Foundation Ties (Piles)

[Hromis1]

Section 12.13.5.2 of the ASCE 7-05 states that ties shall have design strength of at least 10% SDS times factored dead load plus factored live load. (Design category C, tension governs this case).

For the case I am working on my live loads are almost solely crane loads. My live loads are huge as a result of additional design criteria (40% thrust, and 20% tractive, 25% vertical impact allowances).

It appears as if this simplified section is written for "normal" buildings where the difference between live and dead loads is not an order of magnitude.

Anyone else have experience with this problem? I don't see a work around in the code. I was always taught that the lifted load in effect was dampened and not very critical for lower acceleration values?.

 

[Hromis1]

sorry folks, that last sentence should read

"I was always THOUGHT that the lifted load in effect was dampened and not very critical for lower acceleration values?."

 

[Hromis1]

Okay, guys...after some serious research I answered my own problem....found several papers by others dealing with the same problem at AIST.org

IBC does not deal well with heavy industrial buildings..

To explain the situation further...the particular building I am working on has a system of extremely deep built up column sections that transfere lateral loads to the piles and pile caps very effeciently. (Huge moment arms and the load is transfered around by a very stiff horizontal system)..we design around fatigue on these buildings

In other words, it only needs a minimal connection to meet the day to day lateral loads. These lateral loads are far larger than the EQ loads.....

However the vertical load remains very concentrated....(as the crane system moves)

IBC 2006/ASCE 7-05 are going to make me upgrade the pile to pile cap connection based on the vertical load...using this arbitary connection standard....(so much for logical design)......

:sharkattack: