Info

VWf = 115 x 620 = 713 kN For the unreinforced section

100 x 1582 „„,„, with = f)y = pz = 25QQ~^~3Q5 = 0.21%

thus from table 8.2, VRd.c = 0.47N/mm2; therefore

As Vf,d.eff is less than Vrj c the section is adequate, and shear reinforcement is not needed.

3. At the dropped panel the critical section is 2.0 x 205 = 410 mm from the panel with a perimeter given by u = (2a + 2b + 2tt x 2d) = (4 x 2500 + 2?r x 410) = 12 576 mm The area within the perimeter is given by (2.5 + 3d)2 - (4 - tt)(2.0 x 0.205)2 = (2.5 + 3 x 0.205)2 - (4 - 7r)(0.410)2 = 9.559 nr Ultimate shear force.

As VEd,cff is less than VRd,t the section is adequate.

[Note - in the above calculation p\ has been based on column strip reinforcement at the support. Since the critical zone will lie partially in the middle strip, this value will be a minor over-estimate but is not significant in this case.]

Span-effective depth ratios At the centre of the span IOOA,.feq _ 100 x 1605 _ bd ~ 4000 x 205 ~ ' From hgure 6.3 the limiting basic span-effective depth ratio is 32 for class C25 concrete and this is multiplied by a K factor of 1.2 for a llat slab (see table 6.10) giving 32 x 1.2 = 38.4.

actual span-effective depth ratio 6500/205 = 31.7

Hence the slab effective depth is acceptable. To take care of stability requirements, extra reinforcement may be necessary in the column strips to act as a tie between each pair of columns - see section 6.7, and the requirement for at least two bottom bars to pass through each column will be satisfied by the spacings calculated above and shown in figure 8.14.

Was this article helpful?

0 0
Greener Homes for You

Greener Homes for You

Get All The Support And Guidance You Need To Be A Success At Living Green. This Book Is One Of The Most Valuable Resources In The World When It Comes To Great Tips on Buying, Designing and Building an Eco-friendly Home.

Get My Free Ebook


Post a comment