Flat Slab Stahlton

7/28/2019 Flat Slab Stahlton

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Flat Slab


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Contents

2www.stahlton.co.nz

Flat Slab is ideal for short span floors which are

subjected to uniformly distributed loads, and is used

extensively in residential buildings as well as incertain areas of commercial buildings. Flat Slab can

also be used for cantilever balconies as permanent

formwork. Flat Slab is manufactured using a wet

pour process, poured onto a long heated steel bed.

This manufacturing process allows the product to be

poured to any achievable design length and shape,

making Flat Slab versatile and flexible to use on

building sites.

Introduction & Contents

Architects

General1.0 Acoustic Rating1.1 Durability1.2 Thermal Rating1.3 Fire Rating

Consulting Engineers2.0 Loadings2.1 End Seating2.2 Topping2.3 Design Weight Including Topping Concrete

Contractors3.0 Temporary Propping

3.1 Camber3.2 Handling & Storage3.3 Penetrations & Fixings

Specifications4.0 Drawing Call-up4.1 Written Specification Clauses

Specifications4.1 Written Specification Clauses

Key Plan

Flat Slab Sections 1 & 2

Flat Slab Sections 3 & 4

Flat Slab Sections 5 & 6Flat Slab Sections 7 & 8

Flat Slab Section 9

Fixings to Flat Slab

Camber Allowances, Support & Handling

75 & 100 Flat Slab

125 & 150 Flat Slab

Load Span Graph 75 Flat Slab




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General

Stahlton Engineered Concrete supplies Flat Slab to any location inNew Zealand. Four standard depths of Flat Slab are available including

75mm, 100mm, 125mm and 150mm deep by 1200mm wide in

dimension. In some areas we can supply 2400mm wide units, please

check with your local plant to see if this option is available in your

region.

1.0 Acoustic Rating

The Stahlton Engineered Concrete Flat Slab, with a minimum 75mm

depth of topping, will provide a Standard Transmission Class (STC)

rating of 55dB.

1.1 Durability

Stahlton Flat Slab slabs meet exposure classifications A1, A2, B1 & B2

as per table 3.6 in NZS 3101:Part 1:2006 for a 50 year life.

1.2 Thermal Rating

Estimated thermal ratings (R) for Stahlton Flat Slab with 75mm deeptopping are:

75mm 0.10m2 oC/W

100mm 0.12m2 oC/W

125mm 0.14m2 oC/W

150mm 0.16m2 oC/W

These values are a guide only; if fur ther information is required please

contact the Stahlton Engineered Concrete Technical Department .

1.3 Fire RatingAll Stahlton Flat Slab floors with a minimum of 75mm of on site topping

have a 60 minute Fire Resistance Rating (FRR). Refer NZS 3101:Part1:2006

table 4.3 & 4.4 for one-way slabs. Increased FRR can be achieved in

some circumstances; please contact the Stahlton Technical Department

if you wish to discuss further. Any penetrations through the Stahlton Flat

Slab floors must also be fire rated, see page13. Advice should be sought

from the fire protection suppliers regarding suitability of their tested

products with the Flat Slab floor systems.

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Architects

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Consulting Engineers

4www.stahlton.co.nz

2.0 Loadings

Generally common loadings used on residential, office and apartmentbuildings are suitable for Stahlton Engineered Concrete Flat Slab

flooring systems. The Load Span graphs (pages 18-21) assume that

there is maximum strand, the flooring may be temporarily propped,

the floor is simply supported and that loads are uniformly distributed.

Load factors of 1.2G and 1.5Q as per AS/NZS 1170.1 have been allowed

for in the design analysis. Simply compare your factored superimposed

dead and live loads with the allowable shown on the graph i.e. if your

project has G=0.5kPa & Q=3.0kPa, factor accordingly 1.2x0.5 + 1 .5x3.0 =

5.1kPa. Compare this figure with that shown on the y-axis of the load

span graph. Please note high dead loads may induce higher creep

values than expected and advice should be sought from the Stahlton

Engineered Concrete Technical Team for unusual cases.

Flat Slab floors can sustain point loads and line loads. However

significant loadings should be checked by one of the Stahlton

Engineers at the preliminary design stage.

2.1 End Seating

All Stahlton Flat Slab flooring requires a minimum of 75mm or span/180,

whichever is greater, seating onto walls or beams. 15mm of construction

tolerance needs to be added to both of these figures if sitting on an

unarmoured concrete beam. If seating onto a steel beam or armoured

edge concrete beam, 60mm of seating plus 15mm of tolerance is

required. Stahlton Engineered Concrete recommends the use of low

friction bearing strips for Flat Slab. Please refer to NZS 3101 cl 18.7.4B.

Note solid slabs refers to Flat Slab units used in residential applications

and less seating is acceptable if only residential loadings are used.

2.2 Topping

The topping concrete strength should be specified as a minimum of25MPa as per NZS 3101:2006 cl 5.2.1 . The minimum topping depth for

Stahlton Flat Slab at midspan is 75mm. Additional topping depth will

usually be required feathered out to the ends of the units to allow

for an even finished floor level. Floor reinforcement and saddle bars

should be designed and shown on the Consulting Engineers drawings.

Steps in the topping can be formed using suitable density polystyrene,

however the extra topping thickness needs to be accounted for as a

gravity load and allowed for in the design.

Care should be taken when pouring topping not to mound up the

concrete in one place as this can produce large point loads. The

mounding of in situ concrete should not exceed the constructionloadings the units are designed to sustain.

2.3 Design Weight Including Topping Concrete

The following figures are based on the average cross-section for each

product.

Topping Depth of 75mm (1.8kPa) has been allowed

Depth (mm) Design Weight (kPa)

75 3.7

100 4.3

125 5.0

150 5.6


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3.0 Temporary Propping

Temporary propping may be required for Stahlton Flat Slab to increasebottom fibre stress capacity or to even out camber variations in the

flooring soffit .

The natural variations in precamber expected in prestressed members

can be minimized by the use of propping. Under standard uniformly

distributed loadings temporary propping would be expected for spans

exceeding 2.5m, 4m, 5m and 6m for 75mm 100mm, 125mm, and 150mm

deep Stahlton Flat Slab units respectively. A suitably qualified Engineer

will need to be consulted for the design of the propping system.

3.1 Camber

Stahlton Flat Slab units will arrive at site with some positive camber

(hog). This is unavoidable due to the nature of prestressing. The

amount of hog will depend on a number of factors including, amount

of prestress, how long the units have been exposed to the sun and

length of unit to name but a few variables. As a rule of thumb allow

2-3mm of hog for every 1m of span. Generally half of the hog of the

Flat Slab unit will come down after the topping concrete is poured and

any propping is removed. Half of the remaining hog will eventually

come out over time due to creep and shrinkage.

3.2 Handling & StorageStahlton Flat Slab is designed to be lifted at the ends. Specifically

designed lifting chains and hooks or lifting clutches can be used to lift

the units. The Flat Slab unit will arrive on site with provision for hooks

or lifting clutches. These anchoring points should be used without

substitution. All lifting gear should be checked for any wear or damage

regularly as concrete elements can be abrasive.

Stahlton Flat Slab units if stored on site need to be dunnaged near the

lifting points. The dunnage blocks need to be aligned on top of each

other so as not to induce large point loads on the units below.

If props are indicated on the shop drawings, the Flat Slab units will

need dunnaging at these propping locations as well. Care needs to

be taken as to the suitability of the ground the units are stored onand should be checked by a suitably qualified Engineer.

Handling weights for Stahlton Flat Slab are:

1.2m wide 2.4m wide

Depth (mm) kg/m kg/m

75 232 464

100 309 618

125 386 772

150 463 926

3.3 Penetrations & Fixings

Stahlton Flat Slab units can have penetrations core drilled through the

unit in specific locations (see sheet 14). No more than one penetration

per 750mm of span or width of the unit is permitted, as too many

holes will reduce the load capacity of the Flat Slab unit . The area of

concrete around the strand must be avoided altogether. If a strand is

cut onsite, temporary prop either side of the penetration immediately,

then contact Stahlton Engineered Concrete as a design check will

need to be done to ascertain whether the unit is still structurally

sound.

Advice should be sort from the fixing manufacturer as to the

suitability and load carrying capacity of their products in Stahlton

Engineered Concrete Flat Slab.

Units can be designed with additional prestressing tendons to allow

for cutting of occasional tendons, however this needs to be thought

about at the start of the project and built into the design before the

units are cast, bearing in mind that extra strand could induce more

hog in the slab.

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Contractors

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Specifications

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4.0 Drawing Call-Up:

To specify the Stahlton Flat Slab system on your drawings we suggestyou use the following designation;

Stahlton depth Flat Slab with 75mm topping

For example if the project is to be made from 100mm deep Stahlton

Flat Slab with a 75mm deep topping; then the specification would read:

Stahlton 100 Flat Slab with 75mm topping

If Stahlton 75mm deep Flat Slab with 90mm topping is desired then;

Stahlton 75 Flat Slab with 90mm topping

4.1 Written Specification Clauses:Stahlton Flat Slab products in general comply with the following

standards:

NZS 3101:2006 Concrete Structures Standard Part 1 & 2

NZS 3109:1997 Concrete Construction

AS/NZS 4671:2001 Steel Reinforcing Materials

BS 5896:1980 Specification for High Tensile Steel Wire and Standard for

the Prestressing of Concrete

Design(i) The design of Stahlton Flat Slab shall be in accordance with the

requirements and recommendations of NZS 3101:2006 Concrete Structures

Standard Part 1 & 2 and or any recognized international Standard or par t

thereof, for example BS 8110:2007 The Structural Use of Concrete.

(ii) The prestress strand pattern in the Stahlton Flat Slab shall be designed

to sustain the loadings shown on the Consulting Engineers drawings and

allowance will be made for self weight of the unit and topping concrete.

(iii) The Stahlton Flat Slab shall be designed for exposure classification

A1/A2/B1/B2 as per table 3.6 in NZS 3101:2006.

(iv)The Stahlton Flat Slab unit shall have a FRR (Fire Resisting Rating) of60/60/60. Penetrations through the flooring system shall be reinstated to

the required FRR by an approved fire protection system.

(v) Stahlton Flat Slab shall be designed to have a maximum crack width

of 0.3mm under full live load conditions.

(vi) The acoustic STC (Sound Transmission Class) and IIC rating of the floor

system shall meet or exceed 55dB as tested at a registered institution or a

field test of 50dB measured in on-site conditions. These ratings apply to

the finished floor system, including any carpeting and suspended ceiling

systems.

(vii) The Stahlton Flat Slab units shall have a minimum of 75mm end

seating or L/180, whichever is greater, as per clause 18.7.4 in NZS 3101:2006

plus tolerance of 15mm if seated on an unarmoured concrete beam.

Materials

(i) Concrete shall be specifically mixed depending on environmentalconditions and should have a 28 day cylinder strength of 45MPa as a

minimum.

(ii) All concrete shall show signs of thorough compaction otherwise

rejected if repair cannot be undertaken to bring the unit back to the

original specification.

(iii) An air entraining agent complying with BS EN 934-2-2001 may be

included in the concrete mix to improve workability.

(iv)The strand reinforcement used in Stahlton Flat Slab shall be 9.6mm,

11.3mm, 12. 7mm or 12.9mm diameter complying with the requirements of

AS/NZS 4671:2001

(v) Prestressing strand shall be clean and free from deleterious

substances. Superficial rust is acceptable, however strand with corrosion

that has caused surface pitting shall be rejected for the main longitudinal

reinforcement of the unit .

Manufacture

(i) Materials, execution of stressing prestress strand and workmanship

of the Stahlton Flat Slab units shall conform with Stahlton Engineered

Concrete ISO 9001 Quality Assurance Operating Procedures

(ii) Stahlton Flat Slab units shall be nominally 1200mm wide (or 24000mmdepending on manufacturing plant) and made from the nominal depth;

75mm, 100mm, 125mm or 150mm

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Specifications

(iii) The top surface of the Stahlton Flat Slab unit shall have a nominal

roughness of 5mm or more as stipulated in NZS3101:2006 clause 18.5.4.1(a)

(iv) The tolerance for length of the Stahlton Flat Slab units shall be in

accordance with NZS 3109 (usually +/- 10mm).

Handling, Protection & Placing Units

(i) The Stahlton Flat Slab units shall to be designed to sustain all lifting

stresses.

(ii) The Stahlton Flat Slab shall be lif ted only at the lif ting position as

nominated by the manufacturer.

(iii) Stahlton Flat Slab units shall be handled using certified lifting hooks

or clutches. Chain angles must not exceed 30 degrees to the vertical and

must be checked regularly for wear and tear.

(iv) Dunnage used for storing the Stahlton Flat Slab units needs to be of

suitable quality and placed on good ground at the correct points in f rom

the end of the units.

(v) Where units are stacked one above the other, bearing dunnage shall

be positioned in vertical lines.

(vi) The Stahlton Flat Slab shall be handled and placed according to

references contained in the Occupational Safety & Health approved code

of practice entitled Safe Handling, Transportation and Erection of Precast

Concrete

(vii) The units shall not be damaged in any way including chips and

cracks during the erection and placing phase. Any damage should be

bought to the at tention of the supervising Engineer immediately.

Temporary Propping

(i) Design of temporary propping, back propping, bracing systems and

ground conditions to support prop loads shall be carried out by a suitably

qualified Engineer.

(ii) Propping shall not be removed until the topping concrete has reached

at least 75% of the 28 day strength.

(iii) It is the Contractors responsibility to ensure the propping system used

on site meets the criteria as detailed in the aforementioned design and

any additional requirements shown on the Stahlton Engineered Concrete

drawings.

(iv) All proposed systems with supporting calculations shall be submitted

to the Specifying Engineer prior to erection on site for approval.

Topping Concrete

(i) The top surface of the Stahlton Flat Slab units shall be clean and f ree

of all dust, oil or any deleterious substances which may adversely affect

the wet topping bond to the Stahlton Flat Slab units.

(ii) Prewet precast concrete surfaces prior to placing the topping concrete.

(iii) Free water shall be broomed away before the topping is applied.

(iv) Topping reinforcement shall be laid and supported to the Specifying

Engineers requirements and shall be supported to prevent displacement

during concreting.

(v) Topping concrete shall have a minimum aggregate size of ____

(normally 13mm) and a 28 day strength of ____ (minimum of 25MPa) and

be well compacted with mechanical vibrators.

(vi) Topping concrete shall be poured to a true surface so that the

specified thickness of ____ (minimum of 75mm) is achieved at the centre

of the span.

(vii) In-situ concrete shall be cured by the application of an approved

curing membrane or by being kept continuously wet for not less than

seven days.

Fixings & Penetrations

(i) Fixing to the Stahlton Flat Slab units shall be in accordance with the

approved details only and shall not impair or reduce the strength of the

unit in any way.

(ii) Documentation of tested fixings proposed for the project shall be

submitted to the Specifying Engineer prior to installation.

(iii) Penetrations, setdowns or chases to the Stahlton Flat Slab unit or

topping concrete shall be in accordance with the details agreed by the

Specifying Engineer and Stahlton Engineered Concrete prior to any work

being undertaken on site.

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Key Plan Scale: NTS

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Section 2 Scale: NTS



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Fixings to Flat Slab Scale: NTS

Fixings to Flat Slab Scale: NTS


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Handling Scale: NTS

Support Scale: NTS

Camber (hog) Allowances Scale: NTS


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100 Flat Slab Scale: NTS



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18

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0800 STAHLTON | www.stahlton.co.nz

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