SIMPLE DESIGN CHART & SAMPLE CALCULATIONS
INDEX
DESIGN CONSIDERATIONS P2
SIMPLE DESIGN LOAD AND SPAN CHARTS FOR CORCON P3
SAMPLE CALCULATION P6BEAM DESIGN P15
DESIGN CONSIDERATIONS
CORCON is a hybrid moltiribbed slab +beam system using the best properties of a slab coupled with all the advantages of the beam used to stiffen the slab in deflection.
CORCON is a flexible system that can be applied to any span and loading
configuration by the use of inserts which can be used to vary the depth of the CORCON
rib beams - from a nominal 50 m2 depression to 300 m2 deep for extra heavy loads and or long Spam over 8 to 9m. Also by reducing the (c to c) centre to centre spacing from 1200 m2 and continuity the spam can be increased to 26m using post-tensioning.
Small spans - say 3m- use CORCON with "FLAT" insert mould (see the Figure below):
If require structural primary beams could always use upstand beams subject to requirements. (see the Figure below):
SIMPLE DESIGN LOAD AND SPAN CHARTS FOR CORCON
Beams @ 1200 Centres Single Span
Allowable superimposed live load (KPa) C to C spans metres Beam Depth d mm Reqd bar size overla p Avg Conc . vol m3/ m2* Total depth mm 4.0 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 10.0 11.0 14.0 50 2Y12 0.12 184 3 75 2Y12 0.12 209 5 .5^ 100 2Y12 0.12 234 5 1.5 150 2Y12 0.12 284 5 2.5 1 200 2Y12 0.12 334 4 4 2 1^ 250 2Y16 0.13 384 5 5 3.5 2 0.3 3** 300 2Y16 0,14 414 5 5 4 2 1^ 5** 3** 2***
1.5 hour fire rating, stc 49, min cover 85mm, f62 mesh top & 1/250 deflection
* based on 20m2 room ^ roof loads
** post tensioned
*** continuous post tensioned built in primary beam Single Span
Allowable superimposed live load (KPa)
C to C spans metres Beam Depth d mm Reqd bar size overlap Avg Conc. vol m3/m2* Total depth mm 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 50 2Y12 0.10 164 5 5 3 1 1 100 2Y12 0.10 214 5 4.5 2.5 .05 150 2Y12 0.10 264 5 3.5 1.5 200 2Y12 0.11 314 4 2 1 250 2Y16 0.11 364 5 5 4 2 1.5 0.5 300 2Y16 0.12 414 5 5 5 3.5 2 1
0.5-hour fire rating, min cover 65mm, f62 mesh top & 1/250 deflection * based on 20m2 room
^ roof loads Continuous Span
Allowable superimposed live load (KPa) and deflection to span ratio.
C to C spans metres Beam Depth d mm Reqd bar size overlap Avg Conc. vol m3/m2* Total depth mm 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10. 0 10. 5 11. 0 50 2Y12 0.12* 184 2 1/2 70 75 2Y12 0.12* 209 2 1/2 75 100 2Y12 0.12* 234 2 1/3 00 150 2Y12 0.12* 284 2 1/2 75 200 2Y12 0.13* 334 2 1/2 75 250 2Y16 0.13* 384 2 1/3 50 2 1/3 00 300 2Y16 0.13* 434 2 1/3 50 2 1/3 00 2 1/2 50
1.5 hour fire rating, stc 49, min cover 85mm, f62 mesh & y16 @ 1200mm top
SELECTED SECTION PROPERTIES b = 110mm B = 155Mm D = 485mm d = 300mm Fck = 30N/mm2 Fy = 460N/mm2 Conc. Cover = 25mm Rib Spacing = 900mm
Cross sectional Area = 177954.57mm2
Moment of Inertia Ixx = 2468.22E6 mm4
Reinforcement at Mid-Span = 2 * T16 mm Dia.
Reinforcement at Supports = 3 T 12mm Dia.
Moment Capacity at Mid Span = 69.08KN-m
Section Capacity at Support = 81.03
Actual Deflection = 1.14mm
Shear Capacity = 0.86N/Sq.mm
Shear Reinforcement = Please check CORCON test Results.
Concrete Volume per Sq.m of Plan Area = 0.15Cub.m
Reinforcement per Sq.m of Plan Area = 0.26Kg
B
d D
SAMPLE CALCULATION
PROJECT
The Sukhothai Bangkok
JOB REF DECOIN PTY LTD ACN 008 625 590 ABN 30 008 625 590 CALCULATION BY Upul Perera CHECKED BY CALC SHEET PART OF STRUCTURE PRINTED BY Decoin Pty Ltd DATE 09/02/2003
MEMBER REF
LOAD CALCULATIONS
Loading (Guest Room Area)
(A) Rib Self weight = 3.36 kN/m2 Screed + Finishes = 1.177 kN/m2 Services = 0.225 kN/m2 Ceilings = 0.225 kN/m2 Partitions = 421 . 8 434 . 3 kN/m2 - DL Imposed Lead 1.962 kN/m2 - LL n= 14.93 kN/m2 (ult)
Udl for Ribs DL = 8.421 x 1.2 = 10.1 kN/m
LL = 1.962 x 1.2 = 2.4 kN/m
(B) Plant Room Area
Rib Self wt. = 3.36 Screed = 1.1772 Services = 7622 . 4 225 . 0 kN/m2 - DL Live Leads = 7.35 8 kN/m2 - LL N= 18.439 kN/m2 (ULT)
Udl for Ribs DL = 5.715 kN/m LL = 8.829 kN/m (C ) Storage Room, Rib self wt. = 3.36 kN/m2 Screed = 1.177 Services = 7622 . 4 225 . 0 - kN/m2 - DL Imposed Load 4.905 - kN/m2 - LL OUT PUT R e f e r e n c e s t o B S 8 1 1 0
UDL for Ribs, DL = 5.715 kN/m LL = 5.886 kN/m MEMBER
REF
Specimen Calculation
Loading for [live load of 300 kg/m2 Area]
Ribbed slab self wt = 0.14 x 24 = 3.36 kN/m2 Screed = 1.18 Services = 0.225 Ceilings = 0.225 4.99 kN/m2 – DL Live Load = 2.943 kN/m2 - LL
Design Ultimate Load n = 4.99 x 1.4 + 2.943 x 1.6
= 11.69 kN/m2
Uniformly Distributed Load on a Rib
DL = 1.2 x 4.99 = 5.88 kN/m
LL = 1.2 x 2.943 = 3.53 kN/m (service load)
Three load combinations were considered. Please refer Prokon print out sheets #01 to #03.
The rib beam is designed for max. sagging and hogging moment for each span, considering BM and SF envelopes.
OUT PUT MEMBER REF BS8110 Cl 3.3.4 CALCULATIONS
A. Durability and Fire Resistance of Rib Slab
Exposure conditions: It is assumed that these rib beams are used in areas where the concrete surfaces are protected
OUT PUT R e f e r e n c e s t o B S 8 1 1 0 Y20 Y20 Area=140561 mm2 = 0.14 m2 66 125 400
BS8110 Table 3.4 BS 8110 Table 3.5 BS 8110 Fig. 3.2
against weather or aggressive conditions.
Therefore treat as mild Exposure Conditions.
For Grade 30 Concrete (30 Mpa) the Nominal cover requirement is as 25 mm, for Durability requirement,
Note: Above cover requirement is including links
Nominal cover for Ribbed slab for : -
01 hr. Fire Period = 20 mm
02 hr. Fire Period = 35 mm for continuous beams 45 mm for Simply Supported beams
use 35 mm cover for bottom bars
Minimum member Dimensions regeared for Ribbed beams, is 125 mm and Slab thickness of 95 mm for 1 hr fire rating?
Same for 2-hr fire rating is 125 mm ribs & 125 mm slab thickness. MEMBER REF BS 8110 Cl.3.4.4.4 CALCULATIONS
Design for bending.
MaxM + re moment in the span = 71.1 kNm.
Effective Depth (d) = 400 – (35+6+15) = 344 mm
BS 8110 Table 3.27 K= cu f bd M 2 30 344 1179 10 1 . 71 2 6 =0.017 < k’ = 0.156
Hence Compression R/F is not required.
Z=d [0.5 + 9 . 0 25 . 0 k ] < 0.95d =344 x [0.5+ 9 . 0 017 . 0 25 . 0 ] =344 x 0.98 >0.95d Z=0.95d=0.95x344=327mm
Depth to Neutral axis ‘x’ = (d-z)/0.45 =(344-327)/0.45
=37.8mm <100mm min. flange thickness
Hence, Neutral airs is within flange thickness.
area of tension R/F, As = fyz M 87 . 0 2 6 555 327 450 87 . 0 10 1 . 71 mm
h b As w min 100 =0.18 for 0.08 0.4 1179 5 . 95 b bw (As)min = 2 2 555 7 . 68 100 400 5 . 95 18 . 0 mm mm Minimum Steel requirement is satisfactory.
As =555 mm2
MEMBER REF
CALCULATIONS
Maxm Support (at 1st intention Support) = -63 kNm
Effective depth to tension R/F; d=400-(25+6+25+20/2)=334mm
Effective depth to compression R/F; d’=35+6+15= 56mm
BS 8110 Table 327 M/bd2 fcu = 30 334 66 10 63 2 6 = 0.285 > k’=0.156
Compression Steel is required.
Z=d [0.5 + 9 . 0 ' 25 . 0 k ] = 334[0.5 + 9 . 0 156 . 0 25 . 0 ] = 334 x 0.776 = 259 mm x= (d-z)/0.45 = (384-259) / 0.45 = 166.6 mm
Area of compression Reinforcements:
A's=(k-k') fcubd 2 /0.87 fy(d-d') =
334 56
450 87 . 0 334 66 30 156 . 0 285 . 0 2 =261.8 mm2Area of tension R/F : As = k' fcu bd2 / 0.87fyz +A's
As = 259 450 87 . 0 334 66 30 156 . 0 2 +261.8 = 601.6 mm2 minimum tension R/F h b As w . min 100 =0.26 Asmin. = 100 400 5 . 95 26 . 0 = 99.3 mm2 <601.6 mm2 minimum steel requirement is satisfactory.
Compression steel area at support A's = 261.8 mm2
Tension steel area at support As = 601.6mm2
MEMBER REF BS 8110 Table 3.9 Or from equation: BS 8110 Table 3.8 BS 8110 cl.3.4.56 Table 3.8 CALCULATIONS
Check for Shear
Maxm. shear force at 1st interior support = 60.6 kN, Take Maxm shear force at ‘d’ away from face of the support:
V=54.8 kN
Tension Steel provided 2 Y 20 (628 mm2 )
bd As 100 = 334 5 . 95 628 100 =1.968 v = 334 5 . 95 10 8 . 54 3 =1.718 N/ mm2
Design concrete shear stress vc
vc = 0.79 3 1 100 bvd As 4 1 400 d /γm 3 1 25 fcu = 0.79 3 1 628 100 bvd 4 1 25 . 1 334 / 400 3 1 25 30 vc = 0.79 1.250 25 . 1 046 . 1 1.0625 = 0.878 N/ mm2 Asv bv sv (v-vc) / 0.87 fyv sv
c
v sv yv v v b A f 87 . 0
1.718 0.898
5 . 95 2 3 . 28 250 87 . 0 sv 153mm provide R6-150 c/cmax shear link spacing 0.75d= 0.75 x 334 = 250 mm
minimum link requirement Asv 0.4 bv sv / 0.87 fyv
sv v sv yv b A f 4 . 0 87 . 0
5 . 95 4 . 0 2 3 . 28 250 87 . 0 = 322 mm OUT PUTProvide Shear links at 1st interior support
provide nominal links @ R6 -225 c/c
Provide Nominal links R6-225 mm c/c. MEMBER REF Ref. BS 8110 Table 3.10 CALCULATIONS
Check for Deflection, (250mm Rib -n = 11.69kN/m2
b bw = 1179 5 . 95 = 0.081
basic span/Depth ratio = 16.76 (Value between simply supported & continuous)
fs= b sprov req s y A A f 1 8 5 . . = 1 629 538 450 8 5 = 240 N/ mm2 M/bd2 = 2 6 344 1179 10 1 . 71 = 0.509 Modification factor = 0.55 +
2.0 9 . 0 120 477 2 bd M fs M.F. = 0.55 +
0.9 0.509
1.95 2.0 120 240 477 Allowable span = 16.76 x 1.95 x 344 mm =11,242 mm > actual span 7,258 mmHence: Deflection is satisfactory.
CHECK FOR DEFLECTION (BS8110)
DATA
Bending moment at mid span = 114 kNm (Ultimate) Average web width (bw) = 95.5 mm
Effective Flange width (b) = 1179 mm Effective depth at mid span (d) = 394 mm Actual span of rib = 7525 mm
Strength of reinforcement (fy) = 450 N/mm 2
Area of steel required (Asreq.) = 778 mm2
Area of steel provided (Aspro.) = 805 mm 2
Moment redisribution ratio = 1
CALCULATIONS
Basic Span/Span Depth ratio = 16.76
The design service stress (fs) = 271.82 N/mm2
Modification factor = 1.67 1.673
Allowable Span = 11,046 mm Deflection is Satisfactory
Table 3.10 of BS8110
See the BS 8110- Table 3.10 Support Conditions
Rectangular Sections
Flanged Beams with bw/b
<=0.3
Cantilever 7 5.6
bw/b = 0.1 Simply Supported 20 16
Continuous 26 20.8
Note: Linear Interpolation between values given above can be used.
