Shake-Table Studies of a Four-Span Bridge Model with Advanced Materials

As part of a major study on the seismic response of bridge systems with conventional and advanced details, a large-scale model of a 4-span bridge incorporating several innovative plastic hinges was recently tested on shake tables at the University of Nevada, Reno. The bridge model included six columns, each pair of which utilized a different unconventional detail at the bottom plastic hinges: shape memory alloys (SMAs), engineered cementitious composites (ECCs), elastomeric pads embedded into columns, and posttensioning tendons. The bridge model was subjected to two horizontal components of simulated earthquake records of the 1994 Northridge earthquake in California. More than 340 channels of data were collected. Test results showed the effectiveness of the innovative materials in reducing damage and permanent displacements. The damage was minimal in plastic hinges with SMA/ECC and those with built-in elastomeric pads. Conventional reinforced concrete plastic hinges were severely damaged because of spalling of concrete and rupture of longitudinal and transverse reinforcement.