Part 6Structural Design — Section 4 Masonry

FIG. 53 STANDARD HOOK

3. For stirrup and tie anchorage only a $90^{\circ}$ or a $135^{\circ}$ turn plus an extension of at least 5 bar diameters at the free end of the bar.

b) The diameter of bend, measured to the inside of the bar other than stirrups and ties, shall not be less than 5 bar diameters for 6 mm through 20 mm diameter bars. For 25 mm bars through 40 mm, a minimum bend diameter of 6 times bar diameters shall be used.

c) Inside diameter of bend for 12 mm diameter or smaller stirrups and ties shall not be less than 4 bar diameters. Inside diameter of bend for 16 mm diameter or larger stirrups and ties shall not be less than that given in (b).

d) Hooks shall not be permitted in the tension portion of any beam, except at the ends of simple or cantilever beams or at the freely supported ends of continuous or restrained beams.

a) Deformed bars may be used without end anchorages provided development length requirement is satisfied. Hooks should normally be provided for plain bars in tension.

b) Bends and hooks shall conform to accepted standard [6-4(20)] and shall be provided as follows :

1. Bends — The anchorage value of bend shall be taken as 4 times the diameter of the bar for each $45^{\circ}$ bend subject to a maximum of 16 times the diameter of the bar.

2. Hooks — The anchorage value of a standard U-type hook shall be equal to 16 times the diameter of the bar.

c) For stirrups and transverse ties complete development length and anchorage shall be deemed to have been provided when the bar is provided with standard hook as described in 10.5.5.3.

10.5.6.1 Where splices are provided in the reinforcing bars, they shall as far as possible be away from the sections of maximum stress and be staggered. It is recommended that splices in flexural members should not be at sections where the bending moment is more than 50 percent of the moment of resistance; and not more than half the bars shall be spliced at a section. Where more than one-half of the bars are spliced at a section or where splices are made at points of maximum stress, special precautions shall be taken, such as increasing the length of lap and/or using spirals or closely-spaced stirrups around the length of the splice.

10.5.6.2 Lap length including anchorage value of hooks for bars in flexural tension shall be $L_{d}$ (see 10.5.5.1) or $30d_{b}$ , whichever is greater and for direct tension shall be $2L_{d}$ or $30d_{b}$ , whichever is greater. The straight length of the lap shall not be less than $15d_{b}$ or 200 mm.

The following provisions shall also apply:

a) Where lap occurs for a tension bar located at:

1. Top of a section as cast and the minimum cover is less than twice the diameter of the lapped bar, the lap length shall be increased by a factor of 1.4.

2. Corner of a section and the minimum cover to either face is less than twice the diameter of the lapped bar or where the clear distance between adjacent laps is less than 75 mm or 6 times the diameter of lapped bar, whichever is greater, the lap length should be increased by a factor of 1.4.

b) Where both condition (1) and (2) apply, the lap length should be increased by a factor of 2.0.

NOTE — Splices in tension members shall been enclosed in spirals made of bars not less than 6 mm diameter with pitch not more than 100 mm.