• Studies of Integration and Implementation Issues in the Active Control of Lifeline Systems (Masri and Abdel-Ghaffar). The objective of this long range project is to perform analytical and experimental studies on laboratory models of distributed systems resembling generic lifeline systems such as long-span bridges. Analytical studies are being conducted to (a) evaluate the control energy requirements for various active control schemes, (b) establish performance bounds on instrumentation and actuator hardware, and (c) investigate the performance limits of vibration sensing techniques using fiber-optic approaches. A systematic series of active control experiments are being performed to (a) correlate the experimental measurements with predictions on the basis of suitable mathematical models, and (b) to identify technology issues that may impede the full- scale field implementation of the "smart structure" approaches in the future.
• Performance Improvement of Long Period Building Structures subjected to Severe Pulse-Type Ground Motions (Anderson). Recent studies have shown that severe pulse-type ground motions may significantly increase the seismic response of long period structures. In extreme cases, this increased seismic demand, coupled with the action of gravity load, may pose a collapse hazard. The use of the traditional strategy of increasing the members' strength and/or stiffness alone may lead to inadequate and inefficient means of mitigating the problems. The use of innovative procedures for improving the performance of these structural systems is being investigated. Current attention is being focused on the use of supplemental (passive) damping in a mixed flexible-stiff structural system.
• Repair and/or Retrofit of Welded Moment Connections (Anderson and Xiao). The most significant issue to arise from the Northridge earthquake (1994) was the detection of cracking in welded beam-to-column connections of modern steel buildings. Shortly after the earthquake, connection specimens taken from a severely damaged building were delivered to USC for further testing under controlled laboratory conditions to evaluate remaining strength and techniques for repair. A follow up program evaluated various repair procedures and a third program focused on the use of weld overlays for repair. Additional testing is being conducted as a service to local industry.
• Semiactive Damping and Structural Control (Johnson). One of the most promising technologies for mitigating vibration induced by seismic, wind, and human excitations is semiactive damping technology. This method of structural control uses "smart" controllable dampers that retain the stability and reliability of passive damping devices but are controllable, so they can often attain performance comparable to fully active devices but with low-power requirements. This technology is in development for a wide range of structural applications, including "smart" base isolation and "smart" damping of stay cables.
• Controlled Monte Carlo Simulation (Johnson). Standard Monte Carlo Simulation (MCS) is the most versatile and general tool for studying stochastic dynamical systems. These systems appear in a wide range of fields, from economic modeling to the response of structures to earthquake and wind loads. Yet standard MCS can be extremely computationally intensive. This research is developing new "controlled" MCS methods, primarily based on genetic algorithms, that direct more computational effort toward events critical to component and system failures, thereby reducing the computational intensity.
• Earthquake Ground Motion from an Extended Seismic Source buried in a Viscoelastic Half-Space (M. Shinozuka). The main objective of the research is to study the physics of ground motion in the vicinity (near-field) of an extended earthquake fault buried in a layered viscoelastic half-space. The inhomogeneous rupture of the fault responsible for the generation of intermediate and high frequency waves will be described using the specific barrier model of Papageorgiou and Aki. This model has been successfully used in the past to interpret earthquake strong motion data. Also, the model has been used to provide an analytical description of far-field spectra of earthquake ground motion. However, there exists no analytic description of the spectral content of ground motion in the vicinity (near-field) of an extended earthquake fault.
• Development of Computer Codes for Lifeline System Analysis (M. Shinozuka). Computer codes for lifeline system analysis are being developed. In particular, LIFELINE-W was developed on the basis of ARC/INFO for evaluating the seismic performance of water delivery systems. The code was specifically used to analyze the Memphis Light, Gas, and Water Division's water delivery system in Memphis. The documentation of this code is under way. During documentation, improvements of the code will be made. For example, more realistic models for break patterns and leakage phenomena will be incorporated. LIFELINE-W will be modified to be able to perform gas and crude oil transmission system analysis.
• Adaptive Finite Element Analysis of Problems in Structural Mechanics (Wellford). As many numerical algorithms for solving structural mechanics problems are approximate, there is a need for techniques which adapt the mathematical models so as to minimize the inherent error. In finite element procedures, this is often achieved by introducing smaller elements (h-methods), increasing the polynomial degree of the existing elements (p-methods) or repositioning the nodes (r-method). Adaptive methods of various types are being studied to define optimum finite element solution algorithms.
• Modeling of Reinforced Concrete Structures using the Finite Element Method (Wellford). The performance of reinforced concrete structures, under static and dynamic loads, can be quite complex, involving highly nonlinear behavior. This behavior is characterized by nonlinear material behavior in the concrete, including cracking, loss of confinement, and softening behavior under cyclic load. In addition, reinforcing steel bars may have a strain hardening behavior after yield and the bond between the steel and concrete may be broken, resulting in slip and pullout. Complicated localization phenomena may result at concentrated plastic hinges. Computational mechanics and finite element methods are being developed to simulate this complex phenomenon.
• Integration of Finite Element and Computer-Aided Design and Computer-Aided Engineering Tools (Wellford). Computer aided design and computer aided engineering of structures involve the combination of computer graphics, geometric modeling, and solid modeling procedures with analysis, design, optimization and artificial intelligence techniques. The development of integrated design analysis systems based on these subject areas will result in an improvement in the efficiency and accuracy of structural engineering activities. Finite element design analysis procedures are being developed to provide these improved design tools.
• Seismic Behavior of High-Strength Steel Reinforced Concrete Composite Columns (Xiao and Anderson). Experimental studies are conducted to investigate the behavior of steel-reinforced concrete composite (SRC) structural columns subjected to constant axial load and cyclic shear in double curvature. The emphasis is on the evaluation of different shear resisting mechanisms and the influence of member ductility on shear strength. Large-scale column specimens are tested using the newly developed axial and shear loading equipment. The research results will be implemented into design guidelines for hybrid and composite construction.
• Development of Prefabricated Composite Jacketing Systems for Seismic Retrofit of Bridge Columns (Xiao and Martin). In this multi-phase research program, several prefabricated fiber-reinforced-polymer (FRP) composite jacketing systems for retrofitting bridge columns are experimentally evaluated, methods for analysis and retrofit design are developed. The first phase of the program involves testing of half scale model columns with 610 mm diameter circular sections to investigate the effectiveness of prefabricated composite jackets for flexure and shear retrofits. The second phase involves large scale testing and analysis of columns with rectangular sections. The third phase will be focused on the field implementation of the prefabricated jacketing systems for retrofitting actual bridges and long term monitoring.
• Experimental and Analytical Studies of Structures and Structural Elements subjected to Various Loading Histories (Xiao). Problems in analysis and design of structures and components subjected to various loading histories are addressed. In particular, the studies are focused on the effects of variable axial loads due to overturning (proportional to lateral load) or vertical acceleration (non-proportional to lateral load) on seismic behavior of structural columns. Large-scale model columns are tested under combined cyclic lateral and variable axial loads. Various analytical methods are compared with the test results.
• Experimental and Analytical Studies of Mechanical Behavior of Concrete under Triaxial Stresses (Xiao). Research is in progress to investigate the mechanical behavior of concrete under triaxial stress state. The focus is on the study of the interaction mechanisms between the confined concrete and confining materials such as FRP composite or steel jackets, tubes and transverse reinforcing bars.

• J. C. Anderson, Professor
• J. P. Bardet, Professor
• E. A. Johnson, Associate Professor
• S. F. Masri, Professor
• R. L. Nigbor, Research Associate Professor
• M. S. Shinozuka, Research Professor
• M. I. Todorovska, Research Associate Professor
• M. D. Trifunac, Professor
• L.C. Wellford, Professor
• H. L. Wong, Professor
• Y. Xiao, Associate Professor

• Anderson, J.C., and Maranian, P.J. (1998). "Repair/Moment Connections Using Weld Overlays," Proceedings, Third U.S.-Japan Workshop on Steel Fracture Issues, Tokyo, April.
• Anderson, J.C., Duan, X. (1998). "Repair/Upgrade Procedures for Welded Beam to Column Connections," PEER 98/03, Pacific Earthquake Engineering Research Center, University of Southern California, May.
• Anderson, J.C., and Johnston, R.G. (1998). "Performance of a Steel Building which experienced Intense Ground Motion," ASCE Journal of Performance of Constructed Facilities, 12(4), November.
• Bardet, J.P., and Davis, C. (1996). "Performance of San Fernando Dams during the 1994 Northridge Earthquake," ASCE Journal of Geotechnical Engineering, 122( 7), 554-564.
• Bardet, J.P. (1997). "Experimental Soil Mechanics," Prentice-Hall, Upper Saddle River, New Jersey.
• Bardet, J.P., and Davis, C.A. (1998). "Deformation of Embankments from Liquefaction During the 1994 Northridge Earthquake," Transportation Research Record 1633, Transportation Research Board.
• Bertero, V.V., Anderson, J.C., and Krawinkler, H. (1994). " Performance of Steel Building Structures during the Northridge Earthquake," UC/EERC-94/09, Earthquake Engineering Research Center, University of California, Berkeley, 177.
• Betti, R., Abdel-Ghaffar, A.M. and Niazy, A.S. (1991). "Implication of Soil-Structure Interaction of Long-Span Cable-Supported Bridges," Journal of Earthquake Engineering and Structural Dynamics, November.
• Gupta, V.K., and Trifunac, M.D. (1991). " Effects of Ground Rocking on Dynamic Response of Multistoried Buildings during Earthquakes," ASCE Structural Engineering/Earthquake Engineering, 8(2), pp. 43- 50.
• Gupta, I.D., and Trifunac, M.D. (1998). "An Improved Probabilistic Spectrum Superposition," Soil Dynamics and Earthquake Eng., 17(1), pp. 1-11.
• Housner, G.W., and Masri, S.F. (1998). "Monitoring and Control of Smart Civil Infrastructure Systems," Advances in Structural Control, edited by A. Barbat, F. Casciati and J. Rodellar.
• Ivanovic, S.S., and Trifunac, M.D. (1995). "Ambient Vibration Survey of Full Scale Structures using Personal Computers (with examples in Kaprielian Hall)," Report No. CE 95-05, Dept. of Civil Eng., University of Southern California, Los Angeles, CA.
• Ivanovic, S.S., Trifunac, M.D., and Todorovska, M.I. (1999). "On Identification of Damage in Structures via Wave Travel Times," Proc. Nato Advanced Research Workshop on Strong-Motion Instrumentation for Civil Engineering Structures, June 2-5, Istanbul, Turkey.
• Johnson, E.A., Bergman, L.A., and Spencer, B.F., Jr. (1997). "Parallel Implementations of MCS - Comparative Studies from Stochastic Structural Dynamics," State of the Art Report on Computational Stochastic Mechanics (G.I. Schu‰ller, ed.), 12(4), pp. 208-212.
• Johnson, E.A., Voulgaris, P.G. and Bergman, L.A. (1998). "Multiobjective Optimal Structural Control of the Notre Dame Building Model Benchmark," Earthquake Engineering and Structural Dynamics, 27(11), pp. 1165- 1187.
• Johnson, E.A., Baker, G.A., Spencer, B.F., Jr., and Fujino, Y. (1999). "Semiactive Damping of Stay Cables," ASCE Journal of Engineering Mechanics.
• Kojic, S., and Trifunac, M.D. (1991). "Earthquake Stresses in Arch Dames: I-Theory and Antiplane Excitation," ASCE Journal of Engineering Mechanics, 117(3), pp. 532-552.
• Lee, V.W., Chen, S., and Hsu, I.R. (1999). "Antiplane Diffraction of Canyon above a Subsurface Unlined Tunnel," ASCE Eng. Mech. Div., 125(6), 668-675.
• Masri, S.F., Smyth, A.W., and Triana, M.I. (1998). "Probabilistic Representation and Transmission of Nonstationary Processes in Multi-Degree-of-Freedom Systems," ASME Journal of Applied Mechanics, June, pp. 398-409.
• Masri, S.F., Smyth, A.W., and Chassiakos, A.G. (1998). "Detection of Structural Changes through Nonlinear System Identification Approaches," Proc. Asia Pacific Workshop on Seismic Design and Retrofit of Structures, National Center for Research on Earthquake Engineering, Taipei, Taiwan, ROC, 10-13.
• Masri, S.F., Smyth, A.W., and Chassiakos, A.G., Nakamura, M., and Caughey, T.K. (1999). "Training Neural Networks by Adaptive Random Search Techniques," ASCE Journal of Engineering Mechanics, 125(2), pp. 123 - 132.
• Nazmy, A.-S. and Abdel-Ghaffar, A.M. (1990). "3-D Nonlinear Static Analysis of Cable-Stayed Bridges," Journal of Computers and Structures, 34, pp. 257-272.
• Nazmy, A.-S. and Abdel-Ghaffar, A.M. (1990). "Nonlinear Earthquake-Response Analysis of Long-Span Cable-Stayed Bridges: Theory," International Journal of Earthquake Engineering and Structural Dynamics, 19(1), pp. 45-62.
• Nishimura, I., Abdel-Ghaffar, A.M., Masri, S.F. , Miller, R.K., Beck, J.L., Caughey, T.K. and Iwan, W.D. (1992). "An Experimental Study of the Active Control of a Building Model," Journal of Intelligent Material Systems and Structures, Manuscript No. 90-56.
• Shinozuka, M. (1998). "Structural Response Control in New Generation of Civil Infrastructure Systems," Keynote Paper, Proceedings of the 2nd World Conference on Structural Control, Kyoto, Japan, June 28- July 1.
• Shinozuka, M. (1998). "Development of Bridge Fragility Curves," Proceedings of the US-Italy Workshop on Protective Systems for Bridges, New York, NY, April 26-28.
• Smyth, A.W., Masri, S.F., Chassiakos, A.G., and Caughey, T.K. (1999). "On-Line Parametric Identification of MDOF Nonlinear Hysteretic Systems," ASCE Journal of Engineering Mechanics, 125(2), pp. 133-142.
• Trifunac, M.D., and Gupta, I.D. (1999). "A Note on the Statistics of Ordered Peaks in Stationary Stochastic Processes," Soil Dynamics and Earthquake Eng., 17(5), pp. 317-328.
• Trifunac, M.D., Ivonovic, S.S., Todorovska, M.I., Novikova, E.I., and Gladkov, A.A. (1999). "Experimental Evidence for Flexibility of a Building Foundation supported by Concrete Friction Piles," Soil Dynamics and Earthquake Engrg., 18(3), pp. 189- 207.
• Trifunac, M.D., and Todorovska, M.I. (1999). "Recording and Interpreting Earthquake Response of Full-Scale Structures," Proc. Nato Advanced Research Workshop on Strong-Motion Instrumentation for Civil Engineering Structures, June 2-5, Istanbul, Turkey, pp. 2.
• Wellford, L.C., and Chen, C.N. (1989). "Multilevel Finite Element Solution Algorithms based on Multiplicative and Additive Correction Procedures," International Journal for Numerical Methods in Engineering, 28, pp. 27-41.
• Wellford, L.C., and Vahdani, B. (1988). "A Singular Perturbation-finite Element Procedure for the Analysis of Edge Effects in Shell Structures," Computers and Structures, 28,(4), pp. 443-451.
• Wojtkiewicz, S.F., Johnson, E.A., Bergman, L.A., Grigorio, M., and Spencer, B.F., Jr. (1999). "Observations with Regard to Massively Parallel Computation for Monte Carlo Simulation of Stochastic Dynamic Systems," International Journal of Non-Linear Mechanics, 32(4), pp. 721-734.
• Xiao, Y., Priestley, M.J.N., and Seible, F. (1996). "Seismic Assessment and Retrofit of Bridge Column Footings," ACI Structural Journal, 93(1), pp. 79-94.
• Xiao, Y. and Ma, R. (1997). "Seismic Retrofit of RC Circular Columns using Prefabricated Composite Jacketing," ASCE Journal of Structural Engineering, 123(10), pp. 1357-1364.
• Xiao, Y. and Martirossyan, A. (1998). "Seismic Performance of High-Strength Concrete Columns," ASCE Journal of Structural Engineering, 124(3), pp. 241-251.
• Xiao, Y. and Wu, H. (2000). "Compressive Behavior of Concrete Cylinders confined by Carbon Fiber Composite Jackets," ASCE Journal of Materials in Civil Engineering, 12(2), pp. 139-146.
• Xiao, Y., Mahin, S.A., Editors (2000). "Composite and Hybrid Structures," Proceedings of the Sixth ASCCS International Conference on Steel-Concrete Composite Structures, Los Angeles, CA, March 22-24.

 

Research Centers

The Center for Research in Earthquake and Construction Engineering (CRECE) disseminates research data and information to the engineering community regarding design and construction of new facilities and preservation and upgrading of existing structures. Founded in 1986, the center provides a direct link between research and application.

Many Civil and Environmental Engineering faculty are also affiliated with the USC International Institute for Innovative Risk Reduction Research on Civil Infrastructure Systems. In a natural disaster, civil infrastructure systems such as transportation networks, pipeline systems, and other critical life lines, may perform poorly or perhaps even fail. Center faculty strive to develop methods by which advanced and emerging technologies are used to enhance the physical and functional performance of civil infrastructure systems, thus reducing the risk of system failure. Opportunities exist to integrate these technologies into every phase of the life cycle of civil infrastructure systems, including planning, design, construction, operation, maintenance, retrofit, rehabilitation, and demolition. Opportunities exist for graduate students to participate in the Center's ongoing activities, including research on: