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'

SUft: Flone SunreYi*g ! SurueYitlg