Seismic Performance of Shear-Critical Reinforced Concrete Bridge Piers
J.Mander, S.Waheed, M.Chaudhary, S.Chen
University at Buffalo
This report summarizes an investigation of the behavior of a beam to column joint of a 32 year old shear-critical bridge pier and a companion one-quarter scale model of the two column prototype bent under reversed cyclic lateral loading. The prototype specimen was retrieved from the field and prepared for testing by welding a self equilibrating reaction frame onto the reinforcing steel of the cap beam. The model and the prototype were tested under constant vertical (gravity) loads. The cyclic lateral loading was applied through a horizontally connected actuator in case of the model and two parallel actuators inclined at 24o with the horizontal were used for the prototype testing in order to simulate lateral force effects in an entire two-column bent. Experimentally observed shear strengths were compared with code-based strength evaluation techniques. Evaluation shows that the pier would possess inadequate shear capacity and thus be classified as shear-brittle with no ductility capability. It is also shown that if code-based evaluation procedures are followed, this class of bridge pier is classified as unsafe and shear-brittle, but may be capable of resisting minor earthquakes through elastic response. However, if a dependable ductile mechanism is assumed, as demonstrated by good experimental behavior, a safe seismic response can be assumed for all Seismic Performance Categories in the United States.<BR>
Reinforced Concrete Bridge Piers, Reversed Cyclic Lateral Loads, Energy-Based Damage Analysis, Beam Column Joints, Code-Based Strength Evaluation, Experimental Tests, and Shear Strength.