Engineering Commons^™

Seismic Isolation Of A Highly Skewed, Prestressed Concrete Girder Bridge, Bradley Robson, Issam Harik, David Allen

Issam E. Harik

A relatively new approach for designing or retrofitting highway bridges in seismic zones involves isolating the superstructure from the substructure. Through experimental and analytical investigations, this study evaluates the effectiveness of isolating one particular bridge: a highly skewed, prestressed concrete, slab-on-girder bridge. Dynamic testing of the bridge was performed using the pullback, quick-release method. A three dimensional finite element model of the bridge was created. It was refined, or calibrated, to match experimentally determined natural frequencies and mode shapes. Time-history analyzes, using site-specific acceleration records, were conducted for the seismically isolated bridge model and an identical, non-isolated bridge model.

For …

Seismic-Hazard Maps And Time Histories For The Commonwealth Of Kentucky, Zhenming Wang, Issam E. Harik, Edward W. Woolery, Baoping Shi, Abheetha Peiris

Issam E. Harik

The ground-motion hazard maps and time histories for three earthquake scenarios, expected earthquakes, probable earthquakes, and maximum credible earthquakes on the free surface in hard rock (shear-wave velocity >1,500 m/s), were derived using the deterministic seismic hazard analysis. The results are based on (1) historical observations, (2) instrumental records, and (3) current understanding of the earthquake source, recurrence, and ground-motion attenuation relationship in the central United States. It is well understood that there are uncertainties in the ground motion hazard maps because of the uncertainties inherent in parameters such as earthquake location, magnitude, and frequency used in the study. This …

Seismic Analysis Of The Brent-Spence Bridge, Issam Harik, David Allen, Ronald Street, Meiwan Guo, R. Graves, Jack Harison, Mark Gawry

Issam E. Harik

This report presents the findings of a seismic evaluation of the Brent-Spence bridge. The bridge is a double-deck cantilever through truss which was constructed in 1961; it is a critical highway link conveying 1-75 over the Ohio river. While not yet subjected to a moderate or major earthquake, the bridge is within the influence of the New Madrid, Wabash Valley, and Anna seismic zones. The seismic evaluation program consisted of field testing and seismic analysis. The vibrational properties of the main bridge were determined through field testing and used to calibrate a 3-D finite element model. The model was then …