Design grid line grid similar

Cover:

Flexure: column strip, sagging:

K = MEd / bd2fck = 95.1 x 106 / (1000 x 2402 x 30) = 0.055

<Concise EC2Table 15.5>

As = MEd / fydz = 95.1 x 106 / (228 x 500 / 1.15) = 959 mm2 / m

Deflection: column strip:

<Concise EC2 Table 15.10> <Concise EC2 Table 15.11>

cnom = 30 mm as before d

F2 = 1.0 (no brittle partitions)

where o"sn « 283 MPa (from Concise EC2 Figure 15.3 and

Gk / Qk = 3.6, ^ = 0.3, ys = 1.25) S = redistribution ratio = 1.08

(Js « 283 x (959 / 1005) / 1.08 = 250 F3 = 310 / 250 = 1.24

Allowable l / d = 26.2 x 1.2 x 1.24 = 39.0 Actual l / d = 5900 / 240 = 24.5 . OK

Flexure: middle strip, sagging MEd = 37.6 kNm / m By inspection, z = 228 mm

As = MEd / fydz = 37.6 x 106 / (228 x 500 / 1.15) = 379 mm2 / m

By inspection, deflection OK

Check minimum area of reinforcement

Ae,min = 0.26 (fctm / fyk) M > 0.0013 btd where bt = width of tension zone fctm = 0.30 x fck0666 As,min = 0.26 x 0.30 x 300666 x 1000 x 240 / 500 = 361 mm2 / m

<Concise EC2 Table 15.12> <Concise EC2 Table 15.13>

<Concise EC2 Fig. 15.3> <Concise EC2 Table 15.14> <Concise EC2 Fig. 15.3>

Flexure: column strip, hogging:

K = MEd / bd2fck = 131.6 x 106 / (1000 x 2402 x 30) = 0.076

As = MEd / fydz = 131.6 x 106 / (223 x 500 / 1.15) = 1357 mm2 / m

<Concise EC2 Table 15.5>

Flexure: middle strip, hogging: MEd = 18.8 kNm / m By inspection, z = 228 mm As = MEd / fydz = 18.8 x 106 / (228 x 500 / 1.15) = 190 mm2 / m

<Concise EC2 Table 15.5>

(p = 0.08%) = 361 mm2 / m (p = 0.15%) Try H12 @ 300 T2 (376 mm2 / m)

As,min as before

**** The hogging moment could have been considered at face of support to reduce the amount of reinforcement required. This should be balanced against the effect of the presence of a 200 x 200 hole at some supports which would have the effect of increasing K but not unduly increasing the total amount of reinforcement required in the column strip (a 1.5% increase in total area would been required).

Requirements:

There is a requirement to place 50% of A within a width equal to 0.125 of the <9.4.1(2)> panel width on either side of the column. As this column strip is adjacent to the edge of the slab, consider one side only: Area required = (1.5 x 1357 + 3.3 x 192) / 2 mm2 = 1334 m2

Within = 0.125 x 6.0 m = 750 mm of the column centreline.

i.e. require 1334 / 0.75 = 1779 mm2 / m for 750 mm from the column centreline

Allowing for similar from centreline of column to edge of slab:

between edge and to 750 mm from centre of support In column strip, outside middle 1500 mm, requirement is for 1.7 x 1357 - 6 x 314 = 422 mm2 in 750 mm, i.e. 563 mm2 / m

Use H12 @ 175 T2 (646 mm2 / m) in remainder of column strip In middle strip Use H12 @ 300 T2 (376 mm2 / m)

3.5.8 Analysis grid line 2

Consider panel on grid line 2 as being 9.6 / 2 + 8.6 / 2 = 9.1 m wide and continuous spans of 6.0 m. Column strip is 6.0 / 3 = 3.0 m wide.

Figure 3.22

Internal panel on grid 2

Figure 3.22

Internal panel on grid 2

Slab Slab gk = 9.1 x 8.5 kN / m2 = 77.4 kN / m qk = 9.1 x 4.0 kN / m2 = 36.4 kN / m

Actions, load combination and arrangement: Choose to use all-spans-loaded case

Ultimate load, n

By inspection, Exp. (6.10b) is critical. n = 1.25 x 77.4 + 1.5 x 36.4 = 151.4 kN / m

Effective span, leff

Effective span = 5900 mm as before

Design moments in bay, MEd:

Spans (worst case, end span assuming pinned support)

Support (worst case ist support)

Additional moment in column strip only due to perimeter load

<Concise EC2 Table 15.2>

MEd

Column strip, 3.0 m wide

Middle strip, 6.1 m wide

-ve (hogging)

0.75 x 453.2 / 3.0

0.25 x 453.2 / 6.1

= 113.3 kNm / m

= 18.5 kNm / m

+ve (sagging)

0.50 x 453.2 / 3.0

0.50 x 453.2 / 6.1

= 75.5 kNm / m

= 37.1 kNm / m

Punching shear force, VEd, as before

Punching shear force, VEd, as before

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