7/27/2019 Lateral Pile Loads.docx

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7/27/2019 Lateral Pile Loads.docx

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d. Frame action within a groupe. Pile structural stiffnessf. Pile head stiffness

Research emphasizes that the use of p-y curves gives better results than the nh concept (rate of increase of

soil modulus with depth). Many commercial programs (i.e. COM624P, LPILE, FDPIER, and SWM) have typicalembedded p-y curves that allow the design of laterally loaded piles.

To account for pile group behavior:

A. P- Multiplier method

(AASHTO 2007)

Downdrag and lateral squeeze are two geotechnical loading conditions, their occurrence should be carefully

reviewed and they should be considered in the design .

Downdrag causes a drag load that in LFRD is considered to be an additional permanent structural load with

maximum and minimum load factors. It should be considered in the vertical load component. Note that

batter piles cannot be used where downdrag can occur. Also static and seismic drag loads should not be

combined.

Lateral squeeze is a consequence of lateral movements under permanent vertical loads. Lateral squeeze may

result in significant permanent lateral load. Preloading is one of the common methods to mitigate lateral

squeeze. Note that although AASHTO indicates to consider lateral squeeze in the design, no load factor or

guidance are provided. This should be accounted for through the lateral displacement profile imposed on the

pile within the soil layer causing lateral squeeze.

Reference

AASHTO (2007). AASHTO LFRD Bridge Design Specifications. 6th

edition. American Association of State

Highway and Transportation Officials, Washington, D.C.