TOPIC 4: HOOKS Flashcards
Refers to a bend at the end of a reinforcing bar
(rebar) designed to provide anchorage within concrete.
Hook
Are critical components that help ensure the
rebar remains securely embedded in the concrete, improving the bond between the two materials and enhancing the structural capacity of the reinforced concrete element
Hook
What are the different types of Hooks?
- 90-degree hook
- 135-degree hook
- 80-degree hook
Is a rebar that is bent at a right angle (90
degrees) and has a straight extension beyond the bend, also called the “tail” of the hook
90-degree hook
Commonly used in stirrups, ties, and
crossties for shear reinforcement. It is also used for anchoring rebar in beams, slabs, and walls.
90-degree hook
Employed in situations where tension
forces need to be resisted at the ends of the rebar.
90-degree hook
Involves a bend greater than a right
angle, turning the rebar to form a sharper bend with a longer extension tail compared to the 90-degree hook
135-degree hook
Commonly used in seismic reinforcement. It is primarily used in seismic zones for stirrups, ties, hoops, and crossties.
135-degree hook
Commonly found in reinforced concrete columns and beams where additional
confinement of the concrete core is required.
135-degree hook
Also called a “U-hook” or “closed hook,”
involves bending the rebar into a half-circle, bringing the tail of the rebar parallel to the original bar.
180-degree hook
It is commonly used for tension
development in beams, slabs, and walls.
180-degree hook
It is utilized in foundations and footings, where strong anchorage is needed to resist uplift and pullout forces.
180-degree hook
It is also used in confinement
applications, especially in ties and hoops around columns
180-degree hook
According to NSCP 2015 Section 425: Reinforcement Details includes?
- Standard Hooks
- Seismic Hooks
- Crossties
Is a bend or curve at the end of a reinforcing bar (rebar) that is used to anchor it into concrete. The hook improves the bond between the concrete and the rebar.
Standard Hooks
Typical configurations include 90-degree or 180-degree bends.
Standard Hooks
Refers to the smallest allowable diameter to which a reinforcing bar can be bent without causing damage to the bar or compromising its
structural integrity.
Minimum Inside Bend Diameter
Used as transverse reinforcement (such as stirrups, ties, hoops, and spirals) must follow the dimensions specified in Table 425.3.2
Inside Bend Diameter
Consists of steel wires arranged in a grid pattern and welded at their intersections.
Welded Wire Reinforcement (WWR)
It is used to reinforce concrete slabs, walls, and other structures. It provides uniform strength and easier installation compared to individual
reinforcing bars
Welded Wire Reinforcement (WWR)
Are hooks at the ends of stirrups or ties that are used in reinforced concrete to provide additional anchorage and resistance to seismic forces. They are designed to improve the ductility and energy absorption of a structure during an earthquake.
Seismic Hooks
Are crucial for structural elements subject to seismic forces, such as stirrups, ties, hoops, and crossties.
Seismic Hooks
Are reinforcing bars placed horizontally across vertical bars in reinforced concrete columns or walls.
Crossties
What are the conditions for Crossties?
- Crosstie shall be continuous between ends
- There shall be a seismic hook at one end
- There shall be a standard hook at other end with minimum bend of 90 degrees
- Hooks shall engage peripheral longitudinal bars
- 90-degree hooks of two successive crossties engaging the same longitudinal bars
shall be alternated end for end, unless crossties satisfy Section 418.6.4.3 or
425.7.1.6.1
