Stirrups aid in the retention of primary reinforcement bars and prevent columns frombuckling. They are used to secure beams and columns at the right intervals to prevent them from buckling. Additionally, they prevent RCC constructions from collapsing as a result of seismic activity(earthquakes)

Stirrups in Constructions
In concrete construction, a stirrup is used to secure the primary longitudinal rebar in
concrete beams or columns. They are typically square or rectangular in shape and comprise five 90°bends. The bends at the bar's ends overlap.
Stirrups are typically constructed from a rectangular steel component wrapped over the top and bottom bars of the beams. Stirrups serve in the retention of the principal reinforcing bars. Stirrups are required to keep the columns and beams from buckling.

Stirrups are usually arranged diagonally and vertically. This is done to avoid shear failure which is generally diagonal in nature when beams develop cracks. The diagonal shear is mostly induced by compression and tension caused by transverse and vertical tension.
Diagonal tension eventually emerges due to the fact that concrete is stronger in
compression than in tension. This tension is held in check by a steel stirrup that secures the broken surface.
The stirrup spacing along the beam is critical and should be specified by the designer. This will aid in the construction of the stirrups. They are typically placed in areas prone to shearing, such as beneath heavy loads and bearing points.
Concrete is strengthened by passing steel bars through it. Stirrups, on the other hand,are employed to keep things in order.

Stirrups help maintain order and also reinforce the structure at important locations where itmay become vulnerable over time due to use.
Stirrups are not as sturdy as steel rebars. However stirrups are frequently used in conjunction with rebar.While the rebar serves as the concrete's backbone,the stirrups assist the rebar in remainino straignt and providing additiona support to the column of concrete in which it is inserted.

Stirrups contribute to the establishment of much-needed resistance. When pressure from above is applied to the column,the stirrups function similarly to tendons. They assist the
rebar and concrete in providing long-term support for the severe stress.
What ls the Purpose of Rebar Stirrups?
Stirrups are used to secure the primary reinforcement rebar in an RCC construction. Stirrups are used to secure beams and columns at the right intervals to prevent them from buckling.
Types of Stirrups
Stirrups of the following types are frequently used in reinforcement, and in certain instances
the designer alters the stirrups to meet the design requirement.

Single Legged Stirrups(Open Stirrup)
Two-Legged or Double legged Stirrups(Closed) 

Four-Legged Stirrups(Closed).

Six-Legged Stirrups(Closed) 

Helical Stirrups(OpenStirrup) 

Circular Stirrups(OpenStirrup)

Single Legged Stirrups
While single-legged stirrups are not frequently used, they can be advantageous when just two rods need to be bound. Rather than a complete loop,these single-legged stirrups
resemble a flattened U-shape.
Two-Legged or Double
Stirrups with two legs or with four legs are some of the most frequently used stirrup variants in the business. This stirrup requires a minimum of four rods to construct.
Four-Legged Stirrups
The four-legged stirrup is the next step up, and it typically comprises of two overlapping
stirrups that do not completely surround the rods. For instance,if you have eight rods in two rows of four the two overlapping stirrups will encircle six rods each, with the four in the center wrapped in both.