Practice Question: Find Crane outrigger Base Spreader thickness

NCEES Civil PE Specification Means and Methods: Construction Methods


You are setting up a crane equipped with 2 ft by 2 ft outriggers that can take a maximum force of 20 kips. 

You learn that the site has weak soil and you will have to pour a concrete block to act as a spreader for the load.

What is the required thickness of the reinforced concrete spreader based on the soil bearing capacity?

  • Consider a soil bearing capacity of 1500 psf.
  • Consider a vertical stress distribution of 1:1.
  • Ignore Factor of Safety in your calculation.

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