Gregory L. Fenves’s research while affiliated with University of Texas at Austin and other places

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Publications (92)


Erratum for “Krylov Subspace Accelerated Newton Algorithm: Application to Dynamic Progressive Collapse Simulation of Frames” by Michael H. Scott and Gregory L. Fenves
  • Article

August 2020

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54 Reads

Journal of Structural Engineering

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Gregory L. Fenves

Fig. 9.1 3D view of the computational FE model of the bridge-foundation-ground system
Fig. 9.2 Aerial photograph of I-10/215 interchange (©2013 Google -http://maps.google.com)
Fig. 9.3 Seismic instrumentation for North-West connector
Fig. 9.4 Schematic view of connection between column and soil including pile groups
Fig. 9.5 Numerical model for the bridge-foundation-system

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Seismic Response of a Large-Scale Highway Interchange System
  • Article
  • Full-text available

December 2014

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329 Reads

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4 Citations

Geotechnical

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George Petropoulos

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[...]

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Gregory L. Fenves

A numerical simulation of a large-scale highway interchange system under seismic loading conditions is conducted. A three-dimensional (3D) Finite Element (FE) model of an existing bridge system at the Interstate 10/215 interchange (Riverside County, CA) is developed. This interchange is comprised of three connectors at different bridge superstructure elevations. Herein, focus is placed on one of these three connectors (the North-West connector), using the OpenSees FE framework. A strategy to incorporate ground response and soil-structure interaction (SSI) is implemented based on the Domain Reduction Method (DRM) for three-dimensional earthquake simulation. Modeling of this bridge-foundation-ground system is based on blue-prints that were provided by Caltrans (California Department of Transportation). Vibration properties and seismic response behavior for the connector and the soil domain are examined. Different scenarios of bridge response are considered and compared, including fixed-base uniform excitation, and multiple-support excitation with and without the full ground/foundation soil domain.

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Fig. 1. Graphical representation of the Krylov subspace acceleration method 
Fig. 2. MATLAB code for Krylov subspace acceleration algorithm 
Krylov Subspace Accelerated Newton Algorithm: Application to Dynamic Progressive Collapse Simulation of Frames

May 2010

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2,792 Reads

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137 Citations

Journal of Structural Engineering

In the nonlinear analysis of structural systems, the Newton-Raphson (NR) method is the most common method to solve the equations of equilibrium. The NR method is easy to implement and gives an asymptotically quadratic rate of convergence. However, there are some well known shortcomings of the NR method. The Modied Newton (MN) method alleviates some of the problems of NR, but with a asymptotically linear rate of convergence requiring an excessive number of iterations to reach equilibrium. Accelerated Newton (AN) methods strike a compromise between the NR and MN methods. Generally, the compromise is to hold the stiness matrix constant during iteration, but to use selected information from previous iterations to accelerate conver- gence of the MN method. Since the mid 1980s, AN methods based on projections into Krylov subspaces have been developed by researchers in the mathematics community. Of particular interest is the method formulated by Carlson and Miller (1998) involv- ing low rank least squares projections. Its performance in the nonlinear analysis of structures is comparable to NR, requiring only a few more iterations to converge while taking less computational time than both NR and MN.


Interprocessor communication for high performance, explicit time integration

April 2010

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21 Reads

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2 Citations

Engineering with Computers

Parallel, explicit finite element analysis is based almost exclusively on point-to-point interprocessor communication. However, point-to-point communication on multicore architectures results in large performance variability because of shared caches and sockets. The interprocessor communication required during the solution phase must be designed to achieve a high degree of scalability and performance for explicit time integration operators. An analysis of point-to-point communication on different hardware platforms, communication library implementations, and message sizes demonstrates the need for a flexible software design that allows for optimization. Autotuning modules and preliminary performance tests are necessary to identify the optimal combination of calls. Performance differences of point-to-point messaging on multicore machines are illustrated with a test that uses combinations of MPI communication calls. The differences are apparent when cache and sockets are shared among the cores and for message sizes up to 1.5 MB. Alternative communication schemes are shown to perform faster depending on the architecture and message size. Nearly linear scalability results for explicit time integration are demonstrated using the design techniques.


Nonlinear Finite-Element Analysis Software Architecture Using Object Composition

January 2010

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1,525 Reads

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878 Citations

Journal of Computing in Civil Engineering

Object composition offers significant advantages over class inheritance to develop a flexible software architecture for finite-element analysis. Using this approach, separate classes encapsulate fundamental finite-element algorithms and interoperate to form and solve the governing nonlinear equations. Communication between objects in the analysis composition is established using software design patterns. Root-finding algorithms, time integration methods, constraint handlers, linear equation solvers, and degree of freedom numberers are implemented as interchangeable components using the Strategy pattern. The Bridge and Factory Method patterns allow objects of the finite-element model to vary independently from objects that implement the numerical solution procedures. The Adapter and Iterator patterns permit equations to be assembled entirely through abstract interfaces that do not expose either the storage of objects in the analysis model or the computational details of the time integration method. Sequence diagrams document the interoperability of the analysis classes for solving nonlinear finite-element equations, demonstrating that object composition with design patterns provides a general approach to developing and refactoring nonlinear finite-element software.


Seismic Damage Detection of a Full-Scale Shaking Table Test Structure

January 2010

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223 Reads

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120 Citations

Journal of Structural Engineering

A series of full-scale tests was conducted on the E-Defense shaking table facilities in Japan to simulate various levels of realistic seismic damage in a high-rise structural steel building. During the shaking table tests, the specimen experienced damage of the concrete slabs, beam-to-column connections, and nonstructural walls. The densely recorded test data of global and local structural deformation and the extensive acceleration records provide a unique benchmark case for evaluating the effectiveness of vibration-based damage diagnosis methods. Dynamic properties of the specimen were extracted from floor accelerations under the white noise excitations by the frequency response function curve-fitting method and autoregressive with exogenous term method. The natural frequencies of the structure decreased on average 4.1, 5.4, and 11.9% after three levels of seismic excitation, respectively, because of increasing extent of structural and nonstructural damage. The analysis of the vibration data shows that the mode shapes changed very little because the damage was distributed over the entire specimen rather than being concentrated on one floor or story for the high-rise moment frame building.


Statistical Analysis of Vibration Modes of a Suspension Bridge Using Spatially Dense Wireless Sensor Network

July 2009

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87 Reads

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133 Citations

Journal of Structural Engineering

A spatially dense wireless sensor network was designed, developed and installed on a long-span suspension bridge for a 3-month deployment to record ambient acceleration. A total 174 sets of data (1.3 GB) were collected from 64 sensor nodes on the main span and south tower of the Golden Gate Bridge. Analysis of the vibration data using power spectral densities and peak picking provide approximate estimates of vibration modes with minimal computation. For more detailed analysis of the data, autoregressive with moving average models (ARMA) give parametric estimates of vibration modes for frequencies up to 5 Hz. Statistical analysis of the multiple realizations give the distributions of the vibration frequencies, damping ratios, and mode shapes and 95% confidence intervals. The statistical results are compared with vibration properties using the peak picking method and previous studies of the bridge using measured data and a finite-element model. Analysis of the ambient vibration data and system identification results demonstrate that high spatial and temporal sensing using the wireless sensor network give a high resolution and confidence in the identified vibration modes. The estimation errors for the identified vibration properties are generally low, with frequencies being the most accurate and damping ratios the least accurate.


Parametric Bootstrap for System Identification of a Scaled Reinforced Concrete Bridge

April 2009

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13 Reads

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3 Citations

Statistical analysis of the sensor network data is critical in processing the information and establishing frameworks for interpretation and comparison. Sensor networks in structural engineering applications produce small data sets in many cases, including during an event such as an earthquake when the duration of the event is limited to tens of seconds and hence the data sets are small. In the absence of abundant data, the bootstrap method is a statistical technique that can be used to generate the desired parameters. Additionally, compatibility between finite element models and the measured data is often used as a means to validate the model, the data, and the signal processing methods. In this paper the data from a scaled laboratory test of a reinforced concrete bridge specimen is used to demonstrate the effectiveness of both of these methods. A finite element model of the bridge, created in OpenSees, is calibrated such that the modal properties of the model match that of the data. Once the modal properties of the bridge are validated and a system identification model is selected that fits the data, the parametric bootstrap technique is used to generate statistical properties of the modes, including their confidence intervals.



Citations (80)


... They play a crucial role in facilitating the efficient and safe movement of people, products, and services across numerous locations, thereby supporting economic development. It has been recorded that certain bridges suffered damage during recent catastrophic earthquakes, including the 1971 San Fernando earthquake, the 1999 Chi-Chi earthquake in Taiwan, the 1995 Great Hanshin earthquake in Japan, and the 2010 Haiti earthquake [1][2][3][4][5]. Seismic vulnerability assessment plays a crucial role in identifying at-risk bridges and prioritizing retrofitting or replacement measures for unsafe bridges [6]. ...

Reference:

Exploring the Effect of Near-Field Ground Motions on the Fragility Curves of Multi-Span Simply Supported Concrete Girder Bridges
Preliminary report on the seismological and engineering aspects of the January 17, 1994 Northridge earthquake

... The steel material is modelled through a uniaxial bilinear stress -strain relationship with kinematic strain hardening, according to Menegotto and Pinto (1973), coupled with the isotropic hardening rules proposed by Filippou and Fenves (2004). According to the material properties in the experimental study, a yield strength f y = 450 MPa is used for the steel reinforcement, with an elastic modulus of 200.0 GPa and a specific weight considered as 78.0 kN/m 3 . ...

Methods of Analysisfor Earthquake- Resistant Structures
  • Citing Article
  • May 2004

... The North-West connector bridge of the I-10/215 interchange in San Bernardino, Fig. 26 [63]. Structural analysis modeling of the bridge was performed by Kim and Elgamal in 2014 [45]. These studies indicate that there is a fundamental vibrational mode with a period of about 1.5 seconds. ...

Seismic Response of a Large-Scale Highway Interchange System

Geotechnical

... The computer programs SAP2000 Computers and Structures 1997 and 3D BASIS Tsopelas et al. 1994 use the bidirectional Park–Wen model Park et al. 1986, which is a smoothed plasticity model, for FP bearings. This paper presents results using a plasticity model Fenves et al. 1998 with time-dependent parameters. Fenves et al. 1998 difference between the Park–Wen and plasticity models is small for large values of initial stiffness and when the bidirectional evolutionary equation in the Park–Wen model is properly formulated . ...

Analysis and testing of seismically isolated bridges under biaxial excitations
  • Citing Conference Paper
  • June 1998

... The early seismic qualification and response analyses both aimed at porcelain bushings. For example, Gilani et al. evaluated the seismic performance of 196 kV, 230 kV and 550 kV porcelain bushings, respectively [45][46][47]. He et al. conducted shaking table tests for a 1100 kV porcelain transformer bushing [44]. ...

Seismic Evaluation and Retrofit of 230-kV Porcelain Transformer Bushings
  • Citing Article
  • November 2001

Earthquake Spectra

... Output-only system identification (SID) methods are a valuable component of structural health monitoring (SHM); they assist engineers with determining a structural system's operational modal properties and its expected response to dynamic loads. As the collected data contain increasing spatial and temporal information, SID modal estimates will become more accurate [1,2]. However, in fixed sensor networks, the spatial capacity in the data is limited by the number of sensors and their locations thus, additional sensors are required to improve spatial information. ...

Parametric Bootstrap for System Identification of a Scaled Reinforced Concrete Bridge
  • Citing Conference Paper
  • April 2009

... Predicting and assessing the seismic behavior of diff erent types of structures and structural elements is of key importance in performance-based earthquake engineering (Fenves and McKenna, 2007;Freeman, 2000). Consequently, there is an inevitable demand for simulating the behavior of structural lateral load resisting systems when these systems are subjected to ground motions. ...

Computational Simulation for Earthquake Engineering Research and Practice
  • Citing Conference Paper
  • October 2007

... Whyte et al. [25] performed the first fully automated HFT on a simple two-element smallscale structure. That work focused on extending OpenFresco [28,29], the open-source software framework for hybrid simulations developed at UC Berkeley, by improving an existing experimental element to handle temperature degrees of freedom. Schulthess et al. [30] carried out the first experimental validation of a nonlinear HFT on a small-scale sample, a simply supported beam connected at mid-span to a truss element, using the Newton-Raphson algorithm. ...

A Software Framework for Hybrid Simulation of Large Structural Systems
  • Citing Conference Paper
  • October 2007

... A forceBeamColumn element with finite length plastic hinges [64,65] at the ends of the element and Modified Gauss-Radau integration rules [30] has been used to simulate the response of the columns. In particular, the response of the element is assumed to be inelastic at the base of the column and elastic in all the remaining parts. ...

A Plastic Hinge Simulation Model for Reinforced Concrete Members
  • Citing Conference Paper
  • October 2006