Technical Manual. The difference is.

Transcription

1 Technical Manual The difference is

2 innovation, commitment, support. 2

3 For a service with a difference, choose Richard Lees Steel Decking, the UK specialist steel decking company with a 50 year history of innovation in structural flooring products. In fact, ours is a service which has delivered results worldwide, with major projects in over 30 countries, including some of the world s most prestigious buildings. A commitment to excellence drives every aspect of our work, from the innovation that has seen us introduce a number of firsts, to producing top quality products. Perhaps that s why Holorib has become the generic term for steel decking in the UK and consistently outsells any other profile in the UK range. Based on our extensive experience of working at height, we ve even created our own safety net division. On-going development partnerships to create new products and services have introduced the Resotec vibration damping system and synthetic fibre reinforced concrete to the UK market. This is a service that s as complete as it is reassuring; with all the support you need from initial advice to complete installation. The difference is Richard Lees Steel Decking 3

4 Advantages of steel decking: Steel decking acts as permanent or lost shuttering for suspended in situ concrete floor or roof slabs in new or refurbished buildings. On most projects, it will act as all, or part, of the tensile bottom reinforcement for the concrete slabs, hence the term composite. The use of steel decking is especially suitable for fast construction methods. Quick to install, simple, and an ideal complement to steel framed structures make steel decking ideal for both high and low rise buildings. Steel decking is also used to speed up and simplify the construction of brickwork, blockwork and concrete framed buildings. Up to 4 hours fire resistance with exposed soffit can be designed. Composite construction reduces steelwork frame weight. Lower dead load reduces frame and foundation loading. Stiffens steelwork supporting frame. Cover for following trades. Provides a safe working platform. Easily cut and fitted to awkward shapes. Minimal site storage requirements. Needs no (or minimal) propping. Ceilings and services can be easily suspended using standard fixings. 4

5 Contents Steel decking product range page 6 Section properties and notes to tables page 7 Resotec page 16 Fibre reinforced concrete page 18 Guidelines for concrete producers page 26 Shaping the London skyline page 28 Architectural impact across the UK page 34 Guidance notes for design and fixing page 38 Deckspan design software page 46 5

6 Steel Decking Product Range the original: Holorib less concrete Ribdeck E60 longer spans Ribdeck 80 shallow slabs efficient designs Ribdeck AL Holorib Re-entrant profile. Available in the UK since The UK s most widely specified steel decking profile. Simple to detail and install. Virtually continuous plain soffit finish. Excellent load carrying capacity on the finished slab. Use Holorib for its great versatility and strength. Ribdeck 80 Trapezoidal profile. Longer unpropped spans. Excellent bond to the concrete for greater load carrying capacity. Use Ribdeck 80 to reduce the number of steel members in a frame. Ribdeck E60 Trapezoidal profile. Fast to install 1.0m cover width. Designed to minimise concrete volume. Use Ribdeck E60 to reduce the overall cost of a floor slab. Ribdeck AL Trapezoidal profile. Shallowest slabs to satisfy fire insulation requirements. Use Ribdeck AL to minimise ribbed soffit slab depth. Registered trademarks: Ribdeck and Deskspan are registered trademarks throughout Europe. Holorib is a registered trademark in the UK, ROI, Gibraltar, Norway and Sweden and Superib (the same profile as Holorib) is registered in all other Western European countries. 6

7 Section properties and notes to tables Holorib Section Dimensions Standard soffit fixings Ribdeck E60 Section Dimensions Standard soffit fixings Holorib Section Properties (per metre width) Gauge Self Weight Area Inertia YNA mm kg/m 2 kn/m 2 mm 2 cm 4 mm , , , Concrete volume figures in the span/load tables that follow are based on constant slab thickness. To take account of deflection of the decking profile it is recommended that the volume of concrete will equate to: Overall slab depth 9mm for voids + span/250. An additional allowance may also be required to allow for deflections within the supporting structure (refer to building design engineer). Ribdeck E60 Section Properties (per metre width) Gauge Self Weight Area Inertia YNA mm kg/m 2 kn/m 2 mm 2 cm 4 mm , , , Concrete volume figures in the span/load tables that follow are based on constant slab thickness. To take account of deflection of the decking profile it is recommended that the volume of concrete will equate to: Overall slab depth 36mm for voids + span/250. An additional allowance may also be required to allow for deflections within the supporting structure (refer to building design engineer). Ribdeck 80 Section Dimensions Standard soffit fixings Ribdeck 80 Section Properties (per metre width) Gauge Self Weight Area Inertia YNA mm kg/m 2 kn/m 2 mm 2 cm 4 mm , , , Concrete volume figures in the span/load tables that follow are based on constant slab thickness. To take account of deflection of the decking profile it is recommended that the volume of concrete will equate to: Overall slab depth 42mm for voids + span/250. An additional allowance may also be required to allow for deflections within the supporting structure (refer to building design engineer). Ribdeck AL Section Dimensions Standard soffit fixings Ribdeck AL Section Properties (per metre width) Gauge Self Weight Area Inertia YNA mm kg/m 2 kn/m 2 mm 2 cm 4 mm , , , Concrete volume figures in the span/load tables that follow are based on constant slab thickness. To take account of deflection of the decking profile it is recommended that the volume of concrete will equate to: Overall slab depth 25mm for voids + span/250. An additional allowance may also be required to allow for deflections within the supporting structure (refer to building design engineer). In pages 8-15 The performance of each product is given in terms of span/load and simplified fire design tables. Span/load tables 1. Spans shown assume clear span +100mm to the centreline of supports. 2. Designs are fully in accordance with BS 5950: Parts 4 & The dead weight of the slab has been included in the development of the spans shown. However, consideration should be given to finishes, partitions, walls, etc. when reading from the table. 4. Based upon concrete densities at wet stage: normal weight concrete 2400 kg/m 3, lightweight concrete 1900 kg/m A span to depth ratio limit of 35:1 for normal weight concrete and 30:1 for lightweight concrete is generally used. Where isolated single spans occur, these should be reduced to 30:1 and 25:1 respectively. 6. Maximum deflection in the direction of span of the decking is limited to span/130 after taking account of ponding. Simplified fire design tables 1. Tables are applicable for any construction where the mesh may act in tension over a supporting beam or wall (negative bending). This includes end bay conditions i.e. the concrete slab is continuous over more than one span. 2. Loads shown are unfactored working loads and should include all imposed live and dead loads, excluding only the self-weight of the slab. 3. An ultimate load factor of 1.0 is assumed throughout indicates that the area of mesh is less than the minimum for crack control recommended in BS5950: Part 4 7. Construction stage design includes an allowance of 1.5kN/m 2 for construction loading. 8. Composite slabs are designed as simply supported irrespective of the deck support configuration. A minimum crack control and distribution mesh is required in accordance with clauses 6.7, 6.8 and 6.9 of BS5950: Part 4. Alternatively the use of synthetic fibre reinforcement may be deemed acceptable after reference to the relevant design tables and consultation with the structural design engineers. 9. S350 decking is manufactured from material meeting the specification: BS EN S350GD+Z275-N-A-C. It has guaranteed minimum yield strength of 350 N/mm Mesh should satisfy the minimum elongation requirement given in BS4449: For conditions outside the scope of the simplified tables, including all isolated spans, consult SCI publication 56 (2nd edition) or RLSD s Deckspan software. 7. Tables are based on the thinnest gauge of decking available in each product range. Improved performance with thicker gauges may be checked for using RLSD s Deckspan software. 7

8 Holorib - Normal weight concrete Span/load table Normal weight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Normal weight concrete Normal weight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 (mm) Refer to page 7 for notes on the use of these tables the original: Holorib 8

9 Holorib - Lightweight concrete Span/load table Lightweight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Lightweight concrete Lightweight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 (mm) Refer to page 7 for notes on the use of these tables 9

10 Ribdeck E60 - Normal weight concrete Span/load table Normal weight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Normal weight concrete Normal weight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 (mm) Refer to page 7 for notes on the use of these tables less concrete Ribdeck E60 10

11 Ribdeck E60 - Lightweight concrete Span/load table Lightweight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Lightweight concrete Lightweight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 (mm) Refer to page 7 for notes on the use of these tables 11

12 Ribdeck 80 - Normal weight concrete Span/load table Normal weight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Normal weight concrete Normal weight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 A393 (mm) Refer to page 7 for notes on the use of these tables longer spans Ribdeck 80 12

13 Ribdeck 80 - Lightweight concrete Span/load table Lightweight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Lightweight concrete Normal weight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 A393 (mm) Refer to page 7 for notes on the use of these tables 13

14 Ribdeck AL - Normal weight concrete Span/load table Normal weight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Normal weight concrete Normal weight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 (mm) Refer to page 7 for notes on the use of these tables shallow slabs efficient designs Ribdeck AL 14

15 Ribdeck AL - Lightweight concrete Span/load table Lightweight concrete Single - Unpropped Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) FW FW FW Simplified fire design table Lightweight concrete Lightweight concrete Fire Rating Slab Span (m) for given Imposed Load (kn/m 2 ) (Hrs) Depth A142 A193 A252 (mm) Refer to page 7 for notes on the use of these tables 15

16 Resotec is an innovative way to design footfall vibration damping into a building. In the past a great emphasis has been put on countering vibrations through the provision of mass in the structure but with Resotec the building can remain lightweight whilst still benefiting from a low design response factor. 16

17 What is it? Resotec is a thin constrained layer damping membrane that sits between the soffit of the steel decking and parts of the top flange of the steel beams. In these zones there is no mechanical connection between the floor and the supporting structure, allowing the two to move independently under the influence of vibration induced excitation. Where does it go? For maximum effectiveness the Resotec strips are installed on the top flange of a steel beam, extending from each end for approximately one quarter of the length towards the middle of the span. Steel decking can then be laid over the top of the Resotec but it should not be secured down to the beams in any way. Instead fixity is achieved by side lapping and stitching together the sheets to form one continuous membrane. Composite beams In a traditional secondary beam design the shear studs are evenly spaced along the length of the beam. With a Resotec layer installed there can be no shear studs in the outer quarter portion of the beam so a new approach is needed. The result is a 50% partially composite beam design which is illustrated in the Bending Moment diagram. Shear studs are installed in the middle section of the beam and the design allows for partial interaction between the beam and the slab to be developed in this zone only. The bending and shear resistance of the structure in the outer quarter regions of the beam is that of the steel section alone with no composite interaction with the slab. Design assistance Engineers are encouraged to consider the use of Resotec when designing large column free floor areas with lightweight long span beams. Because of the effects Resotec has on the placement of shear studs and the design of the supporting structure it is seldom possible to incorporate Resotec as a last minute solution to a footfall vibration issue. Engineers are therefore encouraged to consider Resotec in the early stages of a building design. Assistance for doing this can be obtained through the use of COMPOS, part of the OASYS suite of structural design programmes, or through contacting Richard Lees Steel Decking. X 50% partially composite beam: BM capacity and demand Strength provided in 100% composite design Effect with Resotec Partially composite Moment (Nm) Beam strength Strength required Length (m) 17

18 Fibre Reinforced Concrete Traditional composite floor slab design makes use of the decking profile to act as tensile reinforcement in the bottom of the slab. It also includes a layer of welded wire fabric in the top of the slab to control cracks, distribute loads around minor openings, resist horizontal shear forces, and to provide continuity over supports in the fire limit state. In many design cases synthetic macro fibre reinforcement can be used to replace the fabric layer and provide added benefits associated with simplicity and speed of construction. STRUX 90/40 fibre reinforcement STRUX 90/40 synthetic structural fibres are marketed by Grace Construction Products Limited and have been used extensively in ground slabs for a number of years. The fibres are 40 mm long with an aspect ratio of 90, giving high strength with a high modulus. They have been designed to provide tight crack control whilst exhibiting excellent dispersion and pumpability characteristics. STRUX 90/40 synthetic structural fibres offer a quick, easy and safe option for providing secondary reinforcement to a composite floor slab. Application In collaboration with Grace Construction Products Limited, Richard Lees Steel Decking have researched and developed a system whereby much of the steel reinforcement in a composite floor slab can be replaced by fibres in the concrete mix. The development of this system required full scale testing of structural floor slabs and the results are therefore only applicable to the unique combinations of decking profile, fibre and fibre dosage tested. The test programme was developed in conjunction with the Steel Construction Institute (SCI) and the results processed by them to produce the design guidance given here. In the pages that follow design information is given for the use of Holorib, Ribdeck E60, Ribdeck 80 and Ribdeck AL with STRUX 90/40 synthetic structural fibres at a dosage of 5.3 kg/m 3 of concrete. These products cannot be substituted with other types of decking or fibres based on the information published here. 18

19 Principal Benefits Extensive testing, specified and verified by the Steel Construction Institute, has shown that STRUX 90/40 can be an ideal replacement for steel fabric reinforcement in steel composite decks designed and supplied by Richard Lees Steel Decking Ltd. This testing has shown that, not only can the STRUX 90/40 reinforcement meet the physical requirements for longitudinal shear and composite interaction in the floor plate, but also that with Holorib, a fire rating of up to two hours can be achieved. Advantages of STRUX 90/40 over steel fabric reinforcement STRUX 90/40 reinforcement is premixed into the concrete so that when concrete is delivered to site it is immediately ready to be pumped and placed. Project time & cost No fabric to lift to level. No fabric storage space required. No fabric to fix, eliminating an entire step from the process. Productivity improvements. Reduction in clashes with the requirements of other contractors. Safety Risk reduction. Removal of all hazards associated with the installation of fabric. Removal of a trip hazard from the floor area prior to and during concreting. Flexibility & ease of application Improved logistics on site. Easier to maintain a clean and clear area for concrete placement. Reduction in pre-pour inspection checks of reinforcement. Concrete arrives on site with STRUX 90/40 already added. Superior crack control STRUX 90/40 fibres are evenly distributed through the concrete and always in the right place. Crack propagation is arrested early. Advantages of STRUX 90/40 over steel fibres The high strength to weight ratio of STRUX 90/40 and high fineness compared to steel fibres leads to very different dosage rates of the two materials. In composite floor slabs STRUX 90/40 is added at a dosage rate of 5.3kg/m 3. A similar application using steel fibres would require a dosage of 30kg/m 3. Clear advantages of STRUX 90/40 include: Ease of addition No specialist equipment is needed to add STRUX 90/40 to the mixing plant. A simple platform or suitable mobile steps will give safe access for adding the material. Safe & easy to handle Individual bags of STRUX 90/40 are light (2.3kg), safe and easy to handle. Span/load/fire tables 1. Spans shown assume clear span +100mm to the centreline of supports. 2. Designs are fully in accordance with BS 5950: Parts 4 & The dead weight of the slab has been included in the development of the spans shown. However, consideration should be given to finishes, partitions, walls, etc. when reading from the table. 4. Based upon concrete densities at wet stage: normal weight concrete 2400 kg/ m 3, lightweight concrete 1900 kg/m A span to depth ratio limit of 35:1 for normal weight concrete and 30:1 for lightweight concrete is generally used. Where isolated single spans occur, these should be reduced to 30:1 and 25:1 respectively. Good pumping characteristics: When used in conjunction with the right mix design, STRUX 90/40 fibres display excellent pumping characteristics, minimising job downtime through equipment problems. Longitudinal shear strength For design in accordance with BS 5950: Part 3, the shear resistance of each shear plane of concrete reinforced with 5.3 kg/m 3 of STRUX 90/40 fibres can be expressed as v r = 2A cv + v p A cv is the cross-sectional area of concrete per unit length of beam. Where the decking spans perpendicular to the span of the beam this area includes the concrete both above the profile and within the decking troughs. If the decking is spanning parallel to the beam then only the concrete above the profile should be considered to be resisting longitudinal shear. A cv Perpendicular To this longitudinal shear resistance may be added a component, v p, arising from the tensile strength of the deck, but only in the situation where the deck spans perpendicular to the beam and it is either continuous across the beam or anchored to it with through-deck welded shear studs. Guidance on the calculation of v p can be found in the appropriate section of BS 5950: Part 3. Shear stud resistance A cv Parallel Testing established that the performance of stud connectors was enhanced when embedded in specimens using concrete reinforced with 5.3kg/m 3 of STRUX 90/40 fibres, compared to identical specimens using conventional reinforcement bars. This was demonstrated by an improvement in both shear resistance and ductility and demonstrates that the BS :1990 codified stud reduction factors (k) can be adopted without additional modification. 6. Maximum deflection in the direction of span of the decking is limited to span/130 after taking account of ponding. 7. Construction stage design includes an allowance of 1.5kN/m 2 for construction loading. 8. Composite slabs are designed to be simply supported irrespective of the deck support configuration. The STRUX 90/40 fibres are included to satisfy the minimum crack control and load distribution requirements of BS 5950: Part S350 decking is manufactured from material meeting the specification: BS EN S350GD+Z275-N-A-C. It has guaranteed minimum yield strength of 350 N/mm2. 19

20 Holorib with STRUX 90/40 fibres Span/load/fire table 1hr Fire Rating Normal weight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) Span/load/fire table Lightweight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) STRUX 90/40 synthetic macro fibres are included in the concrete mix at a dosage rate of 5.3 kg/m 3 Refer to notes on page 19 the original: Holorib 20

21 Holorib with STRUX 90/40 fibres Span/load/fire table 1 1/2 hr Fire Rating Normal weight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) Span/load/fire table Lightweight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) STRUX 90/40 synthetic macro fibres are included in the concrete mix at a dosage rate of 5.3 kg/m 3 Refer to notes on page 19 21

22 Holorib with STRUX 90/40 fibres Span/load/fire table 2hrs Fire Rating Normal weight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) Span/load/fire table Lightweight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) STRUX 90/40 synthetic macro fibres are included in the concrete mix at a dosage rate of 5.3 kg/m 3 Refer to notes on page 19 the original: Holorib 22

23 Ribdeck E60 with STRUX 90/40 fibres Span/load/fire table 1hr Fire Rating Normal weight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) Span/load/fire table Lightweight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) STRUX 90/40 synthetic macro fibres are included in the concrete mix at a dosage rate of 5.3 kg/m 3 Refer to notes on page 19 less concrete Ribdeck E60 23

24 Ribdeck 80 with STRUX 90/40 fibres Span/load/fire table 1hr Fire Rating Normal weight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) Span/load/fire table Lightweight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) STRUX 90/40 synthetic macro fibres are included in the concrete mix at a dosage rate of 5.3 kg/m 3 Refer to notes on page 19 longer spans Ribdeck 80 24

25 Ribdeck AL with STRUX 90/40 fibres Span/load/fire table 1hr Fire Rating Normal weight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) Span/load/fire table Lightweight concrete Multiple - Unpropped Multiple - Propped Support Condition Slab Concrete 0.9 Gauge 1.0 Gauge 1.2 Gauge Depth Volume Imposed Load Imposed Load Imposed Load (mm) (m 3 /m 2 ) STRUX 90/40 synthetic macro fibres are included in the concrete mix at a dosage rate of 5.3 kg/m 3 Refer to notes on page 19 shallow slabs efficient designs Ribdeck AL 25

26 Guidelines for concrete producers The following guidelines are designed to assist concrete producers with the efficient batching and dispersion of STRUX 90/40 synthetic structural fibres and to provide concrete that has the optimum pumping, placing and finishing characteristics for composite floor slab construction. 1. Mix design 1.1 The dosage of STRUX 90/40 for this application has been set at 5.3kg/m 3. This has been determined by extensive research programmes into the behaviour of composite floors using Richard Lees Steel Decking profiles and must not be altered without engineering approval. The addition of fibres will reduce the workability and the apparent paste volume of the concrete. In order to supply a concrete with optimum pumping, placing and finishing characteristics, these effects will need to be addressed by attention to the mix design and the selection of an appropriate and proven superplasticising admixture. The recommended admixture for this application is ADVA, supplied by Grace Construction Products. 1.2 Typically we suggest that an optimum paste volume for concrete with 5.3kg/m 3 of STRUX 90/40 would be achieved with a cementitious content of 360kg and a coarse to fines ratio set at 45%. Where possible, trial mixes should be performed to determine a suitable mix and Grace Construction Products will provide technical advice where requested. 1.3 The exact water content and admixture dose are best determined experimentally. 2. Dry batching 2.1 STRUX 90/40 synthetic structural fibres are supplied in concrete dispersible bags; either 0.5kg or 2.3kg. The whole bags can be added into the mixing operation without the need to open them. The appropriate number of bags can be added to the empty truck prior to loading with concrete. A suitable safe loading platform or safety steps should be provided to give the operator secure access to the mixer truck. 2.2 Once the STRUX 90/40 bags have been loaded, 200 litres of water should then be added. This water addition assists the bags to break up, releasing their contents. 2.3 On completion of the weighing of the aggregates into the weigh hopper, a small amount (e.g tonne) of preferably coarse aggregates should be released into the truck. The contents (now containing the full quantity of fibres, ~ 200 litres of water and a portion of the aggregates alone) should be mixed for 2-3 minutes to allow the coarse aggregates to abrade and disperse the fibres thoroughly. 2.4 The remaining aggregates and cementitious materials can now be loaded into the truck along with further water. Mixing should now proceed as usual, targeting an initial slump of 50-70mm, before the addition of ADVA. Once this has been achieved, the appropriate dosage of ADVA should be added to increase the workability to mm. 3. Wet mixing 3.1 In wet mixed plants the bags of STRUX 90/40 are normally added directly into the mixer prior to charging with aggregates. However this procedure may depend on the mixer and overall plant specifications and it is recommended that Grace Construction Products are consulted for advice on the best method of fibre addition. 26

27 Guidelines for contractors These guidelines are designed to provide contractors with advice on how best to pump, place, compact and finish concrete containing STRUX 90/40 synthetic structural fibre reinforcement for composite floor slab construction. 1. Concrete pumping 1.1 Mix Design and Workability When STRUX 90/40 is used in concrete for Holorib and Ribdeck composite floor slabs it is always used at a fixed dosage of 5.3kg/m 3. This requires careful attention to mix design in order to ensure that there is sufficient paste volume to coat the fibres fully. In general we recommend a pump mix with a minimum fine aggregate to coarse aggregate ratio of 45%. STRUX 90/40 reinforced concrete should be delivered and discharged into the pump hopper at a workability of between 140mm - 180mm, i.e. high enough to allow the concrete to fall through the hopper grill without stacking up, but not so high as to promote segregation of the concrete in the pump line, particularly while pumping has ceased during concrete truck change-over. An approved superplasticising admixture must be used to reinstate the workability lost through the addition of fibres. Grace Construction Products strongly recommends that ADVA be used, which also provides lubrication to the concrete, reducing pumping pressures. 2. Concrete placing, compacting and finishing operations 2.1 Placing the concrete Placing and levelling STRUX 90/40 reinforced concrete should be carried out exactly as per normal concrete. The high dosage of fibre reinforcement in the concrete may give the apparent appearance of over cohesiveness, but raking/levelling will not be affected and will require no more than usual effort. Additionally, where ADVA Floor 200 has been used, this will assist the concrete in levelling, compaction and finishing. 2.2 Compacting the concrete The best plant suited for compacting fibre reinforced concrete is the Magi Screed as figure 1; The concrete should be compacted sufficiently to ensure that adequate paste is brought to the surface to allow easy finishing, particularly when power floating. If this method of applying some form of surface vibration to the fibre reinforced concrete is not used, then a high number of fibres will appear at the surface of the concrete. This may not be an issue if the concrete floor is being covered by insulation etc. but if the specified finish is power floating, then the use of the Magi Screed greatly assists in achieving a satisfactory surface. 2.3 Finishing the concrete surface After compaction with the Magi Screed, an easy float (refer figure 2) is usually passed over the concrete to close up the surface. 2.4 Once the fibre reinforced concrete has been levelled, compacted and floated, it is allowed to cure in accordance with good concreting practice. If a power float finish has been specified, then the surface of the concrete floor is usually closed up using a panning operation, followed by the floating operation as shown in figure 3. If the type of floating machine shown in figure 3 is used, then some fibres will be seen in the surface of the finished concrete floor. If a ride-on machine is used (refer figure 4), then usually all of the fibres disappear during the floating operation. figure 1 figure 2 figure 3 figure 4 27

28 RLSD Shaping the London Skyline 30 St. Mary Axe - The Gherkin Location: 30 St Mary Axe, London, England, United Kingdom Status: Complete Completion Date: 2004 Height: 180 metres Floor Area: 70,000 square metres Architect: Foster & Partners Steel Contractor: Victor Buyck Hollandia JV RLSD Profile: Ribdeck 80 Widely known throughout the world by the nickname The Gherkin, 30 St Mary Axe stands at 180 metres tall, making it on completion the second tallest building in the City of London and the sixth tallest in the Greater London region. Thanks to the efficiency of it s environmentally-conscious design, The Gherkin uses half the power that a similar tower would typically consume, whilst the unique triangulated perimeter structure makes this tall building sufficiently stiff to control wind-excited sways without requiring any additional cross-bracing. The specification of Ribdeck 80 for this project was an integral factor in achieving the ambitious design of this unique building, with its radial steel beam arrangement requiring a decking profile that could span up to 4.75m without any requirement for additional framing or temporary support. Ribdeck 80 was the obvious choice. 28

29 RLSD Shaping the London Skyline The Emirates Stadium, London The Emirates Stadium home of Arsenal Football Club is the second largest stadium in the Premier League, and is widely acknowledged as being one of the finest sporting venues in the world. The stadium is a four-tiered bowl that creates an amphitheatre type arena, with roofing spanning around the curved stands. With any modern sporting venues, it was essential to minimise the number of obstructions that could detract from the viewing experience. Location: Ashburton Grove, London, England, United Kingdom Status: Complete Completion Date: 2006 Height: 42 metres Floor Area: 7,800 square metres Architect: HOK Sport Steel Contractor: Watson Steel Structures RLSD Profile: Ribdeck 80 29

30 RLSD Shaping the London Skyline Canary Wharf Location: Isle of Dogs, London, England, United Kingdom Status: Incomplete Completion Date: Ongoing Height: 235 metres (highest point) Floor Area: See panel opposite Architect: Various Steel Contractor: Various RLSD Profile: See panel opposite Canary Wharf is a large business and shopping development in London, located on the Isle of Dogs in the London Borough of Tower Hamlets, centred on the old West India Docks in the London Docklands. When topped out in 1990, One Canada Square became the UK s tallest building and a powerful symbol of the regeneration of Docklands, as well as being an imposing architectural presence on the London skyline. During the various phases of construction at Canary Wharf, RLSD have supplied over 800,000 square metres of decking profile testament to the quality of service and the superiority of the profiles that we have supplied over the years. 30

31 Canada Square - 147,000 m 2 Ribdeck Canada Square - 101,700 m 2 Ribdeck AL 3 5 Churchill Place - 38,500 m 2 Ribdeck E Churchill Place - 38,700 m 2 Ribdeck E North Colonnade - 34,000 m 2 Ribdeck South Colonnade - 35,000 m 2 Ribdeck Cabot Square & 10 South Colonnade - 68,000 m 2 Ribdeck Cabot Square - 60,000 m 2 Ribdeck Bank Street - 71,700 m 2 Ribdeck AL 10 1 Cabot Square - 65,000 m 2 Ribdeck Cabot Square & 5 North Colonnade - 75,000 m 2 Ribdeck Westferry Circus - 23,500 m 2 Ribdeck AL Bank Street - 59,300 m 2 Ribdeck AL Total decking supplied: 817,400 m2 31

32 RLSD Shaping the London Skyline Willis Building Location: 51 Lime Street, London, England, United Kingdom Status: Complete Completion Date: 2007 Height: 125 metres Floor Area: 51,000 square metres Architect: Norman Foster Steel Contractor: William Hare RLSD Profile: Ribdeck 80 The Willis Building stands opposite the famous Lloyd s building in the heart of the City of London. The building features an iconic stepped design, which was intended to resemble the shell of a crustacean, with setbacks rising at 97 and 68 metres respectively. Constructed between 2004 and 2007, it was a significant addition to the London skyline, becoming the third tallest building in the City after 30 St Mary Axe and CityPoint. The core was topped out in July 2006, with Ribdeck 80 specified throughout the structure primarily due to its excellent load carrying properties and unrivalled ability to carry long unpropped spans. 51 Lime Street is the first in a wave of new skyscrapers planned for the area. 32

33 RLSD Shaping the London Skyline St Pancras International, London The 800m redevelopment, extension and re-branding of St Pancras International echoes the opulence of New York s Grand Central Station, and features a wide range of top quality retail stores, as well as Europe s longest champagne bar, and even a daily fresh farmers market. Famed for it s recently introduced Eurostar train service to continental Europe, the need to accommodate the unusually long Eurostar trains necessitated the extension of the architecturally iconic Barlow Shed. Longer trains also means longer platforms and longer decking spans. RLSD were the obvious choice for providing decking profiles capable of spanning great lengths without compromising load carrying capacity. Location: St Pancras, London, England, United Kingdom Status: Complete Completion Date: November 2007 Floor Area: 27,000 square metres Architect: Rail Link Engineering Steel Contractor: Watson Steel Structures RLSD Profile: Holorib, Ribdeck 80 33

34 RLSD Architectural Impact Across the UK Civil Justice Centre (Manchester) Location: Spinningfields, Manchester, England, United Kingdom Status: Complete Completion Date: 2007 Height: 80 metres Floor Area: 35,160 square metres Architect: Denton Corker Marshall Steel Contractor: William Hare RLSD Profile: Holorib This distinctive building is widely recognisable for the fingers at each end that are cantilevered over the lower levels - it is rumoured that architect Barrie Marshall sketched the entire building by hand and that very little has deviated from his original drawings. On the west side of the building is an imposing 11,000 m 2 suspended glass wall - the largest in Europe. The specification of Holorib throughout the building was an important factor in minimising the construction depth of the floor slab to suit the architect s vision of the slender form of the finger protrusions at each end of the building. 34

35 RLSD Architectural Impact Across the UK Wales Millennium Centre, Cardiff The Wales Millennium Centre is a national centre for performing arts. The architect s concept of the building was to design a structure that expressed Welshness and that was instantly recognisable and distinctive across Europe. The building was designed to reflect the many different parts of Wales with local Welsh materials that dominate its history; slate, metal, wood and glass. With Ribdeck 80 being produced in a factory just 15 miles from the Millennium Centre the specification of this profile went some way to further enhancing the building s Welshness. As a performing arts centre, clearly the acoustics of the building would play an integral part in its success as a venue the specification of Ribdeck 80 allows the internal structure to be acoustically isolated from the main frame, with additional decking used in the roof to shield aircraft noise. Location: Cardiff Bay, Cardiff, Wales Status: Complete Completion Date: 2004 Seating Capacity: 1,900 Floor Area: 37,000 square metres Architect: Capita Architecture Steel Contractor: Watson Steel RLSD Profile: Ribdeck 80 35

36 RLSD Architectural Impact Across the UK Spinnaker Tower, Portsmouth Location: Portsmouth Harbour, Portsmouth, United Kingdom Status: Complete Completion Date: 2005 Height: 170 metres Floor Area: 1,600 square metres Architect: HGP Architects Steel Contractor: Butterley RLSD Profile: Ribdeck 80 The Spinnaker Tower is the centrepiece of the redevelopment of Portsmouth Harbour, and was chosen by Portsmouth residents from a selection of concept designs. The tower reflects Portsmouth s maritime history, representing sails billowing in the wind a design accomplished using two large, sweeping steel arcs. An imposing and stunning addition to the Portsmouth horizon, Spinnaker Tower is the tallest accessible structure in the United Kingdom outside London, with three observation platforms constructed from Ribdeck 80 affording glorious views of up to 23 miles. 36

37 RLSD Architectural Impact Across the UK The Curve Leicester Performing Arts Centre Location: Rutland Street, Leicester, United Kingdom Status: Complete Completion Date: 2008 Floor Area: 2,600 square metres Architect: Rafael Vinoly Architects Steel Contractor: William Hare RLSD Profile: Ribdeck 80 Based in the redeveloped Cultural quarter in Leicester City Centre, the Curve theatre opened in Autumn 2008, and is one of the main flagship projects in the regeneration of the city. This ambitious and innovative design has complete architectural transparency, with the weight of the structure suspended from the roof of the building. The long spanning capacity of Ribdeck 80 allowed the number of steel members in the structure to be kept to a minimum, emphasising the light and airy form of the structure. 37

38 Guidance Notes for Design and Fixing Design pages General 38 Construction Loading 38 Permanent Loading 38 Reinforcement 38 Deflection 38 Temporary Support 39 Durability 39 Full Lateral Restraint 39 Diaphragm Action 39 Composite Beams 39 Perimeter Beams 39 Transverse Reinforcement 39 Shear Studs 39 Reference Literature 39 Delivery page 40 Delivery, Transportation and Access 40 Identification 40 Lifting and Storage 40 Professional fixing pages Installation Service 40 Health & Safety 40 Fall Arrest 40 Fixing and Securing 41 Cartridge Tools 41 Site Testing 41 Edge Trim 41 Cantilevered Deck and Trim 42 Decking on Shelf Angles 42 Decking Around Columns 42 Minimising Concrete Loss 42 Concrete Encased Perimeter Steel Beams 42 Shear STUDS page 43 Spacing of Shear Studs 43 Preparation of Steel Flanges 43 Stud Installation Equipment 43 Installation and Testing 43 Prior to concrete PLACEMENT page 44 Forming Openings 44 Cleaning the Decking 44 Concrete PLACEMENT page 44 Temporary Props 44 Construction Joints 44 Placing and Compacting 44 Curing 44 Composite floor SLAB page 45 Soffit Fixings 45 Holowedge and Ribwedge R80 45 Alphawedge 45 GOOD PRACTICE: These guidance notes have been developed by RLSD during our many years in the Steel Decking Industry. Whilst every effort has been made to ensure that they are comprehensive, we would refer you to the BCSA publication No 37/04 BCSA Code of Practice for Metal Decking and Stud Welding for further guidance. These notes should also be read in conjunction with the prevailing national design guidance and health and safety legislation. Design General RLSD s structural decking can be used as permanent shuttering to an in situ concrete topping, or as both shuttering and tensile reinforcement to form what is referred to as a composite floor slab. Composite floor slabs form the most frequent application and these are designed to the currently applicable design codes (principally BS5950: Part 4). A slab design appropriate to the required application can be selected by a suitably qualified person from reference to either RLSD s span/load tables or using Deckspan software, both of which are available free of charge at When decking is used as permanent shuttering only it is the responsibility of the Project Structural Design Engineer to specify all the slab reinforcement necessary to support the permanent loads, ignoring any contribution from the decking profile. Construction Loading The RLSD design span/load tables generally make allowance for a temporary construction live load of 1.5kN/m 2 in addition to the wet weight of concrete. This should not be exceeded without consultation with the RLSD Technical Advisory Service. The heaping of concrete during placement should be avoided. In the unpropped condition it is normally the construction stage that governs the allowable spans shown in the tables. Construction Loading after Initial Concrete Set The slab strength will generally have been specified by the Project Structural Design Engineer on the basis of support of long-term loads consistent with the building s intended use. In the temporary condition, construction loads from plant used for erecting steelwork or from materials stored for following trades may constitute a more onerous design condition and should be referred back to the Project Structural Design Engineer for assessment. Permanent Loading The self weight of the slab has been taken into account in the design process and need not be included in the imposed loads indicated in the span/load tables. The Project Structural Design Engineer should sum all predominantly uniform applied live, partition, finishes and loads when reading from these tables. Any walls other than lightweight partitions should be considered separately as either line or concentrated loads, and specific calculations should be made to check the adequacy of the selected slab to support them. Reinforcement In all circumstances appropriate crack control and distribution reinforcement should be provided within the slab and this can be in the form of a wire-welded mesh or, in certain situations, as synthetic macro fibres. This reinforcement may also be sufficient to provide the necessary fire resistance for the slab and this can be checked by reference to the RLSD tables for the Simplified Fire Design Method, available in literature and on the RLSD website. Where the design criteria are not covered by the simplified tables, then reinforcing bars, positioned in the decking troughs, will be required, the exact quantity being determined using RLSD s Deckspan software or by reference to the Steel Construction Institute publication 056. Decking can only contribute to the transverse shear reinforcement for the distribution of longitudinal shear forces in composite beams when it is spanning perpendicular to the beam. In addition it should either be continuous across the beam, or the beam flange be wide enough to allow effective anchorage of the deck using shear studs welded in a staggered pattern. Additional reinforcement may also be required to comply with building or other regulations and it is the customer s responsibility to ensure that the necessary design checks and approvals have been granted. Deflection Decking will deflect under the weight of wet concrete as it is placed. The design process takes account of this deflection and limits it in accordance with the relevant code of practice. The additional weight of concrete due to this deflection is factored into this and all subsequent calculations. No account is taken in RLSD s tables or software for any deflection of the supporting steel frame. Those responsible for the placement of the concrete should be made aware of all expected deflections when assessing concrete volumes and finishing techniques. 38

39 As examples, values for lateral restraint with 0.9mm thickness decking are: a) with nails at 333mm centres at sheet ends ENP2 = 8.10 kn/m DAK 16 = 2.40 kn/m b) with nails at 666mm centres at intermediate support ENP2 = 4.05 kn/m DAK 16 = 1.20 kn/m Temporary support Temporary support may sometimes be necessary to sustain the dead weight of wet concrete and any other construction loads. General guidance is provided by RLSD in the form of span/load tables and Deckspan software and, where provided, on project specific installation layout drawings and design calculations. The Project Structural Design Engineer may also specify temporary propping in situations where tighter control on deflections is deemed necessary. The design and safe installation of temporary supports, including any bracing necessary, is the responsibility of the Project Structural Design Engineer. There should be continuous sole and header plates across the full width of every propped bay and the system should be installed so as to ensure zero deflection of the deck at propped points prior to concrete placement. The header plate should offer a wide area of support so as not to locally compromise the structural integrity or the appearance of the decking. Except where specifically advised by RLSD s Technical Department, all temporary props to unsupported slab edges are to be fully in place prior to installation of the edge trim or decking. The same condition also applies to internal props meeting the conditions set out in Table 1. Profile Holorib Ribdeck AL Ribdeck E60 Ribdeck 80 Span >= 4.0 m >= 4.0 m >= 4.0 m >= 4.5 m Table 1: Lower Limit for Pre-installation of Temporary Supports. Temporary supports should remain in place until the concrete has reached a minimum of 70% of its characteristic strength. Durability Decking is produced from galvanised steel strip to BS EN with a standard Z275 coating. When used in a dry and unpolluted environment, such as is the case in the majority of offices, warehouses, hospitals, and schools etc, a design life to first maintenance of years can be expected. Recent documented research would suggest that the predicted performance is likely to approach the higher end of this range. Full Lateral Restraint Guidance on lateral stability of beams can be obtained from SCI publication 093. Positive connection between the composite floor slab and the compression flange of a steel support beam may be achieved using either ENP2 or DAK 16 nails. These nails are capable of resisting lateral forces as required by BS 5950: Part 1, with safe working loads per nail indicated for differing sheet thicknesses in Table 2. Deck Thickness ENP2 DAK 16 (mm) Shear (kn) Shear (kn) Diaphragm Action Guidance on diaphragm action of steel decking during construction can be obtained from the SCI Advice Note AD175 (1995) and by reference to BS 5950: Part 9. Composite Beams Guidance on the design of composite beams is given in BS5950: Part 3: Section 3.1. Within the design there is a requirement for the provision of transfer of horizontal shear forces between the steel beam and the concrete slab. This is commonly achieved with the use of headed shear studs welded through the decking panels to the underlying beam top flange. The Project Structural Design Engineer should ensure that sufficient studs can be welded within the confines of the metal decking troughs to achieve the required degree of shear connection. In particular it is important to avoid the specification of beams with top flanges that are too thin and/or too narrow to accept off-centre welded studs. (Refer to Shear Studs section for further guidance - page 43). Perimeter Beams If perimeter beams, and beams adjacent to internal slab openings, are to be designed as composite L beams, then the edge of the slab should extend a minimum distance of 6 times the stud diameter beyond the beam centreline. In most cases this will equate to a minimum distance of 114mm. If this condition is satisfied but does not exceed 300mm, then reinforcement should be specified in the form of U bars detailed below the heads of the studs. If the edge distance exceeds 300mm, then the composite beam may be designed as an internal beam (albeit with reduced effective composite flange width) and reinforcement added as required to satisfy longitudinal shear transmission rules. Transverse Reinforcement The concrete flange of a composite beam is subjected to splitting forces and these may be resisted in part by contributions from the concrete, decking, top mesh and any additional steel bars crossing the beam perpendicular to the span direction. Any contribution from the decking should only be considered where the decking spans onto the beam and is either continuous across or is securely anchored to it with through deck welded shear studs. The decking contribution should be ignored where it spans parallel to the composite beam being considered. Any shortfall in transverse shear resistance is normally compensated for by the design and inclusion of additional reinforcement bars. Shear Studs Shear studs are manufactured from low carbon steel with minimum values of yield point of 350 N/mm 2, ultimate tensile strength 450 N/mm 2, and elongation 15%. The studs should be headed and for through deck welding they should be specified with a shank diameter of 19mm. Studs should protrude a minimum of 35mm above the shoulder of the decking profile and the covering of concrete over the head of the stud should be a minimum of 15mm. The shear capacity of headed studs embedded in solid concrete is tabulated in BS 5950:Part 3:Section 3.1. In composite slabs the studs may be affected by the proximity of the webs of the steel decking sheet and their capacity may be reduced. Refer to BS5950:Part 3:Section 3.1 for reduction factor formulae. Reference Literature MCRMA Technical Paper 13 / SCI Publication P300: Composite Slabs and Beams Using Steel Decking: Best Practice for Design and Construction. BCSA Publication 37/04: Code of Practice for Metal Decking and Stud Welding. BS 5950: Structural Use of Steelwork in Building. Table 2: Safe Working Load per Nail 39

40 Delivery Delivery, Transportation and Access Loads are normally delivered by articulated vehicles of approximately 16 metres in length and with maximum gross weights of up to 36 tonnes. Decking will normally be delivered in full loads. Suitable access to and from unloading points on sites must be provided and maintained by the client. Delivery vehicles have a maximum unloading time of 2 hours. Unless otherwise agreed in writing before delivery, offloading and lifting to level and position is the responsibility of the customer. Deck Width (mm) Height (mm) Holorib Ribdeck E Ribdeck AL Ribdeck Table 3: Approximate Maximum Sizes of Bundles Bundle length will depend on decking panel lengths. Export/shipped bundles may differ please ask for details. Lengths of decking manufactured in accordance with RLSD layout drawings or customer schedules are normally consolidated into compact, banded bundles as shown in Table 3. These bundles may weigh up to 2 tonnes and cover an effective area up to 100 square metres when laid, depending on the profile, gauge and length of the panels being delivered. Table 4 gives the mass per linear metre (kg/m) of each profile and gauge to assist in the calculation of individual bundle weights. Deck Gauge of Steel Holorib Ribdeck E Ribdeck AL Ribdeck Identification Where appropriate, bundles will be marked to correspond with RLSD layout drawings, with a bundle label identifying the product, the site, and a schedule reference code. To further aid identification, each panel of decking has its gauge and yield stress stamped in the base of the trough on the overlap return side of the sheet and each bundle has a paint splash colour identification code on one side as shown in table 5. Steel Yield Gauge of Steel (mm) Stress S350 BLUE/ YELLOW/ ORANGE/ RED/ BLACK BLACK BLACK BLACK Table 5: Colour Coding for Deck Bundles Lifting and Storage The customer should arrange for bundles to be lifted using two double wrapped chains, with care taken to avoid excessive pressure across the sheets. Careless use of the slings can cause panels to buckle. Under no circumstances should the bundles or sheets be removed from delivery vehicles by tipping, barring or similar means. Bundles should be lifted directly from the delivery vehicle and placed on the building framework at the correct level and in positions appropriate for installation. Generally one bundle of decking will be positioned in each steelwork bay. The sides of the bundles are identified with paint splashes and these marked sides must all face the appropriate set out point. Care must be taken to avoid local overloading of the structure. Table 4: Mass of Deck Panels (kg/m) The maximum sheet length on a particular project could be governed by one or more of the following: manual handling limitations, support configuration, transportation and access for loading deck bundles onto the steel frame. installation Except in situations where fixing is contracted to RLSD, it is the customer who is responsible for the safe execution of the works. All users, installers and persons working in the proximity of the decking should be made familiar with the recommendations in this section. Installation Service RLSD provides the UK s most experienced and professional installation service. Operating throughout the country, installing decking on projects ranging from 10m 2 to over 100,000m 2, RLSD can provide fully-trained construction teams backed by expert safety, construction and technical departments. The company also boasts externally-accredited management systems for health, safety and the environment to OHSAS and ISO Health and Safety Decking is manufactured to ISO 9001 from high yield steel coated with zinc and may be covered with a soluble protective lubricant which does not adversely affect performance. The sheets will have sharp edges and corners. COSHH data sheets are available for all hazards/activities associated with the handling and fixing of RLSD decking. Fall Arrest It is recommended that appropriate fall arrest systems are used. Generally safety netting is advised for steel-framed structures; air bags or similar for other structures. Details of the appropriate fall arrest system, together with a risk assessment covering the safety system installation method, should be included in the detailed installation method statement prepared by the decking installer prior to commencement of work. 40

41 Fixing and Securing Prior to the commencement of installation of the decking the supporting structure must be in a sound and stable condition. Steelwork must be adequately restrained and support for the decking must be provided around columns, splices, openings and other penetrations. Brickwork, blockwork and concrete supports must be adequately cured. Steelwork Concrete Other Materials (incl. Brick and Block) 50mm 70mm 70mm Table 6: Minimum Bearing Requirements for Decking Decking MUST be suitably secured to avoid excessive deflection or dislodgement during construction. The fixings should be placed at 333mm maximum spacing at panel ends and 667mm maximum spacing on intermediate supports. No pedestrian access to the installed decking should be permitted until it has been securely fixed to the supporting structure and access is recommended to be limited to essential construction personnel once installation is complete. In the case of a steel support structure, low power powder-actuated fastenings such as Hilti ENP 2 can be used with the DX 750 cartridge tool to make this connection. In situations where shear studs are subsequently to be welded through the decking, a lighter gauge nail such as Hilti DAK 16 can be used with the DX A40 or A41 cartridge tools at the discretion of the Project Structural Design Engineer. Alternatives to Hilti nails are available through companies such as Spit, or decking can be secured to steelwork using self-tapping screws. Decking may be secured to brickwork, blockwork and concrete supports provided that the top surface is flat and level and that the top course of bricks or blocks are of solid construction. Special masonry fixings, such as the Hilti HPS-1 Hammer Screw and Hilti X-SW Soft Washer Fastener can be considered, but in all instances it is recommended that the decking installer refers to the fixing manufacturer s recommendations for the system to be used. Decking may be cut on site to accommodate notching around obstructions such as columns but this may affect the design of the sheet and its spanning capability. In such situations special consideration should be given as to the adequacy and completeness of bearings and to the spanning capability of cut sheets, adjacent sheets and the finished floor slab. A petrol-driven disc cutter is the preferred method for cutting deck sheets and edge trim on site. It is recommended that all profiles in the Ribdeck range be seamstitched at regular intervals along their length using self-tapping screws. Care should be taken to ensure that the seam stitch screws effectively penetrate and engage with the under-lapping deck sheet. Ribdeck E60 Ribdeck 80 Ribdeck AL 1.0 m 1.5 m 1.0 m Table 7: Max imum Spacing of Seam Stitch Screws Note: The guidance given here applies to the shallow deck range of profiles supplied by RLSD. Separate guidance should be sought on the safe installation of deep deck profile CF225. The nails are suitable for fastening decking and edge trim to structural steelwork up to 630 R m N/mm 2 and a minimum thickness of 6mm. Technical advice on the use of these tools can be obtained from Hilti Technical Advisory Service, Manchester (Freephone , gbsales@hilti.com, web Alternative tools and fixings can be obtained from Spit (tel: , support@itwspit.co.uk, web Site Testing Once nails have been installed, the effectiveness of the fixing can be determined by comparing appearance of the installed nail with guidance diagrams and other information in the manufacturer s literature. Edge Trim Galvanised steel edge trim is not a structural component. It is used only as permanent formwork to retain the wet concrete slabs, avoiding the need for timber shuttering. It is normally supplied in 3m lengths but may be in 2.5m lengths if obtained directly from our stock depots. Thicknesses, or gauges, are usually 1.0mm or 1.2mm, but can be up to 2mm when needed. Edge trim is supplied complete with restraint strapping in standard 1.2m lengths to be cut to suit on site. Fixing screws are only provided when RLSD is carrying out installation. Edge trim can be secured to the end of a decking sheet using selftapping screws (see detail 1) or to the main support structure using the same fixings as used for securing the decking (details 2 & 3). Fixings to the top flange are normally made at each end of the edge trim sheet and at no more than 600mm centres along its length. Edge trim is delivered to site in straight lengths and is cut to suit on site. To approximate a curve, the edge trim can be cut on site to form a facetted face and the frequency of fixings may need to be increased accordingly. Restraint straps are used to control the outward deflection of the edge trim under pressure from the wet concrete and should generally be installed at no more than 600mm centres and at an angle no steeper than 45 o. Restraint straps will normally be provided in 1.0 mm gauge but this may be increased where additional rigidity is demanded. Cartridge Tools Hilti cartridge tools are commonly used to install ENP 2 and DAK 16 nails. No external power source is required. These tools should be used only by suitably-trained personnel in accordance with manufacturer s instructions. When detailing steelwork for the support of metal decking sheets, consideration should be given to the physical dimensions of the cartridge tool, which must be held perpendicular to the fixing surface and will experience a re-coil effect on firing. WARNING: Steel decking is a structural element of the construction and should always be installed by a competent contractor to avoid adverse effects on following trades. As a minimum requirement, valid CSCS cards for steel decking and/ or stud welding should be held by all workers involved in the installation of these products. 41

42 Cantilevered Deck and Trim Special consideration should be given to cantilevers. Guidance is given here on the use of both decking and edge trim as cantilevered shuttering. It is the responsibility of the Project Structural Design Engineer to assess whether any additional reinforcement is required to enable the finished floor slab to carry the design imposed loads. In the direction of span of the decking sheets, a maximum cantilever distance of 600mm is recommended. This limit is based on health & safety considerations and is not affected by the gauge or profile of decking, or the depth of concrete to be poured. It is important that the back span of the decking sheet is securely anchored at no more than the recommended maximum spacing for end and intermediate supports respectively. Unsupported side cantilevers of decking are NOT permitted in any circumstances. Edge trim cantilevers are measured from the toe of the beam flange. The maximum cantilever length permitted varies with concrete depth to be poured and with gauge of edge trim. When cantilevering edge trim to the distances shown in Table 8, the maximum spacing of the restraint straps and fixings to the beam top flange should follow the guidelines given previously for non-cantilevered edge trim. Overall Deck End Deck Side Edge Trim Slab From Beam Centreline From Toe of Beam Depth Any Gauge n/a n/a n/a n/a 150 Table 8: Maximum Cantilever Distances For conditions outside of the scope of Table 8, permanent supports or temporary propping may be required. Please refer to the RLSD Technical Department for further guidance. Decking on Shelf Angles Where decking is required to be supported on shelf angles, the following checks are made to ensure it is physically possible to place panels of sufficient length to achieve 50mm minimum end bearings. Similar arrangements are necessary where the decking panels sit on the bottom flanges of steelwork. l m i n = L c l e a r + 2 x 50mm l m a x = L c c B / 2 - T w / 2-20mm [- T r s a if angle leg upwards] Where: l m i n is the minimum allowable sheet length l m a x is the maximum allowable sheet length L c l e a r is the clear distance between toes of shelf angles L c c is the centre to centre spacing of the beams B is the smaller of the two flange widths T w is the web thickness of the other beam T r s a is the thickness of the vertical leg of the shelf angle Decking Around Columns Decking should be cut on site to fit into the webs of columns that penetrate the floor plate. Where there are no beams available as supports, and where column penetrations exceed 250mm in width, the steel frame supplier should provide additional support (such as welded on angle brackets) in the web of the column. Decking Support Details at a Column Web Minimising Concrete Loss Wherever possible, decking sheets are butt jointed with ribs lined through. Gaps up to 5mm in width can be tolerated without significant leakage of concrete over the top flange of the beams. Gaps greater than 5mm should be sealed using a method such as adhesive tape or expanding foam. At the building perimeter the decking should either continue out to butt up against the edge trim or be sealed using a 0.7mm gauge galvanised steel closure plate or preformed polystyrene inserts. For the treatment of side lap joints of decking refer to the earlier section on seam stitching requirements. Where the decking changes direction of span it may be necessary to stitch the edge of the last sheet to the supporting beam and seal off the ends of the perpendicularly-spanning sheets with closure plates or preformed polystyrene inserts. Concrete Encased Perimeter Steel Beams Concrete encasement may be specified as part of the fire resistant design of perimeter steel members. The preferred method of construction is for concrete encasement to be carried out off site prior to erection of the steel frame. If the encasement only extends to the top of the steel beam, then metal decking installation can proceed as normal. In situations where pre-encasement is not practical, the following solution is offered for Holorib floor slabs only. The Holorib decking should be fitted to the perimeter steel beams as normal to provide a working platform and then cut back to the line of the shuttering once it has been installed around the beam. The Project Structural Design Engineer should check that the shuttering system has been designed to support the decking and subsequent weight of wet concrete, and if not, to specify the inclusion of an adequate temporary propping system as indicated in the diagram. B L c c T r s a L c l e a r T w The shelf angles are structural supports and the Project Structural Design Engineer should ensure that they are fit for purpose. In addition it is important that the angles project a minimum of 50 mm beyond the top flange of the steel beam to enable a cartridge tool or similar to be used to secure the decking to the supporting structure. A sufficient quantity of hairpin tie bars, as determined by the Project Structural Design Engineer, should be positioned in each trough of the Holorib decking prior to placement of the concrete. 42

43 Shear Studs Shear studs are normally welded through the decking to the top flange of the steel beam. To avoid burn through of the beam flange the studs should be welded directly above the web (on the beam centreline) or the flange should have a minimum thickness of 0.4 times the shank diameter (0.4 d = 7.6mm generally). It is preferable to limit the number of studs to a maximum of 2 per trough, wherever possible. As the number of studs increases beyond this limit, the decking becomes more susceptible to localised heat warping and weld splatter can interfere with subsequent welds. An alternative to welded shear studs is the Hilti HVB shear connector. These connectors are L shaped galvanised steel sections that are secured to the steel beam flange using the Hilti DX750 powder actuated tool. The mechanical properties of the HVB connectors are different to those of welded studs and a substitution should not be made without the consent of the Project Structural Design Engineer. A greater number of HVB connectors are needed to provide the same degree of shear connection as when using welded studs, and particular attention should be paid to the space available for placing these within the confines of a steel decking profile. Guidance and assistance on the application of the HVB system is available from Hilti (tel: ). Stud Installation Equipment The preferred method for welding shear studs is through the use of mains power. This provides a quiet, clean and environmentallyfriendly option. The supply should be 3 phase with 415 V / 150 A per phase. The welding convertor, measuring 0.5m cubed and weighing 0.5 tonne, is connected to this supply through a watertight 150 amp plug and socket. Where RLSD is carrying out installation using a chassis mounted mobile generator unit, access to within 7.5m of the structural steel frame will be required. This unit consists of a 200 KVA diesel generator and welding convertor housed in the rear of a vehicle which is 7m long, 2.6m wide and 3.5m high. From this position stud welding can be carried out at a radius of up to 80m. Spacing of Shear Studs In order to maintain effective shear connection, both maximum and minimum spacings are defined for the studs. The maximum longitudinal spacing is defined to prevent localised vertical separation of the slab from the beam. Minimum spacings are defined to ensure that each stud is adequately embedded in concrete and that concentrations of compressive force do not occur as a result of overlapping zones of influence around adjacent studs. Where access for the welding rig to within 7.5m of the frame is restricted, a steel section may be welded to the frame and extended to a position from which the 7.5m access rule may be applied. This steel section should, as a minimum, be a steel plate measuring 100 x 10mm. In situations where access for the mobile rig is restricted and mains power is not available, a static generator can be provided. This 200 KVA generator is housed in a unit measuring 3m long, 2m wide and 2m high and with a gross weight of 5 tonnes. This unit will emit diesel fumes when in operation and should be positioned on the structure in a well-ventilated area which is verified as suitable for this purpose by the Project Structural Design Engineer. Consideration should also be given to the method of safely re-fuelling the unit and to the safe storage of fuel in a bunded diesel bowser on the site. Installation and Testing Welded shear studs should be installed and tested in accordance with BS5950:Part 3:Section 3.1, the recommendations of the manufacturers of the welding equipment and studs, and the project specific design and layout. On projects where RLSD have installed the studs, any testing in addition to this should be carried out prior to the demobilisation of personnel and equipment to avoid any additional charges for return visits. The studs should not be welded closer than 20mm clear distance from the edge of the top flange Preparation of Steel Flanges Any impurities present at the welding interface will lead to a decrease in weld quality. RLSD profiles are formed from steel with a Z275 galvanised coating and the through deck welding process can be successfully applied to this material provided that the top flange of the steel beam is not primed, painted or galvanised and is also free from dirt, grease and loose rust. Light rusting that occurs after shot blasting is acceptable. In the welding zone, the decking should fit closely against the beam top flange, a condition that can generally be assured by the installer at the time of welding. 43

44 PRIOR TO PLACEMENT OF CONCRETE Forming Openings The following guidelines are offered for forming openings in a slab. It is the responsibility of the Project Structural Design Engineer to ensure the slab will be adequate to support the design imposed loads after the formation of any openings. RLSD s responsibilities exclude the design, supply or installation of any framing or reinforcement and the boxing out of decking to form openings. Openings can be classified in terms of the width measured perpendicular to the span of the decking: 1) Up to 250mm wide No special treatment is required. The opening should be boxed out and the decking only cut out using a reciprocating saw or nibbler when the slab has cured. 2) Between 250mm and 700mm wide The opening should be formed as above but additional reinforcement bars should be designed and added as necessary to spread the load laterally around the opening, supplement the slab strength immediately parallel to the opening, and control crack widths at corners. 3) Over 700mm wide Structural trimming steel should be added to the framing arrangement before the decking is installed. Health and Safety note: Due consideration should be given to the means of providing protection against falls and accidental passage through of materials at whatever stage openings are formed in the slab. One method that can be used is to provide a temporary cover to the opening using unconcreted decking secured to a special edge trim. Deck Over Void The three size categories, outlined here, relate to isolated openings. If openings are grouped such that a gap of less than 1.5 times the width of the largest opening exists between them, then consideration should be given to the combined width. Cleaning the Decking It is recommended that any debris on the decking be removed by the contractor after all reinforcement has been positioned and openings boxed out and immediately prior to concreting. Slight surface grease or oil residue from the decking manufacturing process does not affect the design bond strength between decking and concrete and therefore need not be removed. Any residual ceramic ferrule fragments left over after breaking them away from the welded shear studs can be left distributed over the decking surface and lost within the concrete pour. CONCRETE PLACEMENT Temporary Props Immediately prior to concrete placement, it is recommended that checks are made to ensure that temporary propping is installed: a) where indicated on RLSD drawings if supplied under the contract; b) where shown to be required on RLSD standard span/load tables; c) where indicated on project specific design calculations. Care should be taken not to over-jack these props whilst ensuring that the prop header is in continuous and level contact with the deck soffit. The propping system should extend to the full width of the bay and be left in place for a minimum of 14 days after the concrete has been placed to ensure that sufficient shear bond resistance is developed. Construction Joints Continuous concrete pours in excess of 1,000m 2 can be achieved on composite floor slabs. If the limits of the pour do not coincide with permanent slab edges, a construction joint should be formed. The construction joint should wherever possible be positioned over permanent supports at the ends of decking panels, not over intermediate supports which would result in only one span of a multiple span sheet receiving concrete. Where it is not possible to have the construction joint at a sheet end, it should be positioned such that no more than 1/3 of the final span is left unconcreted. Placing and Compacting Care should be taken when concreting in extremes of temperature. If the air temperature falls below 4 o C, then the concrete should be discharged from the mixer at a temperature of no lower than 10 o C and be protected from frost and maintained at no lower than 5 o C for 72 hours after placement. In hot weather the concrete temperature when deposited should not exceed 32 o C and measures should be taken to prevent drying out of the surface before any curing protection can be applied. Where possible the concrete should be pumped or discharged from a skip in a controlled manner over an intermediate beam of a multiple span sheet and spread evenly into the adjacent spans. For single span slabs and in situations where the concrete must be discharged directly on to the span, care should be taken not to allow the concrete to fall from a height exceeding 1.0m nor for heaping to a depth significantly in excess of the design slab depth. Work should progress transversely across each bay in a direction such that the lap joints are approached from the side of the overlapping sheet. If the workability of the concrete is too low, then it will not be possible to achieve full compaction and an acceptable finish. Advice should be obtained from the concrete supplier on any measures to be taken to recover the workability of the mix. Under no circumstances should water be added to the concrete after it has left the batching plant. The concrete should be compacted using a power driven beam or plate vibrator. Immersion vibrators should not be used. Care should be taken to avoid over-vibration as this could cause segregation of the mix, leakage through deck joints, and surface laitance. Curing Concrete should be protected from the harmful effects of sun, wind, cold and rain during the first stage of hardening. The protection should be applied as soon as possible after placing the concrete and be designed to prevent surface drying for a minimum of 7 days. No concrete should be disturbed for at least 24 hours after placing. 44

45 COMPOSITE FLOOR SLAB Loading of the composite floor slab to its full design load should only take place once the concrete has reached its target strength. Early loading of the slab can have detrimental effects on the long-term strength and load-bearing capacity of the structure. The use of the floor slab for storage of materials or as a working platform for further erection of the structure should only be attempted with the prior approval of the Project Structural Design Engineer. Soffit Fixings The Holorib and Ribdeck ranges of steel decking allow the suspension of lightweight services and fixtures from removable wedge-shaped fixings. It is important that the correct wedge fixing and decking are paired together and that the wedges are not inserted into lap joints. Table 9 shows the options available, together with the safe static working load that can be suspended from each fixing when attached to a fully cured composite floor slab. Profile Wedge Type Thread Size Safe Static (mm) Working Load (kg) Holorib Holowedge , 8, Ribdeck E60 Alphawedge 6, 8, Uni-Deck BN1Z 6, 8, Ribdeck 80 Ribwedge R Alphawedge 6, 8, Uni-Deck BN1Z 6, 8, Ribdeck AL Alphawedge 6, 8, Uni-Deck BN1Z 6, 8, The wedges are designed to act as vertical anchors only and should not be used as nuts. To avoid local overloading of the floor slab the wedges should not be closely grouped, a nominal 600 mm grid being recommended as a minimum. Design advice for closer groupings should be obtained from the project structural design engineer or from RLSD Technical Department. Dynamic loads should NOT be supported by wedge fixings. Proprietary anchors can be embedded in the slab and used as directed by the manufacturer and where approved by the Project Structural Design Engineer. Table 9: Safe Static Working Loads Holowedge and Ribwedge R80 The Holowedge and Ribwedge R80 suspension fixings are available from RLSD. They are supplied for use with all gauges of decking and are formed in mild steel grade EN1A, electrolytic zinc plated and bright passivated to BS EN 12329/ To help identify that the Holowedges and Ribwedge R80s have been supplied by RLSD and are the correct size and shape to carry the loads indicated in Table 9, they are uniquely embossed as illustrated. Installation Procedure: 1) Ensure that the correct wedge is selected. 2) Thread wedge onto the required bolt or rod. 3) Insert wedge in to dovetail rib from below and rotate through 90 o so that the sloped faces of the wedge bear on the decking ribs. 4) The bolt or rod should then be finger tightened up to the roof of the dovetail or to a washer set against the soffit of the decking. 5) Use mechanical tightening to finish. Holowedges Ribwedges Alphawedge The Alphawedge suspension fixing is available from Lindapter International Ltd (tel: ). It is designed for use with all gauges of Ribdeck E60, Ribdeck 80 and Ribdeck AL. Guidance on the use of Alphawedge fixings is available from Lindapter International Ltd. 45

46 Deckspan Design Software for Holorib, Ribdeck E60, Ribdeck AL and Ribdeck 80 available to download free of charge at

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