Report No.: CCEER-04-9

Title: Seismic Retrofit of Two-Column Bents with Diamond Shape Columns

Authors: Kandasamy Sureshkumar, M. Saiid Saiidi, Ahmad Itani and Samaan Ladkany

Date: November 2004

Sponsoring Agency: Nevada Department of Transportation (NDOT) and Federal Highway Administration (FHWA)

Performing Organization:
Department of Civil Engineering/258
University of Nevada, Reno
Reno, NV 89557


This study was focused on evaluating the seismic performance of two-column bents with diamond shape columns and the development of retrofit methods. The bents are from the main structure of a freeway bridge in Las Vegas, Nevada built in the 1960's. The diamond shape of the columns is unique to this bridge. Two identical quarter-scale specimens were built. One two-column bent was tested as built and the other was retrofitted and tested. The bents were tested in the strong direction of the columns, subjected to the 1994 Northridge earthquake until failure. The as-built specimen failed due to shear failure of a column. The columns of the second specimen were wrapped with carbon fiber reinforced plastic (CFRP). The bents were analyzed theoretically using Drain 3-DX, a finite element program and the results were compared. The experimental results led to design recommendations for multi-column bents with diamond shape columns.