RAFT FOUNDATION DESIGN (BS8110 : PART 1 : 1997) TEDDS calculation version 1.0.05;
A sslabtop
A sedgetop
h slab
A s e d g e l in k
h hco reslab
hedge aedge
h h c o r e t h ic k A s e d g e b t m
bedge
Soil and raf d!finiion Soil d!finiion Allowable bearing pressure; pressure;
allow ! "00#0 k"#m "00#0 k"#m$
"umber o% t&pes o% soil %orming sub'soil;
On! $%! onl$
Soil densit&;
Fir&
Depth o% hardcore beneath slab;
hhcoreslab ! 1'0 mm; 1'0 mm; (Dispersal allowed %or bearing pressure
check) Depth o% hardcore beneath thickenings;
hhcorethick ! 1'0 mm; 1'0 mm; (Dispersal allowed %or bearing pressure
check) Densit& o% hardcore;
γ hcore 0#0 k"#m* hcore ! 0#0 k"#m
+asic assumed diameter o% local depression;
φdepbasic ! 1'00mm 1'00mm
Diameter under slab modi%ied %or hardcore;
φdepslab ! φdepbasic ' hhcoreslab ! 1'0 mm 1'0 mm
Diameter under thickenings modi%ied %or hardcore;
φdepthick ! φdepbasic ' hhcorethick ! 1'0 mm 1'0 mm
Raf *la+ d!finiion ,a,a- dim dimen ensi sion on#m #maa- dime dimens nsio ion n bet betw ween een oi oint nts; s;
lma- ! 0#000 m 0#000 m
Slab thickness;
hslab ! 1'0 mm 1'0 mm
/oncrete strength;
%cu ! "0 "#mm "0 "#mm$
oissons ratio o% concrete;
ν ! 0#
Slab mesh rein%orcement strength;
%&slab ! '00 "#mm '00 "#mm$
artial sa%et& %actor %or steel rein%orcement;
γ s ! 1#1'
rom /2/A document 3/oncrete ground %loors4 Table 5 ,inimum mesh reuired in top %or shrinkage;
A1"; A1";
Actual mesh provided in top;
A9 (A**la+o% , 9 && -&)
,esh bar diameter;
φslabtop ! 10 mm 10 mm
/over to top rein%orcement;
ctop ! '0 mm '0 mm
Average e%%ective e%%ective depth o% o% top rein%orcement; rein%orcement;
dtslabav ! hslab ' ctop ' φslabtop ! 90 mm 90 mm
,inimum e%%ective depth o% top rein%orcement;
d tslabmin ! dtslabav ' φslabtop#$ ! 8' mm
Ed.! +!a& d!finiion verall depth;
hedge ! "'0 mm
6idth;
bedge ! "'0 mm
αedge ! "' deg
Angle o% cham%er to hori7ontal; Strength o% main bar rein%orcement;
%& ! '00 "#mm$
Strength o% link rein%orcement;
%&s ! '00 "#mm$
8ein%orcement provided in top;
" T1 +ar* (A*!d.!o% , "' &&)
8ein%orcement provided in bottom;
" T1 +ar* (A*!d.!+& , "' &&)
9ink rein%orcement provided;
T1 l!.* a 00 /r* (A* -* , 0#7'" &&)
+ottom cover to links;
c beam ! '0 mm
E%%ective depth o% top rein%orcement;
d edgetop ! hedge ' ctop ' φslabtop ' φedgelink ' φedgetop#$ ! 7 mm
E%%ective depth o% bottom rein%orcement;
d edgebtm ! hedge ' cbeam ' φedgelink ' φedgebtm#$ ! 8 mm
In!rnal *la+ d!*i.n /!/2* Ba*i/ loadin. Slab sel% weight;
wslab ! $: k"#m * × hslab ! #3 k"#m$
ardcore;
whcoreslab ! γ hcore × hhcoreslab ! #0 k"#m$
A%%li!d loadin.
wDudl ! 0#0 k"#m$
w9udl ! 7#0 k"#m$
In!rnal *la+ +!arin. %r!**4r! /!/2 wudl ! wslab = whcoreslab = wDudl = w9udl ! 1#3 k"#m$
Total uni%orm load at %ormation level;
PASS - w udl <= q allow - Applied bearing pressure is less than allowable In!rnal *la+ +!ndin. and *!ar /!/2 A%%li!d +!ndin. &o&!n* E%%ective span o% slab;
l slab ! (φdepslab = dtslabav)#$ ! 70 mm
wswult ! 1.: × wslab ! '#0 k"#m$
Appro-imate sel% weight cantilever moment at edge; ,esw ! (wswult × π × lslab$) × (lslab#*) # ($ × π × lslab) ! 0#"k"m#m Sel% weight shear %orce at edge;
>sw ! wswult × lslab # $ ! 1#8 k"#m
5o&!n* d4! o a%%li!d 4nifor&l$ di*ri+4!d load*
wudlult ! 1.: × wDudl = 1.? × w9udl ! 11# k"#m$ , eudl ! (wudlult × π × lslab$) × (lslab#*) # ($
× π × lslab) ! 1#0 k"m#m
>udl ! wudlult × lslab # $ ! "#0 k"#m
R!*4lan &o&!n* and *!ar* Total moment at edge;
,Σe ! 1#" k"m#m
Total shear %orce;
>Σ ! '#8 k"#m
R!infor/!&!n r!64ir!d in o% @ %actor; 9ever arm; Area o% steel reuired %or bending; ,inimum area o% steel reuired; Area o% steel reuired;
@slabtop ! ,Σe#(% cu × dtslabav$) ! 0#00" 7 slabtop ! dtslabav × min(0.5B 0.5 = √(0.$5 ' @slabtop#0.)) ! 8'#' mm Asslabtopbend ! ,Σe#((1.0#γ s) × % &slab × 7slabtop) ! 8 mm$#m Asslabmin ! 0.001* × hslab ! 19' mm$#m Asslabtopre ! ma-(AsslabtopbendB Asslabmin) ! 19' mm$#m
PASS - Asslabtopreq <= Asslabtop - Area of reinforcement provided in top to span local depressions is adequate S!ar /!/2 v ! >Σ#dtslabmin ! 0#039 "#mm$
Applied shear stress; Tension steel ratio;
ρ ! 100 × Asslabtop#dtslabmin ! 0#"3
Design concrete shear strength;
vc ! 0#8" "#mm$ PASS - v <= v c - Shear capacity of the slab is adequate
In!rnal *la+ d!fl!/ion /!/2 +asic allowable span to depth ratio;
8atiobasic ! 7#0
,oment %actor;
,%actor ! ,Σe#dtslabav$ ! 0#17 "#mm$
Steel service stress;
% s ! $#* × % &slab × Asslabtopbend#Asslabtop ! #01' "#mm$
,odi%ication %actor;
, slab ! min($.0B 0.55 = C(:"#mm$ ' % s)#(1$0 × (0."#mm$ = , %actor ))) ,slab ! #000
,odi%ied allowable span to depth ratio; Actual span to depth ratio;
8atioallow ! 8atiobasic × ,slab ! 1"#000 8atioactual ! lslab#dtslabav ! 8#000 PASS - Ratioactual <= Ratioallow - Slab span to depth ratio is adequate
Ed.! +!a& d!*i.n /!/2* Ba*i/ loadin. whcorethick ! γ hcore × hhcorethick ! #0 k"#m$
ardcore; Edge beam 8ectangular beam element;
wbeam ! $: k"#m * × hedge × bedge ! "#9 k"#m
/ham%er element;
wcham%er ! $: k"#m * × (hedge ' hslab)$#($ × tan(αedge)) ! 1#1 k"#m w slabelmt ! $: k"#m * × hslab × (hedge ' hslab)#tan(αedge) ! 1#1 k"#m
Slab element; Edge beam sel% weight;
wedge ! wbeam = wcham%er = wslabelmt ! 7#0 k"#m
Ed.! +!a& +!arin. %r!**4r! /!/2 E%%ective bearing width o% edge beam;
bbearing ! bedge = (hedge ' hslab)#tan(αedge) ! 7'0 mm
Total uni%orm load at %ormation level;
wudledge ! wDudl=w9udl=wedge#bbearing=whcorethick ! 19#" k"#m$ PASS - w udledge <= q allow - Applied bearing pressure is less than allowable
Ed.! +!a& +!ndin. /!/2 Divider %or moments due to udl4s;
βudl ! 10#0
A%%li!d +!ndin. &o&!n* Span o% edge beam;
ledge ! φdepthick = dedgetop ! 17 mm
wedgeult ! 1.: × wedge ! 9#8 k"#m
wedgeslab ! ma-(0 k"#mB1.: ×wslab×((φdepthick#$×*#:)' ' (b edge=(hedge' hslab)#tan(αedge)))) wedgeslab ! 0#0 k"#m
Sel% weight and slab bending moment;
,edgesw ! (wedgeult = wedgeslab) × ledge$#βudl ! #9 k"m
Sel% weight shear %orce;
>edgesw ! (wedgeult = wedgeslab) × ledge#$ ! 8#' k"
5o&!n* d4! o a%%li!d 4nifor&l$ di*ri+4!d load*
wedgeudl ! wudlult × φdepthick#$ × *#: ! '#7 k"#m
+ending moment;
,edgeudl ! wedgeudl × ledge$#βudl ! 1#7 k"m
Shear %orce;
>edgeudl ! wedgeudl × ledge#$ ! "#9 k"
R!*4lan &o&!n* and *!ar* Total moment (hogging and sagging);
,Σedge ! "#3 k"m
,a-imum shear %orce;
>Σedge ! 1# k"
R!infor/!&!n r!64ir!d in o% 6idth o% section in compression 7one;
b edgetop ! bedge ! "'0 mm
bw = bedge + (hedge/tan(αedge))/2 =
Average web width;
675 mm
@ %actor;
@edgetop ! ,Σedge#(% cu × bedgetop × dedgetop$) ! 0#00
9ever arm;
7edgetop ! dedgetop × min(0.5B 0.5 = √(0.$5 ' @edgetop#0.)) ! '
mm Asedgetopbend ! ,Σedge#((1.0#γ s) × % & × 7edgetop) ! 0 mm$
Area o% steel reuired %or bending;
Asedgetopmin ! 0.001* × 1.0 × bw × hedge ! 9' mm$
,inimum area o% steel reuired;
Asedgetopre ! ma-(A sedgetopbendB Asedgetopmin) ! 9' mm$
Area o% steel reuired;
PASS - Asedgetopreq <= Asedgetop - Area of reinforcement provided in top of edge beams is adequate R!infor/!&!n r!64ir!d in +oo& 6idth o% section in compression 7one;
b edgebtm ! bedge = (hedge ' hslab)#tan(αedge) = 0.1 × ledge ! 9 mm
@ %actor;
@edgebtm ! ,Σedge#(% cu × bedgebtm × dedgebtm$) ! 0#001
9ever arm;
7edgebtm ! dedgebtm × min(0.5B 0.5 = √(0.$5 ' @edgebtm#0.)) ! 3
mm Asedgebtmbend ! ,Σedge#((1.0#γ s) × % & × 7edgebtm) ! 9 mm$
Area o% steel reuired %or bending;
Asedgebtmmin ! 0.001* × 1.0 × bw × hedge ! 9' mm$
,inimum area o% steel reuired;
Asedgebtmre ! ma-(AsedgebtmbendB Asedgebtmmin) ! 9' mm$
Area o% steel reuired;
PASS - Asedgebtmreq <= Asedgebtm - Area of reinforcement provided in bottom of edge beams is adequate Ed.! +!a& *!ar /!/2 vedge ! >Σedge#(bw × dedgetop) ! 0#0' "#mm$
Applied shear stress;
ρedge ! 100 × Asedgetop#(bw × dedgetop) ! 0#180
Tension steel ratio; rom +SF110'1G1 ' Table *.F
vcedge ! 0#"' "#mm$
Design concrete shear strength;
v edge <= v cedge + !"#$mm % - &herefore minimum lin's required Asv HuponHsvreedge ! 0.:"#mm$ × bw#((1.0#γ s) × % &s) ! 0#31 mm
9ink area to spacing ratio reuired;
Asv HuponHsvprovedge ! "edgelink×π×φ edgelink$#(:×svedge) ! 0#7'" mm
9ink area to spacing ratio provided;
PASS - Asv (upon(svreqedge <= Asv (upon(svprovedge - Shear reinforcement provided in edge beams is adequate orn!r d!*i.n /!/2* Ba*i/ loadin. orn!r +!arin. %r!**4r! /!/2 Total uni%orm load at %ormation level;
wudlcorner ! wDudl=w9udl=wedge#bbearing=whcorethick ! 19#" k"#m$
PASS - w udlcorner <= q allow - Applied bearing pressure is less than allowable orn!r +!a& +!ndin. /!/2 /antilever span o% edge beam;
lcorner ! φdepthick#√($) = dedgetop#$ ! 11"1 mm
5o&!n and *!ar d4! o *!lf !i.
wedgeult ! 1.: × wedge ! 9#8 k"#m wcornerslab ! ma-(0 k"#mB1.: ×wslab×(φdepthick#(√($)×$)'(bedge=(hedge'
'h slab)#tan(αedge)))) wcornerslab ! 0#0 k"#m Sel% weight and slab bending moment;
,cornersw ! (wedgeult = wcornerslab) × lcorner $#$ ! 3#" k"m
Sel% weight and slab shear %orce;
>cornersw ! (wedgeult = wcornerslab) × lcorner ! 11# k"
5o&!n and *!ar d4! o 4dl* ,a-imum ultimate udl;w cornerudl ! ((1.: ×wDudl)=(1.?×w9udl)) × φdepthick#√($) ! 10#7 k"#m +ending moment;
,cornerudl ! wcornerudl × lcorner $#? ! # k"m
Shear %orce;
>cornerudl ! wcornerudl × lcorner #$ ! 3#1 k"
R!*4lan &o&!n* and *!ar* Total design moment;
,Σcorner ! ,cornersw= ,cornerudl ! 8#7 k"m
Total design shear %orce;
>Σcorner ! >cornersw= >cornerudl ! 17# k"
R!infor/!&!n r!64ir!d in o% of !d.! +!a& @corner ! ,Σcorner #(% cu × bedgetop × dedgetop$) ! 0#00
@ %actor;
7 corner ! dedgetop × min(0.5B 0.5 = √(0.$5 ' @corner #0.)) ! ' mm
9ever arm; Area o% steel reuired %or bending; ,inimum area o% steel reuired;
Ascornerbend ! ,Σcorner #((1.0#γ s) × % & × 7corner ) ! '7 mm$ Ascornermin ! Asedgetopmin ! 9' mm$ Ascorner ! ma-(AscornerbendB Ascornermin) ! 9' mm$
Area o% steel reuired;
PASS - Ascorner <= Asedgetop - Area of reinforcement provided in top of edge beams at corners is adequate orn!r +!a& *!ar /!/2
bw = bedge + (hedge/tan(αedge))/2 =
Average web width;
675 mm
vcorner ! >Σcorner #(bw × dedgetop) ! 0#039 "#mm$
Applied shear stress;
ρcorner ! 100 × Asedgetop#(bw × dedgetop) ! 0#180
Tension steel ratio; rom +SF110'1G1 ' Table *.F Design concrete shear strength;
vccorner ! 0#"17 "#mm$ v corner <= v ccorner + !"#$mm % - &herefore minimum lin's required
9ink area to spacing ratio reuired;
Asv HuponHsvrecorner ! 0.:"#mm$ × bw#((1.0#γ s) × % &s) ! 0#31 mm
9ink area to spacing ratio provided;
Asv HuponHsvprovedge ! "edgelink×π×φ edgelink$#(:×svedge) ! 0#7'" mm
PASS - Asv (upon(svreqcorner <= Asv (upon(svprovedge - Shear reinforcement provided in edge beams at corners is adequate orn!r +!a& d!fl!/ion /!/2 +asic allowable span to depth ratio;
8atiobasiccorner ! 7#0
,oment %actor;
,%actorcorner ! ,Σcorner #(bedgetop × dedgetop$) ! 0#1"0 "#mm$
Steel service stress;
% scorner ! $#* × % & × Ascornerbend#Asedgetop ! "1#77 "#mm$ , corner !min($.0B0.55=C(:"#mm$'% scorner )#(1$0×(0."#mm$=,%actorcorner )))
,odi%ication %actor;
,corner ! #000 ,odi%ied allowable span to depth ratio; Actual span to depth ratio;
8atioallowcorner ! 8atiobasiccorner × ,corner ! 1"#000 8atioactualcorner ! lcorner # dedgetop ! #033
PASS - Ratioactualcorner <= Ratioallowcorner - )dge beam span to depth ratio is adequate
