## Design grid line C

Effective depth, d d = 300 - 30 - 20 / 2 = 260 mm Flexure: column strip and middle strip, sagging

K = MEd / bd2fck = 140.5 x 106 / (1000 x 2602 x 30) = 0.069 z / d = 0.94 z = 0.94 x 260 =244 mm

As = MEd / fydz = 140.5 x 106 / (244 x 500 / 1.15) = 1324 mm2 / m

Deflection: column strip and middle strip,

F2 = 1.0 (no brittle partitions'1"") F3 = 310 / (7s where

where

(Tsn = (500/ 1.15) x (85 + 0.3 x 40) /16.6 = 254 MPa (or « 253 MPa (From Concise EC2 Figure 15.3 for Gk / Qk = 2.1, y/2 = 0.3 and yg = 1.25)

^ = redistribution ratio = 1.03 « 253 x (1324 / 1570) / 1.03 = 207 F3 = 310 / 207 = 1.50** . Allowable l / d = 20.3 x 1.2 x 1.50 = 36.5

<Concise EC2 Table 15.5>

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

* As punching shear force (rather than a beam shear force) 'effective' span is not appropriate.

Cladding and strip of slab beyond centre of support. ftt Otherwise for flat slabs 8.5 / 9.5 = 0.89 as span > 8.5 m. <7.4.2(2)>

^ In line with Note 5 to Table NA.5, 1.50 is considered to be a maximum for 310 / <rs.

§§§ Note: Continuity into columns will reduce sagging moments and criticality of deflection check (see Section 3.5.14).

**** Note requirement for at least 2 bars in bottom layer to carry through column <9.4.1(3)>

Flexure: column strip, hogging: MEd = 222.3 kNm / m

K = MEd / bd2fck = 222.3 x 106 / (1000 x 2602 x 30) = 0.109

As = MEd / fydz = 222.3 x 106 / (231 x 500 / 1.15) = 2213 mm2 / m

Flexure: middle strip, hogging: MEd = 95.3 kNm / m

K = MEd / bd2fck = 95.3 x 106 / (1000 x 2602 x 30) = 0.069

As = MEd / fydz = 95.3 x 106 / (247 x 500 / 1.15) = 887 mm2 / m

Requirements:

There is a requirement to place 50% of At within a width equal to <9.4.1(2)>

0.125 of the panel width on either side of the column. Area required = (3 x 2213 + 3 x 887) / 2 mm2

1.e. require 4650 / 1.5 = 3100 mm2 / m for 750 mm either side of the column centreline.

Use H20 @ 100 T2 (3140 mm2 / m) 750 mm either side of centre of support

In column strip, outside middle 1500 mm, requirement is for Area required = 3.0 x 2213 - 16 x 314 mm2 = 1615 mm2

Within = in 3000 - 2 x 750 mm = 1500 mm i.e. 1077 mm2 / m

Use H20 @ 250 T1 (1256 mm2 / m) in remainder of column strip

Perpendicular to edge of slab at edge column:

Design transfer moment to column Mt = 0.17 bed2fck <9.4.2(1), I.1.2(5)> where be = cz + y = 400 + 400 = 800 mm <Fig. 9.9>

K = MEd / bd2fck = 275.8 x 106 / (800 x 2602 x 30) = 0.170

As = MEd / fydz = 275.8 x 106 / (213 x 500 / 1.15) = 2978 mm2 / m

++++ The hogging moment could have been considered at face of support to reduce the amount of reinforcement required.

This reinforcement to be placed within cx + 2cy = 1100 mm <SMDSC>

Try 10 no. H20 T1 N-bars in pairs @ 200 (.3140 mm2) local to column

(max. 200 mm from column)

Note:

Where a 200 x 200 hole occurs on face of column, be becomes 600 mm and pro rata, As required becomes 2233 mm2 i.e. use 4 no. H20 each side of hole (2512 mm2).

### Perpendicular to edge of slab generally

Assuming that there is partial fixity along the edge of the slab, top reinforcement capable of resisting 25% of the moment in the adjacent span should be provided

Check minimum area of reinforcement

4.min = 0.26 (frtm / fyk) M ^ 0.0013 btd where bt = width of tension zone

Asmin = 0.26 x 0.30 x 300666 x 1000 x 260 / 500 = 390 mm2 / m

(p = 0.15%) Use H12 @ 200 (565 mm2 / m) The reinforcement should extend 0.2h from edge = 600 mm <9.3.1.4(2)> ## Greener Homes for You

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