Which of the following statements are correct, with respect to wind load analysis as per IS:875 (Part 3)? i) For a given basic wind speed, the value of Risk Coefficient k1 decreases if the mean probable design life of structure in years is increased. ii) Value of factor k2 decreases, if the category of structure changes from Category 1 to Category 4. iii) When upwind slope is less than 3°, the value of Topography factor k3 may be taken as 1.

Which of the following statements are correct, with respect to wind load analysis as per IS:875 (Part 3)? i) For a given basic wind speed, the value of Risk Coefficient k1 decreases if the mean probable design life of structure in years is increased. ii) Value of factor k2 decreases, if the category of structure changes from Category 1 to Category 4. iii) When upwind slope is less than 3°, the value of Topography factor k3 may be taken as 1. Correct Answer ii) and iii)

As per IS: 875, CL: 5.3.1, for a given basic wind speed risk coefficient increases with increase in design life of structure. For instance, for all general buildings having design life 50 year risk coefficient is 1 for basic wind speed of 33 m/s and for same basic wind speed risk coefficient for important structures such as hospitals is 1.05 having design life of 100 years. Hence, statement ‘1’ is False.

K₂ factor is the height and terrain multiplier. As per IS 875, CL: 5.3.2, for a given height of terrain, k₂ decreases, if the category of structure changes from Category 1 to Category 4. Hence, statement ‘2’ is True.