Infrastructure systems are essential to the functioning of contemporary societies and economies. A major disruption to the built environment can lead to severe public safety issues and economic losses. Within the past few decades, modern control and information technologies have been rapidly developed in an attempt to improve the reliability of individual utility systems by exchanging technologies across them. One of the major ramifications is the emergence of interdependencies among these critical infrastructure systems, especially when facing major disruptions. Failure of an individual system becomes more likely to affect the functionality of other interconnected infrastructure systems. In order to mitigate such consequences, the mechanics of interdependencies and failure propagation among the systems must be understood. This research focuses on the development of a framework for probabilistically quantifying interdependent responses of two essential infrastructure systems - telecommunication and electric power systems - subjected to seismic hazards, which are one of the most powerful and geographically extensive threats. The study explores the effects of seismic hazards beyond the obvious seismic-induced physical damage to utility system facilities. In particular, the seismic evaluation of telecommunication systems considers the degradation of system performance due to physical damage and the abnormally high usage demands in telecommunication systems expected after catastrophic earthquakes. Specifically, a newly developed seismic-induced congestion model is proposed, and the probabilistic formulations of the critical interdependencies across telecommunication and power systems are presented in a probabilistic framework. The study illustrates the procedure for fragility analysis of interdependent systems and presents a practical application through a test bed implementation in Shelby County, TN. From this study, telecommunication systems are found to be very vulnerable to seismic-induced congestion. The electric power interdependencies amplify the degradation in telecommunication systems up to 50% in their vulnerability while electric power operations are heavily dependent upon telecommunication infrastructures and the fragility median of electric power system observability can decrease by 30%. The study also indicates up to 100% overestimation of the independent fragility analysis and the results reveal the relationship between system topology and the sensitivity of system performance to the intensity of interdependencies. The proposed methodology is expected to be a valuable tool for decision making in evaluating seismic mitigation strategies and also to provide the foundation for future studies on interdependent responses of other critical infrastructures.

Ports play a critical role in transportation infrastructure, but are vulnerable to seismic hazards. Downtime and reduced throughput from seismic damage in ports results in significant business interruption losses for port stakeholders. Current risk management practices only focus on the effect of seismic hazards on individual port structures. However, damage and downtime of these structures has a significant impact on the overall port system's ship handling operations and the regional, national, and even international economic impacts that result from extended earthquake-induced disruption of a major container port. Managing risks from system-wide disruptions resulting from earthquake damage has been studied as a central element of a Grand Challenge project sponsored by the National Science Foundation Network for Earthquake Engineering Simulation (NEES) program. The following thesis presents the concepts and methods developed for the seismic risk management of a port-wide system of berths. In particular the thesis discusses the framework used to calculated port losses: the use of spatially correlated ground motion intensity measures to estimate damage to pile-supported marginal wharves and container cranes of various configurations via fragility relationships developed by project team members, repair costs and downtimes subsequently determined via repair models for both types of structures, and the impact on cargo handling operations calculated via logistical models of the port system. Results are expressed in the form of loss exceedance curves than include both repair/replacement costs and business interruption losses. The thesis also discusses how the results from such an analysis might be used by port decision makers to make more informed decisions in design, retrofit, operational, and other seismic risk management options.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on December 22, 2009). Thesis advisor: Dr. Brent L. Rosenblad. Includes bibliographical references.

A confined masonry (CM) wall consists of a masonry wall panel surrounded by reinforced concrete (RC) members on its perimeters. Low-rise CM structures are widely used in earthquake-risked (EQ-risked) rural or suburban areas all over the world. Most of these structures fail in shear pattern under lateral EQ loads, and some of them collapse under a severe or even a moderate EQ due to inappropriate design. On the other hand, buildings constructed of RC frames have much better performance in resisting EQs, since their RC members have larger dimensions and heavier reinforcing ratios than those in CM structures. Nonetheless, RC-frame buildings are normally too expensive for most inhabitants in less developed regions. In this study, as an improvement to the conventional CM buildings for EQ resistance and for the sake of post-EQ restoration, a hybrid masonry – RC (HMR) structure, whose working mechanism is different from that of a conventional CM structure, is proposed. The RC members (i.e. “tie beams” and “tie columns”), which function only as confinement in a CM building, will resist most of gravity load and part of lateral EQ load in an HMR structure, while the wall panels will take most of lateral EQ load and part of gravity load. This is achievable by slightly increasing the sizes and reinforcing ratios of RC members in HMR structures. Such buildings will not collapse in the absence of masonry wall panels because the gravity load bearing system is still intact. On the other hand, as the wall panels in the proposed HMR structure will absorb most of the energy induced by lateral EQ load, severe damages will be controlled within the wall panel region, so that only the wall panels need to be replaced instead of rebuilding the whole structure after the EQ event. To investigate the mechanical behaviours of masonry assemblages to be used in HMR structures, a series of experimental tests were conducted. Having established the relevant material properties for HMR structures, finite element (FE) simulation was performed to verify its work mechanism. Prior to applying the FE simulation to HMR structures, the FE technique was first applied to simulate the behaviours of two concrete-brick masonry panels under diagonal compression loading and a CM wall under cyclic lateral loading. The results show a good correlation between the experimental results and the simulated ones. This has validated the feasibility of using the FE software to study the proposed HMR structure. The theoretical simulation results show that in a properly designed HMR wall, depending on the masonry reinforcing details and the boundary conditions of simulated load cases, about 70% of the gravity load imposed on the RC beam will be transferred to the RC columns and more than 80% of the seismic energy (in terms of strain energy) will be absorbed by the masonry panel. Therefore, it is obvious that the proposed HMR structure is very feasible to replace the conventional CM structure in resisting EQ attacks with no risk of collapse. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

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The Best Master's Thesis Award of the Hong Kong Section, American Society of Civil Engineers (2005-06) / published_or_final_version / abstract / Civil Engineering / Master / Master of Philosophy

No description available.

A survey of earthquake disaster mitigation strategies and building principles which could applied in rural areas of the Less Developed Countries. Earthquake vulnerability of traditional buildings and problems of earthquake hazard mitigation in these countries are discussed, along with some strategies that may help reduce the impact of future earthquakes. The performance of rural buildings during past earthquakes is analyzed to have a clear understanding of building behaviour during an earthquake. After the analysis, the research traces various recommendations and safe building techniques that would improve the earthquake-resistance of these buildings. Moreover, the study reviews problems often involved in implementing mitigation measures and in transferring technical information to semi-illiterate and unskilled workers, in conjunction with some methodologies on how to transfer information to the rural population. The study concludes by outlining the urgency for the need of pre-earthquake mitigation strategies and suggests some ideas to help narrow the gap which exists between the available information on earthquake mitigation measures and its application in those countries most affected by earthquakes.

Multiple experimental and computational tests are performed on precast concrete structures designed for damage avoidance. These structures accommodate non-linear behaviour by rocking at specially detailed connections. Unbonded prestress is employed to provide a restoring force and supplemental devices are used to dissipate energy. Tests are performed on a 30 percent scale bridge pier and an 80 percent scale 3D beam-column joint subassembly. Several detailing strategies are developed and tested. Straight and draped tendon profiles are considered. Supplemental energy dissipation is provided by yielding mild steel devices or lead-extrusion dampers. The lead-extrusion dampers are tested both externally and internally. Detailing at the joint region is refined in an effort to provide a cost-effective and simple solution. A closure pour is considered to simply the construction process. Results indicate it is possible to eliminate virtually all damage at the beam-column joint with minor increased cost from steel armouring. The lead-extrusion damper is shown to be 'resetable', and therefore would not have to be replaced following a seismic event. Two seismic financial risk methodologies are developed to investigate the enhanced performance inherent to ductile jointed structures. A rapid method is introduced which simplifies the intensive computational effort necessary to perform loss studies. A distribution-free computational method is also examined. The methods are demonstrated with a case study of bridge piers designed to different seismic design codes and a bridge designed for damage avoidance. The bridge pier designed for damage avoidance is shown to have an expected annual loss of approximately 25 percent that of the conventional ductile piers.

Topography effects, the modification of seismic motion by topographic features, have been long recognized to play a key role in elevating seismic risk. Site response, the modification of ground motion by near surface soft soils, has been also shown to strongly affect the amplitude, frequency and duration of seismic motion. Both topography effects and 1-D site response have been extensively studied through field observations, small-scale and field experiments, analytical models and numerical simulations, but each one has been studied independently of the other: studies on topography effects are based on the assumption of a homogeneous elastic halfspace, while 1-D site response studies are almost exclusively formulated for flat earth surface conditions. This thesis investigates the interaction between topographic and soil amplification, focusing on strong ground motions that frequently trigger nonlinear soil response. Recently, a series of centrifuge experiments tested the seismic response of single slopes of various inclination angles at the NEES@UCDavis facility, to investigate the effects of nonlinear soil response on topographic amplification. As part of this collaborative effort, we extended the search space of these experiments using finite element simulations. We first used simulations to determine whether the centrifuge experimental results were representative of free-field conditions. We specifically investigated whether wave reflections caused by the laminar box interfered with mode conversion and wave scattering that govern topographic amplification; and whether this interference was significant enough to qualitatively alter the observed amplification compared to free-field conditions. We found that the laminar box boundaries caused spurious reflections that affected the response near the boundaries; however its effect to the crest-to-free field spectral ratio was found to be insignificant. Most importantly though, we found that the baseplate was instrumental in trapping and amplifying waves scattered and diffracted by the slope, and that in absence of those reflections, topographic amplification would have been negligible. We then used box- and baseplate-free numerical models to study the coupling between topography effects and soil amplification in free-field conditions. Our results showed that the complex wavefield that characterizes the response of topographic features with non-homogeneous soil cannot be predicted by the superposition of topography effects and site response, as is the widespread assumption of engineering and seismological models. We also found that the coupling of soil and topographic amplification occurs both for weak and strong motions, and for pressure-dependent media (Nevada sand), nonlinear soil response further aggravates topographic amplification; we attributed this phenomenon to the reduction of apparent velocity that the low velocity layers suffer during strong ground motion, which intensifies the impedance contrast and accentuates the energy trapping and reverberations in the low strength surficial layers. We finally highlighted the catalytic effects that soil stratigraphy can have in topographic amplification through a case study from the 2010 Haiti Earthquake. Results presented in this thesis imply that topography effects vary significantly with soil stratigraphy, and the two phenomena should be accounted for as a coupled process in seismic code provisions and seismological ground motion predictive models.