Seismic Testing of Bridge Columns Incorporating High-Performance Materials

This article reports on a study undertaken to evaluate the use of high-performance concrete and high-performance steel reinforcement that are now being combined to adequately meet stringent, and often conflicting, seismic and durability requirements. The authors constructed and tested two 35%-scale bridge column units, representing typical construction of the approach structure for the Oakland touchdown substructure of the new San Francisco Oakland Bay Bridge. The quasi-static reversed cyclic loading tests were conducted in the Powell Structural Research Laboratories at the University of California, San Diego. The tests compared the seismic performance of columns built with high-performance materials with that obtained from columns constructed incorporating Grade 60 ASTM A 706 reinforcement. Self-consolidating concrete with a specified compressive strength of 55 MPa (8 ksi) was used throughout. Results determined that both units can be designed to form flexural plastic hinges and can sustain drift levels of approximately 4% without failure. The presence of self-consolidating concrete did not adversely affect the response of the units in terms of early concrete cover spalling or bar anchorage, or any other way. The authors note that the response of components designed for earthquake resistance with high-performance reinforcing steels can be predicted accurately if an adequate value for the equivalent plastic hinge length is used in the analysis.