Title:
Seismic Retrofit of Hinged and Fixed Reinforced Concrete Bridge Columns with Short Bar Anchorage in Footings
Author(s):
Ihab S. Darwish, M. Saiid Saiidi, and David H. Sanders
Publication:
Structural Journal
Volume:
96
Issue:
6
Appears on pages(s):
988-996
Keywords:
bridges; columns; ductility; flexural strength; shear strength.
DOI:
10.14359/774
Date:
11/1/1999
Abstract:
A large number of bridges in the U.S. have been identified as having potentially inadequate detailing to resist earthquakes. A common deficiency in many columns of these bridges is short dowel bars in the footings and short lap splices at the base of the columns. In addition, the columns are poorly confined and lack adequate shear strength. This paper addresses these deficiencies in oblong tapered bridge columns and presents a new retrofit technique to restore the capacity of the columns and to improve ductility. Six 0.4 scale model specimens were constructed and tested. The first two specimens represented as-built details of existing bridge columns: one with a fixed-base detail, and the other with a one-way hinge detail. The other four specimens were identical to the two as-built models, but were retrofitted to address their deficiencies. Unlike steel jackets used in previous studies, the jackets used in this study were connected to a base plate that was anchored to the footing. This detail was necessary because of the short anchorage of starter bars in the footings. Results from testing the four retrofitted specimens showed that the adopted retrofit technique enabled the columns to reach their design strength under cyclic lateral loading. The retrofit also enhanced the shear strength and the ductility of the columns.