Seismic Response Predictions of Bridge Pier

The lateral response of a proposed 200 ft (61 m) high reinforced concrete bridge pier to strong motion earthquakes is described. Conceived by New Zealand Railway Engineers, the inverted V-frame pier has a sacrificial steel pin incorporated in each leg. The pier is idealized to a one degree-of-freedom system and considerations are limited to lateral loading but the effect of gravity is considered and found to be significant. Results of step by step numerical integration of equations of motion, using digitized earthquake records, confirm that the inclusion of localized energy absorption reduces the response relative to that predicted for a similar structure having no sacrificial pins but indicate that the neglect of gravity effects is not justified. The concept appears both feasible and worthwhile.