Conferences, Lectures, & Seminars
Events for October
-
DATA AND DISCOVERY ON LIQUEFACTION-INDUCED LATERAL GROUND DEFORMATIONS
Thu, Oct 16, 2008 @ 10:30 AM - 12:30 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
by Fang Liu, PhD candidateSonny Astani
Dept. of Civil and Environmental EngineeringABSTRACT:Liquefaction-induced lateral ground deformations posed considerable threatens to lifeline systems in urban areas in the past. In the practice of liquefaction evaluation in geotechnical earthquake engineering, empirical relations and procedures received special appreciation. They benefited from vast amount of case histories collected and documented after major earthquakes. Advances of technologies transformed the way collecting, documenting, distributing, and utilizing this perishable information. The research effort was concentrated on exploring the feasibility of new information technologies for managing and distributing data pertinent to liquefaction damages, and on deriving and assessing data-driven models pertinent to liquefaction-induced lateral ground deformation.
New information technologies were demonstrated for generating and distributing post-earthquake reconnaissance reports. The newly emerging technique, known as embedded metadata in pictures, allowed portable pictures that possessed embedded information. The metadata-based approach enhanced the automation level in generating PER reports, and enabled a complex of possible applications. A lightweight Information system was developed for distributing collected case histories of liquefaction together with relevant geotechnical information over the Word Wide Web. Supported by a customized database and external data from remote servers, the proposed system enabled dynamic and rapidly responsive Web applications to share information through the Internet.
The performance of gently sloping grounds was investigated using sliding block theory under statically unstable conditions due to temporary loss in shear strength. The major efforts were concentrated on quantifying in probabilistic terms the contribution of earthquake motions to the amplitude of lateral deformations once the instability had triggered. The Monte Carlo simulation was performed for a set of actual strong motion records and an idealized infinite gentling sloping ground in order to derive the empirical relations.
Finally, a case study was presented as an example to demonstrate the value of case histories collected over years, and to evaluate the performance of three existing empirical models for liquefaction-induced lateral ground deformations. Empirical relations were integrated in a GIS system, leading to maps of liquefaction severity and liquefaction-induced lateral deformations.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
-
COMPUTER MODELING FOR WAVE OSCILLATION PROBLEMS IN HARBORS AND COASTAL REGIONS
Tue, Oct 21, 2008 @ 10:00 AM - 12:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Oral Defense byXiuying Xing, PhD CandidateSonny Astani
Department of Civil and Environmental EngineeringABSTRACT:Harbors are built to provide a sheltered environment for the mooring of ships and vessels. For some wave periods the semi-enclosed harbor basin acts as a resonator to amplify the wave motions in the harbor due to the combined effects of wave diffractions, refractions and multiple reflections from the boundaries. This undesirable wave motion could induce significant ship motions, damage ships and dock facilities, and delay loading and unloading activities if the resonant wave periods are close to that of the ship mooring system. Harbor planners and engineers need to study the wave induced oscillations as new harbor layouts are contemplated.
This dissertation study presents a finite element model which could be used for predicting the response characteristics of harbors and bays of arbitrary shape and variable depth. The model incorporates the effects of wave reflection, refraction, diffraction and dissipation losses due to boundary absorption, bottom friction and energy losses due to the flow separation at the entrances. The model has been applied to three harbors (Crescent City Harbor in northern California, Pohang Harbor in Korea, and Hualien Harbor in Taiwan) and two bays (San Pedro Bay in southern California and Bay of Fundy in the east coast of Canada and US). The results from the finite element model have been shown to agree surprisingly well with the field data obtained from events such as earthquake generated tsunamis and hurricane induced wave oscillations, as well as normal day observations. The results reveal the fact that the wave oscillation condition inside a harbor or bay is determined by the local layout and bathymetry. The harbor or bay responds to the incident wave in a predictable manner irrespective to the sources of driving forces such as typhoon, tsunami, winter storms, etc. The study also explains the tremendous tide phenomena at Bay of Fundy.
Modification strategy studies for reducing the seiche problems in Pohang Harbor and Hualien Harbor have also been presented. The model is shown to be an effective engineering tool for harbor planning and design to derive ways of eliminating or altering the harbor response so that the harbor may indeed provide a sheltered environment for moored ships and vessels.Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
-
Identifying and Quantifying the Impact of Air Pollution Source Areas by...
Wed, Oct 22, 2008 @ 10:00 AM - 12:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Nonparametric Trajectory AnalysisOral Defense by:Chien-Cheng Pan, PhD candidateSonny Astani
Dept. of Civil and Environmental EngineeringABSTRACT:In order to improve air quality, it is necessary to identify and quantify the sources of airborne pollution. Local emissions are more easily to control compared to regional emissions since multiple agencies and states are not involved in the regulatory process. Generally two types of air quality models, source oriented models and receptor oriented models, are used to evaluate the impact of emission on air quality on a local, regional, and global scale. Source oriented models require detailed information on emission composition, rates and local meteorological data. Therefore, they are not suitable for sources of fugitive emissions and intermittent or temporary emissions, which cannot easily be quantified. On the other hand, receptor models need chemical composition data to identify and quantify sources affecting the monitoring sites. However, pollutants without distinguishable "fingerprints", such as SO2, O3 cannot be apportioned by this method. A new hybrid source receptor model was previous develop and is called Nonparametric Trajectory Analysis (NTA). It is based on nonparametric kernel smoothing and backtrajectory analysis. NTA was developed to identify and quantify local sources of species measured on a very short time scale, i.e, minute, and it has gotten some encouraging results. However, NTA sometimes produces artifacts areas that appear to be sources but not, this is especially true for sources very close to the receptor. A major objective of this study is to address this difficulty.The NTA gives a map of the average concentration at the receptor when the air passes over each point on the map. This NTA map is obviously related to the local sources affecting the receptor, but it is not a map of the sources. One way to extend the NTA method is the Point Source Response (PSR) method. The NTA map can be considered a linear combination of responses to number of point sources. The NTA map for a point source at each point on a grid is calculated. Next, the weighted sum of the PRS maps that best fits the NTA map for the real data is estimated by principal components regression. In this way, the size and location of source affecting the receptor are estimated.This method is illustrated by application to 1- minute SO2 data from Long Beach, and 1-minute PM10 data for Rubidoux along with meteorological data from nearby monitoring stations in South Coast Air Basin of Southern California. The result identified offshore ships in the Long Beach harbor and transportation hubs close to the intersection of freeway 710 and freeway 405 as major SO2 sources. For the Rubidoux area, aggregate, and asphalt factories, and construction sites are identified as source of PM10.Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
-
Tidal Saltwater Wetlands and Coastal Water Quality
Thu, Oct 23, 2008 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Abstract:Stanley GrantProfessor of Environmental EngineeringChair, Department of Chemical Engineering and Materials ScienceUniversity of California, IrvineAbstract:Tidal saltwater wetlands are the ocean's last line of defense against polluted surface water runoff from urban watersheds. After entering tidal wetlands, runoff-associated pollutants undergo dilution and transport by what Zimmerman called the "tidal whirlpool", and transformation by myriad physicochemical and biologically mediated processes. Here I present field measurements and modeling studies of fecal indicator (FIB) and nutrients in Newport Bay, Orange County, California. Results from this field and modeling effort shed light on: (1) the maximum volume of runoff a tidal saltwater wetland can receive, above which its pollutant treatment capacity is compromised; (2) design principles for optimizing pollutant treatment in restored tidal saltwater wetlands; and (3) the level of model complexity needed to accurately describe pollutant fate and transport in these complex systems.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
-
VIBRATION OF NEARBY STRUCTURES INDUCED BY HIGH-SPEED RAIL TRANSIT
Mon, Oct 27, 2008 @ 02:00 PM - 04:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Oral Defense by Pei-wen ChenSonny Astani
Department of Civil and Environmental EngineeringAbstract:This dissertation is centered around the need for analyses concerning ground borne vibration caused by high speed rail transit. As the speed and weight of the trains increase, the vibrations caused by the transportation system can affect the local environment and economy. Selected for a case study is the Taiwan High Speed Rail (THSR); it's readily available geotechnical and structural data and make it an ideal case for a detailed analysis. TheTHSR route traverses through densely populated areas of Western Taiwan where modern computer technological institutes are located. The ground borne vibration has affected that industry and caused costly relocation of the factories. The work herein focuses on the vibration generated by deeply embedded piles of the elevated track while most previous analyses were based on ground surface induced vibrations. It is shown that the soil-structure interaction effect of a resonant bridge can contribute to amplify the vibration at higher speeds.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes