The bottom portion of concrete gravity dam is usually stepped in order to

Explanation:

Concrete or Masonry Gravity Dam:

• The bottom portion of concrete or a masonry gravity dam is usually stepped is stepped at the base to increase the shear strength at the base and at other joints.
• It also enhances the bonds between the dam and the rock foundation.
• By ensuring a better bond between the surfaces the shear strength of these joints should be increased as much as possible.

Additional Information

Brief about Gravity dam:

• It is defined as a structure that is designed in such a way that its own weight resists external forces.
• This type of structure is most durable, solid, and requires little maintenance.

• They may be constructed of masonry or concrete.

• The thickness of the dam provides resistance to sliding.
• It can be constructed on any site where the natural foundation is strong enough to bear the weight of the dam.
• It is most suitable when the foundation is strong.
• Most of the gravity dams are solid so that no bending stress is introduced at any point.
• The failure of this dam, if any, is not sudden. It gives enough warning time before the area to the downstream side is flooded due to the damage to the structure.