Minimum Concrete Cover

@ S1

@ S1 @ S1

High bond wires

@ 11501 mm

@ | 250 I mm @ | 350 1 mm

s1 = spacing of longitudinal wires

5.2.5 Anchorage of links and shear reinforcement

P(1) The anchorage of links and shear reinforcement shall normally be effected by means of hooks, or by welded transverse reinforcement. High bond bars or wires can also be anchored by bends. A bar should be provided inside a hook or bend.

(2) For the permissible curvature of hooks and bends, see 5.2.1.2(2).

(3) The anchorage as a whole is considered to be satisfactory:

— where the curve of a hook or bend is extended by a straight length which is not less than:

• 15_01 or 50 mm if it is a continuation of an arc of 135° or more [Figure 5.7 a)];

• | 10 01 or 70 mm if it is a continuation of an arc of 90° [Figure 5.7 b)].

— where there are near the end of a straight bar:

• either two welded transverse bars [see Figure 5.7 c)],

• or a single welded transverse bar, the diameter of which is not less than | 141 times the diameter of the bar [see Figure 5.7 d)].

5.2.6 Additional rules for high bond bars exceeding | 32 mm | in diameter 5.2.6.1 Construction details

P(1) Bars of 0 > | 32 mm | shall be used only in elements whose minimum depth is not less than | 15 01.

Minimum Concrete Cover
Figure 5.7 — Anchorage of links

P(2) When large bars are used, adequate crack control shall be ensured either by using surface reinforcement (see 5.4.2.4) or by calculation (see 4.4.2).

(3) The minimum concrete cover should be c T 0.

(4) The clear distance (horizontal and vertical) between individual parallel bars or horizontal layers of parallel bars should be not less than the maximum bar diameter or dg + 5 mm where dg is the maximum aggregate size.

P(1) For bar diameter 0 < | 32 mm | the values f-^ in Table 5.3 (see 5.2.2.2) should be multiplied by the coefficient (| 132 | - 0)/100. (0 in mm).

5.2.6.3 Anchorages and joints

P(1) Large diameter bars shall be anchored as straight bars or by means of mechanical devices. They shall not be anchored in tension zones.

P(2) Lapped Joints shall not be used either for tension or compression bars.

(3) The rules given below are complementary to those given in clauses 5.2.3.

(4) In the absence of transverse compression, additional transverse reinforcement is needed in the anchorage zone in beams and slabs, additional to the shear reinforcement.

(5) For straight anchorages (see Figure 5.8 for the notation used) the additional reinforcement in (4) above should not be less than the following:

— in the direction parallel to the lower face:

— in the direction perpendicular to the lower face: ASv = n2 |0.25| As

where: As n1 n2

denotes the cross sectional area of an anchored bar, is the number of layers with bars anchored at the same point in the member, is the number of bars anchored in each layer.

(6) The additional transverse reinforcement should be uniformly distributed in the anchorage zone with spacings which should not exceed approximately five times the diameter of the longitudinal reinforcement.

Figure 5.8 — Additional reinforcement in an anchorage zone where the bar diameter is greater than | 32 mm | and there is no transverse compression

(7) For surface reinforcement, 5.4.2.4 applies, but the area of surface reinforcement should not be less than 0.01 Act,ext in the direction perpendicular to large diameter bars, and 0.02 Act,ext parallel to those bars (notations, see Figure 5.15).

5.2.7 Bundled high bond bars

5.2.7.1 General

P(1) Unless otherwise stated, the rules for individual bars also apply for bundles of bars. In a bundle, all the bars shall be of the same diameter and characteristics (type and grade).

(2) In design, the bundle is replaced by a notional bar having the same sectional area and the same centre of gravity as the bundle.

The "equivalent diameter" of this bar is such that:

where nb is the number of bars in the bundle, which is limited to:

nb r 4 for vertical bars in compression and for bars in a lapped joint, nb r 3 for all other cases.

(3) For a bundle, 5.2.1.1(2) applies, while using the equivalent diameter 0n, but measuring the clear distance from the actual external contour of the bundle of bars. The concrete cover measured from the actual external contour of the bundles should be c > 0n.

5.2.7.2 Anchorage and joints

P(1) Anchorage or lapping of a bundle of bars shall be achieved by anchorage or lapping of the individual bars. Only straight bar anchorages are permitted; they shall be staggered.

(2) For bundles of 2,3 or 4 bars, the staggering distance of the anchorages should be | _1.2,_ 1.3 and 1.41 times the anchorage length of the individual bars respectively.

(3) The bars should be lapped one by one. In any case not more than 4 bars should be present in any one section. The lapped joints of the individual bars should be staggered as given in (2) above.

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Responses

  • thomas wolf
    Is there a maximum crack spacing in concrete & eurocode?
    3 years ago

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