July 2023
    Country-wide Evaluation of Spent Fuel Storage Casks using a Phased Approach for Nonlinear Seismic Analysis

    Julio Garcia, Payman Tehrani, Natalie Doulgerakis, William Johnson

    DOE/NRC Natural Phenomena Hazards (NPH) Meeting at the U.S. Nuclear Regulatory Commission Headquarters in Rockville, MD in October of 2022.

    Because spent nuclear fuel (SNF) will be stored at interim spent fuel storage facility installations (ISFSI) for an extended period of time, there is an unreviewed condition related to the behavior of the SNF within these dry storage systems during earthquakes. Thus, Sandia National Laboratory is leading a shake table test program to better quantify […]

    June 2022
    Undercut Anchors for Structural Applications

    Philipp Mahrenholtz, Ph.D., Mark Ziegler, P.E. and Derrick Watkins, Ph.D., S.E.

    Structure Magazine, April 2022

    Undercut anchors are an ideal post-installed anchor category as their load transfer mechanism is bearing, similar to that of headed studs cast into concrete. Their mechanical interlock prevents the anchor from pulling out and results in high load capacities and small displacements. They can be designed such that with sufficient embedment depth and other design […]

    April 2022
    Modeling the Seismic Response of Spent Nuclear Fuel in Dry Storage

    Nick Klymyshyn, Julio Garcia, Payman Tehrani

    Pacific Earthquake Engineering Research Center (PEER) Researcher's Workshop, May 17, 2021

    The US Department of Energy’s Spent Fuel and Waste Science and Technology (SFWST) program is investigating the mechanical loading of spent nuclear fuel (SNF) to close knowledge gaps and inform the range of relevant loads for mechanical testing of irradiated SNF.  The SFWST program has performed full scale dynamic testing of multimodal transportation and cask […]

    August 2019
    Consideration of Non-Uniform Embedment on the Response of Nuclear Plant Structures

    Asa Bassam, Huy Tran, Ben Kosbab

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    The effects of foundation embedment on the seismic response of structures have long been recognized in the analysis and design of nuclear power plant (NPP) structures. Some design standards allow simple methods to address the embedment effects. However, these methods are only suitable to consider the effects of soil embedment on uniformly embedded structures. There […]

    August 2019
    Application of Seismic Ground Motion Incoherency Effects in SASSI on Soil Sites with Multiple Foundations

    Huy Tran, Kaniel Tilow, Benjamin Kosbab, Harsh Nandan

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    Inclusion of incoherency effects in soil-structure interaction (SSI) analysis provides a more realistic determination of earthquake induced building structural responses than those obtained considering coherent ground motion. Separately, industry demand for high-fidelity, comprehensive coupled structural models that often directly include structure-soil-structure interaction (SSSI) effects continues to increase. Combining incoherency and SSSI effects has raised questions […]

    August 2019
    A Case Study on the Structural Analysis and Fragility Calculation Due to Seismic Impact Between Adjacent Structures

    Asa Bassam, Ben Kosbab, Payman Tehrani, Hamed Ebrahimian

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    In this study, the seismic impact between two adjacent structures with different lateral stiffness is investigated through a computational model. The method used for the impact analysis in this study is based on the Hertz contact law combined with a non-linear damper activated during the impact to allow consideration of energy dissipation during the impact […]

    August 2019
    Structure-Soil-Structure Interaction Effects: A Case Study Comparing Two Approaches

    Julio García, Benjamin Kosbab, Andrii Nykyforchyn, Sunay Stäuble and Jens-Uwe Klügel

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    The seismic SSSI effects in the nuclear island buildings for a representative plant are considered. The nuclear island consists of four buildings. The seismic SSSI effects on the lightest and smallest building (building of interest) are analyzed with two different approaches (ASCE 4-16, 2017). First, a model that includes all four buildings (explicit SSSI model) […]

    August 2019
    Benchmark Study on Impedance Functions of Large Pile Foundations

    Peter Rangelow, Tobias Richter, Vladimir Nincic, Benjamin Kosbab, Julio A. García, Hans-Georg Hartmann, and Jörgen Johansson

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    In the nuclear power industry large pile groups are used world-wide at soil sites with soft and weak near-surface soil layers as foundations for both safety and non-safety related structures. Entire nuclear power plant (NPP) facilities are founded on piles in areas of low to moderate seismicity, as for example in Belgium (Doel 3), Brazil […]

    August 2019
    Soil-Pile-Structure Interaction Analysis: Implementation of Flexible Alternative Theoretical Approach in SASSI Framework

    Julio A. García, Benjamin Kosbab, Huy Tran, Tobias Richter, and Peter Rangelow

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    This paper introduces a new alternative for soil-pile-structure interaction analysis, based on established soil-pile interaction theory, which accommodates a wide range of foundation conditions. A description of the theoretical formulation and its implementation into the prevalent SASSI software framework via SC-SASSI (SC Solutions, 2018) is provided in this paper, including examples and usage recommendations. A […]

    August 2019
    Cost Basis for Utilizing Seismic Isolation in Nuclear Power Plants

    Kaivalya Lal, Sai Sharath Parsi, David Scott, Koroush Shirvan, Michael Cohen, Paul Kirchman, Benjamin Kosbab, and Andrew Whittaker

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    The benefits of seismically isolating nuclear power plant buildings, in terms of reducing seismic risk, are well established but the possible impacts on overnight capital cost are unknown. Projects funded by EPRI and ARPA-E are now underway to characterize possible reductions in overnight capital cost of new build plants, with a focus on the financial […]

    August 2019
    An Enhanced Equivalent Linear Soil-Structure Interaction Analysis Approach for Seismic Applications

    Iman Talebinejad, Payman Khalili Tehrani, Ben Kosbab, Michael Perez

    Transactions of the 25th International Conference on Structural Mechanics in Reactor Technology. Charlotte, NC. Aug. 4-9, 2019.

    This paper proposes enhancements to the equivalent linear approach of simulating the site soil response for the seismic soil-structure interaction analysis of structures in a nuclear power plant to better represent the physical behavior of soil. The equivalent linear site response approach in frequency domain is the state of practice which is widely used to […]

    October 2018
    Free-Field Displacements Calculated with Green’s Functions Implemented in SC-SASSI

    Julio Garcia, Benjamin Kosbab, and Huy Tran

    DOE/NRC Natural Phenomena Hazards Meeting, Rockville, Maryland, October 23-24, 2018

    A key step in the formulation and solution of the soil-structure interaction (SSI) problem is the calculation of the displacements of the soil without the presence of a structure, also known as free-field displacements. The free-field displacements are used as basis for the formulation of the compliance matrix or soil flexibility matrix. A new approach […]

    October 2018
    Numerical Modeling of Concrete Building Pounding During Seismic Events-A Case Study

    Asa Bassam, Ph.D., S.E., P.E., Ben Kosbab, Ph.D., and Payman Tehrani, Ph.D., P.E.

    DOE/NRC Natural Phenomena Hazards Meeting, Rockville, Maryland, October 23-24, 2018

    Review of existing literature on the topic of building pounding suggests that impact can not only result in potential structural damage, but can also result in large high frequency accelerations, that could cause malfunction of equipment installed within the buildings. The magnitude of impact effects caused by pounding is case-specific, and reliable methods to approximate impact effects are limited, […]

    August 2018
    Effects of Nonlinearities on Seismic Soil-Structure-Interaction Behavior of a Nuclear Plant Reactor Building: A Case Study

    Payman Khalili Tehrani, Iman Talebinejad, Benjamin Kosbab, Andrii Nykyforchyn, Sunay Stäuble, Jens-Uwe Klügel

    TINCE 2018 - Technological Innovations in Nuclear Civil Engineering, Paris, France, August 29-31, 2018

    A comparative seismic soil-structure-interaction (SSI) study was performed for the reactor building of a nuclear power plant in Switzerland in order to gain insights into the relative significance of nonlinear response effects which may be triggered during beyond-design-basis seismic events. The case study reactor building is founded on 20m of gravel underlain by bedrock and with an embedment depth […]

    April 2018
    Integrated Seismic Soil-Structure-Interaction and Detailed Structural Analysis for Retrofit Strategy Planning of a Gravity-Based Offshore Platform with Isolated Box Girder Deck

    Payman Khalili Tehrani, Harsh Nandan, Alex Krimotat, Keith Mash, Rohit Anand, Rune Nilsen

    Structures Congress 2018, Fort Worth, Texas, April 19-21, 2018

    An offshore Gravity Based Structure (GBS) and the underlying seabed soil layers were analyzed to evaluate the seismic retrofit strategy to extend the platform’s useful life and increase its production capacity. The GBS is a steel structure consisting of a box shape caisson substructure and a Box Girder Deck (BGD) which supports the topsides. The BGD and topsides […]

    April 2018
    Using Seismic Isolation to Simplify and Standardize NPP Designs

    Benjamin Kosbab, Chingching Yu, Andrew Whittaker

    2018 International Congress on Advances in Nuclear Power Plants, Charlotte, NC, April 8, 2018

    Recent studies have demonstrated that the capital cost of new nuclear is not dominated by the Nuclear Steam Supply System (NSSS) and balance-of-plant (BOP) technologies, but rather by the indirect costs, i.e. how the plants are built (including labor costs), engineering costs (including licensing) and owner’s costs (especially interest during construction). Therefore, cross-cutting technologies that […]

    August 2017
    Soil-Structure Interaction: Project Gains Through Use of High-Performance Computing

    Ben Kosbab, Julio Garcia, Wei Li, Huy Tran, Iman Talebinejad, Asad Bassam, and Kaniel Tilow

    Transactions of the 24th International Conference on Structural Mechanics in Reactor Technology. Busan, South Korea. Aug. 20-25, 2017.

    For decades, the System for Analysis of Soil Structure Interaction (SASSI) program and its derivatives has been an accepted and favoured analysis tool for treatment of seismic soil-structure interaction (SSI) effects on nuclear facilities. With continued advances in the fields of structural and geotechnical engineering, and increasing detail and refinement of analysis models, SASSI has […]

    August 2017
    Seismic SSI Analyses in the Nuclear Industry: Time Domain vs. Frequency Domain

    Payman Khalili Tehrani, Benjamin Kosbab, Huy Tran

    Transactions of the 24th International Conference on Structural Mechanics in Reactor Technology. Busan, South Korea. Aug. 20-25, 2017.

    The nuclear industry has been a pioneer in recognizing the importance of Soil-Structure Interaction (SSI) and its effects on the dynamic response of structures and components during an earthquake. Equivalent linear analysis in frequency domain (ELFD) is the current state of practice for performing seismic SSI analysis of nuclear facilities. While the ELFD method produces […]

    August 2017
    Seismic Isolation of a Nuclear Structure: Impacts on Construction Cost and Seismic Risk

    Ching-Ching Yu, Chandrakanth Bolisetti, Benjamin Kosbab, Justin Coleman, and Andrew Whittaker

    Transactions of the 24th International Conference on Structural Mechanics in Reactor Technology. Busan, South Korea. Aug. 20-25, 2017.

    Base isolation will substantially reduce horizontal seismic demands in structures, systems and components (SSCs) in nuclear facilities, thus providing opportunities to increase seismic safety and reduce construction cost. Although past studies have characterized the benefits of seismic isolation in terms of increased safety, the possible reductions in construction cost have not been quantified. The over excavation, additional reinforced concrete […]

    August 2017
    The Revolutionary Blockchain – An Opportunity for Engineering Stewardship

    Daniel R. Robles, P.E. and Matthew E. Bowers, P.E

    ACSE Innovation Contest

    The hallmark of an advanced economy is the extent, condition, and efficiency of its public and private infrastructure. The advent of Blockchain technology gives society the capability to represent value stored in infrastructure with an electronic token validated by engineers. The implications are staggering. Markets would elevate the engineering profession to the status of financial […]

    July 2017
    Seismic Performance Evaluation of Underground Structures – Past Practice and Future Trends

    Youssef M.A. Hashash, Michael Musgrove, Shideh Dashti, Phoebe Cheng

    3rd International Conference on Performance-based Design in Earthquake Geotechnical Engineering (PBD-III)

    Underground structures are an integral part of civil infrastructure and play an ever-increasing role in a rapidly urbanizing world. Underground structures have generally performed better than aboveground structures during earthquakes when transient motions are considered. Nevertheless, underground structures are vulnerable to ground failure such as fault displacement, liquefaction and slope instability. This paper reviews past performance of […]

    January 2017
    Site Response Analysis Considering Strain Compatible Site Period

    Hoss Hayati, Robb E.S. Moss

    Soil Dynamics and Earthquake Engineering, Volume 92, January 2017, Pages 551-560

    In practice it is common to estimate site effects using a single proxy, or single variable such as 30 m shear wave velocity (Vₛ₃₀) or site period. Many studies have investigated merits of proposed proxies with contradicting recommendations. Yet, most studies indicate the single proxy approach is less than ideal, resulting in large uncertainty. To provide a better […]

    October 2016
    Comparative Study of Time-Domain versus Frequency-Domain Seismic Soil-Structure Interaction Analysis of Pressurized Water Reactor Containment Building

    Payman Khalili Tehrani, Benjamin Kosbab

    DOE Natural Phenomena Hazards (NPH) Workshop 2016

    The equivalent linear approach in frequency domain (ELFD) is the current state of practice for performing seismic soil-structure interaction (SSI) analysis of nuclear facilities. Although the ELFD method would produce reliable results for small to medium intensity ground motions, its application to analyze structures under large seismic events is debatable. The latter is due to the […]

    October 2016
    Probabilistic Soil-Structure Interaction Analysis of Nuclear Power Plant Structures for Probabilistic Risk Assessment

    Benjamin Kosbab, Wei Li, Mark Stewart, and Richard Drake

    DOE Natural Phenomena Hazards (NPH) Workshop 2016

    As a partial response to post-Fukushima Near-Term Task Force (NTTF) Recommendation 2.1 from the Nuclear Regulatory Commission (NRC), several operating nuclear power plants commissioned seismic probabilistic risk assessment (SPRA) studies to evaluate the impact of modern seismic hazard estimates on seismic safety. The current study focuses on the structural response analysis performed for various structures […]

    May 2016
    Seismic SSI Analysis of Nuclear Power Plants: Time Domain versus Frequency Domain

    Payman Khalili Tehrani, Benjamin Kosbab

    Engineering Mechanics Institute Conference 2016

    The seismic Soil-Structure Interaction (SSI) analysis of nuclear facilities is usually performed in frequency domain where the response of the soil-structure system’s components is modeled as linear. The linear response assumption may be appropriate for small- to medium-intensity seismic events; however, the Seismic Probabilistic Risk Assessment (SPRA) of nuclear facilities requires the study of the […]

    February 2016
    Evaluation of a New Interface Forcing Function for Analysis of Structures Under Automobile Missile Impacts

    Asad Bassam, Nezar Abraham

    ASCE Geotechnical and Structural Engineering Congress 2016

    The safety related structures in nuclear power plants often need to be designed to withstand the effects of tornado generated missile impacts. The heaviest missile to consider is often an automobile which is a soft missile due to its large deformations during the impact. Due to the large mass of this missile, it often has the highest kinetic […]

    December 2015
    Seismic Analysis of Nuclear Power Plants

    Julio Garcia

    Mexican Association of Civil Engineers, Mexico City, 2015

    Attending an invitation from the Mexican Society of Geotechnical Engineering (SMIG), the Mexican Society of Structural Engineering (SMIE) and the Mexican Society for Earthquake Engineering (SMIS), Julio Garcia of SC Solutions presented a lecture on the topic: Seismic Analysis of Nuclear Power Plants. The event was held on December 3, 2015 at the Mexican Association of Civil Engineers, […]

    October 2015
    Rapid Post-Earthquake Safety Evaluation of Bridges

    Roy A. Imbsen P.E. D.Engr, Shahriar Vahdani, P.E. Ph.D, Jinquan Zhong P.E. Ph.D

    California Strong Motion Instrumentation Program SMIP 2015

    A new procedure for rapid post-earthquake safety evaluation of bridges is being developed, using existing strong motion records, PGA data immediately available following an earthquake, and fragility databases, to assist responsible parties in making timely, informed decisions regarding post-earthquake bridge closures. The New Carquinez Bridge was selected to demonstrate the procedure. This paper provides a […]

    September 2015
    An Innovative Procedure for Load Rating of Suspension Bridges

    Hassan Sedarat, Iman Talebinejad, Alexander Kozak, Joyce Lee, Farid Nobari, Alex Krimotat

    Western Bridge Engineer's Seminar 2015

    Over two hundred million trips are taken daily across structurally deficient bridges in the nation’s 102 largest metropolitan regions, per 2013 ASCE Report Card for America’s Infrastructure. The average age of the nation’s 607,380 bridges is currently 42 years. The nation has an entire generation of bridges, constructed in the 1950s and 1960s, that need […]

    June 2015
    Numerical Simulation of Fluid-Structure Interaction in Fluid Storage Tanks

    Payman Khalili Tehrani, Alexander Kozak, Eric Abrahamson, Alex Krimotat

    Engineering Mechanics Institute Conference 2015

    Fluid-Structure Interaction (FSI) may contribute significantly to the structural demands on fluid storage structures during the seismic events because of sloshing and impulsive wall pressure. A variety of simplified approaches are used in engineering practice to quantify the FSI effects via either closed-form solutions or the use of discrete analogs to represent the fluid domain. […]

    August 2014
    Nonlinear Response History Analysis of Seismic Soil-Structure and Fluid-Structure Interactions for Buried Reinforced Concrete Fluid Storage Structures

    Payman Khalili-Tehrani, Alexander Kozak, Phoebe Cheng, Hassan Sedarat, Alex Krimotat, Wally Bennett, Michele McHenry

    Engineering Mechanics Institute 2014

    A series of nonlinear seismic time history analyses was conducted in LS-DYNA to evaluate the seismic performance of buried reinforced concrete fluid storage structures. This study is aimed at presenting a sophisticated modeling procedure in time domain for soil-structure (SSI) and fluid-structure (FSI) interactions with limited focus on FSI. The current state-of-practice for modeling SSI […]

    July 2014
    Period of Interest – The Confluence of Site Response Analysis and Soil-Structure Interaction

    H. Hayati, M. E. Bowers, and R. E. S. Moss

    Tenth U.S. National Conference on Earthquake Engineering 2014

    Code-based procedures rely on a simplified sub-structure approach for analyzing soil structure interaction (SSI) effects. This simplified approach separates the site response analysis (SRA) from the SSI problem. Such separation prohibits a holistic view of the entire soil-structure system under seismic loading. Specifically, perspective is lost on the concurrent period migration of the structure and […]

    June 2014
    Time Series Based Damage Detection and Localization in an Offshore Platform Using Wireless Sensor Networks

    Harsh Nandan, Eric Abrahamson, Xiangyu Wang, Carl Brinkmann

    33rd International Conference on Ocean, Offshore and Arctic Engineering Proc. ASME. 45431; Volume 4B: Structures, Safety and Reliability, V04BT02A054. June 08, 2014 OMAE2014-24652

    Continuous structural integrity monitoring (SIM) can be a valuable complementary tool to the current practice of periodic inspections in detecting damage in jacket platforms.  This paper demonstrates the technical feasibility of adopting the recent advances in onshore SIM technology for offshore jacket platforms. Both the analysis method and hardware technology are investigated.  To demonstrate the […]

    March 2014
    Implementation of Damage Detection Algorithms for the Alfred Zampa Memorial Suspension Bridge

    I. Talebinejad, H. Sedarat, A. Emami-Naeini, A. Krimotat, Jerome Lynch

    Proc. SPIE Vol. 9063, 906312 (9 March 2014) Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2014 • © 2014 SPIE; doi: 10.1117/12.2044539

    This study investigated a number of different damage detection algorithms for structural health monitoring of a typical suspension bridge. The Alfred Zampa Memorial Bridge, a part of the Interstate 80 in California, was selected for this study. The focus was to implement and validate simple damage detection algorithms for structural health monitoring of complex bridges. […]

    March 2014
    Real-Time Estimation of the Structural Response Using Limited Measured Data

    Hassan Sedarat, Iman Talebinejad, Abbas Emami-Naeini, David Falck, Gwendolyn van der Linden, Farid Nobari, Alex Krimotat, Jerome Lynch

    Proc. SPIE 9063, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2014, 906311 (9 March 2014) • © 2014 SPI; doi: 10.1117/12.2044617

    This study introduces an efficient procedure to estimate the structural response of a suspension bridge in real time based on a limited set of measured data. Unlike conventional techniques, the proposed procedure does not employ mode shapes and frequencies. In this study, the proposed technique is used to estimate the response of a suspension bridge […]

    March 2014
    Stability of Circular Bridge Column Reinforcing Bar Cages

    Builes-Mejia, J. Camilo; Itani, Ahmad M.; Sedarat, Hassan

    Concrete International, The magazine of the American Concrete Institute -- an international technical society

    This peer-reviewed article presents an investigation conducted to determine the behavior of bridge column reinforcing bar cages subjected to lateral loads. Two full-scale cages were tested until failure to determine the response to lateral displacement and identify progressive collapse sequences. Using the results from the experimental study, nonlinear static and dynamic finite element analyses were […]

    September 2013
    The Importance of Considering Column Top Rotations in the Displacement of Triple Friction Pendulum Isolators for Tall Column Structures

    Eric Abrahamson, PE, Ph.D., and Fletcher Waggoner, PE

    Western Bridge Engineer's Seminar 2013

    The SR520 North West Approach replacement project will consist of 40 spans of isolated, elevated roadway. The design includes approximately 100 triple friction pendulum isolator bearings atop columns supporting the superstructure. A detailed ADINA model was generated, which used a nonlinear user-derived element for the isolation bearings, coupled in the two principal horizontal directions. During […]

    May 2013
    Efficient Techniques in Finite Element Analysis and Seismic Evaluation of Suspension Bridges

    Hassan Sedarat, Alexander Kozak, Joyce Lee, Alex Krimotat, Vince Jacob, Steve Mitchell

    Seventh National Seismic Conference on Bridge and Highways (7NSC), Bridge Resilience for earthquake and other natural hazards, Oakland, May 20-22, 2013.

    Three important challenges in the finite element modeling and seismic analysis of a suspension bridge are addressed in this paper.  Firstly, since suspension bridges are highly nonlinear geometrically, the construction sequence should be simulated to accurately characterize the initial stresses in the structural components. For this purpose, an automated procedure that iteratively corrects the geometry […]

    May 2013
    Using Field-Measured Ambient-Induced Vibration Responses for Finite Element Model Calibration of the Carquinez Bridge

    Amir A. Mosavi, Iman Talebinejad, Hassan Sedarat, Yilan Zhang, Pat Hipley, Edward Thometz, Vince Jacob, Jerome Lynch

    Seventh National Seismic Conference on Bridge and Highways (7NSC), Bridge Resilience for earthquake and other natural hazards, Oakland, May 20-22, 2013.

    A  Finite  Element  (FE)  model  which  can  precisely  predict  the  actual  dynamic  responses  of  a  bridge  is necessary  for  accurate  condition  assessment  and  health  monitoring  purposes.    However,  most  of the bridge FE models  initially developed  for  design purposes may  not  be  able  to  accurately simulate  the  current response of the bridges due to various  reasons.  […]

    May 2013
    Nonlinear Load-Deflection Behavior of Reinforced Concrete Drilled Piles in Stiff Clay

    Payman Khalili-Tehrani, Eric R. Ahlberg, Changsoon Rha, Anne Lemnitzer, Jonathan P. Stewart, Ertugrul Taciroglu, and John W. Wallace

    Journal of Geotechnical and Geoenvironmental Engineering, Volume 140, Issue 3 (March 2014) 10.1061/(ASCE)GT.1943-5606.0000957, 04013022

    The results of three full-scale lateral load tests of cast-in-drilled-hole RC piles are evaluated to provide insights into the soil-pile interaction behavior as represented by p-y curves (p 5 soil reaction/length; y 5 lateral pile deflection) spanning from elastic conditions to mobilization of the soil capacity. The test sequence enables evaluation of the diameter effects on the […]

    May 2013
    Dynamic Response of a Floating Bridge to a Moving Light Rail Train

    Hassan Sedarat, Iman Talebinejad, Alexander Kozak, Alex Krimotat, Tom Cooper, John A. Harrison, John Sleavin, Paul Cornish

    ASCE, 2013 Structures Congress, Pittsburg, Pennsylvania, May 2-4, 2013.

    This study pertains to the vehicle–bridge interaction analysis of Homer M. Hadley Memorial Bridge located in Seattle, Washington. The bridge carries the westbound and reversible lanes of Interstate 90 across Lake Washington and is the widest and fifth-longest floating bridge in the world. Based on the proposed plan to design and construct a light rail […]

    March 2013
    Calibrating a High-Fidelity Finite Element Model of a Highway Bridge Using a Multi-Variable Sensitivity-Based Optimisation Approach

    Amir A. Mosavi, Hassan Sedarat, Sean M. O'Connor, Abbas Emami-Naeini, & Jerome Lynch

    Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance, DOI:10.1080/15732479.2012.757793

    This article presents the implementation of a calibration procedure for a finite element (FE) model of a state highway bridge using sensory data measured on the bridge. The objective is to modify the high-fidelity FE model of the bridge so that its dynamic behaviour matches, as closely as possible, that of the bridge under analysis. […]

    February 2013
    Nonlinear Dynamic Analysis of a Track Bridge Structure Designed for a Floating Bridge

    H. Sedarat, A. Kozak, I. Talebinejad, V. Jacob, A. Krimotat, T. Cooper, J. Sleavin, P. Cornish

    IMAC-XXXI-Society for Experimental mechanics (SEM): Conference & Exposition on Structural Dynamics, Engineering Nonlinearities in Structural Dynamics, Garden Grove, California, February 11-14, 2013.

    The addition of Light Rail Trains (LRT) to the Homer M. Hadley Memorial Bridge, the widest floating bridge in the world located in Seattle, Washington, is currently in its design process. The design team has concluded that a transition Track Bridge (TB) is necessary to accommodate large movements induced by the floating bridge in relation […]

    April 2012
    Finite Element Model Updating of a Skewed Highway Bridge Using a Multi-Variable Sensitivity-Based Optimization Approach

    Amir A. Mosavi, Hassan Sedarat, Sean M. O’Connor, Abbas Emami-Naeini, Vince Jacob, Alex Krimotat, Jerome Lynch

    Proc. SPIE 8347, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2012, 834727 (April 26, 2012); doi:10.1117/12.916163

    A Finite Element (FE) model which can precisely predict the actual dynamic responses of a bridge is necessary for accurate condition assessment and health monitoring purposes. However, most of the bridge FE models initially developed for design purposes may not be able to accurately simulate the current response of the bridges due to various reasons. […]

    January 2011
    Optimal Sensor Placement for Health Monitoring of Civil Structures

    G. W. van der Linden, A. Emami-Naeini, R .L. Kosut, H. Sedarat, and J. P. Lynch

    2011 American Control Conference, San Francisco, CA, USA, June 29 - July 01, 2011, pp. 3116 -3121, 2011.

    G. W. van der Linden, A. Emami-Naeini, R .L. Kosut, H. Sedarat, and J. P. Lynch In this paper we focus on comparing three candidate approaches to the optimal placement of sensors for state estimation-based continuous health monitoring of structures. The first aims to minimize the static estimation error of the structure deflections, using the […]

    November 2010
    Stability of Bridge Column Rebar Cages During Construction

    J. Camilo Builes-Mejia, Ahmad M. Itani, Hassan Sedarat

    Center for Civil Engineering Earthquake Research, Department of Civil Engineering/258, University of Nevada, Reno, NV 89557 November 2010

    The lateral behavior and stability of bridge column rebar cages were investigated to reduce the potential of failure and collapse during construction. Rebar cages are temporary structures made of longitudinal and transverse reinforcing bars that are connected by tie wire connections. Recent collapses during construction exposed the vulnerabilities of these temporary structures to accidental loads […]

    August 2010
    California Toll Bridges Analytical Model Strong Motion Instrumentation Program (CSMIP) Calibration Project

    Alex Krimotat, Hassan Sedarat, Alexander Kozak, Steve Mitchell, Hubert Law, Chien Tai Yang, Ignatius Po Lam

    California Department of Transportation (Caltrans)

    Caltrans’ Toll Bridge Seismic Retrofit Program involved performing vulnerability assessments and retrofit designs for the state-owned toll bridges. To determine bridge response and evaluate seismic performance, a finite element model of each toll bridge was created using the finite element program ADINA. Following recommendations of the Seismic Advisory Board the project main goals included the following: (a) update the […]

    July 2010
    Practical Application of Advanced Seismic Analysis of Structures in a Production Environment

    H. Sedarat, A. L. Kozak, A. V. Krimotat, and A. Itani

    9th U.S. National & 10th Canadian Conference on Earthquake Engineering (9USN/10CCEE) Toronto, 2010

    In the current state-of-practice of the performance-based design of structures, simplified procedures are often used to evaluate the deformation capacity of structural systems. One specific example is using the rotation limits for the deformation-controlled elements. This paper suggests the use of the strain limits, instead, and presents an efficient nonlinear analytical technique to compute the strain demand values for both […]

    March 2010
    Near-Optimal Sensor Placement for Health Monitoring of Civil Structures

    G. W. van der Linden, A. Emami-Naeini, R. L. Kosut, H. Sedarat, J. P. Lynch

    Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2010, Ed. Peter J. Shull, Aaron A. Diaz, H. Felix Wu, doi: 10.1117/12.847704, Proc. of SPIE Vol. 7649, San Diego, CA, USA, March 7-11, 2010.

    In this paper we focus on the optimal placement of sensors for state estimation-based continuous health monitoring of structures using three approaches.  The first aims to minimize the static estimation error of the structure deflections, using the linear stiffness matrix derived from a finite element model.  The second approach aims to maximize the observability of […]

    March 2010
    A Two-Tiered Self-Powered Wireless Monitoring System Architecture for Bridge Health Management

    M. Kurata, J. P. Lynch, T. Galchev, M. Flynn, P. Hipley, V. Jacob, G. W. van der Linden, A. Mortazawi, K. Najafi, R. L. Peterson, L.-H. Sheng, D. Sylvester, E. Thometz

    Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2010, Ed. Peter J. Shull, Aaron A. Diaz, H. Felix Wu, doi: 10.1117/12.848212, Proc. of SPIE Vol. 7649, San Diego, CA, USA, March 7-11, 2010.

    Bridges are an important societal resource used to carry vehicular traffic within a transportation network. As such, the economic impact of the failure of a bridge is high; the recent failure of the I-35W Bridge in Minnesota (2007) serves as a poignant example. Structural health monitoring (SHM) systems can be adopted to detect and quantify […]

    December 2008
    Contact Interface in Seismic Analysis of Circular Tunnels

    Hassan Sedarat, Alexander Kozak, Youssef M.A. Hashash, Anoosh Shamsabadic, and Alex Krimotat

    Reference: TUST1130, in: Tunnelling and Underground Space Technology incorporating Trenchless Technology Research. Online publication complete: 25-DEC-2008, DOI information: 10.1016/j.tust.2008.11.002

    The seismic analysis of underground structures requires a careful consideration of the important effect of shear strains in the soil due to vertically propagating horizontal shear waves. These strains result in ovaling deformations of circular tunnels or racking deformations of rectangular tunnels. Closed-form solutions as well as numerical analyses are used to characterize this soil-structure […]

    July 2008
    Seismic Vulnerability Study of the Auburn-Foresthill Bridge

    Wei Li, John Quincy, Mark Reno, and Hassan Sedarat

    Sixth National Seismic Conference on Bridges and Highways: Seismic Technologies for Extreme Loads, 2008 Multidisciplinary Center for Earthquake Engineering Research State University of New York, 107 Red Jacket Quadrangle, P.O. Box 610025 Buffalo, NY 14261-0025 USA

    The Auburn-Foresthill Bridge is a 2,428 ft steel suspension bridge that links the towns of Auburn and Foresthill, California and was built in1973. While it is ranked 3rd in the U.S., it is the tallest bridge in California. The bridge is located in the seismically active Foothills fault zone and is supported by two 403 ft tall unconfined […]

    January 2008
    Modeling of Steel Plate Girder Superstructures for Seismic Analysis

    Hassan Sedarat, Ahmad Itani

    Transportation Research Board of the National Academies, 87th Annual Meeting, January 2008

    Contact us at for more information about this paper.

    January 2007
    Seismic Response of Precast Tunnel Linings

    G.J.E. Kramer, H. Sedarat, A. Kozak, A. Liu, J. Chai

    Rapid Excavation and Tunneling Conference Toronto, 2007

    Precast concrete segmental lining systems have been gaining widespread use in seismically active areas and a single-pass version of such a system has been developed for use on the Silicon Valley Rapid Transit (SVRT) Project in San Jose, California. The response of tunnel linings to seismic shaking is often predicted using engineering judgment, elastic closed-form […]

    January 2003
    Seismic Design of the Cooper River Bridges Replacement Main Span Unit

    Michael Abrahams, John Bryson, Jaw-Nan Wang, Hassan Sedarat

    You can read more about SC-Solutions’ work on the Cooper River Replacement bridge here. Contact us at for more information about this specific paper, Seismic Design of the Cooper River Bridges Replacement Main Span Unit.

    April 2002
    Use of Performance Based Design and Analysis for Seismic Evaluation of Major Bridge

    A. Krimotat

    All large structures are vulnerable to earthquake damage. Local failures or total collapse of such structures represent not only immediate concern for loss of life and repair costs, but also major economic impacts due to loss of service. Engineers are asked to use advanced analytical procedures in order to assess the seismic vulnerability of existing structures, design with more […]

    January 2002
    Design of the Taiwan High Speed Rail Viaducts

    J.D. Place, A. Krimotat, M.J. Barron

    The Taiwan High Speed Railway is currently one of the world’s largest BOT infrastructure projects. Due for completion in 2003, the railway runs down the western side of Taiwan linking all the main centres of population. A major constraint on the design of the viaducts is the interaction between the track and the structure during […]

    April 2001
    A Study of the Pile-Wharf Deck Connection at the Port of Oakland

    D. Oyenuga, E. Abrahamson, A. Krimotat, A. Kozak, T. Labasco, and F. Lobedan

    in Ports 2001: American’s Ports–Gateways to the Global Economy, 2004.

    This paper presents the results of a detailed study of the batter pile-wharf deck connection at the Port of Oakland under their Wharf and Embankment Strengthening Program (WESP). It provides insight into the failure mechanisms of the designs studied and an evaluation of their reliability.

    March 2001
    Seismic Soil-Tunnel-Structure Interaction Analysis And Retrofit of the Posey-Webster Street Tunnels

    Anoosh Shamsabadi, Hassan Sedarat, Alexander Kozak

    2nd UJNR (United States and Japan Cooperative Program in Natural Resources) Workshop on Soil-Structure Interaction, March 6 to 8, 2001, Tsukuba, Japan

    The purpose of this paper is to present the Soil-Tunnel-Structure Interaction analysis performed for the “innovative” seismic retrofit of the Posey and Webster Street Tunnels located in the San Francisco Bay area. The tunnels are situated between two major faults, the Hayward Fault and the San Andreas Fault (Figure 1). Due to its close proximity […]

    January 2001
    Analysis of Existing Piles with Missing Data in Seismic Retrofit Design at the Port of Oakland

    D. Oyenuga, S. Abe, H. Sedarat, A. Krimotat, S. Salah-Mars, and K. Ogunfunmi

    Ports '01: America's Ports: Gateway to the Global Economy: pp. 1-10

    This paper presents results of a study conducted during the Seismic Risk Evaluation Phase of the Port of Oakland’s (California) Wharf and Embankment Strengthening Program (WESP). It estimates the response of existing piles with missing pile-driving records, to lateral load. The Pile Integrity Test (PIT) was used to determine pile tip elevations at the relevant […]

    November 2000
    Seismic Analysis and Design of the AISI LRFD Design Examples of Steel Highway Bridges

    Ahmad M. Itani, Hassan Sedarat

    Report No. CCEER 00-8, Center for Civil Engineering Earthquake Research, Department of Civil Engineering, University of Nevada, Reno, November 2000

    October 1999
    SR5 Lake Washington Ship Canal Bridge Pushover Analysis

    Thomas A. Ballard, Hassan Sedarat

    Computers and Structures, Volume 72 (1999), Pages 63-80 Pergamon Press

    In this paper the results of SC Solutions’ performance-based evaluation of the as-built Unit 10 frame of the SR5 Lake Washington Ship Canal Bridge are presented. This unit is a three-span frame, located between bridge piers 24 and 27 on the north approach to the bridge and extends approximately 329 ft between expansion joints. A three­ dimensional […]

    August 1999
    Performance-Based Seismic Design for Bridges

    Juan Murillo, Thomas Cooper, Alex Krimotat

    Structures for the Future - The Search for Quality IABSE Symposium, Rio de Janeiro, August 1999, Volume 83

    Design criterion and methodologies have been developed and implemented that require bridges to be without significant damage following severe ground shaking. The design philosophy used to obtain these results is often referred to as “Performance Based Design.” These criteria differ from traditional codes in that they correlate levels of damage noted in laboratory testing and […]

    July 1999
    Seismic Modeling, Analysis, and Design of Modern Steel Bridges

    Ahmad M. Itani, Alex Krimotat, and Camille G. Rubeiz

    Mid-America Highway Seismic Conference, March 1999, St. Louis, MS

    The current AASHTO Specifications do not have adequate guidelines for seismic modeling and analysis of steel bridges. Bridge designers in seismic zones have always raised concerns about the adequacy of beam models in performing seismic analysis of steel bridges. This paper discusses the dynamic characteristics of five medium span steel bridges that were modeled using […]

    June 1999
    Active Control in Structures

    H. Sedarat, H. Sedarat, R. Kosut,

    13th ASCE Engineering Mechanics Division Conference held in Baltimore, June 13-16, 1999

    In this paper the application of control theory to structural engineering has been presented from a structural engineering perspective. The objective of this paper is to summarize key steps that are required to design an active control system for a structure. Total acceleration feedback with H2/LQG controller is used in this paper. The structural control […]

    May 1999
    Alameda Tubes Seismic Retrofit Studies

    Alexander Kozak, Hassan Sedarat, Alex Krimotat

    Computers & Structures, Volume 72, Issues 1-3, 8 July 1999, Pages 233-251, Available online 24 May 1999, DOI information: 10.1016/S0045-7949(99)00008-5

    As a part of the Posey and Webster Street Tubes seismic retrofit project, finite element analysis was used to study the soil–structure interaction behavior due to earthquake ground motions. This paper summarizes the nonlinear analysis activities for the Alameda Tubes. The overall objective of these studies was to estimate the responses of the as-built and […]

    October 1998
    Utilizing Pushover Analysis for Seismic Performance of Steel Bridge Structures

    Thomas A. Ballard, Alex Krimotat, Robin Mutobe

    Seismic retrofit of steel bridges requires more advanced analysis techniques to determine capacities and predict inelastic performance parameters. Normal engineering analysis practice assumes linear-elastic behavior for structural members, which fails to reliably account for re-distribution of forces due to member non-linear behavior and dissipation of energy due to material yielding. The performance criteria for the 1958 Carquinez Strait […]

    September 1998
    Seismic Soil-Structure Interaction Analysis for Immersed Tube Tunnels Retrofit

    Youssef M. A. Hashash, M.ASCE, Wen S. Tseng, M.ASCE, and Alexander Krimotat

    In Geotechnical Special Publication. (75 II ed., pp. 1380-1391)

    Two immersed tube tunnels used for vehicular traffic in the seismically active San Francisco Bay Area were built over 30 years ago with little consideration to seismic effects. A seismic retrofit study was conducted to assess the vulnerability of the tubes to seismic shaking and to develop necessary retrofit schemes. Three-dimensional soil-structure interaction models of […]

    June 1998
    Proof-Testing of Latticed Members and Their Connections on the San Francisco – Oakland Bay Bridge

    Astaneh-Asl, A., Dameron, R.A., Itani, A., Krimotat, A. and Uang, C-M

    Report No. UCB/CEE-Steel- 98/03, Department of Civil and Environmental Engineering, University of California, Berkeley, June 1998.

    The purpose of this research was to provide the information required to finalize seismic retrofit design of the San Francisco-Oakland Bay Bridge. The emphasis was on conducting cyclic tests of half-scale specimens representing laced members and joints of the Bridge. The study indicated that the dominant failure mode of the members tested was local buckling […]

    June 1998
    Non-Linear Seismic Analysis of Carquinez Bridges

    Semyon Treyger, P.E., Thomas A. Ballard, P.E., Alex Krimotat, and Robyn Mutobe

    Computers & Structures, Volume 64, Issues 5–6, September 1997, Pages 1041-1052, Proceedings of the 11th ADINA Conference

    This paper discusses the particular features and benefits of ADINA with respect to the requirements of advanced seismic analysis as applied to the Carquinez Strait Bridges in California. Major aspects of earthquake related analyses are discussed, i.e., static lateral push-over analysis, ground motion specification for dynamic analysis, and significant structural behavior phenomena associated with geometric […]

    July 1995
    Seismic Analysis of Complex Structures: Practical Application Issues and Case Study

    A. V. Krimotat and R. M. Mutobe

    SC Solutions, Inc., 1451 Grant Road, Mountain View, CA 94040, U.S.A.

    All large structures are vulnerable to earthquake damage. Local failures or total collapses of such structures represent not only immediate concern for loss of life and repair costs, but also major economic impacts due to loss of service. The 1989 Loma Prieta and 1994 Northridge earthquakes in California provided dramatic examples of the vulnerability of […]

    error: Content is protected !!