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Medhat A. Haroun

Professor, Civil & Environmental Engineering
The Henry Samueli School of Engineering

PH.D., California Institute of Technology

Phone: (949) 824-5016, 5333
Fax: (949) 824-2117

University of California, Irvine
E4165 Engineering Gateway
Mail Code: 2175
Irvine, CA 92697
Research Interests
Structural and earthquake engineering
Research Abstract
Performance of Liquid Storage Tanks During the 1989 Loma Prieta Earthquake
Investigator: M.A. Haroun
Research Assistants: W. Chen and S. Mourad
Support: National Science Foundation

The 1989 Loma Prieta Earthquake induced a few incidents of damage to liquid storage tanks, and even to one retro-fitted tank. This research presents data analysis as related to the performance of tank structures through: documentation of the damage sustained by storage tanks; calculation of the dynamic response of representative tanks and correlation of the computed response with observed damage or lack of damage; study of the effects of site amplification of long period components on the sloshing phenomenon and on rocking motion of tanks founded on Bay mud; and comparison of induced seismic forces with those specified by available codes and standards. The outcome of the study assists in refining and turning available methods of analysis, and in providing improved design procedures.

Experimental Evaluation of Retrofit Mechanisms for Precast R/C Tilt-up Wall-Foundation Connections
Investigators: M.A. Haroun and S.I. Hilmy
Research Assistants: A. Salama and C. Yland
Support: National Science Foundation

An experimental program is being conducted for seismic rehabilitation of existing connections between precast, reinforced concrete, tilt-up walls and their foundation. This cost-effective construction type is widely used for office buildings, factories, stores, and warehouses. Many of the existing wall-foundation connections lack adequate ductility and detailing, and most of them could experience shear slip failure or rocking under strong ground shaking. The research work includes a comparison between assumed and actual elastic and inelastic capacity of the foundation-wall connection; an evaluation of the effectiveness of the corrective measures intended to increase the connection strength and ductility; and recommendations on evaluation criteria and design guidelines for the rehabilitation of existing structures. This is a joint effort between researchers at UCI and Dames & Moore, a leading seismic rehabilitation engineering firm.

(aid Hilmy is Senior Structural Engineer at Dames & Moore.)

Seismic Behavior of Unanchored Liquid Storage Tanks
Investigator: M.A. Haroun
Research Assistants: A. El-Zeiny and W. Chen
Support: National Science Foundation

This project is an analysis of the extremely complex behavior of unanchored tanks under horizontal and vertical excitations. The study is conducted in three major phases: a nonlinear representation of the response of the tank's bottom plate under uplifting forces, taking into account the nonlinear contact with the foundation, large deformations, inelastic response, interaction with the underlying soil, and behavior under impact; an equivalent static analysis of the coupled response of the shell, the liquid, and the bottom plate; and an analysis of the nonlinear sloshing response of the liquid and evaluation of the corresponding hydrodynamic pressures. The analysis also is being extended to include the actual time-dependent nonlinear response under moderate to severe earthquake motions.

Seismic Quantification of Liquid Storage Tanks
Investigator: M.A. Haroun
Research Assistants: W. Abou-Izzeddine, H. Bhatia, H. Mobarek, and L. Wang
Support: American Society of Civil Engineers
National Center for Earthquake Engineering Research
National Science Foundation

The researchers are investigating many of the problems associated with the earthquake behavior of liquid storage tanks such as shell buckling, soil-tank interaction, and structural reliability. Fragility curves for towers supporting elevated vessels have been developed. Methods for evaluating the seismic capacity of special tanks have been devised. The researchers also are evaluating and documenting currently available information on seismic analysis and design in an effort to bridge the gap between academic and practical applications. They also are addressing issues as they relate to the wide range of types of storage tanks -- from large tanks and reservoirs to small storage vessels in industrial plants.

Seismic Retrofit of Existing Liquid Storage Tanks
Investigator: M.A. Haroun
Research Assistants: H. Bhatia and A. E-Zeiny
Support: Fluor Daniel, Inc.
National Center for Earthquake Engineering Research

Current standards and guidelines available for the seismic design of ground-based tanks do not address retrofit schemes for existing tanks, and over-strengthening of tanks on "ad hoc" basis may only serve to change the modes of failure. A major component of the research work deals with evaluating the effectiveness of a few corrective measures intended to increase the seismic resistance of tanks. As examples of these schemes are a system of vertical and radial stiffeners to reduce wall vulnerability to buckling; an effective anchoring system to reduce tank uplift; a knuckle-type joint at the wall-roof connection to resist the high localized pressure; and a baffle system to dampen liquid sloshing.

Vibration Suppression Through Liquid Oscillations
Investigator: M.A. Haroun
Research Assistants: S. Mourad, P. Pence, and A. Won
Support: UCI Committee on Research

Both passive and active liquid-motivated control systems for suppression and reduction of the lateral drift of high-rise buildings are being examined theoretically and experimentally. The control system relies mainly on water oscillations in tube-like containers to augment the structural damping. Limitations on the effectiveness of the control system in reducing the lateral drift are evaluated. The passive component of the system has many beneficial characteristics such as having a clear, simple, and well-defined vibration mechanism which requires minimum maintenance, and the dynamic characteristics can be easily changed to tune the natural frequency and damping to any structural changes.
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