hollow core design

8/3/2019 Hollow Core Design

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CONCRETE TECHNOLOGY L.L.C.1- INTRODUCTION

Hollow core slab which is a precast,prestressed concrete member with a continues voidsprovided to reduce weight and , therefore, cost and as a side benefits, to use for concealedelectrical or mechanical runs

Primarily used for floor or roof deck system, and panels, spandrel members and bridge deckunits.

2- MANUFACTURING

Hollow core slab units are casting using extrusion system, where a very low slumpConcrete is forced through the machine.The cores are formed with argues or tubes with the concrete being compacted

Around the cores as shown below.

FIGURE (1)

Hollow cores m anufacturing

3-Why CTS hollow core slab

3-1-CTs hollow core slab providing economical, efficient floor and roof system.

The hollow core slabs voids may be used for electrical or mechanical runs.

3-2-The casting of the hollow core slab units is performed by high technology procedures gives the slab a

high quality and very low use of material and a very fast delivery.

3-3-The hollow core slab provides the efficiency of a prestressed member for load capacity , span range

and deflection control.

Excellent fire resistance is another attribute of the hollow core slab.

Used as floor ceiling assemblies hollow core slabs have the excellent sound transmission characteristics.

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4-Product Detail

Hollow core slab 200 mm




Hollow core slab 265 mm Hollow core slab 500 mm

DIFFERENT HOLLOW CORE SLAB SECTIONS5-structural design5-1-Services Concrete Technology gives here the guide for you to design the hollow core slab units, but the

final decision is for our experienced structural engineers whom always will be ready to assist andadvise you on all matters related to the design of the hollow core slab units.5-2-How to check your slab As the most of precast members, hollow core slab design as a simply supported slab in accordance with

British standard BS110. The main structural functions of floors are span, load bearing, transverse

distribution of vertical loads, diaphragm distribution of the horizontal actions as well as resistance against

fire and accidental actions affecting the floor elements or the supporting structure.

For guidance only concrete technology gives here curves for the slab design range and the load capacity for

the varies slab thickness for varies strands on page 4 to page 7

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0

5

10

15

20

25

30

SPAN (METER)

SER

VICE

LOADS

(KN

/m2

)

4 NOS 9.3 mm 5 NOS 9.3mm 6 NOS 9.3mm

4 NOS 9.3 mm 15.26 10.68 7.7 5.66 4.2 3.12 2.3

5 NOS 9.3mm 19.3 13.64 9.97 7.46 5.66 4.32 3.31

6 NOS 9.3mm 23.14 16.52 12.18 9.2 7.07 5.49 4.2

7 NOS 9.3 mm 23.57 19.3 14.3 10.88 8.43 6.62 4.97

8 NOS 9.3mm 24.3 20.17 15.99 12.22 9.52 7.52 5.69

9 NOS 9.3mm 24.97 20.74 17.04 13.05 10.19 8.07 6.41

3 3.5 4 4.5 5 5.5 6

ALLOWABLE SERVICE TOTAL LOADS FOR D

CURVES ARE CALCULATED USING BS8110 CODE -Maximum service design load(qsls) in

FOR GUIDANCE ONLY

SLAB PROPERTIES:

-PRECAST SLAB WEIGHT = 2.04 KN/m2

-JOINTED SLAB WEIGHT = 2.16 KN/m2-CONCRETE GRADE C50

-FIRE RATE REI60

-AREA OF SECTION = 0.102 m2

-DEPTH OF SLAB = 150 mm

-NOMINAL WIDTH OF SLAB = 1200 mm

-NO. OF VOIDS = 8 VOIDS

-DIMENSION OF ONE VOID = AS SHOWN

-PRESTRESSING STEEL YIELDING

..STRESS = 1630 KN/mm2

-REINFORCEMENT COVER = 35 mm

LOAD CHARTS AND TABLES

HCS-150mm-For higher slab capacity concretec provide Concrete Grade 60 and different Void pr

-This curves is based on 1 hour fire rate and it may be change according to every p


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0

5

10

15

20

25

SPAN(METER)

SERV

ICE

LOAD

(KN

/m2

)

4 NOS 9.3mm 2 NOS 9.3mm + 2 NOS 12.5 mm 4 NOS 12.5mm 5 NOS 12.5mm 2 NOS 9.3mm

4 NOS 9.3mm 11.7 8.72 6.6 5.03 3.83 2.9 2.16

2 NOS 9.3mm + 2 NOS 12.5 mm 17.03 12.94 10.01 7.85 6.2 4.92 3.9 3.08 2.41

4 NOS 12.5mm 17.51 15.08 13.18 10.57 8.48 6.87 5.58 4.55 3.46 2.38

5 NOS 12.5mm 18.39 15.85 13.86 12.27 10.83 8.86 7.3 6.04 4.65 3.41

2 NOS 9.3mm + 5 NOS 12.5mm 19.54 16.87 14.77 13.09 11.7 10.13 8.4 7.01 5.86 4.52

7 NOS 12.5mm 19.83 17.12 15 13.29 11.89 10.71 9.15 7.66 6.44 5.39

4 4.5 5 5.5 6 6.5 7 7.5 8 8.5

SLAB PROPERTIES:


-JOINTED SLAB WEIGHT = 2.63 KN/m2

-CONCRETE GRADE C50

-FIRE RATE REI60



-NOMINAL WIDTH OF SLAB= 1200 mm


-DIAMTERE OF ONE VOID = 155 mm


..STRESS = 1860 N/mm2


CURVES ARE CALCULATED USING BS8110 CODE-Maximum service design load(qsls) in excess of slab weight in KN

FOR GUIDANCE ONLY ALLOWABLE SERVICE TOTAL LOADS FOR DIFFERENT SL


HCS-200mm-For higher slab capacity concretec provide Concrete Grade 60 and different Void profi

-This curves is based on 1 hour fire rate and it may be change according to every proj


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SPAN (METER)

SERVICELOADS(KN/m2)

4 NOS 9.3 mm 2 NOS 9.3mm + 2 NOS 12.5mm 4 NOS. 12.5 mm 6 NOS 12.5

4 NOS 9.3 mm 16.36 12.18 9.19 6.97 5.29 3.98 2.94 2.1 1.42

2 NOS 9.3mm + 2 NOS 12.5mm 22.34 18.18 14.05 10.99 8.67 6.86 5.42 4.26 3.31 2.53 1.87

4 NOS. 12.5 mm 23.06 19.75 17.17 14.93 11.98 9.68 7.86 6.38 5.18 4.18 3.34 2.64 2.03

6 NOS 12.5 mm 24.84 21.31 18.56 16.36 14.56 13.05 11.78 10.53 9.24 7.78 6.55 5.52 4.63 3.63

8 NOS 12.5 mm 26.55 22.81 19.9 17.56 15.65 14.06 12.71 11.55 10.55 9.67 8.89 8.21 7.09 5.72

10 NOS 12.5 27.97 24.05 21 18.55 16.55 14.89 13.47 12.26 11.21 10.29 9.48 8.76 8.12 7.42

4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5

CURVES ARE CALCULATED USING BS8110 CODE-Maximum service design load(qsls) in excess of slab weight

SLAB PROPERTIES:


-JOINTED SLAB WEIGHT = 3.82 KN/m2

-CONCRETE GRADE C50

-FIRE RATE REI60





-DIAMTERE OF ONE VOID = 185 mm-PRESTRESSING STEEL YIELDING



FOR GUIDANCE ONLY


HCS-265mm

ALLOWABLESERVICE TOTAL LOADS FOR DIFFERENT SLA

-For higher slab capacity concretec provide Concrete Grade 60 and different Void profil

-This curves is based on 1 hour fire rate and it may be change according to every proje


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5

10

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25

30

35

SPAN (METER)

SER

VICE

LOADS

(KN

/m2

)


5 NOS 12.5 mm 26.54 20.26 13.87 9.72 6.88 4.85

7 NOS 12.5mm 28.36 22.63 18.64 14.78 10.87 8.08

8 NOS 12.5mm 29.15 23.28 19.19 16.17 12.77 9.62 7.29

9 NOS 12.5 mm 29.87 23.87 19.69 16.61 14.24 11.06 8.48

10 NOS 12.5mm 30.53 24.41 20.15 17 14.59 12.4 9.59

11 NOS 12.5mm 31.12 24.9 20.57 17.37 14.91 12.97 10.3

5 6 7 8 9 10 11

SLAB PROPERTIES:


-JOINTED SLAB WEIGHT =3.87 KN/m2

-CONCRETE GRADE C50

-FIRE RATE REI60



-NOMINAL WIDTH OF SLAB= 1200 mm-NO. OF VOIDS =4 VOIDS




-Maximum service design load(qsls) in excess of slab weight in KN/mCURVES ARE CALCULATED USING BS8110 CODE


HCS-320mm

FOR GUIDANCE ONLYALLOWABLE SERVICE TOTAL LOADS FO

-For higher slab capacity concretec provide Concrete Grade 60 and different Void pr

-This curves is based on 1 hour fire rate and it may be change according to every p


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5

10

15

20

25

SPAN (METER)

SER

VICE

LOADS

(KN

/m2

)


5 NOS 12.5 mm 13.02 9.35 6.72 4.78 3.3 2.15

7 NOS 12.5mm 19.72 14.64 11.01 8.32 6.28 4.69 3.16

9 NOS 12.5mm 21.37 18.36 15.05 11.66 9.08 7.08 5.03

11 NOS 12.5 mm 22.4 19.27 16.78 14.46 11.44 9.09 6.88

13 NOS 12.5mm 23.28 20.04 17.48 15.41 12.82 10.27 8.25

14 NOS 12.5mm 23.67 20.39 17.79 15.69 13.47 10.83 8.73

8 9 10 11 12 13 14

CURVES ARE CALCULATED USING BS8110 CODE -Maximum service design load(qsls) in excess of slab weight in KN/m2

SLAB PROPERTIES:



-CONCRETE GRADE C50

-FIRE RATE REI60




-NO. OF VOIDS =4 VOIDS





HCS-400mm

FOR GUIDANCE ONLY

-For higher slab capacity concretec provide Concrete Grade 60 and different Void pro

-This curves is based on 1 hour fire rate and it may be change according to every pr


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5

10

15

20

25

30

35

SPAN (METER)

SER

VICE

LOADS

(KN

/m2

)


6 NOS 12.5 mm 11.42 8.44 6.18 4.41 3.01 1.89

8 NOS 12.5mm 16.93 12.99 10 7.67 5.83 4.33 3.11

10 NOS 12.5mm 22.2 17.35 13.66 10.79 8.51 6.68 5.17

13 NOS 12.5 mm 28.25 23.36 18.72 15.1 12.23 9.92 8.02

17 NOS 12.5mm 29.82 26.27 21.31 17.32 14.16 11.63 9.52

11 NOS 12.5mm 30.6 27.17 23.17 18.91 15.53 12.8 10.57

10 11 12 13 14 15 16

SLAB PROPERTIES:



-CONCRETE GRADE C50

-FIRE RATE REI60




-NO. OF VOIDS =4 VOIDS




CURVES ARE CALCULATED USING BS8110 CODE-Maximum service design load(qsls) in excess of slab weight in KN/m2


HCS-500mm

For higher slab capacities concretec provide Concrete

Grade 60 and different Void profiles for higher capacities

FOR GUIDANCE ONLY ALLOWABLE SERVICE TOTAL LOADS FO

-For higher slab capacity concretec provide Concrete Grade 60 and different Void pro

-This curves is based on 1 hour fire rate and it may be change according to every pr


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6-STRUCTURAL TOPPIN G

Hollow core slab are normally used without structural topping. However, in the case of seismicaction, frequent changes of load or important point loads, topping may be indicated.

The thickness should be at least 50 mm, concrete quality C40. The hollow core slab and thetopping will act as a composite slab and the moment capacity of the hollow core slabs can beenhanced.

FIGURE (3)SHOWING STRUCTURAL TOPPING AND REINFORCEMENT MESH

7- Diaphragm action

The diaphragm action of hollow core slab is realized through a good joint design to transfer ofhorizontal forces to the main structure system.The peripheral reinforcement plays a determinate role not only to cop with the tensile forces ofthe diaphragm action but also to prevent the relative horizontal displacement of the hollow coreunits, so that the longitudinal joints can take up shear forces.The positioning and minimum proportioning ties, required by PCI codes, is shown in the figurebelow.

FIGURE (4)SHOWING DIAPHRAGM ACTION

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8-OPenings

Opening in hollow core slabs are made as indicated in the figure. The dimensions are limit to thevalues given in the table. The small holes may be formed at the center of the longitudinal voids.The maximum void size is limited to the width of the void.

Holes are normally made in the fresh concrete during the production process.The edges of the opening are rough. The possible dimensions for openings are given in the table.

L / B HCS 150-265

Corner (1)Front (2)Edges (3)

600/400600/4001000/400

Center (4)Square openingRound holes

100/400core minus 20 mm

Voids, which are wider than the width of the precast, are trimmed using transverse supports such

as steel angles or concrete beams. The steel angles can be supplied in case of client request.

FIGURE (5)SHOWING LARGE OPENING

FIGURE (6)SHOWING ALLOWABLE CUT OUT IN HOLLOW CORE SLAB

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9--Bearing length

The nominal bearing length of simply supported hollow core slab is give in

Support length (a)Supporting material Slab thickness

Nominal

length

Minimum

effectivelength

Concrete or steel 150mm - 265 mm 70 mm 50 mm

BrickMasonry

150mm - 265 mm 100 mm 80 mm

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10-Connection details

1PAGE 9

CONNECTION BETWEEN HOLLOW CORE SLAB

AND PRECAST WALL RESTED ON IT

CONNECTION BETWEEN CANTILIVER HOLLOW CORE SLAB

AND PRECAST WALL

SECTION SHOWING REINFORCEMENT IN JOINTS

BETWEEN TWO ADJACENT HOLLOW CORE SLABS

SECTION SHOWING CONNECTION BETWEEN

HOLLOW CORE SLAB AND PRECAST BEAM


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11-Storage and transportation

11-1-Storage

When storing hollow core slabs the following requirements should be taken into consideration:

-Storage should only be permitted on solid ground forming a level footing.

-Slab stacks are recommended to be a maximum of 3.50 5.00 m high depending on the slabtype.Only slabs of the same length and with no large recesses should be stacked together and directlyon top of each other.

FIGURE (7)

FIGURE (8)

Hollow cores storage-Wooden spacers should be used. All spacers should be stacked exactly on top of each other .seefig.( 4 , 5 )

-Special care should be given to slab with large openings.They must be stored in separate piles with only some 2-3 slabs on top of each other.The overhanging length beyond spacers should be between 200mm-400mm in normal practiceand a maximum of 1000mm, when top reinforcement is used. All damage caused to slab in thestockyard should be reported to the quality control staff.

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-Transportation

The hollow core slabs are hoisted with specially designed clamps hanging on a steel spreaderbeams. The use of ailing alone is strictly forbidden.

Hollow core slab are transporting from our factory to the site on flat bed trailers.

Full slabs are lifted using the specially designed lifting equipments (as shown).

- flat bed trailer Used for transportation- Lifting Equipments

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-Erection

The erection of hollow core slab should be done according to the instructions of concrete.Technologys

design engineers If needed concrete technology will provide

method of statements of the principles of site erection.After erection the longitudinal joints

between the hollow core slab should b filled with grout,the joint should be filled carefully since they fulfill

a structural function bothin the transversal load distributionand the horizontal floor diaphragm action.

When a structural topping is to be used, it is advisable to fill the longitudinal point, Immediately prior to the

casting of the topping.

-Fixing

There are several ways of fixing hanging loads to the hollow core slabs for example, specialsockets drilled into the voids, anchors placed into the longitudinal joint or the top of the slab.

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hollow core design

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