The Pontfical urd Royal
University of Santo TomasThe Catholic University ofthe Philippines
of ArchitectureSUR: Plane &,nveying
AS3 - Reinforced Concrete Design
Part l: Reinforcement Details. -Recommended Clear Distance between Bars
o Not less than bar diameter nor more than 25mm for beams
o Not less than 1.5bar diameter nor more than 40mm for columns
. o When bars are placed several layers, the clear distance between layers must not
be less than 25mm
o Maximum spacing of main reinforcing bars in slabs and walls is equal to 3 times
the wall or slab thickness or 500mm whichever is smaller. Spacing for Ties for Columns
o Not more than 16 times bar diameter
o Not more than 48 times tie diameter
o Not more than the least dimension of the cross section
. Standard Hooks (NSCP,4s ed. t;gg?J,
o A 9Oo, 135o, 18Oo bend made at the end of a reinforcing bar according to industry
standards with radius based on the bar diameter.
o 180o bend plus Adb extension, but not less than 65mm at free end of bar.
o 90" bend plus 12db extension, at free end of bar.
" For Stirrups and Tie Hooks
o 15mm barand smaller, 90o bend plus 5db extension at free end of bar.
o 20mm bar and 25mm, 90" plus t2db extension at free end of bar.
o 25mm bar and larger, 135o bend plus 5db extension at free end or bar"
Port II: Siab
* 0ne-Way Slab* A concrete slab of uniform thickness reinforced in one direction and cast
integrally with parallel supporting beams. One-way slabs are suitable only for
relatively short spans. This type of slab is supported by two parallel beams, the
beam framing into girders in turn framing into columns. The reinforcement in
the slab run in one direction only, from beam to beam, hence the slab is known
as 0ne-way Slab.
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Member
Minimum Thickness, h
Members not supporting or attached to partitions or other construction
likely to be damaged by large deflections
Solid One-Way
Slab
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Minimum Main Reinforcing Ears = 12mm
Minimum TemPerature Bars = 10mm
Maximum Spacing of Main Bars = 3t or 450mrn
Maximum Spacing of Temperature Bars = 5t or 450mm
steelcovering = 2cmm
Clear Distance frorn center of reinforcing bars to the bottom of slab = 25mm
Temperature Bars
r [s = 0.0C2 bt for Grade 300 (fu = 300Mpa)
. As = 0.0018 bt for Grade 400 (fy = 400Mpa)
Minimum Thickness of One-WaY Slab
. Simply SuPPorted = L/ZO
. One End Continuous = Ll24
' Both Ends Continuous = L|ZA
. Cantilevered = LILA
" FrineipalReinforcement. Reinforcement designed ta absorb the stresses from applied loads and
rnoments"
" ShniftkageReimforsrnemth ! , - ^.-^-*] -l- -^s *--*^*,.1;*,'i-. +^ +ka *rinein:l- fie!nlUfuetIieiiL P!erLsu Hsr h'srrqlsurer Lu Cri! rt irr*rrqr
-t=h +n ehcnrh thp etrpcsps r"esultine from shrinkage-\l*u (u qsJvl u 'e " - '' - _
&[s* ea iled, Tcrnperature Reinfa reerneRt'
. CoRerete ToPPing. A thin layer of high-quality ceRcrete plaeed over
surfaee "
a concrete to form a floor
" &*ne{ing tayer, .,ri thin lalo*r *f ms:rtxt'spreael eiri a m*ist*neef and pi"epmred *xisting e*nrr*te
;;tJrfa{:r} f:ri*:" tn i*'*ring # ftsw f{:1r:{r*tle 5!ei}'
reinfers'eernent tn e 0ne-waY
or changes in temPerature"
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. Expansion Joint ,, .. A joint or gap b'dtween adjacent parts of a building or structure or concrete work
which permits their relative movement due to temperature changes {or other
conditions) without rupture of damage. Also called Contraction Joint.. Construction Joint
. A joint where two successive placements of concrete meet.. lsolation Joint
. Often called Expansion Joint, it allows movement between concrete slab and
adjoining columns and walls of a building.. ControlJoint
. Joint that creates lines of weakness so that cracking that may result from tensile
stress occurs along predetermined lines.. Beam-and-Girder Slab
' A one-way slab supported b), secondary beams which in turn are supported by
primary beams or girders.. Continuous Slab
. A reinforced concrete slab extending as structural unit over three or more
supports in a given ciirection. A continuous slab is subject to lower bending
moments than a series of discrete, simply supported slabs.
. Flat Plate. A concrete slab of uniform thickness reinforced in two or more directions and
supported directly by columns without beams or girders. FIat plates are suitable
for short to medium spans with relatively light live loads. Since there are no
column capitals or drop panels, shear governs the thickness of a flat plate.
' FIat slab. A flat plate thickened at its column supports with column capitals and drop
panels to increase its shear strength and moment-resisting capacity" Flat slabs
are suitable for heavy loaded spans"
. Waffle slab* A two-way *one rete slab rcinforeed by ribs in twc direetions. Waffle slah are able
to earry heavier loads and spans longer distances than flat slabs. Supporting
beams and dr*p panels can be forrned by omitting in selected areas.
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_a...- Two-waY Slab , !.- r.^-^ r!*a*ianc.Aconcreteslabofuniformthicknessreinforced!ntwodirections:"OU:l
integrallywithsupportingedgebeamsorbearingwallsonfoursides..lw"-w"vslabsareeconomicalformediumspanswithintermediatetoheavyloads.
' Minimum Thickness = Perimeter/l80
' Maxirnum Spacing of Main Bars = 3t or 450mm
.Spacingofbarswithinthecolumnstripis3l2timesthespacingatthecenter'
Partlll: Column. Reinforced Congete Column
oAconcretedesignedtoacttogetherwithverticalandlateralreihforcementinresistingappliedforces.Reinforcedconcretecolumnconstitutingtheprincipalsupportsforafloororroofshouldhaveaminimumdiameterofl0in{254mm)or
'ifrectangularinsection,a-minimumthicknessofSin(203mm)andaminimum
t*':"T;"J:::il:t:tfi;IffiL"s an unsupported height or not greater
thanlotimestheshcrtestlateraldimensionofthecrosssection.rLohEColumn-whentheunsupportedheightismorethanl0timesthe
shortest lateral dimension of the cross section'
' Tied colTon.r*r" corumn reinforceci with vertical bars and individual lateral ties'
Lateral ties should have a diameter of at least 10mm (3/8in) spaced apart not
morethan48timestiediameters,l.6timesbardiametersortheleastdirnensionof the column section'
r vertical Reinforcement - Longitudinal reinforcement placed in concrete
columntoabsorbcompressivestresses,resistbendingstressesandreduce the effects of ffeep and shrinkage in the column'
gLateralReinforcernent*spiratreinforcementorlateraltiesplacedina^-r,'*a +n lrtcrallv restrain the vertieai reinforcement and
concrele ut.,lui I rI i iv ru rvr -.' '
prevent buckling" sting of an evenly
, Spiral Reinforcement * Lateral reinforcement const
spaced continuous spiral held firmly in place by vertical spacers'
.BundledReinforcement-Reinforcementemployedconsistingoftwoto
fourbarstiedindirectcontactwitheachothertoserveroractasoneunit reinforcement plaeed at the corner of lateralties'
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' Spiral Column
o A concrete column with spiral reinforcement enclosing a circular core reinforced
with vertical bars'
. tateral Reinforcement for Compression Members
o SPiralReinforcement. spirals shall consist of evenly spaced continuous bar or wire of such size
and so assembled to permit handling and placing without distortion frorn
designed dimensions'
rForcast.in.placeconstruction,sizeofspiralsshallnotbelessthantomm
diameter'.ClearspacingbetweenspiralsshallnotexceedT5mmnorlessthan
25mm.r Anchorage of spiral reinforcement shall be provided by 1% extra turns of
spiral bar or wire at each end of a spiral unit'
Splicesinspiralreihforcementshallbelapsplicesof4Sdbbutnotlessthan 300mm or welded'
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