Enhancing bridge construction and fiscal efficiency
With the growing demands facing public infrastructure and the shortage of necessary funds, State Highway Agencies (SHA) across the nation are increasingly being forced to explore cost-effective, safe, and efficient solutions to implement in response to these challenges. The high cost, safety factors, and out-of-service and user cost considerations make bridges and their associated work a particular focus of many in the industry. This thesis highlights two areas within the field of bridge engineering design and management that will continue to aid SHAs in their goal of producing safe, efficient, and innovative products that serve the public well.
Substructure bridge components are designed to resist gravitational forces such as dead load and vehicular live load, as well as lateral forces including wind, vehicular braking and centrifugal force effects. Significant lateral forces can create “uplift” conditions on some portions of the foundation. A review of current design techniques regarding uplift in the oft used pile-to-pile cap connection indicates a lack of uniformity in the design process across state agencies stemming from minimal research performed in this area. Additionally, approved uplift anchors for use in the field have not been tested. In order to close this gap, twenty-one full scale steel H-pile specimens were fabricated and tested in Iowa State University’s Structural Engineering Laboratory to test the capacity of the pile-to-pile cap connection under static tensile loading. Findings revealed that 1) capacity of bare piles is generally underestimated and could be more frequently considered for uplift design; 2) concrete cracking leads to a loss of bond in these types of connections; and 3) positive anchorage and/or embedment that extends above the lower rebar mat of the footing is necessary to develop a high capacity connection.