Tensile and Compression Static Load Test

[kooko]

Is there any reason why static compression and tensile load tests cannot be performed on the same pile? The subcontractor wants to use dead weight for compression test and reaction piles for tensile test.

 

[GeoPaveTraffic]

What the contractor is purposing is commonly done. They are using one pile (the test pile) to test compressive load. While that load is applied, all the reaction piles are in tension, so you could run several uplift tests. One question that often comes up is how much load is in each of the reaction piles? You can assume that the load is evenly distributed to the reaction piles; and you will like be pretty close. If you want to know how much load is really in the reaction piles you can instrument the load frame.

Another problem that often occures is can you get enough tension load in the reaction pile?

 

[dgillette]

Can't think of a reason you couldn't. Maybe you would want to do the compression test first (so you don't try to do the compression test after the tension test has pulled the tip off its bearing), then let it sit a day or two for set-up to be reestablished before you do the tension test.

 

[civilperson]

If you run the compression test to failure, then the tensile values may be lessened.

 

[dgillette]

civilperson - Aside from the rate of displacement, how is running the compression test to failure different from what happens during driving? The movement is downward in both cases, so there isn't a reversal of strain until the tension test is started. (Of course, you do need the delay to allow set-up between driving and compression testing, and between compression testing and tension testing.)