Which of the following relation is correct?
- ADesign Load = Characteristic Load
- BDesign Load = Characteristic Load + Partial factor of safety
- CDesign Load = Characteristic Load / Partial factor of safety
- DDesign Load = Characteristic Load × Partial factor of safetyCorrect
Solution
Concept
Formula for design load calculation
Formula
Design Load = Characteristic Load × Partial factor of safety
Step-by-step solution
1. Design Load is the load used in structural design to account for uncertainties in loading. 2. It is calculated by multiplying the characteristic load by an appropriate partial safety factor for loads. 3. Therefore, Design Load = Characteristic Load × Partial factor of safety. Answer: D
Explanation
In limit state design, the design load is obtained by multiplying the characteristic load by an appropriate partial factor of safety for loads. This factor accounts for potential load variations and unexpected overloads over the structure's service life. Hence, option D correctly expresses Design Load = Characteristic Load × Partial factor of safety.
Why the other options are wrong
A) Design load incorporates safety factors and is higher than the characteristic load. B) The partial factor of safety is multiplied by the characteristic load rather than added to it. C) Dividing by a safety factor decreases the value, which applies when calculating design material strength.
Shortcut
Design Load = Characteristic Load × Partial Factor of Safety.
Common mistake
Dividing by the partial safety factor instead of multiplying, confusing design load with design material strength.
Correct answer: D) Design Load = Characteristic Load × Partial factor of safety