Design for beam shear

Support A (and E)

At d from face of support

VEd = 394.6 - (0.400 / 2 + 0^252) x 128.5 = 336.5 kN <6.2.1(8)>

Maximum shear resistance:

* 12 no. H20 B (3768 mm2) used to suit final link arrangements.

12 no. H25 used to suit final arrangement of links.

By inspection, VRdmax OK and cot 0 = 2.5

However, for the purpose of illustration: check shear capacity,

where

: 0.6 [1 - fck / 250] = 0.516 : 35 / 1.5 = 23.3 MPa : angle of inclination of strut. By inspection, cot-1 0 << 21.8. But cot 0 restricted to 2.5 and .*. tan 0= 0.4. VRd,max= 1.0 x 2000 x 090 x 252 x 0.516 x 23.3 / (2.5 + 04) = 2089.5 kN

Shear links: shear resistance with links VRd.6 = (Aew / s) z fywd cot 0>

acw bw z

fcd 0

where

= Area of legs of links/link spacing = 0.9d as before = 500 / 1.15 = 434.8 = 2.5 as before

Asw / s > 336.5 x 103 / (0.9 x 252 x 434.8 x 2.5) = 1.36

Minimum Asw / s where

0.00095

2000 mm as before a = angle between shear reinforcement and the longitudinal axis. For vertical reinforcement sin a= 1.0

Maximum spacing of links longitudinally = 0.75d = 183 mm Maximum spacing of links laterally = 0.75d < 600 mm = 183 mm H10s required to maintain 35 mm cover to H25

.*. Use H10 @ 175 cc both ways i.e H10 in 17.***** legs @ 175 mm cc (Asw / s = 5.38)

<9.2.2(5), Exp. (9.4) > <Exp. (9.5N) & NA>

By inspection, the requirement for minimum reinforcement and, in this instance, for H10 legs of links will outweigh design requirements. Nonetheless check capacity of Asw / s = 5.38

= 5.38 x 0.9 x 252 x 434.8 x 2.5 = 1326.3 kN Maximum shear at support = 517.9 kN i.e. capacity of minimum links not exceeded.

' (2000 mm - 2 x 25 mm cover - 10 mm diameter) / 175 = 11 spaces, .'. 12 legs

By inspection, the requirement for indirect support of the ribs of the slab using 87 mm2 / rib within 150 mm of centreline of ribs (at 900 mm centres) and within 50 mm of rib/solid interface is adequately catered for and will not unduly effect the shear capacity of the beam.

Use H10 in 12 legs @ 175mm cc (Asw / s = 5.38) throughout beam

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