-
Designed and detailed (BS 8110: 1997) J. B. Higgins and B. R.
Rogers MA. CFng, MI(I
Contents Foreword 2 Introduction This third edition of Designed
and detailed has been revised to BS 8110 : Part I:
1997, and the amendment dated 15 September 1998. Although there
have been 3 BS 8110 and limit state design several amendments to
the code since 1985, the latest and most significant change
has been the reduction in the partial safety factor for
reinforcement m from 1.15 6 Design information . . to 1 .05. With
higher stresses, less steel is required. However, the total saving
may 7 Structural summary sheet not be fully realised because there
are other considerations such as choosing a
practical arrangement of bars, and the deflection in the case of
shallower 8 Floor slab members.
10 First-floor main beam The calculations have also been revised
for the loading requirements of BS 6399 Part 1: 1996 and Part 2:
1995.
16 Edge beam . Design charts in BS 8110 : Part 3: 1985 may still
be used to provide a 18 Columns conservative solution, and one of
these charts has been included for the design of
columns. Lap lengths for these members have also been taken from
BS 8110, 22 Foundation Table 3.27, but adjusted for the design
stress of 087f. 24 Shear wall The tie reinforcement for robustness
is designed at its characteristic strength. If the
characteristic bond stress is used for calculating laps and
anchorage lengths, then 26 Staircase the values in Table 3.27 may
be multiplied by I 05/l4. This publication takes a
conservative practical approach and uses directly the values
given in Table 3.27. 28 Column design chart Observant users of
previous editions will appreciate the skill that is evident in
the
29 Further information setting out of the calculations and the
drawings. This is the work of the late Jim Higgins, whose care in
the production of the original artwork was meticulous. Sadly, he
never saw the second edition in print. I hope that my amendments to
this third edition will not detract from his fine workmanship.
Special thanks are due to Tony Threlfall for his advice and
suggestions for this edition.
Railton Rogers
-
Introduction
The purpose of this publication is to apply the principles of
limit stale design given in BS 8110 by means of a simple worked
example for a reinforced concrete building frame. The calculations
and details arc presented in a form suitable for design office
purposes and are generally in accordance with the following pLihI
ications.
BRITISH STANDARDS INSTITtJTION Siructural use 0/concrete. Part I
. Code of practice/or design and construction. Milton Keynes, BSI.
1997. 120 pp. BS 8110 Part I: 1997. H M STATIONERY OFFICE. Building
and buildings. The Building Regnlation.v 1991 (Amended 1994). HMSO,
London. 21 pp. Statutory Instruments No. 2768. BRITISH STANDARDS
INSTITUTION Loading/or buildings. Part I . Code 0/practice br dead
and inposed loads. Milton Keynes. BSI. 1996. It) pp. BS 6399 : Part
I 1996.
BRITISH STANDARDS INSTITUTION. Loading/or buildings. Part 2.
Code 0/practice Jiir wind loads. Milton Keynes, BSI. 1995. 82 pP BS
6399 : Part 2: 1995. BRITISH STANDARDS INSTITUTION. Loading /ir
buildings. Part 3. (ode 0/practice /r imposed roo/ loads. Milton
Keynes. BSI. 1988. 23 pp. BS 6399 : Part 3: 1988. BRITISH STANDARDS
INSTlThTIO'J. Specification /or scheduling, dimensioning, bendin'
(111(1 cutiin' steel rein/irceinent/r concrete. Milton Keynes, BSI.
1989. 20 PP BS 4466 : 1989. IIIE C( )NCR VIE SOCIETY. Model
procedure /ir the presentation 0/ calculation,r. London (now
Slough). 1981 . Technical Report 5, second edition. 18 pp. THE
CONCRETE SOCIETY AND THE INSTITUTION OF STRUCTURAL F.NGINEERS,
5iandard method o/detailnig structural concrete. London. The
Institution. 1989. 138 pp.
-
BS 8110 and limit state design
c:)bjective To serve its purpose, a structure must be safe
against collapse and be serviceable in use. Calculations alone do
not produce safe, serviceable and durable structures. Equally
important are the suitability of the materials, quality control and
supervision of the workmanship. Limit state design admits that a
structure may become unsatisfactory through a number of ways which
all have to be considered independently against defined limits of
satisfactory behaviour. It admits that there is an inherent
variability in loads, materials and methods of design and
construction which makes it impossible to achieve complete safety
against any possible shortcoming. By providing sufficient margins
of safety, the aim of limit state design is to provide an
acceptable probability that the structure will perform
satisfactorily during its intended life. Limit states can he
classified into two main groups: (I) the ultimate limit state,
which is concerned with the provision of
adequate safety; (2) the serviceability limit states, which are
essentially concerned with
durability. Generally, in practice, there are three limit states
which are normally considered for reinforced concrete and these are
given in the Table below.
Serviceability limit states Ultimate limit state Deflection
Cracking
Objective Provision of adequate safety
Structure should not deflect so as to impair use of
structure
Cracking should not be such as to damage finishes or otherwise
.
impair usage
Loading regime Design ultimate loads Design service load
Performance limit Structure should not fail
Deflection should not exceed specified limits
Crack width should not exceed 03 mm generally
Characteristic values For the testing of materials, a
statistical approach can be applied to the variations within
materials which occur in practice. A normal or Gaussian
distribution curve is assumed to represent the results of the tests
and a value known as the characteristic value can be chosen below
which not more than 5% of the test results may be expected to lie.
The characteristic strength is given by the equation:
Characteristic strength = Mean or Average strength L64 X Standard
deviation Ideally, a characteristic load should be similarly
defined, as a load with a 5% probability of being exceeded during
the lifetime of the structure. Flowever, it is not yet possible
to-express loading in statistical terms, so the Code uses the loads
defined in BS 6399: Parts 1, 2 and 3.
3
-
Desiqn toads The design load is given by the equation: Design
load = Characteristic load X
where 'r is a partial safety factor for loading. This factor
takes into account the possibility that the loads acting on the
structure may be greater than the characteristic values. It also
takes into account the assumptions made in the method of analysis,
and the seriousness of failure to meet the design criteria for a
particular limit state. The consequence of collapse is much more
serious than exceeding the serviceability limits and so this is
reflected in the higher values of the partial safety factors.
Components of load have to he considered in their most unfavourable
combinations, Sc) sets of values of for minimum and maximum design
loads are required. For example, the worst situation for a
structure being checked for overturning under the action of wind
load will he where the maximum wind load is combined with the
minimum vertical dead load. Lower values of ;' are used for the
combination of wind, imposed and dead loads than for the
combinations of wind and dead, and dead and imposed loads, as the
probability Df three independent design loads achieving their
maximum value at the same time is less. The table below gives the
partial load factors for the ultimate limit state.
Combination of loads
Partial safety factor to be applied to dead load imposed
load
wind when effect of load is load
adverse beneficial adverse heneficEal
1 Dead and imposed 2 Dead and wind 3 Dead and wind
with imposed
14 14 12
10 10 12
16
12
1)
12
14 12
Deiin strenqths The design strength is given by the equation:
Characteristic strength [)esign strength =
______________________
where is a partial safety factor on the material strength. This
factor takes into account the variation in workmanship and quality
control that may normally be expected to occur in the manufacture
of the materials. The values of to he used for the two materials
when designing for the ultimate limit state are given below:
Values of , for the ultimate limit state Reinforcement I .05
(oncrete Flexure or axial load IS Shear strength without shear
reinforcement 125 Bond strength 14 Others (e.g. bearing stress)
15
iOLisiuest In addition to providing a structure that is capable
of carrying the design loads, the layout should be such that damage
to small areas of a structure or failure of single elements will
not lead to a major collapse. The Code requires that in all
buildings the structural members should be linked together in the
following manner: (a) by effectively continuous peripheral ties at
each floor and roof level:
4
-
(b) by internal ties in two directions approximately at
right-angles, effectively continuous throughout their length and
anchored to the peripheral ties at each end (unless continuing as
horizontal ties to columns or walls);
(c) by external column and wall ties anchored or tied
horizontally into the structure at each floor and roof level;
(d) by continuous vertical ties from foundation to the roof
level in all columns and walls carriing vertical loads.
In the design of the ties, the reinforcement may be assumed to
be acting at its characteristic strength with no other forces
present but the tie forces. Reinforcement provided for other
purposes can often be used to form part or the whole of these ties,
so that in the design process, when the required reinforcement for
the usual dead, imposed and wind loading has been found, a check
can be made to see whether modifications or additions to the
reinforcement are required to fulfil the tie requirements.
Durabflty and re resislance At the commencement of the design,
the following should be considered: the climate and environmental
conditions to which the concrete will be
exposed; the concrete quality; the cover to the reinforcement.
It should also be noted that the quality of the construction
process and the Iirst hours after casting of the concrete have a
major influence upon the subsequent durability of the structure.
The cover for protection against corrosion may not be sufficient
for fire protection, so this should be considered at the onset of
the design, and also the dimensions of the members. The Code gives
maximum water/cement ratios, minimum cement contents and minimum
characteristic strengths for concretes suitable for use in various
environments with specified covers and using 20 mm nominal maximum
size aggregate. The minimum grades will generally ensure that the
limits on free water/cement ratio and cement content will be met
without further checking.
Appflcation Durability and fire resistance requirements are
considered at the onset of the design process because this
determines the grade of concrete, the cover, and the size of the
members. Usually, for most structures, Part 1 of the Code will be
used in which it is assumed that the ultimate limit state will be
the most critical limit state. Design will therefore be carried out
at this limit state, followed by checks to ensure that the
serviceability limit states of deflection and cracking are not
reached. In special circumstances, other limit states, such as
vibration or the effects of fatigue, may require consideration.
Should it be necessary to calculate deflections and crack widths,
methods are given in Part 2 of the Code. The serviceability limit
state of deflection may be the limiting requirement for floor slabs
with large span/effective-depth ratios. This can he checked before
the reinforcement is determined, although some engineers may prefer
to follow the procedure where the check is made after the
reinforcement has been found. Simplified detailing requirements for
the curtailment of the reinforcement may be used for beams and
slabs which fulfil certain design conditions. Nowever, for other
situations, the curtailments should be taken from a bending moment
envelope and be in accordance with the general recommendations of
the Code.
5
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Design information
Client W Co#.ai Architect Engineer responsible BRJZers /j,
Building Regulation authority or other and Date of submission
TLe. LIL14 'a, 5SiO T tnj L of Cocre.tc Past 'j. S7 Pout P 2
IO5)ckr PCU B8 Relevant Building Regulations and Design Codes
Lbon Intended use of structure Fire resistance reqLnrements
Roof 5 -
F1'oo irvoecj C) &ct tL3r 4.QkW/ Sjr- 4O k4/ Fors a LXc
Co4
General loading conditions
Speed 2 a/ec (basic Factors 105 Sb = 171, S 1.0 S = 1 O S Co'84,
C +O(*r.') ,., O3((),C_r=QO2S
Wind loading ccnditrons
e.'Jere. 4 (Vd ('ixaS) (S6llOTcie3.2) Exposure conditions -
v\O
AoLjo, beac rreure 2oo Subsoil conditions
R1c fs o k4 ov wcik Foundation type ,r-A4e. 4o wt '20. , a
(IIOTcIb3.) Material data
L. strek - fL 4o - 1iJ'c '
Sdf wet 4'ok4/ AU S-oir,. ov ore
Other relevant information
-
Structural summary sheet
3 1'2..4.2
t, AU CoCa z, Mbean , bW4w
-l wall
W1 t5-rAI4cE. i, IiP w orce r4 eA
e4A kax- vodk. . Lr brG L EW kor
prviAed. b ctrc or. r4 /ui, o4 r4 /"44 -3
C C
Ft C2o4\0) = 2Q+lG 3G(Ok,
P - Perpcc ;te It. ter e a - w wc
7
G 5ooO=4oooO
0
0-I 175
11 fl5
S S S 0
T"{P1CALLOOR PLA4
oox3oO OOx'oO SO OO
3
T'-(PICAL cRoSS- C'TtoJ. SJe: ICryo,, CoS,$.275Ox'l75OxOO
C C- cPc
P ><
Ir. rEt, w
C C C cc C C Tia PRVSi -
-
Floor slab interior-span solid slab
175
5000
BS 8110 ref. CALCULATIONS OUTPUT
3.?, T c3 3 34
DugPB%t.vr' ct FR.E REITA4C W.L4S4 ov hr U4 CovCt.ov of ik cover
.. '2o si.
3.r.2,4 Tb(3,12
LoA O.17E x 24 4.2
F (G4t ) 0. r toc.d = 4.7kt{/
Cpa.ge c) = 4. okN/ Dgvtoati t.1r47+ 1.x4) 50
3k 4.7kN/2 401 F
32.4 Iable3i2
ULXIMATE /Vs Iraror r.spo. o.oC,3F =0.OCx,43x5O = 2O.4kh/ wct
4.DrtS
4.44
Tb(e8
FCEfrT k 2o.4 0 0Th 4o-1ox4S2 t4 ppor.
oc'23 = i4s(o.S+J(o.Z ) = i (buto.x1494s:
A5- PA 204x1& - O.95 O.9546Ox14l5 - Cdr5cear o.S4.91O3' 0.22
M/w lc?x 14S
=
Top&otow T12. 0o (iiJ) ok.
TQ6k Tok3IO
DLaC.T(oi.4 6k /4faeq rio = PA 2o4d0',. 031 2x4(O33O I4')
- 3 x 317 cr or WOr re.L.'.ft. 1 5 . Atlte '21.5
'I 5000
- 33 $(o 149 , r4o oc. 2U.27 CR.Acl(ii 447
p-cj bt.twee. bo.r OC 12 34 k 11 , ( 2 oO ., rttQ. cJck.4 . c.*j
ak.. k. 3.12.3.4
TAbteZ7
r PV(op..J o..ct4We5 ITR..iALii Ft = 3kN/.wd Torce 4t( 7 ( 4t)_
4r.Lw>Ft
4S.x lo 44,0 -'fl' :#3oo. T12.e3oo (377
-
I
tso.l. 5T10.-41 2)00
i1loo 4
T "
'
-
C3*'Z)
5T10-41r2 It, I
S-rto--3GO'r2 I
L I (2+3) I
.J
Commentary on bar arrangement BS 8110 ref Bar marks Notes
All bars are labelled in the form described in the Standard
method of detailing structural concrete, e.g. 45T12-l-300B1 means
that in the bottom outer layer there are45 Grade 460 Fype 2
deformed 12 mm nominal size bars at 300 mm centres and the bar mark
is -I-. The bars are numbered in the likely sequence ot fixing; the
positions of the first and last bars in a string are indicated in
plan and section. Intermediate bars have been omitted for
clarity.
Table 3.25 Minimum area of tension reinforcement = 00013 X 1000
>< 175 = 228 mm2/m. 3.12.11.2.7 Maximum clear spacing of
tension bars = lesser of 750 mm or 3d, i.e. 3d = 3 )< 149 = 447
mm.
h < 200, therefore no further check on spacing 1 Main tension
bars Tl2 @ 300, A = 377 mm2 > minimum 228 mm2/m. OK.
If curtailed, A = 377/2 = 189 mm2 < minimum 228 mm2/m not OK.
3.12.3.4 Bars lapped 300 mm at bottom support to provide continuous
tie. Table 3.25 2,3 Secondary bars use T10 @ 300 (262 mm2/m).
3.12.8.11 4,5 Minimum lap = 300mm > IS )< 10 = 150 mm.
Lapping reduces bar lengths for easier handling on site.
7 Laps are shown staggered for effective crack control. 3.4.1.5
6 Minimum transverse reinforcement is placed across the full flange
width of the edge beam (minimum
width = 650 mm, see page 16). Table 3.25 Minimum area = 00015
)< 1000 >< 175 = 263 mm2/m use TlO @ 300 (262 mm2/m).
8 Main tension bars over support 112 @ 300 as bar mark I.
3.12.10.3 One curtailment shown at 03 effective span from face of
support. Further curtailments prevented by
minimum area and spacing requirements similar to mark I.
9
i,TIOc30OTQt
Al 1.
)
5Tt0-5JT' Mt.
B I
II U-
'2 .1 L
ST tO -51
1oo 1
30O
I L%o
'1
3
8T1O-2.00 '7T1O-3)2 Mt.
4
1
2
1
@_Th F
i_ (2) _i T10- 1300 7 TI 0- 'z) e2 AlL
4T'2-1- 300 P LA.1 (r4 '2 ovfte4 r c[ti)
A It AR. = alecY4J &r5
.45s Att
A-A
,z tt. - CovE.R toote 5= 20 $cale; i;o-
-
First-floor main beam two-span flanged beam
BS 8110 ref. CALCULATIONS OUTPJT
.2.I.21 Su.FR.P1ME. AL'-t'5 A taa.r ett. Ljs e.LLa.r ro4kcgd e'
b er rMrv S C tD forces. F-or t -1oo be co(s.bosje &iiiwecL to
be xed. 4 tse be(oi c 1ve. Ti. t'i.ov,. w ot prove rot rcd rert.
Lart* 1L4 to a-re. takcr b sc-ur wcAk.
3 To.bk6
3,34
D ' F Ri STA CG COVW for vt co t.ov of eposurc 2o. ov1 cove ?OO
wbefor -
cover t Ii4K5 20
.2122 LAPD4G p4 toc o75o.b CPe&) 5c4.7 2.S se-ieLt
(o.o.r7s)o.3 x 24 = '23 oGa.w 2B.kW/, (.B) = x4 2o.Ok4/, Mv ce o4
i4 +
'(2 + 32 'i& k/s
103K 2S&k4/. Oc 2OOk/t. t.4
.i2k/M +t ) Bi Moie.m () .O ve4tl.Q% uie.4:
BA 1' cZUIL4 rowv AvJ I 12 ------ Ctk I 1oo4 wp
LtperCowC. Lower II Scur (k)
CASEJ1 CM IS%t Lij*- Cokiv v# ower sc-0- (1)
CDiLAI stf, Ler se (-!)
- 17$ 2O + 4o2 - 348k + Qc + ba + ii - 24 oo 22
(8't'2 -19 2.7( 4- 4$ 2So 28 - 4 4-it 7 + 'a-
34 #1's 2$2 i'2o 3
iii -
.54 e4 + 2o4 - 1- 33 + 2'
+ 17 - 52 - 4
1% 1 0 10
f =460 ............. tto
8000 6000 300
-
CALCULATIONS
MDN-E'JT ..NvLOPE
Rrnto V
FogcE E1LOPE
40 r CASE I 17S o .5S (SQ..e ii') 402 2&L (
O') II 1 (2o'J') II 34 S2 (I)
III o
{1 eatA.
wecoc 32S L
-UI
La6t I trbut&i
2? I 22 I
EveLop.
3511
oao
00 m.
1 I 2BBR I 3001 L
-
= 282
i55 k1 0.4
0.s 46o vw1
=
0
&s 2
0
s'. t&or (. .3 a 4T25
1 . . I,
440 J__ Lj4co
2 T 2B
Co
:vta.-vt Supor:
BS 8110 ref. CALCULATIONS OUTPUT
Fcor. ?JL Q1 = 0.7
K' O.4o2(0.7O.4')_01(O.7_Q.4)2 K Ot21 > O1o4 bd2
= 4oxooi4.4
42O 0.02'3
Mu 3EAM., t.FLOof E') 322t /ct 3.4.4.4 = o.io4
efoe 50 O > O7 /O.4,):. /c i-04 os ______ - so 04S A5 32.
< 10 t756 - 0.5x4Ox0.9Sx4SO
FroM .M.evop11) 2.2.1 = i5x tO
40 x OOx 45O (O.So. ') D2 :.- cl .4) As i,xtO O'Sx4,0.x 0.9rLx
450 ckovcbox: 775 o'S.c.4Ox4S1 75 x to
312'32'2 ..IC.b4rcksr= 190x S0/5) 2 x 4o,( '25 M
Frv .Vf. Cvveloe M
=
.M.evei.oe, 3.4.j. E. . .OO+ 0.14 x (,00O M = OO7, cu
A 13x 10
4 T 2 E (tO tc...o ".
= O.O,4
657 MAM
So -
2T25
__
j nPoo )25,, a.6
1t40
12
4o 4So Ce4c Abt9e4
we.b o.oo K300X 500 = -se. or-.oVe.r Spport,0.002fx3Q0oO=
TLc 2 T 2S (8lr.
t&4%SLO
-
BS 8110 ref CALCULATIONS OUTPUT
34.G
T.6te3'B
TIe7 2 45.5 Tbe37
Tobe7
SkEAR REll4PORcMEJT Ccve. tior, re.L,, 2T2 (82 w2)
4ooA - 100x2 073, \!c 0S7(- b OO4SO / t'vvk A 6 0.4 OOx 04
OSS(2O ' = 075 ' 4B0 00TrR2oo
.(vO7O4.o59/2 Sv 3oo 0'
d.4SO
Skct R12 Lk oo io 2 A/ o.7s j 2 J .50 j 1t T6137 4StO Loao 8LM
V.f.d 2t V/N/ j(oo vv 0% Ay tlS Lks R'l2C. 175
R. 2 3- i 12 R 1 300 R..t'2. @ 3oo
,,
L.H 25 2M
'32 jsc O.o
tSS j.14
R.L V1G875 k..N
.o3 2S
37 O.'9
p.51 O.7
34..1 T.bIe9 3.4, bkto
FLECTION1 b-Lo= M 2x 4(oOic I75i27 23/2 b 42Ox4SO2 3x 1%O
325
ctor i..5 224 Acto - &000 - 450 . ,
'2.t1.2.
Tk32g 3ViII2 3 I2124 2i2
C AC t rk ba pa 1
:c-.k ct; J
1V\ T'VLOY. \'L4. I 0/ f & xtr-.f sport T 2o
+ 18 I.e.raS $..4por-t T 30
0 e,
-
153k Nn Extntot QIon4 T.C.P(3.1,S a. cL450.
2) b = 300. (. C t.Lo. ct. 5 =
/IT.C.P to pt, we4- M 2 Commentary on bar arrangement US 8110
ref Bar marks Noics
lius beam shows loose splice bars at each column intersection.
Ihis met hod simplifies detailine and 0 sing and the span cage can
readily he prefabricated.
I Tension bars arc stopped 50 mm from each column lace to avoid
clashing with the column bars 3.3.1.2 shown in section A--A.
Nominal cover 20 + 12 32 mm > 25 mm, say 35 mm. 3.12.9.1 2
Remaining tension bars stopped off as shown in the curtailment
diagram above. 3.12.8.14 ('heck masimum amount of reinforcement at
laps < 40 breadth
4 >< 25 = 100 mm < 0-4 X 300 = 12)) mm OK. 3 loose bars
arc fixed inside column bars as shown in section BB. Although
designed as compression 3.12.3.4 bars, these bars also act as
internal ties and lap 1000 mm with the adjacent span bars for
continuity.
4 The two tensioil bars are stopped 51) mni from the column Oice
to avoid the column bars beyond. 5,10 loose Ibars are bxcd insidc
the column bars and provide continuitS for column and internal
ties.
3.12.11.1 ('heck minimum distance between tension bars 25 mm
(aggregate si/c f 5 mm). 30)) 200 - 100 mm ' 25 mm OK.
3.12.9.1 Top legs propect from centre-line into span. minimum
dimensions shown in the curtailment diagram. '4
c,2R12 - 11
5
i4eoO
A 'ZTi6- G
t '12 t
2
4 A-A
___
-
: O
'2T2,-2
ELE VAI 1 For o ba.c 4 r .stcxxce M o 2T2S ('3&2
= c1_ xO.95[j] M= O.5fx4x, (3.4.4.4.) a bdxO a= Top: b=300,
/4o.9i2)MJ7 Bt,n: b 1420> = 0., M13'5km. 4LY Mo Ev.ve1opii.
& ____ 1o l_o.I_ _____ 1s
CURTA1LMT DIAGRAM.
'75 bOO
-
M A1P4 EAM
cer
LNK DARAIY\
3.12.3.6
3.12.8.14 3.12.8.3
10
3.12.8.3 6.9
3.12.9.1
3.12.4.1
7.8
Bottom lcts lap minimum 00)) mm with span bars to provide
continuity for the internal tie. 'lop legs 5 + 450 1315 mm ) let
both legs Bottom lees 200 100)) 1200 mm ) project 350 mm. say. Note
that the bottom lees are raised to avoid the 40i rule in the lower
layer. ('heck hearing stress inside bends. Jy ' 55 br each radius
to simplify bending. 'lop legs 535 - 450 05 mm ) let both legs
Bottom legs 20(1 4- 1001) 1200 mm ) project 1200 mm. say. Else r 4d
minimum radnis bends. link hanger bars arc same length as bar marks
I and 4. Bar is one size larger than links (n' inimum 12 mm). 'Ihe
tension bars over the support stop as shown in the curtailment
diagram. These hai's arc Oxed inside the column reinforcement as
shown in section BB. 'Ihese bars are bundled vertically in pairs to
reduce congestion and this also allows a gap(ninimuni 75 mm) for
insert mii of a vibrator.
II ('hosed links, shape code hi. are arranged to suit the link
diagram above. Open top links, shape code 77. arc not suitable for
the sites shown.
3.12.8.12 Note that links it laps are spiLed at ilot greater
than 200 mm since cover I'S bar size. 15
-
Edge beam interior-span flanged beam 1=
t f '350 5000 300
BS 8110 ref. CALCULATIONS OUTPUT
To.bIe 33,34
DL,RAILITY FIRE. 'S1iCE NDw2aJ Cver tjqr Ovc cf ex?oure =
4OA..
3OOwde. be.4 for ir.ero /vLLMtA Co/e.r 4O%W%
LoAi Ie44 CooA 4!rov 2x2 294
6-3 25.0 o-7kL .'
ose4 i osab(p.t W'25 2.sokM. byi (o.4 544o 125.0kg. k= QO.7kJ k=
2Ok. F =i'zsok.
TAb(e..35 ULTtMATE .M'S IrorsorC M.oo8F OO&xt?x5 O.OkW Wtt4.
a: M E O.07 12Sx 4S
444
3.415
Ta'5 4;,Io
Tcbk7
5Qx0' OO5 t.rLor os: bd2 4ox oox'2So (o.s+a;- 0'O) A: 0Xi0 442.
o5,46OxO'S7x2&D
M4-Ltcuy; e.fewi4t = - 43.9x Cu 40X650x 2902 002., A
SrorceO5SF*12S6875kN, fc'ot reforea.rc2T20 'Larforce G8'75_ (D.
I+ 0.28) 2S
1oo4 o.is 5BxD = 0.G3N) bd 3oo,'2PO / 3oox2.BO v o3) M - 43.SIo'
2 x 4o 2 5ox29O - 3x 4o2 272N/rn . Moft.a,. fi*4or 153 ,1Aow*bLe.
s&r/cff.dLp rto = 22 x
1 ooo 17.2 2O .'. k.
l2cI.2A Tcbe ) 3.12 (.2.4
CAc OFO rs 27/ (sedeco) 7o \9>1s CC A(oJb d&rcpczc 2g T0p
2 ar5o chkC
= 41000 220 ,coc rdtsre O0 QvJLQ CtE'oe 5.Cj'% 2L
,1 I
ok oiIc27 3..U TIE. PR.oVl,O4 -eLF4. A5j . U'L'Tt2, 4t= . x74 45
3oc To - 'ZTVZ.
-
Bar marks Notes Horizontal bars in this member provide the
peripheral tie. Minimum lap = 300 mm. I The two tension bars are
stopped 50 mm from the column lace to avoid clashing with the
column bars shown in section A-A. Separate splice hars are fixed
inside vertical column bars. Minimum area = 30% A = 03 x 364 = 109
rnm. Use 2'T 12 = 226 mrn. I ap = 35 >< 12 >< 109/226 =
203 mm > 15 x 12 = 180 mm < 300 nim. Use 300 mm lap.
3 Link hanger bars also provide support for slab top
reinorcenienI. Minimum area = 20% A sI1pT1 = 02 x 436 = 87 mm. Use
2T 12 = 226 mm.
4 Tension reinforcement over support is fixed inside vertical
column bars. Bars are curtailed at 025 span from lace of support =
025 x 5000 1250 mm > 45 x 21) = 900 mm
5 Closed links are shape code 61
'23R405-200 A1
je- co
2 T '2O 4 n
A EL EV Ar iot
-75
ScaL1e1tO 44 3
COVE o ks =40
U U
t 21 i
Commentary on bar arrangement ItS 8110 ref 3.12.8.11
A-A Sc4, t:"ZO
3.12.10.2 Figure 3.24 Table 3.27 3.12.10.2 Figure 3.24 3.12.10.2
Figure 3.24
17
-
Columns slender and short columns
EW / = O.S (E4o: 4.5
AD TcP
4.o-
boov)
or O tv\
= I52> iS
= 40 = 460 lst
14000 15000 1j 300 300
8000 6000
BS 8110 ref CALCULATIONS ouTPur
2I2.1 5ue,-FAM A4ALi'$lS - rEje.r to bpMe.iO. UR(L4Tt c4
RsTca
cover- or U4 Co 4or4 o expo're 2o . ' 40 oooot Ikreroj 2o w...
Tk' 3 4
cover 4 -..k',
tvoi 2o(a.3o xr 4Ovst*w, It4TRAL CoL-u (u..ctaii -- oof) AXtAL
LOA o4 M*1P'T$ ifrow. ANALX
EAML$ k.N
COLUM Ic LoADS CGLMaMJTS k IMP0cED
E2
aa t 2 1. 2. d 2 1 2 1 2 oa 49
210 244 %33
S4 4 53 5 i4 J 133 34 4 32. sa J 9 9 100 53 3 3
3aFL 2 249
29o 117
140 U7
t3 SB 32
1B4 ivj
32 s& 3' ,
. S 37 I9 6G,7
24.F-(. 298 249
2o 117
140 17
i3 i5 32
i54 117
5 S S
9 9 14 32 b93 1 FL 3oo
252 292 120
14 liB
37 ts 134
ics 120
g 34 -
5. i4 14 873 42, 12Th U82
I 8000 I ooo
LOAD CA1
1oo1=' LoA CASE 2
(PoLr -, 1 atfecti.ve = j3 3 &
TabI 319
8l '3
N-IS (3 D.9 E4co c2.SxA.5 =
4 ,0,
-
1N1RNAL COLL4Mt.J (oo- t)ot.4 Ld Ca o.d z. tOO * Q' 773 7
beo4 i27 -
M1, 0, M2 S, O.4M. 7.k 04 M - O.(DW\2 = O+0x i fI4 > 7.
2 1 ( e'y tDSIx0.xl3S
.4' "T a kb') 2ooo =
DOS3oO qreLe..s o
U23x S44 2.3S < L. 22 (-' b")
M = 42> 29k, _____
oe 1. bove t oor, cvv.t oc4 a2 od, oJ:
C' t'255 L76 cN. M 4 1c,
0 - 0. x .34 = 2o.4kNr., _______ -
______ - ____ D Mow..t 204 + O- M = 4 > 358 Ti RO','SiO L0.4
i.os(2i 28i N 2 0/460 (1 0 . 9O w
BS 8110 ref. CALCULATIONS OUTPUT
t4 + 544
Po_,t t
324
33.. t
Ei 3
S 3'3 Prt I
3. 2.7 2
(b M+M 658 k. = x si = 2''9 k.
2'2 L - 5'8xi0_ = - oo '2-44 a 3O-4o-i3 = 247.
2.47 - __
- - = Q32O
O2S 4Qx.OOx47xlci3 74ik.. I. N> t- 4T'S (%oi)
=
K - _______ = O2 23-741 = .4
ioox%O -
-
fr\ cb cLa.-, Ce.ck
, _______
=
= _____
1v1 0,
Mt.
;5 k.
CcLrt 9t.2B') 3
k.
_
c247
4T'25 (tOGOIvw)
ok,
ok.
" 51. M
23.9-7
5'8 > fr2 2.o
19
-
--
ectLie k-S 0'S Cerc
LK= O9x
= 2ZI
0.9 (evct 0.9 x
Y= 'L15 b
CoAcLo; =
=
usiv.43 oac -
BS 8110 ref.
CALCULATIONS OUTPUT
EXTRJAL COLUMt4 (Foo R..ooF) AtAL LoA1 cd MME,.iT AL
TOTAL
u-AM LOADS k CoLuMtt b$1QN L0A CLM0MT$ k. IMPO$E.D loP
oTToA4
LDAO C4E t '1 i 2 2. ' 1 2 1 2 t. C
i92 i.7 4? 4 i0 5 S4 9 98 oS SW.
. rt 247 25S U 42 4 k2.o S
25B i1
S 2a
15 95
SW.
24.
eti3e
r.o-v
c4e
1!5
247 1J2!
26
25 il5
it & 13 120 25
S 5Th l
125
t25
G1 L5 L2$
S 105
95 joS
ti7 SW
t. 245 2S3 ii V74 2&. U9 7&& 10 E'oO 4 ' SW.
24e t'25 2S 25 ii 1 : 4.02 1D54 16O oor) c
Ft (t)LCLA1)
SOT CoLM
e (.rt PSQc S
4T2B C i90 P%
I3\) top., boo3) CD4Ov
=
EO
S399 Por 1.
PrI I
N Osx oO+44-cY924O O5S k,
fr\ z
Asu c 300- U8 N11hi7xJO 4.3
- 237 - 079
-k-- oo 0osc. 2
= '2.3, A5=.2o7o
B.o' 1st.c,+fa4 'i (4T' i%D2)
20
154, ;
iS kN. 7 k1L b
-
I(4TEiNAL COLL..U1M F'2 ExTR.AL COLUMN Fl LLv,k,
J VertcaS it.rs
-;------ ----f--
Ltrvk_J Vt.ai Se4o, ? c (1
.
.
-
4
Y9J 4 4.
COV.R t0k'= 40
.
;4
:
-4 i I coR t,
.
F c-I L
-,
;1
SCALES i: 5O j 'ZO -
-
The presentation shown above is schematic. This tabular method
adapts readily to element repetition. The sections are shown in
their relative positions adjacent to the vertical reinforcement.
Main bars, area> minimum 04% bh. Slope of crank at lower end =
1:10 maximum. Crank offset = 50 + 10% =55 mm. Minimum crank length
= 350 mm (140). Length of short projection beyond crank =
compression lap +. say, 75 mm for tolerance. Reinforcement area at
laps < 10% bh. Bars project above first-floor slab level to
provide a compression lap above the kicker. Bar projection = 35 x
087/095 x 25 mm + 75 mm for kicker = 875 mm, i.e. compression lap =
800 mm.
2 A single link is provided, since each vertical bar is
restrained by a corner. Minimum size = 25/4, use 8 mm. Maximum
spacing = 12 x 25 = 300 mm. (R8 @ 300.) Cover to vertical bar = 40
mm> 15 x 25 = 375 mm. Links extend to underside of floor slab.
Normally, starter bars are detailed with the footing, as column F2.
It can be economic to detail starters with the column above as
shown. In this case it is advisable to schedule the starter bars so
that they can be processed together with the footing. Note with
this detail that the section at mid-height also applies to the
starter bar arrangement. The starter bars would be shown dotted on
the footing detail together with a suitable cross-reference. Bars
project above the top of the base to provide a compression lap
above the kicker = 35 x 087/095 x 25 + 75 = 875 mm, i.e. lap = 800
mm. As bar mark 1, but bars provide a tension lap above 1st floor
kicker. Cover = 50 mm. Clear distance between adjacent laps =
100mm
-
Foundation reinforced pad footing
BS 8110 ref. CALCULATIONS ourPuT
Tob{e33 4 URAbLITY )Assoi.i roder4e*pesire '0 . U se. ow.sat 4o
cover No..sd cover 40M,l.r4$ LOADI.JC - '1 (iet paqe19) De.4
I&.e'1 r0t.kN. ICxr CIu-ec 12.7 718 1's1
127/i,4=D =443 I58 /,(toi 0kN/v etr ov roFk concete
4or4.foa4
. P,.4 r9uw4 5YC2OO -10) = 7. s .. Acio,t 2'7S rove4 =
7.57fw
U.L.S. Dtcv. ressu . 2Jo3kP4w
.4.4.4
. o6t.v aoco1uw' 63x 'i.7S 2 = Avers c - c,o-4o-z5 =
fr\ 3x 0' 0.017 = 4o,27S0xS52 543x 10' 244Sw :
o.954xO.9SS35 (Q5122) 44 3.i.3.4(') 4
3 113 4(2) 3L7.2
ULTIP.4ATh SAR Co4.or I Sk
- V4f . t91 fI3751so%s) :ookM 2 1375 , r V . SO'IO' i5o
's.3S
force V 4n coLa.= x f37s-a'so-2xS3S} i . k4 2 1375 12.
V 't " 27SOcS3S Co4.or 2 p L4.v S\Qr) *.e ore. cka) V 1O SI
-
T
.4
A
_J2O-t- &5OI
PLAN
4T25 -2 Cover =40
Mn,.
2aB--3oo I ;
COVER. BI 4O 2\4
-is A A Scak, i:SO Commentary on bar arrangement It 81 1() ret
Bir rnark 1\oles 3.12.8.1 1 Straight bars extend full width of
base, less end covers. Table 3.27 Bars should project a minimum
tension bond length beyond the column face = 35 >< 20 = 700
mm
< 1150 nim OK. 3.3.1.4 The underside of base is concrete
blinded, cover = 40 mm.
Column starter bars are wired to bottom mat. Minimum projection
ahose the top of base is a Table 3.27 compression lap + kicker = 35
x 087/095 x 25 + 75 = 875 mm. i.e. lap = 800 mm (see p. 21).
3 Links are provided to stahi Imie and locate the starter bars
during construction. These are the same site as the column links
above.
23
-
460
ist 175 -
4000 250
900 14300
Shear waD external plain concrete wall
BS 8110 ref. CALCULATIONS OUTPUT
.94.3 14. 2> 2 WALL
T&bk 33 )PALtT'( Ft $TAC NS ccvr ( svexe. x?ocLsre. 40w, ()
LL4 . '20
F-y- rest&-e 17 kAI = i.2> t4oLsr 4o 2Ow.wt.
, lc.rt ye stc ck.. C.
O.S(3Z3+8.S) 49.5k/ 5Q V3t O.7(24x1E GS.1 C&ct.c c4
1t4.kJM
a,.r+x4xO.8') 27.8kN/. ;. c4_ BS (99 CLf 2 0
-
B 8110 ref Bar marks Notes fable 3.27
3.3.1.4 Table 3.25 2 3.9.4.19
Table 3.27
3
4,5,6
3.12.3.4 7,8
9
Wall starters match vertical reinforcement. Minimum projection
of horizontal legs beyond the wall face is a design tension bond
length = 35 x 182/377 < 12 = 203 mm < 287 mm. This provides
the footing reinforcement. Minimum projection above top of base is
a compression lap + kicker = 35 x 2 + 75 = 495 mm, say 525 mm, i.e.
lap = 450 mm. Underside of footing is concrete blinded, cover = 4(1
mm. Minimum longitudal reinforcement provided. Minimum vertical
reinforcement. Area = 254 x 1000 >< 175 = 438 mrn'Im. (T 2 @
300 EF = 754 mm2/m.j T 12 bars provide reasonable rigidity for
handling and help stabilize the cage during erection. Minimum
projection above top of firstfloor level is a compression lap +
kicker = say 25 mm. Lap = 450 mm. Minimum horiiontal reinforcement.
Area = 438 mni7m. (T10 @ 200 EF = 786 mm'/m.) Provide at least a
tension lap = 35 x 0 = 350 mm. say 450 mm to satisfy shrinkage and
thermal requirements. Bars are placed outside vertical
reinfircenient to provide maximum control against shrinkage and
thermal cracking. Those bars in the wall 05 in below firstfloor
slab act also as interna] ties. Tension lap 6)r tie = 35 ><
10 = 350 mm, say 450 mm. Peripheral tie at first floor. 1,bars at
either end provide continuity with edge beams. Laps. say 450 mm.
Wall spacers maintain location of each face of reinforcement.
25
Commentary on bar arrangement
-
Staircase 3500
end-span continuous slab
175
5060
BS 8110 ref. CALCULATIONS OUTPUT
3? T.$ Ie 3 4 RLVrt 4 RE.1STAI4C. c'- .toor ri ) o. z
LoA4 Ave.rMe ctb L c.e.cc o.k... = 2so
.0 = 05
cZt.c ce4 SoaA .. .5 k/ = 4.OkJ3/ (14GS 1.4.o)5.o =
17.5kN/1k
k Q, S kN/ k 4.Okt/ F T3S .4'I 1tivtor SLLr= o.itFL=
Q'11x77.5x'O 43.
TI1AT .Ms eo r4et O = 3$. 3Id/M. E
L2Q
w*st 44
To.bte.38
4FOR.CMeNT 1\ jsL. .i-.ter.or sc.pport. , 2 0.049 = 04
43.1
-
Table 3.27 1,5,6
Table 3.25 2,,9
Fig 3.25 3,4
3.12.10.3.2 7
Table 3.25 10,11
34 Tio-E
Main tension reinlorcemcnt. Lap lengths and anchorage bond
lengths = 35 x 12 = 420 mm, say 450 mm. Laps arc located to
facilitate likely construction sequences. Similar for bar marks 12,
13 and 15. Secondary reinforcement. Minimum area = 00013 x 1000 x
75 = 228 inniim. Use 110 (a) 300 = 262 mm/rn. Main tension
reinlorcement over support .50% curtailed at 03 span, remainder at
0 IS span. both measured from lace of support. Similar for bar mark
14. libars provide 50% midspan reinforcement in both top and bottom
at end support = 05 >< 571 = 286 mmlrn. Use 110 @ 15(1 = 524
mill/ni to match spacing of span bars. 1.ap, say 450 mm. Optional
ruinfoi cLnlent Minimum ULd = 228 mm Simil u for h ii mai k 16
27
Cove.r
FUCHT '5' CCVE
Commentary on bar arrangement BS 8110 ref Bar marks Notes
-
Column design chart
28
CJ E E z
0 z
Rectangular columns
50
45
40
35
30
25
20
15
10
5
0 1 23 4 5 6 7 8 9 10 11 12 2 44 - 4 :3
M/bh 2 N/mm2
fcu 40 460
d/h 080
-
nformation from the Reinforced Concrete Council
Spreadsheets Many of the design principles used in this
publication will be covered by spreadsheets for reinforced concrete
design now being developed by the Reinforced Concrete Council.
Versions for both BS 8110 and EC2 are in preparation. For details
write to the RCC at Century House, Telford Avenue, Crowthorne,
Berks RG45 6YS.
Buildability and whole building economics It should be stressed
that the structural solution presented in this publication has been
chosen for the purpose: of illustrating analysis, design and
reinforcement detailing principles. A typical building frame
accounts for only 10% of the whole construction cost, but affects
foundations, cladding and service provision. The choice and details
of a building's structure should reflect both buildability and
overall building economics. Analysis of these factors using a
structural optimisation program* or charts from a publication**
suggests that a flat slab alternative may save around 2% of overall
building costs and ten days' construction time. Similarly,
rationalisation and simplification of reinforcement will normally
speed construction and hence reduce overall construction costs and
programme time. Excessive curtailment and tailoring of
reinforcement to save material at the expense of rationalisation
will prove counter-productive. These aspects are currently being
investigated at the European Concrete Building Project at
Cardington, and will result in the publication of best practice
guidance. With increasing emphasis on the cost in use of buildings,
there is a trend towards the use of exposed soffits for passive
cooling. This move to whole life costs will modify the optimum
solution, and deep ribbed or coffereci slabs are a favoured option
to meet daylighting, thermal mass, ventilation and acoustic
requirements. * Concept - a computer program that allows the rapid
semi-automated choice of concrete frame while considering whole
building costs. Produced by the Reinforced Concrete Council.
Available from the RCC on 01344 725733. ** Economic concrete frame
elements - a pre-scheme design handbook, based on BS 8110, that
helps designers choose the most viable concrete options. Produced
by the Reinforced Concrete Council. Available from the ECA on 01344
7257U4.
IBC
-
Designed and detailed (BS 8110: 1997) J. B. Higgins and B. R.
Rogers BRITISH CEMENT ASSOCIATION PUBLICATION 43.501
OBC
Cl/Sf B (28) q4 (K)
UDC 624.073.33.012.45: 624.04.001.3
(Ofl@rete