Sheet Piling

Sheet Piling –Past, Present, and Future

Richard J. Hartman, PhD, PEHartman Engineering

Steel Sheet PilingThe Early Years

Currently Available Steel Sheet Piling

Flat Web

Hot rolled

Cold formed

Z-Piles

Manual Calculations Evolved intoComputer Analysis

(1972)

Pressure Envelope Originally Developed by Terzaghi and Peck in 1965

For wall with 2 or more brace levels

A trapezoidal or rectangular pressureenvelope is a tool developed to easily calculatethe maximum loads applied to bracing.However, it does not provide:

1) the maximum bending moment insheet piling, or

2) assurance that the wall will remainstable during excavation.

We will review an example

SAMPLE

SAMPLE

SAMPLE

8.5 k/ft

Seepage forces can cause pipingand destabilize the soil in the bottomof a cofferdam

Analysis can be performed manuallyusing flow nets. This method hasbeen available for more than 60years.

Water Surface

Water LevelLoose Fill

Silty Sand

Weathered Rock

Groundwater

500

500

1,0001,000

1,000

1,500

1,500

1,500

500

2,000

2,000

2,500

Item Traditional (Allowable Stress) LRFD

Toe FS LF x active pressureRF x passive pressure

Sheet StrengthBrace Strength

LF x active pressureRF x strength of member

Allowable Stress – LRFD (Load and Resistance Factor Design)

f= FyFS

Item Traditional (Allowable Stress)

LRFDAASHTO

Toe FS (1.5-2.0) (1.5) LF x active pressure(0.5) RF x passive pressure

Sheet StrengthBrace Strength

(1.5) LF x active pressure(0.9) RF x strength of member

Allowable Stress – LRFD (Load and Resistance Factor Design)

f= FyFS (1.5)

What’s in the Future for the Product?

• New metallurgy?• Higher strength?

• Maintain ductility• Maintain weldability

• New shapes?• Deeper and thinner

• Maintain drivability • Recognize stability issues

What’s in the Future for the Design Process?

• Software to integrate the steps?• Develop pressure diagram• Perform sequential load analysis• Check seepage• Check heave• Check global stability

• Will we lose the ability to think the process through?

List of Resources:1.) U.S. Army Corps of Engineers

Design of Sheet Pile WallsEm 1110-2-2504

2.) U.S. Army Corps of EngineersDesign of Sheet Pile Cellular Structures, Cofferdams, and Retaining Structures

EM-1110-2-2503

3.) Naval Facilities Engineering CommandFoundations and Earth Structures

Design Manual 7.02

4.) Federal Highway Administration GeoTechTools

Geotechnical Publications

5.) American Association of State Highway and Transportation OfficialsLRFD Bridge Design Specifications

Section 11 – Abutments, Piers, and Walls

6.) American Association of State Highway and Transportation OfficialsGuide Design Specifications for Bridge Temporary Works