What Is Mean By Bent Up Bars

a as assumed in the design.

(6) The diameter of the shear reinforcement should not exceed | 12 mm | where it consists of plain round bars.

(7) The maximum longitudinal spacing smax of successive series of stirrups or shear assemblies is defined by the following conditions (with Vsd, VRd1 and VRd2 as defined in 4.3.2):

— if 1/5 VRd2 < Vsd r 2/3 VRd2: smax = 0.6 d 8 300 mm (5.18)

— if Vsd > 2/3 VRd2 : smax = 0.3 d 8 200 mm (5.19)

(8) The maximum longitudinal spacing of bent-up bars is defined by:

(9) The transverse spacing of the legs in a series of shear links should not exceed: if Vsd r 1/5 VRd2: smax = d or | 800 | mm whichever is the smaller for Vsd > 1/5 VRd2: Equation 5.18 or 5.19 applies.

(10) The provisions for the control of diagonal cracking are given in 4.4.2.3(5).

5.4.2.3 Torsional reinforcement

(1) The torsion links should be closed amd be anchored by means of laps or according to a) of Figure 5.7 and form an angle of 90° with the axis of the structural element.

(2) The provisions of 5.4.2.2(3)-(6) are also valid for the longitudinal bars and links of beams subjected to torsion.

(3) The longitudinal spacing of the torsion links should not exceed | ukS | (see 4.3.3.1, Figure 4.15, for the notation).

(4) The spacing in (3) above should also satisfy the requirements in 5.4.2.2(7) for maximum spacing of links.

(5) The longitudinal bars should be so arranged that there is at least one bar at each corner, the others being distributed uniformly around the inner periphery of the links, spaced at not more than | 350 mm | centres.

5.4.2.4 Surface reinforcement

(1) In certain cases it may be necessary to provide surface reinforcement either to control cracking or to ensure adequate resistance to spalling of the cover.

(2) skin reinforcement to control cracking should normally be provided in beams over 1 m deep [see 4.4.2.3(4)].

(3) surface reinforcement to resist spalling arising, for example, from fire or where bundled bars or bars greater than 32 mm diameter are used, should consist of wire mesh or small diameter high bond bars and be placed outside the links as indicated in Figure 5.15.

(4) The minimum cover needed for the surface reinforcement is given in 4.1.3.3(6) and (7).

(5) The area of surface reinforcement Ag surf should be not less than | 0.011 Act ext in the direction parallel to the beam tension reinforcement.

Act ext denotes the area of the tensile concrete external to the links, defined by Figure 5.15.

(6) The longitudinal bars of the surface reinforcement may be taken into account as longitudinal bending reinforcement and the transverse bars as shear reinforcement provided that they meet the requirements for the arrangement and anchorage of these types of reinforcement.

(7) Any surface reinforcement in prestressed beams can be taken into account as in (5) and (6) above.

— if 1/5 VRd2 < Vsd r 2/3 VRd2: smax = 0.6 d 8 300 mm

— if Vsd > 2/3 VRd2 : smax = 0.3 d 8 200 mm (for VRd2, see section 4.3.2.4 Equations 4.25 and 4.26

The maximum longitudinal spacing of bent-up bars is defined by: smax = |06| d (1 + cot a)

Bent Bars Beams

Figure 5.15 — Surface reinforcement

150mm

Figure 5.15 — Surface reinforcement

5.4.3 Cast in situ solid slabs

(1) This section applies to two-ways solid slabs and to one-way solid slabs where b and leff T 4h (see 2.5.2).

5.4.3.1 Minimum thickness

(1) For a solid slab, the absolute minimum thickness is | 50 mm |.

5.4.3.2 Flexural reinforcement

5.4.3.2.1 General

(1) For the detailing of the main reinforcement, 5.4.2.1 applies with ai = d in 5.4.2.1.3.

(2) Secondary transverse reinforcement should be provided in one-way slabs

Generally, this secondary transverse reinforcement should be at least | 20 % | of the principal reinforcement.

(3) 5.4.2.1.1(1) and(2) give the minimum and the maximum steel percentages in the main direction.

(4) The maximum spacing of the bars is as follows:

— for the principal reinforcement, | 1.5 h d 350 mm |, where h denotes the total depth of the slab;

— for the secondary reinforcement, | 2.5 h d 400 mm |.

(5) Rules 5.4.2.1.3(1)-(3), 5.4.2.1.4(1)-(3) and 5.4.2.1.5(1)-(2) apply.

5.4.3.2.2 Reinforcement in slabs near supports

(1) In slabs, half the calculated span reinforcement should continue up to the support and be anchored therein.

(2) Where partial fixity occurs along one side of slab, but is not taken into account in the analysis, the top reinforcement should be capable of resisting not less than one quarter of the maximum moment in the adjacent span; this reinforcement should be provided along a length of not less than 0.2 times the adjacent span measured from the inner face of the support.

5.4.3.2.3 Corner reinforcement

(1) If the detailing arrangements at a support are such that lifting of the slab at a corner is restrained, suitable reinforcement should be provided.

5.4.3.2.4 Reinforcement at the free edges

(1) Along a free (unsupported) edge, a slab should normally contain longitudinal and transverse reinforcement generally arranged as shown in Figure 5.16.

(2) The normal reinforcement provided for a slab may act as edge reinforcement

U-shaped link free edge

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Responses

  • destiny baudoin
    What is bentup bars slabs?
    8 years ago
  • carl
    Why bars are bent up in edges near slab?
    2 years ago
  • jukka-pekk
    What is skin reinforcement?
    8 months ago

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