Conferences, Lectures, & Seminars
Events for April
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Multiscale Computational Simulation of Progressive ....
Mon, Apr 05, 2010 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
... Building Collapse and Other Collapse-Related Stuff Speaker: Sherif El-Tawil,Professor, Civil and Environmental Engineering Department,University of Michigan, Ann Arbor, MIAbstract:
Simulating the response of a steel building to extreme loading, especially all the way up to collapse, is complicated by the need to account for a number of interlinked processes that take place along widely disparate length scales. At the micro-scale, micrometer sized voids in the steel matrix can nucleate and coalesce leading to the formation of a crack. At the macro-scale, the crack can grow forming a discontinuity (centimeters in length) that leads to a rapid change in member structural properties. At the structural-scale, i.e. in regions measured in meters, the damaged member can trigger instability in subassemblage response potentially leading to a chain of other interlinked micro-, macro- and structural-scale processes that ultimately stop when the building system reaches equilibrium or collapses into a debris pile. My talk will start off by describing my general research interest in multi-scale collapse modeling then focus on simulating progressive structural collapse and some of the engineering aspects that influence the collapse-resistance of steel buildings. Digressing from the main topic of the presentation, I will describe some tools that we have developed to visualize our simulation results in virtual and augmented reality environments with the purpose of assisting and training first response teams. The talk will conclude with a short discussion of emergency occupant egress from distressed buildings and our ongoing efforts to address this area.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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Probabilistic seismic risk assessment of infrastructure systems ...
Wed, Apr 07, 2010 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
.. Using efficient sampling and data reduction techniquesNirmal Jayaram, Ph.D. Candidate, Stanford UniversityAbstract:Risk assessment of spatially-distributed building portfolios or infrastructure systems requires quantification of the joint occurrence of ground-motion intensities at several sites, during the same earthquake. This talk will present an overview of techniques to quantify the needed joint distributions using observations from past earthquakes, and describe how these distributions can be used in probabilistic seismic risk assessments of spatially-distributed lifelines. Lifeline risk assessment presents challenges related to describing ground-motion intensity over a region, and related to the computationally expensive task of repeatedly analyzing performance of a lifeline system under many damage scenarios. A simulation-based framework will be presented that develops a small but stochastically-representative catalog of earthquake ground-motion intensity maps that can be used for lifeline risk assessment. The approach dramatically reduces required computational expense, while also maintaining a set of simulations that is consistent with all conventional probabilistic seismic hazard analysis calculations. The feasibility of the proposed approach is illustrated by using it to assess the seismic risk of a simplified model of the San Francisco Bay Area transportation network. A catalog of only 150 intensity maps is generated to represent hazard at 1,038 sites from ten regional fault segments causing earthquakes with magnitudes between five and eight.
Location: Kaprielian Hall (KAP) - 209 ( Webex is available upon request)
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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Design, Technology, and Process;Team California, 2009 Solar Decathlon
Wed, Apr 14, 2010 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Speaker: Timothy Hight, Associate Professor and Chair, Department of Mechanical Engineering, Santa Clara UniversityAbstract:Santa Clara University and California College of the Arts joined forces to compete in the 2009 DOE Solar Decathlon competition, resulting in an overall third place finish. An SCU student team led the engineering effort, and CCA students led the architectural design, while both schools collaborated on these and many other aspects, such as communications and interior design. This talk will discuss some of the technologies chosen for the Refract House (including an integrated all PV roof, radiant heating and cooling, and whole home control system), as well as the tradeoffs and compromises inherent in the bold architectural design, and the process used for design and project management for this student-led team
Location: Kaprielian Hall (KAP) - 209 (
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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The Hydrogeochemistry of Pond and Rice Field Recharge:
Thu, Apr 15, 2010 @ 01:00 PM - 02:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
..Implications for the Arsenic Contaminated Aquifers in Bangladesh Speakers: Rebecca B. Neumann, Ph.D., NOAA Climate and Global Change Postdoctoral Fellow at Harvard University Abstract: Researchers have puzzled over the origin of dissolved arsenic in the aquifers of the
Ganges Delta since widespread arsenic poisoning from groundwater was publicized two
decades ago. Previous work has concluded that biological oxidation of organic carbon
drives geochemical transformations that mobilize arsenic from sediments; however, the
source of the organic carbon that fuels these processes remains controversial. A
combined hydrologic and biogeochemical analysis of a typical site in Bangladesh, where
constructed ponds and groundwater-irrigated rice fields are the main sources of recharge,
shows that only recharge through pond sediments provides the biologically degradable
organic carbon that can drive arsenic mobilization. Chemical and isotopic indicators
suggest that contaminated groundwater originates from excavated ponds and that water
originating from rice fields is low in arsenic. In fact, rice fields act as an arsenic sink.
Irrigation moves arsenic-rich groundwater from the aquifers and deposits it on the rice
fields. Most of the deposited arsenic does not return to the aquifers; it is sorbed by the
field's surface soil and bunds, and is swept away in the monsoon floods. The findings
indicate that patterns of arsenic contamination in the shallow aquifer are due to rechargesource
variation and complex three-dimensional flow.Location: Kaprielian Hall (KAP) - 209 (Available by Webex upon request)
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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USC- AGC Symposium 16
Tue, Apr 20, 2010 @ 05:30 PM - 09:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
The Symposium will hightlight the new risks and opportunities of sustainability in the AEC industry from the perspective of the owner, architect, general contractor, and subcontractor. Each role views the industry from different aspects, giving this year's program a unique, in-depth look at sustainability as it relates to the design and construction industry.Agenda:Opening Remarks by John A. Perez, Speaker of the AssemblySpeakers:Thomas Smith, NBC UniversalMark Rios, FASLA, FAIA, Rios Clementi Hale StudiosMichael Deane, Turner ConstructionSteve Watts, CSI Electrical Contractors
Location: Galen Center
Audiences: By Invitation Only
Contact: Evangeline Reyes
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Multidisciplinary Performance-Based Design Processes
Wed, Apr 21, 2010 @ 01:00 PM - 02:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Speaker: John Haymaker, AIA, PhD, LEED ap, Assistant Professor, Civil and Environmental Engineering, Stanford UniversityAbstract:Modern design challenges require multidisciplinary stakeholders and designers to systematically generate and analyze large spaces of alternatives for multiple criteria. This is a complex social and technical process that requires clear and rapid communication. I present case studies that illustrate how and why current practice is unable to do this efficiently and effectively. A fundamental social and technical shift to new performance-based design methods is needed. I describe an industrial scale platform of methods that my research team is developing to address this need: The Process Integration Platform (PIP) helps teams communicate and manage multidisciplinary processes;
Design Scenarios helps them transform requirements into parametric design spaces; Process Integration and Design Optimization (PIDO) automates the analysis of these spaces for daylight, energy, structure, cost and other criteria; Multi-Attribute, Collaborative Design, Analysis, and Decision Integration (MACDADI), facilitates fast, formal, collaborative decision making; The Design Exploration Assessment Method (DEAM) measures design challenges, strategies, and explorations to assist in new process development and selection.
These methods enable design teams to more efficiently and effectively execute multidisciplinary performance-based design processes.Location: Kaprielian Hall (KAP) - 209 (Avaiable on Webex upon request)
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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A Bayesian Network Framework for Seismic Infrastructure Risk Assessment & Decision Support
Thu, Apr 22, 2010 @ 01:00 PM - 02:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Title: Speaker: Michelle T. Bensi, Ph.D. Candidate, University of California, BerkeleyAbstract:A Bayesian network (BN) is a probabilistic graphical model that represents a set of random variables and their probabilistic dependencies. The variables may represent demand or capacity values, or the states of components and systems. BNs are graphical and intuitive, facilitate information updating, can be used for identification of critical components within a system, and can be extended by decision and utility nodes to solve decision problems. In particular, the facility for information updating renders the BN an ideal tool for infrastructure risk assessment and decision support. Evidence on one or more variables (e.g. observed component capacities, demands, or states) can be entered into the BN and this information propagates throughout the network to provide an up-to-date probabilistic characterization of the performance of an infrastructure system under an evolving state of information.This presentation will begin with a brief introduction to BNs. Next, a broad overview of a BN framework for infrastructure seismic risk assessment and decision support will be presented. Components of the framework include: (1) a seismic demand model of ground motion intensity as a spatially distributed Gaussian random field accounting for finite fault rupture and directivity effects, (2) models of component performance, (3) models of system performance, and (4) the extension of the BN to include decision and utility nodes to aid post-earthquake decision-making. Like all computational methods, BNs have limitations. In particular, calculations in BNs can be highly demanding of computer memory. A discussion of work done to address this limitation will be presented. An illustrative example will demonstrate the main ideas and approach. The presentation will conclude with a broader discussion of the use of BNs for modeling hazards, processing information, and aiding decision making with the goal of improving infrastructure system performance and reliability
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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Spectroscopic insights to the Fe(II)-Fe(III) redox system at mineral surfaces:
Tue, Apr 27, 2010 @ 02:00 AM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
... Implications for iron mineral formation and contaminant reduction.Speaker: Dr. Philip Larese-Casanova, Geology and Geophysics Department, Yale UniversityAbstract: The attenuation of groundwater contaminants has been closely linked with the chemical reactivity of native iron minerals. Dissolved Fe(II) can provide electrons that reduce contaminants to less toxic products, and this electron transfer process is catalyzed by reactive surface sites on Fe(III) minerals. However, the Fe(II)-Fe(III) redox reactions occurring at mineral surfaces are not fully understood because it is difficult to target and directly observe the physical and chemical activity of surficial iron atoms. Over the past few years, our observations of iron surfaces have become more sensitive by using 57Fe-Mössbauer spectroscopy with selective use of 57Fe and 56Fe isotopes. The process of dissolved 57Fe(II) sorption onto 56Fe(III) oxide surface sites (56hematite) was revealed instead to be a combined process of 57Fe(II) sorption and electron transfer to the bulk oxide, forming a new 57Fe(III) surface layer. 56Hematite has a capacity for this 57Fe(III) layer growth beyond which stable sorbed 57Fe(II) atoms reside on its surface. The transferred electrons within hematite rapidly hop among Fe atoms, a process others predicted to occur using computational methods. These spectroscopic observations are the first of their kind and highlight the need for new metal sorption models to account for redox-active sorbents. Contaminant reduction by dissolved 57Fe(II) and 56Fe(III) oxides results in further 57Fe(III) surface layer growth and the formation of new surface iron minerals, such as nano-sized 57goethite on 56hematite or 57lepidocrocite on 56magnetite, and these surface precipitates can alter the rate of contaminant reduction. Fe surface precipitates can also form via microbial Fe(II)-oxidation, and we have quantified iron phases formed (57lepidocrocite and 57goethite) during microbial oxidation of 57Fe(II) by the Fe(II)-oxidizing bacterium Acidovorax sp. BoFeN1 and have examined their dependence on geochemical solution conditions. Overall, contaminant reduction by the Fe(II)-Fe(III) redox couple is highly dependant on the supporting mineral substrate, and subtle changes to mineral surfaces or geochemical conditions can have profound effects on contaminant reduction rates or Fe(III) mineralogy.
Location: Kaprielian Hall (KAP) - 209 )
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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An Analytically Enriched Finite Element Method for Cohesive Crack Modeling
Thu, Apr 29, 2010 @ 10:00 AM - 11:00 AM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Speaker: Dr. James V. Cox, Soild Mechanics Department, Sandia National Laboratories, Albuquerque, NM 87185-0346jvcox@sandia.govAbstract:Meaningful computational investigations of many solid mechanics problems require accurate characterization of material behavior through failure. A recent approach to fracture modeling has combined the partition of unity finite element method (PUFEM) with cohesive zone models. Extension of the PUFEM to address crack propagation is often referred to as the extended finite element method (XFEM). In the PUFEM, the displacement field is enriched to improve the local approximation. Most XFEM studies have used simplified enrichment functions (e.g., generalized Heaviside functions) to represent the strong discontinuity but have lacked an analytical basis to represent the displacement gradients in the vicinity of the cohesive crack. As such, the mesh had to be sufficiently fine for the FEM basis functions to capture these gradients.In this study enrichment functions based upon two analytical investigations of the cohesive crack problem are examined. These functions have the potential of representing displacement gradients in the vicinity of the cohesive crack with a relatively coarse mesh and allow the crack to incrementally advance across each element. Key aspects of the corresponding numerical formulation are summarized. Analysis results for simple model problems are presented to evaluate if quasi-static crack propagation can be accurately followed with the proposed formulation. A standard finite element solution with interface elements is used to provide the accurate reference solution, so the model problems are limited to a straight, mode I crack in plane stress. Except for the cohesive zone, the material model for the problems is homogenous, isotropic linear elasticity. The effects of mesh refinement, mesh orientation, and enrichment schemes that enrich a larger region around the cohesive crack are considered in the study. Propagation of the cohesive zone tip and crack tip, time variation of the cohesive zone length, and crack profiles are presented. The analysis results indicate that the enrichment functions based upon the asymptotic solutions can accurately track the cohesive crack propagation independent of mesh orientation. Example problems incorporating enrichment functions for mode II kinematics are also presented. The results yield acceptable crack paths compared with experimental studies. The applicability of the enrichment functions to problems with anisotropy, large strains, and inelasticity is the subject of ongoing studies. Preliminary results for a contrived orthotropic elastic material reflect a decrease in accuracy with increased orthotropy but do not preclude their application to this class of problems
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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Preliminary Reconnaissance Report: 12 January 2010 Haiti Earthquake
Thu, Apr 29, 2010 @ 01:00 PM - 02:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Speaker: Eduardo A. Fierro1), and Cynthia L. Perry2)1) President of BFP Engineers, Inc., Berkeley, California USA2) Vice-President of BFP Engineers, Inc., Berkeley, California USAAbstract: After 240 years, the Enriquillo Plantain Garden Fault ruptured on 12 January 2010 at 4:53PM, resulting in a 7.0 Magnitude (USGS) earthquake in the vicinity of Port-au-Prince, Haiti. The epicenter was located at 18.457°N and 72.533°W and 25 km (15miles) WSW of Port-au-Prince. The earthquake has been a disaster for Haiti; at the time of this writing there are 170,000 confirmed deaths with estimates over 200,000 deaths. The National Palace, Palace of Justice, National Assembly, Supreme Court, Prison Civile de Port-au-Prince, and buildings housing the ministries of finance, education, public works, communication and culture have all been damaged. Power, water, and communications have been disrupted. This report is based on field reconnaissance by Eduardo Fierro. Mr. Fierro was on the ground in Port-au-Prince on Thursday January 14. His photos and observations were made from January 14 to 20, 2010. The primary objective of this initial trip was to observe the performance of building structures, industrial facilities, and infrastructure from a structural engineering perspective. This report documents places and structures that Mr. Fierro personally observed during his visits including Port-au-Prince, Cite Soleil, Petion Ville, Carrefour and other towns en route to Leogane
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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The Gap Bootstrap
Fri, Apr 30, 2010 @ 03:00 PM - 04:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Speakers: Dr. Clifford H. Spiegelman (TAMU), Soumendra Lahiri (TAMU), Justice Appiah (UNL), and Laurence Rilett (UNL)Abstract:In many areas of application, multivariate data are collected routinely over long time periods. Examples include hydrocarbon pollution monitoring, and automated highway volume traffic monitoring. The dominant part or the dependence for these types of data is short term. The gap bootstrap uses a divide, estimate, assess and combine strategy to provide asymptotically optimal or near optimal estimators. In spirit, it is similar in approach to kernel regression estimation, except that the joined pieces are not contiguous in time. We will show that for smooth enough estimators, and some useful dependence models that the resulting estimators are asymptotically efficient and have uncertainties that are accurately assessed using a case bootstrapping approach. Examples will use Origin-Destination (OD) modeling in transportation.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes