Maximum effective slenderness ratio (KL/r) is an important parameter for determining the stability of a member under compressive loads. It is necessary to ensure that the slenderness ratio of a member is within the specified limits to prevent buckling failure. In the case of members carrying compressive loads resulting from dead load and imposed loads, the maximum effective slenderness ratio is given as 180 (option D).

- Definition of slenderness ratio:
The slenderness ratio (KL/r) is a dimensionless parameter used to assess the stability of a member. It is defined as the ratio of the effective length (KL) of the member to its radius of gyration (r). The effective length is the actual unsupported length of the member, whereas the radius of gyration is a measure of the member's resistance to buckling.

- Importance of slenderness ratio:
The slenderness ratio is crucial because it determines the critical buckling load of a member. If the slenderness ratio exceeds a certain limit, the member becomes more prone to buckling failure, resulting in reduced load-carrying capacity and compromised structural integrity.

- Factors affecting slenderness ratio:
The slenderness ratio is influenced by various factors, including the material properties, cross-sectional shape, end conditions, and loading conditions of the member. For a given material and cross-sectional shape, the slenderness ratio increases with longer lengths and smaller radii of gyration.

- Limiting slenderness ratio for compressive loads:
The maximum effective slenderness ratio for members carrying compressive loads resulting from dead load and imposed loads is specified to ensure structural stability. The limit of 180 is commonly used in design codes and standards to prevent buckling failure in these members.

- Justification for the answer:
Option D, with a maximum effective slenderness ratio of 180, is the correct answer because it falls within the accepted range for members carrying compressive loads resulting from dead load and imposed loads. This value ensures that the member is sufficiently stable and can resist buckling under the given loading conditions.

In conclusion, the maximum effective slenderness ratio (KL/r) for members carrying compressive loads resulting from dead load and imposed loads is 180. This limit is crucial to prevent buckling failure and maintain the structural stability of the member.