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A contribution to the study of the performance of steel pipe piles welded to concrete pier cap beams under seismic loads

University of British Columbia

The Ministry of Transportation and Highways of B.C. implemented a modular bridge program in the Province. In the case of a seismic event, ductility is intended to be achieved through yielding of the steel pipe piles. Each pile has a full strength, overhead weld connecting it to an embedded plate which is cast into the precast concrete abutments and pile caps. The steel piles are intended to undergo plastic hinging; however, a high quality overhead weld is not easy to achieve under adverse site conditions. The performance of the weld under seismic loads is not the only concern. There is limited information on the design of large embedded plates using deformed bar concrete anchors made from deformed wire. This investigation focused on the connection between the steel pile and the concrete cap beam. Two full scale pile segments underwent reversed cyclic loading in order to determine the strength and ductility of the connection. Non-linear, two dimensional modelling and linear, three dimensional finite element modelling was performed. The first specimen failed by the desired plastic hinging. The flail strength weld between the pipe and embedded plate did not fail. The strength and ductility of the connection was as predicted. However, there were initial signs that the deformed anchor bars welded to the embedded plate were debonding. The second specimen was a slightly larger pipe welded to the same concrete beam. The second specimen experienced an embedded plate anchorage failure. The strength and ductility were both well below the desired levels. Although the anchors were longer than the recommended development length, the majority of bars slipped rather than fractured. This slippage led to the low strength and poor ductility. The higher than specified anchor strengths combined with the effects of cyclic loading have been identified as the primary reasons for the disturbing debonding which was observed.

Thesis/Dissertation

application/pdf

2009-02-06

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http://hdl.handle.net/2429/4228

Civil Engineering

University of British Columbia

UBCV

DSpace