Cast-in-place (CIP) concrete piles consisting of steel casing filled with reinforcing steel and concrete are the preferred type of piling for WSDOT’s permanent bridges. Steel casing for cast-in-place piling shall not be considered in pile capacity design or in pile to pile cap connection design.

Other pile types such as precast, prestressed concrete piles, steel H piles, timber piles, auger cast piles, and steel pipe piles shall not be used for WSDOT permanent bridge structures. These types of piles may be used for temporary bridges and other non-bridge applications subject to approval by the State Geotechnical Engineer and the State Bridge Design Engineer.

Micropiles shall not be used for new bridge foundations. This type of pile may be used for foundation strengthening of existing bridges, temporary bridges and other non-bridge applications subject to approval by the State Geotechnical Engineer and the State Bridge Design Engineer.

Battered piles shall not be used for bridge foundations to resist lateral loads.

The above limitations apply to all WSDOT bridges including mega projects and design-build contracts.

Background:

The above recommendation on pile types is the outcome of lengthy discussions and meetings between the bridge design, construction and geotechnical engineers. These limitations are to ensure improved durability, design and construction for WSDOT pile foundations.

In seismic applications there is a need for bi-directional demands. Steel H piles have proven to have little bending capacity for the purposes of resisting seismic load while circular CIP piles provide consistent capacities in all directions. Also, CIP pile casing is generally available in a full range of casing diameters. CIP piles are easily inspected after driving to ensure the quality of the finished pile prior to placing reinforcing steel and concrete. All bending strength is supplied by elements other than the casing in accordance with BDM policy.

Precast, prestressed concrete piles, and timber piles are difficult to splice and for establishing moment connections into the pile cap.

Micropiles have little bending capacity for the purposes of resisting lateral loads in seismic applications.

The above limitations do not apply to bridges currently under final design, or to bridges with currently completed foundation reports.

If you have any questions regarding these issues, please contact Bijan Khaleghi at 705-7181.

cc:   Mohammad Sheikhizadeh, Bridge Construction - 47354