDM) with respect to parameters associated with the structure-foundation-soil systems, including floor mass, story stiffness, and soil stiffness. The DDM allows for computation of the time history of response sensitivity with respect to each parameter, in addition to the deterministic, or mean, time history response computed as part of an ordinary, non-linear, dynamic analysis. The response time histories can then be used to make a first-order approximation of the change in building response with respect to prescribed changes in a given parameter. The results of these analyses demonstrate that the effects of structure-soil-structure interaction are generally negligible for the steel, moment-resisting frame structure pairs investigated. The rigid shear walls demonstrated effects of structure-soil-structure interaction, particularly in the smaller wall mimicking the motion of the larger wall. Further research is needed in this area, particularly in refining the soil model to more fully reflect the response of realistic soil. Graduation date: 2013

2013-04-30T00:00:00Z Fetzer, Peter C. http://hdl.handle.net/1957/38535 2013-05-09T18:02:36Z 2013-03-18T00:00:00Z

Behavior of open grid steel bridge decks under service and fatigue loads Fetzer, Peter C. Open grid steel bridge decks have been in use for nearly a century. These open grid decks provide an economical and lightweight alternative to traditional reinforced concrete decks. As the transportation infrastructure continues to deteriorate, open grid decks can be used as a cost effective way to rehabilitate structurally deficient bridges. Open grid decks weigh less than conventional reinforced concrete decks and reduce the dead load on a bridge superstructure, thereby increasing the live load capacity. While modern bridge design specifications have evolved to LRFD principles, present design methods for open grid decks are mostly empirical and based on historic practice and performance. Further, fatigue limit states in practice tends to be controlled by cracking in the weak direction, for which no design provisions currently exist. A comprehensive research program was developed to address these issues. The results provide a better understanding of grid deck behavior, and will improve detailing and design provisions. Graduation date: 2013

2013-03-18T00:00:00Z Conner, Jeremy C. http://hdl.handle.net/1957/38534 2013-05-09T17:54:47Z 2013-05-01T00:00:00Z

Quantification of landslide movement in a forested environment Conner, Jeremy C. Landslides are an insidious natural hazard, which can result in significant damage to public infrastructure. Limited monitoring tools are available, particularly tools suitable for use in forested environments. These tools often only allow a few locations across the slide to be monitored. Terrestrial Laser Scanning (TLS) shows promise as a monitoring technique given the high spatial resolution and accuracy at which measurements can be made. However, current procedures can be time consuming, require advanced skill and judgment by the analyst, and typically require manual methods of feature extraction to quantify landslide movement. To overcome these limitations, this thesis presents and investigates a new methodology to detect and monitor landslide movement in a densely forested area using natural features such as tree trunks. The presented methodology searches through the noisy point cloud dataset to find trees and then fit circles to points sampled on the tree trunk. Next, comparing the movement of the circles between time series terrestrial laser scan surveys provides quantified displacements distributed across the landslide. For quality control purposes a parametric analysis was conducted and revealed that the root mean square error (RMS) of the circle fit and the difference in calculated tree radii between epochs are the dominant parameters in correctly pairing trees between epochs. For the test dataset, the optimal values were a RMS circle-fit of less than 1.5 cm and less than 1.0 cm for the calculated difference in tree radii. Application of the methodology to a case study of Johnson Creek Landslide (JCL) showed that TLS can determine landslide movement comparable to conventional monitoring methods. The displacements observed on markers were within 2 cm from the displacement observed from traditional methods such as total station monitoring. TLS also provides more samples than currently observed for this location, allowing increased detail for landslide modeling and monitoring. Graduation date: 2013

2013-05-01T00:00:00Z Ko, Harrison T. http://hdl.handle.net/1957/38478 2013-05-07T15:07:50Z 2013-04-02T00:00:00Z

Hydraulic experiments on impact forces from tsunami-driven debris Ko, Harrison T. Impact by an idealized shipping container on a column were observed for tsunami flow in a large-scale wave flume modeled at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. Two specimen types, aluminum and acrylic, were tested; and each specimen was tested in two orientations, longitudinal and transverse. The debris specimens were constructed to be 1:5 scaled versions of standard shipping containers with container capacities of one twenty-foot equivalent unit (TEU). Hydraulic experiments were compared with corresponding in-air impact experiments using the same experimental configuration to assess the hydrodynamic effects in increasing the impact force. Experiments were conducted by varying flow conditions, velocity, nonstructural mass, impact angle, and debris specimen material. Hydraulic Longitudinal Aluminum Test results showed a 10% increase in measured impact force when compared to the corresponding In-Air Test. Transverse Aluminum and Longitudinal Acrylic Tests showed upwards of a 40% increase in measured impact force when compared to their corresponding In-Air Tests. The impact durations measured from the in-air test provided a lower bound for the impact duration measured for the in water tests. Hydraulic effects were shown to increase the impact duration by an average of 20%. Nonstructural mass was shown to have no significant impact on the measured peak impact force, however an increase of non-structural mass appeared to increase the measured impulse as expected. Graduation date: 2013

2013-04-02T00:00:00Z