For a bored concrete pile, estimated safe load is 200 kN. Upto what load (kN) initial load test should be conducted for initial test pile? Use IS 2911-Part 4 guidelines.
- A200
- B100
- C150
- D500Correct
Solution
Concept
As per IS 2911 (Part 4), initial pile load testing is performed up to 2.5 times the safe load, while routine pile load testing is performed up to 1.5 times the safe load (working load).
Formula
Initial Test Load = 2.5 × Safe Load
Step-by-step solution
1. Identify the given estimated safe load: Safe Load = 200 kN. 2. Recall the IS 2911 (Part 4) provision for an initial load test: Test load = 2.5 × Estimated safe load. 3. Calculate the maximum test load: 2.5 × 200 kN = 500 kN.
Explanation
According to IS 2911 (Part 4), an initial load test is conducted to determine the ultimate load capacity of the pile and is carried out up to a minimum of 2.5 times the estimated safe load (or until failure occurs). For an estimated safe load of 200 kN, the test load is 2.5 × 200 = 500 kN. A routine load test, on the other hand, is conducted up to 1.5 times the safe load.
Why the other options are wrong
A: 200 kN is 1.0 times the safe load, which is just the working load itself. B: 100 kN is half the safe load, which is incorrect. C: 150 kN is less than the safe load and does not correspond to any standard test load criteria.
Shortcut
Initial test = 2.5 × Safe load; Routine test = 1.5 × Safe load.
Common mistake
Confusing the initial load test multiplier (2.5 times safe load) with the routine load test multiplier (1.5 times safe load, which gives 300 kN).
Correct answer: D) 500