TOPIC 4: HOOKS

Question 1

Refers to a bend at the end of a reinforcing bar
(rebar) designed to provide anchorage within concrete.

Answer 1

Hook

Question 2

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

Answer 2

Hook

Question 3

What are the different types of Hooks?

Answer 3

1. 90-degree hook
2. 135-degree hook
3. 80-degree hook

Question 4

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

Answer 4

90-degree hook

Question 5

Commonly used in stirrups, ties, and
crossties for shear reinforcement. It is also used for anchoring rebar in beams, slabs, and walls.

Answer 5

90-degree hook

Question 6

Employed in situations where tension
forces need to be resisted at the ends of the rebar.

Answer 6

90-degree hook

Question 7

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

Answer 7

135-degree hook

Question 8

Commonly used in seismic reinforcement. It is primarily used in seismic zones for stirrups, ties, hoops, and crossties.

Answer 8

135-degree hook

Question 9

Commonly found in reinforced concrete columns and beams where additional
confinement of the concrete core is required.

Answer 9

135-degree hook

Question 10

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.

Answer 10

180-degree hook

Question 11

It is commonly used for tension
development in beams, slabs, and walls.

Answer 11

180-degree hook

Question 12

It is utilized in foundations and footings, where strong anchorage is needed to resist uplift and pullout forces.

Answer 12

180-degree hook

Question 13

It is also used in confinement
applications, especially in ties and hoops around columns

Answer 13

180-degree hook

Question 14

According to NSCP 2015 Section 425: Reinforcement Details includes?

Answer 14

1. Standard Hooks
2. Seismic Hooks
3. Crossties

Question 15

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.

Answer 15

Standard Hooks

Question 16

Typical configurations include 90-degree or 180-degree bends.

Answer 16

Standard Hooks

Question 17

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.

Answer 17

Minimum Inside Bend Diameter

Question 18

Used as transverse reinforcement (such as stirrups, ties, hoops, and spirals) must follow the dimensions specified in Table 425.3.2

Answer 18

Inside Bend Diameter

Question 19

Consists of steel wires arranged in a grid pattern and welded at their intersections.

Answer 19

Welded Wire Reinforcement (WWR)

Question 20

It is used to reinforce concrete slabs, walls, and other structures. It provides uniform strength and easier installation compared to individual
reinforcing bars

Answer 20

Welded Wire Reinforcement (WWR)

Question 21

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.

Answer 21

Seismic Hooks

Question 22

Are crucial for structural elements subject to seismic forces, such as stirrups, ties, hoops, and crossties.

Answer 22

Seismic Hooks

Question 23

Are reinforcing bars placed horizontally across vertical bars in reinforced concrete columns or walls.

Answer 23

Crossties

Question 24

What are the conditions for Crossties?

Answer 24

1. Crosstie shall be continuous between ends
2. There shall be a seismic hook at one end
3. There shall be a standard hook at other end with minimum bend of 90 degrees
4. Hooks shall engage peripheral longitudinal bars
5. 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