- Author
- Taylor, A. W. | Stone, W. C.
- Title
- Jacket Thickness Requirements for Seismic Retrofitting of Circular Bridge Columns.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- National Science Foundation and Iowa State University. Practical Solutions for Bridge Strengthening and Rehabilitation. Session 5. Repair and Strengthening Technologies. April 5-6, 1993, Des Moines, IA, Klaiber, F. W.; Sanders, W. W., Jr., Editors, 249-258 p., 1993
- Keywords
- bridges (structures) | seismic retrofitting | columns | steel jacketing
- Abstract
- Steel jacketing is a common seismic retrofit strategy for circular, spirally-reinforced concrete bridge piers. With this technique two steel half-cylinders are welded together, encasing the column in a cylindrical jacket. Usually a cement grout is pumped into the annular space between the jacket and the column. The purpose of the steel jacket is to supplement existing lateral reinforcement within the column, providing additional lateral confinement to the concrete in regions of potential seismic damage. Although jacketing is recognized as an effective and relatively inexpensive method for improving column ductility, little guidance is available for determining the required thickness of the jacket. In this study jacket thickness requirements were investigated using a time-step inelastic analysis algorithm which incorporates a hysteretic failure rule and a cumulative damage model. A variety of column designs were subjected to a range of real earthquake acceleration histories, and the resulting damage lvels, or "damage indices" were calculated. These same columns were then re-analyzed with steel jackets of varying thicknesses. It was determined that a relatively thin steel jacket - on the order of a few millimeters in thickness - can dramatically improve the seismic performance of a column. Guidelines are presented for calculating required jacket thicknesses, and practical considerations regarding the installation and performance of jackets are discussed.