Value Engineering County Bridge Replacement-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes value engineering for the foundation design of a county bridge replacement. The existing 1913 bridge is 30 feet wide; the replacement will be 49 feet wide, with three lanes and a pedestrian sidewalk. Site constraints include a 200-foot-wide river, limited construction access, potential scour during major storms, shallow bedrock, and the need for pile toe fixity.<br /><br />The proposed foundation initially used 173 steel-cased micropiles, with design compression capacities of 170 kips at the abutments and 210 kips at the center pier, plus at least 8 feet of bedrock embedment.<br /><br />Working together, engineers and contractors evaluated alternatives to reduce construction time and cost. Driven steel H-piles were selected for the west abutment: 52 vertical piles and 26 battered piles, designed for compression and, where applicable, tension loads. The design addressed scour, toe and head fixity, and installation requirements, including hammer performance and driving criteria.<br /><br />Rock-socketed drilled shafts were selected for the center pier. Each shaft has a steel-cased section extending to bedrock and a reinforced-concrete rock socket with at least 10 feet of embedment. The installation process includes casing, drilling and cleaning the socket, placing the reinforcing cage, and tremie-concreting.<br /><br />The project illustrates how value engineering can match foundation systems to site conditions, contractor capabilities, and project requirements. Replacing the proposed micropiles with driven piles at the west abutment and drilled shafts at the center pier reduced anticipated construction time and material costs.

Keywords

value engineering

bridge replacement

foundation design

micropiles

driven H-piles

rock-socketed drilled shafts

scour resistance

bedrock embedment

construction cost reduction

county bridge