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Flat Slab Solution

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    Technical Manual & Documents August 2006

    Version: 2 - December 06

    BubbleDeck Voided Flat Slab Solutions

  • Contents:

    Site Erection & Installation information Type A Filigree Element

    Test Report Summary

    Technical Papers

    Acoustic Performance

    Disproportionate Collapse Resistance

    Fixings & Holes

    Filigree Element Drawings

    Zurich Insurance Approval

    Kiwa KOMO Test Certificate

  • Site Erection &Installation Manual

    Type A Filigree Elements

    Edition 4, Revision C: September-06

    BubbleDeck StructureSolutions

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    Site Erection and Installation ManualType A Filigree Elements

    Introduction

    BubbleDeck is a structural voided flat slab system that reduces dead weight of a floor slab by 33%,allowing longer spans between column supports and a whole range of other design, cost andconstruction benefits. The system eliminates all other supporting structure such as beams or walls the completed floor slab spans in two directions directly onto pre-cast or in-situ reinforced concretecolumns.

    BubbleDeck is usually manufactured as partly pre-cast filigree elements, combining the benefits gainedfrom off-site MMC techniques of factory manufacture in controlled conditions, ensuring quality controland consistency, with on-site completion of the final concrete pour, resulting in a seamless completedfloor slab - without the issues associated with fully pre-cast methods arising from dry joints resulting innoise transfer needing additional work to seal gaps, finish with additional construction layers. When thesite topping concrete has been cast a BubbleDeck structure is complete providing integral overallbuilding stability, fire resistance, weatherproofing, and sound insulation.

    Site erection and installation is simple and fast, well within the capabilities of any competent concretecontractor or sub-contractor. During previous projects over 800m2 of BubbleDeck has been erectedand completed within 4 working days. The elements are manufactured 3 metres wide (upon requestprior to ordering 2.4 metres wide where site access is restricted) and the length is varied, to suit projectfloor-plate configuration and transport efficiency, up to a maximum of 10 metres long.

    For more background information about the BubbleDeck system please study our separate ProductIntroduction Brochure prior to reading further.

    Pre-Construction Planning

    We believe the key to achieving a successful construction build is meticulous preparation andplanning, with good communication. Well in advance of construction commencing on site BubbleDecksmanagerial and technical team will closely work with you - advising on and defining a detailedprogramme for the timing and phasing of drawing preparation, drawing review, drawing sign-offapproval, element manufacture and element delivery to site to match your strategic approach andreflect your overall construction programme.

    Please take into account there is a lead in period from the date of placing your BubbleDeck order typically 2 to 3 weeks for our design / general arrangement drawing work plus 6 to 8 weeks forpreparation, producing production / installation drawings and manufacturing of the elements (on largerprojects drawing and manufacturing will be undertaken in phases to match your constructionprogramme) before we can commence site deliveries. Between these periods you need to allowsufficient time for submitting our design / general arrangement drawings to your Approved Inspectorand receiving Building control approval, although in special circumstances and smaller projects we cancollapse these periods if our other commitments allow.

    The pre-construction planning stages comprises:-

    1. Issuing to us frozen For Construction Architects / Engineers general arrangement plans,sections and relevant details in ,dwg file format together with final loading information andfirm order / deposit payment.

    2. Preparation by us of BubbleDeck full engineering design and general arrangement plans,showing element layout, and submission to you for review and technical approval.

    3. Submission by you of our design / drawings to Approved Inspector. Referral by you to usof any queries and us providing answers / further information as may be required.

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    4. Confirmation from you Building Control approval receipt and issuing to us sign-off approvalof BubbleDeck design / general arrangement drawings.

    5. Develop together programme for production / installation drawings, manufacturing anddelivery to site

    6. Preparation by us of a detailed programme for production / installation drawings,manufacturing and delivery to site. Review by you and issuing to us programme approval.

    7. Confirm to us your planned sequence of erecting the BubbleDeck elements on site.8. Confirm to us your requirements for any phasing, day joints, and service riser holes above

    250mm diameter you want pre-forming in the factory.9. Planning by you of fixed / mobile crane provision and location providing adequate capacity

    to lift heaviest elements.10. Advising us of your arrangements for site access and any access restrictions / procedures.11. Providing our advice on technical and practical construction issues.12. Selection by you of preferred propping system and arranging propping beam layout to be

    issued to us for review and comment.13. Preparation by us of production / installation drawings (projects above 2,000 m2 in phases

    as programmed) and submission to you for review and formal sign-off approval.14. Preparation by us of Quality and Delivery Control forms showing planned loading of

    elements onto our transport trailers, submission to you for review and approval.

    BubbleDeck Drawing / Manufacturing / Delivery Programme

    Planning erection of Slab Elements

    Prior to us commencing preparation production / installation drawings (see Stage 7 above) you mustconfirm to us your planned sequence of erecting the BubbleDeck elements on site during construction.This sequence has to be incorporated on our drawing element numbering at an early stage andpassed to our factory in order to ensure a) the correct element edge profiles are manufactured, and b)plan the sequence of manufacturing / transporting elements.

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    a) Element Edge Profiles: Longitudinal edges of elements require different detailing dependant upontheir position see drawing below showing slab edge cross-sections element as planned. It isimportant the large splay shown on the right hand longitudinal edge is present at every junctionbetween two elements to provide adequate concrete cover, for fire resistance and durabilityperformance, to the loose reinforcement splice bars laid across the elements joints on top of the pre-cast concrete layer.

    Direction of Site Erection

    Detail of Element Longitudinal (Variable up to 10m long) Edges

    Detail of Element Short (3m or 2.4m long) Edges

    b) Manufacturing and Transporting Sequence: We will programme the order of manufacturing elementsand loading of the elements onto our transport to reflect, as closely as practically feasible, yourplanned erection sequence. However, for transport efficiency and safety, some elements have to beloaded on the transport trailers out of sequence to their erection order (e.g. small elements have to bestacked on top of larger elements), in which case these elements can be temporarily lifted off andstored elsewhere on site while the transport trailer is unloaded. The order of loading elements onto thetransport trailers will be shown on our Quality and Delivery Control form.

    Formal drawing review & sign off prior to manufacture

    Once you have reviewed and we have received your sign-off of our production / installation drawingswe can then implement manufacture of materials and the elements and be ready to commence sitedeliveries of elements and loose rebar within 4 weeks time.

    We appreciate progress of construction on site can be affected by many external factors includingexceptionally adverse weather and other events beyond your control. If you need to change theprogramming of BubbleDeck deliveries and/or manufacture in response to such events pleaseimmediately inform us so we can then re-programme to your requirements. Once BubbleDeck trailershave left our factory we regret we are unable to defer site delivery without passing on additionaltransport and storage / trailer hire costs. We have even advanced deliveries to keep up with quickerthan expected progress constructing BubbleDeck slabs on site.

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    BubbleDecks Construction Package

    As part of our service we will supply you with the following construction information, advice, productsand assistance:-

    Project Stage Service / ProductBubbleDeck Design Engineering Design of BubbleDeck floor slabs & drawings.

    Submitting design to you for review and sign-off. Liaison withyou about any checking engineer / Approved Inspector queriesand providing further information as required.

    BubbleDeck DrawingProduction

    Preparation of manufacturing and construction drawingscomprising i) Element layout plan, ii) Loose bottom reinforcement(site installation), iii) Loose top reinforcement (site installation), iv)Bubble pattern v) Pre-cast reinforcement (incorporated intoelements at factory). Submitting drawings to you & Consultantsfor review and sign-off.

    Construction Planning Preparing programme for manufacture and supply of products tosite, agreeing with you and placing orders for materials andmanufacturing.

    Preparation of bar bending schedules for loose reinforcement.

    Providing site operatives with product induction seminar.Product Advice and Support Providing our advice on technical and practical construction issues.

    BubbleDeck Site Erection and Installation Manual.BubbleDeck Health & Safety Policy.Quality and Delivery Control Forms.

    Manufacturing Product Manufacture of filigree elements comprising top / bottom meshreinforcement / additional bar reinforcement / plastic bubble voidformers / 60mm pre-cast concrete layer.

    Loose Reinforcement Manufacturing and supplying all loose reinforcement required tocomplete BubbleDeck slabs.

    Site Delivery Monitoring and arranging BubbleDeck Filigree Elements & loosereinforcement delivery, on time, using between 8 metre to 13.6 metrelong flatbed trailers.

    Site Support Technical advice and guidance to yourselves and site operatives onsite installation & construction works.

    Site Inspections Site inspections of BubbleDeck installation & loose reinforcementchecking prior to casting of in-situ concrete.

    Insurance / Guarantees Following completion of works on site and account settlemententering into suitable Collateral Warranty/s (subject to wordingacceptable to our Insurers) as may be required and provision of ourProfessional Indemnity & Public Liability Insurance cover.

    Concrete Column / Wall Construction

    Important: In accordance with good practice and British Standards DO NOT overpour r.c.columns / walls in order to avoid reducing the slabs effective depth at support locations. Onlyuse enough concrete to bring r.c. columns / walls up to the underside of the BubbleDeck flat slablevel. In the event r.c. columns / walls are concreted above this level our inspector may requirethe concrete to be cut down around the perimeter of r.c. columns / walls to ensure adequateconnection with the BubbleDeck slabs.

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    Combined Column / Wall & BubbleDeck Construction Method

    While sequencing of site operations is your responsibility to decide we recommend the most efficientmethod, saving valuable site time and overheads, is to plan construction of supporting r.c. columnsand walls together with the BubbleDeck floor slab in one combined erection operation as detailed inthe following table:-

    Stage Operation Activities1 Column / wall

    reinforcement & formwork(Prior to BubbleDeck

    element delivery)

    a) Fabricate & erect r.c. column & wall reinforcement.b) Fabricate formwork shuttering with horizontal plywood topflange 200mm wide extending out from vertical shuttering &bracket supported by vertical shuttering.

    2 Temporary Propping(Prior to BubbleDeck

    element delivery)

    a) Erect Temporary Propping beams. (Refer to Stage 1 below)b) Erect formwork shuttering and (when suitable stable proppingsuch as SGB GASS system is used) brace upper formwork offtemporary propping frames.

    Note: When column / wall formwork is to be braced off slab it willbe more convenient to erect this before erecting temporarypropping)

    3 BubbleDeck ElementErection

    a) Receive, lift and place BubbleDeck elements onto temporarypropping beams. (Refer to Stage 2 below)

    4 Loose Reinforcement a) Install BubbleDeck loose reinforcement (Refer to Stage 3below)

    5 Slab shuttering a) Fabricate and erect perimeter & tolerance joint shuttering(Refer to Stage 4 below)

    6 Slab Preparation a) Prepare columns, walls and BubbleDeck slab for concreting(Refer to Stage 5 below)

    7 BubbleDeck Site Inspection a) Notify us of the date set for concreting (Refer to Stage 6below)

    8 Pouring Site Concrete a) Pour concrete firstly into columns and walls, vibrate andcompact. Then as a continuous process pour concrete ontoBubbleDeck slabs (Refer to Stage 7 below)

    This combined erection method has the advantages of a) Condensing a two stage sequence(erecting & casting columns / walls first and then BubbleDeck slabs second) into a one stagesequence; b) Providing s stable & firm platform for casting columns / walls; c) Eliminatingseparate concrete deliveries for columns / walls and slabs; and d) ensuring a good bondbetween column / wall and BubbleDeck slab site concrete.

    Stage 1 Erect Temporary Propping

    During erection each slab must be placed on suitable temporary propping beams arranged in parallelrows mounted on props sufficient to adequately support the weight of the pre-cast filigree elementsplus the loose reinforcement fixed on site, concrete poured on site and all other site construction loadsapplied during final pouring of the concrete topping and curing of the slab.

    The maximum distance between propping beams must not be greater than 1.8 metres The maximum distance of the propping beams from slab edges must be as follows:

    - from an edge where a slab is supported on brick or concrete walls 300mm- from an edge next to construction tolerance joints 200mm

    Propping beams must be at right angles to the direction of the reinforcement girders pre-cast in theelement. Normally the girder reinforcement is placed parallel to the length of each slab but this mustalways be checked against the manufacturing and installation drawings. The propping beams, and

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    individual props below, must form a stable platform prior to placing filigree elements onto them andmaintained stable during casting of the site concrete.

    Important: Removal of the temporary propping is NOT allowed before each slab is curedsufficient to support its own weight and temporary construction loads.

    Typical cross-section of temporary propping system

    Back-ProppingWhen consecutive floor slabs within one block are to be constructed above each other either:- a) theslab below the one being constructed must be back-propped, or alternatively b) each completed slabmust be self-supporting within the maximum allowed deflection.

    Option a) Prior to erecting propping for the next, subsequent, slab above the completed slab removethe propping from below the completed slab and erect back-props at 1.8m intervals (without parallelbeams) at either mid-span or third-span, dependant upon length of spans involved.

    Option b) Prior to erecting propping for the next, subsequent, slab above loosen the props below thecompleted slab, to allow the floor to reach its maximum deflection, and then tighten the props again.This is to ensure additional loads from the slab being erected above is taken on its own props ratherthan adding to loads onto the floor directly below, avoiding weight accumulation from consecutivefloors placing unnecessary strain on props and other construction elements.

    Typical arrangement of props and propping beams

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    Stage 2 Delivery, Offloading and Lifting Elements

    Site Delivery: We deliver the elements on flatbed trailers typically between 12m to 13.6m long,excluding drivers cab. The filigree elements will be stacked on top of each other up to a maximum 2.1metres overall height. For example, with BD280 slabs there will be maximum 7 layers of slabs, with atransport height of 250mm each plus wooden packers typically 50mm deep separating each element,making an overall height of 2.1 metres above the trailers bed. Each individual load will be planned sothe weight of a load will be a maximum 25.3 Tonnes and you must provide suitably hard and levelaccess for our delivery transport to reach the offloading position you have determined.

    Important: Upon arrival of the delivery trailers on site it is your responsibility to carefully inspectthe filigree elements for quality and to ascertain any damage that has been incurred duringtransport. Any damage to the filigree elements, or other unacceptable characteristics, must bereported by you to us by entering the details on our Quality and Delivery Control Form and faxingthis back to our Head Office within 2 hours of trailer arriving on site. Once the elements havebeen lifted off the trailer we may be unable to determine when any damage occurred and in thisevent we cannot accept responsibility.

    Following your inspection the delivery driver will require you to sign the Quality and Delivery ControlForm to confirm you have received the elements, which will be retained by him / her for our records.After removing all the filigree elements from the flatbed trailer the wooden transport packing beams /blocks must be replaced back onto the trailer before it leaves site, for return to our factory and re-use.Any transport materials that are not returned to our transport operator will be contra-charged by us toyour account.

    Loaded trailers arriving on site

    Offloading Filigree Elements: It is your responsibility to provide attendance and adequatemechanical equipment (fixed or mobile crane with minimum 6 Tonne lifting capacity) for offloadingelements from the trailers upon their arrival at site. For optimum working efficiency werecommend you plan site operations to allow the filigree elements to be lifted off thetrailers and moved straight into their final position on the temporary propping.

    However, for transport efficiency and safety some elements are loaded onto the trailer out ofsequence to their erection order, in which case or in the event of site circumstances preventing finalplacing the filigree elements can be temporarily stored elsewhere on site. The elements must betransversely supported on timber packers laid between the bubble rows (sat on the topreinforcement mesh) at maximum 1.8 metres centres resting on flat, level, ground and protected fromsoiling by mud, dirt, or other materials. Elements can be stacked on top of each other to a maximum7 layers high.

    While we will organise and plan deliveries in accordance with your programme as earlier agreedwith us (refer to Pre-construction Planning above) we are unable to accept any responsibility for

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    any delays with deliveries or construction progress arising from events outside our control suchas unexpected access restrictions or force majeure.

    Lifting and Placing Filigree Elements: The filigree elements must ONLY be lifted by the lattice beamgirder reinforcement. Lifting hooks must ALWAYS be attached under the upper angles of the girderreinforcement diagonal web bars. Lifting hooks must NEVER be attached to the upper reinforcementmesh as this would be unsafe.

    Lifting hooks under girder diagonal web bars

    It is your responsibility to organise and provide suitable lifting equipment All lifting equipment formust be tested and certified capable of lifting a minimum of 6 Tonnes, appropriate for thepurpose as described below, and must meet all legal health and safety requirements.

    Each individual element requires the use of EIGHT lifting hooks, in 2 parallel rows of 4 hooks eachattached around the lattice girders positioned approx. 1/5 of the total element length in from each end.The upper part of the hoisting system (4 suited chains) must be at least 6 metres minimum in length.Chain branches to the eight lifting hooks must be equal lengths. When in use, care should be takenthat lifting forces are equal at each lifting hook point and the element remains horizontal during lifting.Before lifting attach suitable ropes at two opposite corners of the element for guiding element intoposition on the propping beams

    Typical lifting chain configuration

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    Lifting element into position

    Positioning of Filigree Elements on Propping: It is important the elements are lifted into position inthe planned erection system, and care is taken with correct positioning of the elements. Each elementmust be positioned the correct way round (often obvious from position of column cut outs and buildingshape, but please refer to element installation drawings) so the top chamfer along the longitudinaledge is butted up to the adjacent elements vertical longitudinal edge. Adjacent elements must NOThave their top chamfers facing together.

    Important: During final positioning of the elements ensure the bubble pattern between adjacentelements are aligned as shown on the installation drawings, so the spaces between bubble rowson adjacent elements line to facilitate inserting splice reinforcement across the element joints.

    Aligning bubbles between element s

    For quick installation of the bottom splice reinforcement we recommend when the first element is in finalposition the bottom splice bars are temporarily slid fully in between the bubble rows on top of the pre-cast concrete layer before the adjacent element is placed. At a later stage please remember to slidethe bottom splice bars back across the element joint between the bubble rows in the adjacent element,so the bars are finally positioned half in one element and half in the adjacent element prior toconcreting.

    Sliding bottom splice bar central over joints

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    Site Adjustment of Filigree Elements: The filigree elements are designed and manufactured to suitthe buildings configuration and column / wall layout. They arrive on site with cut-outs / recesses / stepsfor column or wall positions (including a 100mm shear zone margin between r.c. columns / walls andthe pre-cast concrete layer) and larger service holes already formed, therefore they should not requireany site adjustment. However it has been known for columns to be erected out of position on site andin this unusual event it is possible to carefully alter the filigree element with a disc cutter to maintain the100mm shear zone margin between r.c. columns / walls and the elements pre-cast concrete biscuit.

    Important: The upper and diagonal bars in the lattice beam girder reinforcement must NOT be cuton site as they have an important structural function both during lifting and once in place.

    Lattice beam girder

    Cut-Outs, Recesses and Service Holes: During the manufacturing process polystyrene void formersare fixed in these locations to create areas without any concrete bottom biscuit. During erection of theelements these are quickly broken out with a suitable mallet.

    Stage 3 - Fixing Loose Reinforcement.

    We provide site installation drawings for reinforcement fixed at the bottom of the slab (directly on top ofthe pre-cast concrete biscuit formwork without spacers or on top of site shuttering on spacers) andreinforcement fixed at the top of the slab (directly on top of the top mesh reinforcement), together withaccompanying bar bending schedules. These must be studied and closely followed at all times, if youhave any question please call our site support officer or Head Office for assistance. The sequence forfixing loose reinforcement is at your discretion, however we recommend the following procedure isadopted:-

    Typical Reinforcement Type Installation / Fixing Procedure1. Bottom Joint Splice bars Inserted loose between every bubble directly on top of the pre-

    cast concrete biscuit permanent formwork. If they have beeninserted into one element during lifting elements into position, aswe recommend, then simply slide the bars across the jointbetween adjacent elements to sit with equal lengths both sides ofthe joint between elements.

    2. Bottom Shear bars Inserted loose between bubbles in positions shown on drawingsacross holes, openings and returns in slabs where applicable

    3. Beam Strips within slabdepth

    Where applicable assemble bars into cages and fix between and / oraround columns (if shown on drawings)

    4. Perimeter Hairpins / Bars Slide hairpins in between bubble rows and slide in top / middle/ bottom edge bars around slabs perimeter, tying to hairpins asshown on drawings

    Do not cut top bar

    Do not cut diagonal bars

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    5. Column Shear Reinforcement Insert bottom bars across columns directly on top of the pre-castconcrete bottom formwork. Fix bars over top mesh reinforcement(between the bubbles) across and around column heads as shownon drawings, tying in place to mesh.

    Note: where shear studs or shear rails have been pre-cast intoelement at factory there may not be any bars to be fixed on site.

    6. Top Joint mesh / bar reinforcement

    Purpose made mesh sheets are placed with the bars between bubblerows and tied in place equally across the joint between adjacentelements. In certain locations, for engineering reasons, splice barswill be placed equally across the element joints between bubble rowsand tied to the top mesh reinforcement, as shown on the drawings.

    Other loose Reinforcement As building configurations vary it is not possible to describe allpossible non-typical loose reinforcement configurations (such ascages for steps between main slab and cantilever slab) requiring sitefixing. This non-typical reinforcement will be shown and detailed onthe site installation drawings.

    Important: Top joint mesh reinforcement must fit between the bars above columns to avoidexcessive layers of steel and difficulty with achieving required concrete cover.

    Stage 4 Constructing Shuttering

    Once the perimeter loose reinforcement has been installed work on erecting perimeter andconstruction joint shuttering can commence. Temporary works are your responsibility to determine, butour recommendations are:-

    Location Shuttering Erection ProcedurePerimeter Shuttering Cut sheet of 18mm ply into strips with width of finished slab

    depth. Fix 75x50mm battens along back edge at top and bottom.Where BD element is tight to edge of finished slab simply plugand screw through bottom batten & ply shuttering straight intocentre of pre-cast concrete permanent formwork edge. Fix topof ply shuttering by wire tying back to top mesh reinforcementfrom screws fixed into top batten.

    When an in-situ concrete edge strip has been planned to makeup the overall floor-plate width then construct perimetershuttering with timber gallows brackets & plywood perimeter /soffite shuttering in traditional manner, except bracket bottombatten can be plugged and screwed to underside of pre-castconcrete permanent formwork.

    100mm shear zone marginaround r.c. columns / walls *

    Cut sheet of 18mm ply into strips 200mm wide, plug and screw50x50 battens to face of r.c. columns / walls (top 18mm belowslab soffite), slide ply into position. Plug and screw external edgeof ply shuttering into underside of pre-cast concrete permanentformwork.

    * Note: When our combined column / wall and BubbleDeckconstruction method is adopted (see page 6) the pre-assembled column / wall formwork top flange eliminatesany need for this operation.

    80mm construction tolerancejoints

    Cut sheet of 18mm ply into strips 180mm wide and prop up tounderside of pre-cast concrete permanent formwork.

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    Note: We can manufacture and supply cast into elements a pre-formed BubbleDeck Fast Edgesteel permanent formwork, eliminating the need for constructing perimeter shuttering on site enquire for further details at time of placing order.

    Stage 5 Preparation for ConcretingThe pre-cast concrete permanent formwork edges are manufactured to a high accuracy and caretaken to get a tight joint during laying the elements can render joint filling unnecessary. When jointsbetween slab elements have not been closely butted they must be filled to prevent grout seepage.Should this be required joint filling can be undertaken with either mortar grout or a small bead ofsilicone sealant inserted at the bottom of the splay joint between elements. This is most easilyundertaken prior to installing the loose splice reinforcement.

    Important expanding foam must NOT be used for joint filling as the uncontrollable thicknesscan adversely reduce concrete cover to splice reinforcement impairing durability and fireresistance of the finished slab.

    Prior to pouring topping concrete remove element labels, unused tying wire, unused reinforcement,loose concrete and all other debris or foreign matter. Then immediately before placing in-situ concretepower-wash top of the pre-cast concrete permanent formwork to clean off residual dirt and moisten thepre-cast concrete surface.

    Important maintain the pre-cast concrete biscuit top surface, particularly during hot weather, ina damp (not wet) condition to ensure a good bond between the pre-cast concrete permanentformwork concrete and the in-situ concrete.

    Stage 6 BubbleDeck Site Inspection

    Once you are able to predict when all loose reinforcement will be fixed please contact our Site SupportAdviser to notify the date you intend to pour concrete and arrange our site inspection. He will thenarrange for our technical representative to visit site and undertake a full inspection of the BubbleDeckelement and loose reinforcement installation. Following inspection our technical representative willissue you with an inspection record listing any work that needs to be undertaken prior to siteconcreting, or confirming the installation is ready for concreting and the work is to our approval.

    Important - While we always seek to provide a quick and efficient service we do need at least 2working days notice of any site concrete pour to be able to ensure our inspection team areavailable to attend site. It is essential we are able to inspect prior to site concreting in order tobe able to covert your project with our Professional Indemnity and Product Liability Insurancecover.

    Stage 7 Pouring Topping Concrete

    Important When ordering concrete please take into account the volume taken up by the bubblevoid formers mean the concrete volume is NOT arrived at by taking the pour area x depth fromtop of shuttering to pre-cast concrete permanent formwork. The concrete volume to order can beestimated, dependant upon BubbleDeck slab depth type, from the following table:-

    BubbleDeckSlab Type

    Overall Slab Depth(inc. pre-cast filigree)

    Concrete pour Volumem3 / m2 plan area

    Max aggregatesize

    BD230- A 230 mm 0.108 10mmBD280 -A 280 mm 0.141 10mmBD340 -A 340 mm 0.185 15mmBD390 -A 390 mm 0.213 15mmBD450- A 450 mm 0.247 15mmBD520- A 520 mm 0.294 15mmBD600- A 600 mm 0.341 15mm

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    When pouring concrete evenly distribute across the area and avoid placing in heaps. Due to thelimited space between the bubbles a thin vibrating poker MUST be used to compact the concrete,remove any entrained air and to ensure a good flow around the bubbles. Avoid separation occurringdue to the vibrating of shuttering, reinforcement and/or bubbles that can result in segregation of theconcrete mix. Once the concrete has been poured a steel beam or power float is then used to levelthe top and finish to an even and level surface.

    Pouring, Vibrating & Floating Site Concrete

    Stage 8 Removing Temporary Propping

    During construction planning we will confirm to you the minimum period for removal of propping beforeback-propping. This is usually between 8 to 14 days from pouring of the site concrete as long as the 7or 14 day concrete test results have confirmed the site concrete has reached at least 60% of its finaldesign strength, but can vary dependant upon our floor slab design, strength of site concrete, andambient temperatures.

    Once you have received the 7 day concrete test results please forward them to our Head Office, ourtechnical team will then confirm to you it is acceptable to remove temporary propping. If you are thenproceeding to construct another floor immediately above the one just completed please refer to thesection about Back Propping on Page 7 of this Manual.

    Subsequent Site Operations

    Lightweight FixingsThere is a minimum of 20mm concrete below the centre of each bubble, but just a short distance awayfrom the bubble centre the concrete depth quickly increases to 70mm plus up the side of each bubble.Therefore fixings for attaching light and medium weight articles can be made using normal methods(plug & screw / expanding anchors, etc.) to provide adequate fixings for wiring conduits, small cabletrays, small ventilation ducts and the like.

    Heavy Weight FixingsWhere stronger fixings are required to resist higher pull out (downward) forces from heavy loads to besuspended from the soffite we recommend our Bubble layout drawings are inspected to determinewhere fixings will occur directly below or close to the edge of a bubble. Where fixing locations andlengths are likely to project into a bubble void we recommend Hilti HIT HY20 Injection Resin Anchorwith HIT sieve, item no. 00068613, are used. Hilti also produce a range of other fixing systemsdesigned for fixing through into voids.

    Holes through slabsHoles can easily be diamond core drilled through the completed BubbleDeck slab. Due to the two wayspanning attributes of BubbleDeck slabs there are few limitations on the positioning of holes, exceptnear columns where loads are transferred from the slab into the columns and shear forces are highest.

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    Service risers larger than 250mm square should be designed into the slab for forming in the factory &boxing out on site prior to pouring insitu concrete. Pipe holes up to around 250mm diameter are bestdiamond core drilled after casting of slabs to ensure optimum vertical alignment. There is great flexibilitywhere these can be placed because the slab will span around such holes. The only limitations are toavoid cutting off too much support when holes are formed near supporting columns / walls, or a seriesof holes in a row in certain situations, but these can be allowed for during design stage.

    Prior to forming holes in completed slabs larger than 250mm diameter, within 500mm of a supportingcolumn / wall, or multiple holes in close proximity please refer to our Technical Department for advicebefore undertaking such works.

    BubbleDeck UKUK Office4 Firs Close, Ellesmere Road,St Martins, Nr Oswestry,Shropshire, SY11 3LTTelephone: +44 (0)1691 774242Facsimile: +44 (0)1691 774294E-Mail: [email protected]

    BubbleDeck Site Erection & Installation ManualEdition 4C September 2006

    Head Office, Channel Islands, &IrelandWhite Lodge, Wellington Road,St. Saviour, JERSEY, C.I., JE2 7TETelephone: +44 (0)1534 725402Facsimile: +44 (0)1534 739115E-Mail: [email protected]

  • BubbleDeckTests and Reports Summary

    June 2006 Issue 1

    BubbleDeck UK Head OfficeWhite Lodge,Wellington Road,St. Saviour, JERSEY, C.I., JE2 7TETelephone: +44 (0)1534 725402Facsimile: +44 (0)1534 739115E-Mail: [email protected]

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    Results from Tests, Studies and Reports

    Tests have been carried out in Denmark, the Netherlands and in Germany.The conclusions are unambiguous:

    BubbleDeck will distribute the forces in a better way (an absolute optimum) than any other hollow floorstructures.Because of the three-dimensional structure and the gentle graduated force flow, the hollow spheres will haveno negative influence and cause no loss of strength.

    BubbleDeck behaves like a spatial structure - as the only known hollow concrete floor structure.

    The tests reveal that the shear strength is even higher than presupposed.This indicates a positive influence of the balls. Furthermore, the practical experience shows a positive effectin the process of concreting the balls cause an effect similar to plasticiser additives.

    All tests, statements and engineering experience confirm the obvious fact that BubbleDeck:-

    in any way acts as a solid deck and therefore

    will follow the same rules/regulations as a solid deck (with reduced mass), and further,

    leads to considerable savings

    Contents

    A. Bending Strength and Deflection behaviour 3

    B. Shear Strength 3

    Punching Shear 4

    Dynamic Punching Shear 5

    C. Anchoring 5

    D. Fire 5

    E. Creep 6

    F. Sound 6

    G. In General 7

    H. Comparison of Cost Price 7

    Miscellaneous 8

    Savings 8

    Approval by Authorities 8

    Conclusion 9

    Appendix 1 - Tests and Reports References

  • Page 3 of 10

    A. Bending Strength and Deflection Behaviour

    Report from the Eindhoven University of Technology / the Netherlands Enclosure A1.

    The dissertation is executed hand in hand with the Technical University of Delft / the Netherlands.

    BubbleDeck is compared to a solid deck both practically and theoretically.The behaviour is exactly as for a solid deck, both for short- and long-term situations.The results are shown for the deck thickness 230 mm (type 1) and 455 mm (type 2).

    Test Report (Biegung) from the Technical University of Darmstadt / Germany - Enclosure A2.

    The results from practical tests are compared with a theoretic analysis, concluding consistencybetween theory and practice.The differences in deflections are very small, and explained by a slight difference in stiffness:

    In % of a solid deck BubbleDeck vs. solid deck

    Same strength Same bending stiffness Same concrete volume

    Strength 100 105 150 *

    Bending stiffness 87 100 300

    Volume of concrete 66 69 100

    * On the condition of the same amount of steel. The concrete it self has 220 % greater effect.

    Based on the report, articles have been published in the: Darmstadt Concrete (Annual journal on Concreteand Concrete Structures) - Enclosure A3, summarising several tests.

    B. Shear Strength

    The results of a number of practical tests confirm - once again the obvious - that the shear strengthdepends only on the effective mass of the concrete.For calculating, a factor 0.6 is used on the shear capacity for a solid deck of identical height.This guarantees a large safety margin.

    Report from AEC Consulting Engineers Ltd. / Professor M.P. Nielsen - The Technical University of Denmark Enclosure B1.

    The shear strength as well as punching shear was tested.The tests were carried out on test elements with thickness on 188 mm.The shear capacity was measured for the ratio of a/d (distance from imposed force to support dividedby deck thickness) on 1.4.

    Shear strength (bending)The shear capacity is measured to 81 % compared to a solid deck.

    Punching shearThe average shear capacity is measured to 91 % compared to the calculated values of a solid deck.

    Report from A+U Research Institute / Professor Kleinmann - the Eindhoven University of Technology / theNetherlands Enclosure B2.

    A solid deck is compared with two types of BubbleDeck one with loose girders (type L) and one withsecured girders (type V) deck thickness of 340 mm.The shear capacity is measured for two ratios of a/d (distance from imposed force to support dividedby deck thickness). The results were:

  • Page 4 of 10

    Shear capacity (in % of solid deck) a/d = 2.15 a/d = 3.0

    Solid deck 100 100

    BubbleDeck, secured girders 91 78 (81)1

    BubbleDeck, loose girders 771 Corrected for test-elements with longer time for hardening

    Darmstadt Concrete (Annual journal on Concrete and Concrete Structures) - Enclosure B3.

    Based on the test report (Biegung) from the Technical University of Darmstadt in Germany(Enclosure A2). a/d = 3.7The shear capacity is measured to 72 78 % of a similar solid deck.

    Report "Optimising of Concrete Constructions" / John Munk & Tomas Moerk - The Engineering School inHorsens / Denmark Enclosure B4.

    A solid deck is compared with BubbleDeck no girders were used (only binding wire) in the samples deck thickness of 130 mm.The shear capacity is measured for a ratio of a/d (distance from imposed force to support divided bydeck thickness) of a/d = 2.3. The results were:

    Shear capacity (in % of solid deck) a/d = 2.3

    Solid deck 100

    BubbleDeck, no girders 76

    Punching Shear

    Report from AEC Consulting Engineers Ltd. / Professor M.P. Nielsen - The Technical University of Denmark Enclosure B1. The average shear capacity is measured to 91 % compared to a solid deck.

    Darmstadt Concrete (Annual journal on Concrete and Concrete Structures) - Enclosure B3.

    Tests were conducted with BubbleDeck slabs of 230 and 450 mm.Local punching did not occur. The crack pattern was similar to the crack pattern of solid decks.

    The test results are summarized in the following graph:

    Shear capacity

    0

    20

    40

    60

    80

    100

    120

    0.0 1.0 2.0 3.0 4.0

    a / d (distance from imposed force to support divided by deck thickness)

    Cap

    acit

    y in

    % o

    f a s

    olid

    de

    ck

    Solid deckBubbleDeck (experimental - average values)BubbleDeck (theoretical)Design value

  • Page 5 of 10

    Dynamic Punching Shear

    Report, "Punching Shear Strength of BubbleDeck" by Anders Brnden, Jens Christian Haukohl and MartinHoft Jrgensen - The Technical University of Denmark Enclosure B5.

    The normalized ultimate load is defined by:

    ( )hdu,perimetercontrol;fhu

    P

    f cc

    u +=

    =

    which, used on the experimental results, gives the following Whler chart:

    Whler chart of dynamic tests

    y = 0.024x -0.044

    0.000

    0.005

    0.010

    0.015

    0.020

    0.025

    0.030

    0.035

    0 500 1000 1500 2000 2500 3000 3500 4000

    Number of applied stresses (in thousands)

    No

    rmal

    ized

    ult

    imat

    e lo

    ad

    u

    / fc

    C. Anchoring

    Test Report by Koning & Bienfait b.v. / The Netherlands Enclosure C1.

    Three test blocks of BubbleDeck are compared with three test blocks of a solid deck samereinforcement. The anchoring in the two types is identical.The balls do not influence the anchoring.

    Report BYGDTU R-074 2003 by Gudmand-Hyer - Technical University of Denmark Enclosure C2

    A guidance to calculate the Moment Capacity in a BubbleDeck joint.

    D. Fire

    TNO-Report for the Weena Tower / Rotterdam Enclosure D1

    330 mm deck is fire-safe 60 minutes with concrete cover 20 mm.

    TNO-Report - Enclosure D2

    230 mm deck is fire-safe in 120 minutes with concrete cover 35 mm.

    TNO is waiting for the CUR-Committee presenting new proposals to concrete regulationsconsidering BubbleDeck. As soon as CUR present their conclusions for BubbleDeck, TNOwill change their recommendations.

    Until then TNO recommends to follow the present hollow core regulations, saying:

    Separation: No separation due to fire for at least 120 minutes.

  • Page 6 of 10

    Bending moment: Satisfactory up to a span of 6.6 m with reinforcement 08/10.The span can be increased following an increase in steel dimensions.

    Shear stress: No problems are expected.

    TNO admits that BubbleDeck is closer to the solid deck than to the hollow core deck.

    A draft calculation over the internal pressure from heated air - Enclosure D4

    Heated air imposes no influence (no danger) on the construction.

    German Test Certificate Number P-SAC 02/IV-065 according to DIN 4102-2 - Enclosure D3

    The German "Materialforschungs- und Prfungsanstalt fr das Bauwesen Leipzig e.V." has issued theGerman Test Certificate Number P-SAC 02/IV-065 concerning Fire Resistance according to DIN4102-2 (in accordance with ISO 834-1).

    Design recommendation: The minimum concrete cover of the lower reinforcement as a function of theperiod and the fire resistance:

    Fire resistance (min)Steel stress Steelutilization 30 60 90 120 180

    190 66 % 17 mm 17 mm 17 mm 17 mm ---

    286 100 % 17 mm 29 mm 35 mm 42 mm 55 mm

    E. Creep

    Report from the Eindhoven University of Technology / the Netherlands Enclosure E1.

    No significant difference between BubbleDeck and a solid deck.

    Darmstadt Concrete (Annual journal on Concrete and Concrete Structures) - Enclosure E2.

    No significant difference between BubbleDeck and solid deck.Differences can be due to the fact that the tests only were considered in a one-way-span.

    F. Sound

    Report from Adviesbureau Peutz & Associes bv: Comparison of BubbleDeck vs.Hollow core Enclosure F1.

    A comparison was made between BubbleDeck and hollow core deck prior to the construction ofWeena Tower. Deck types of similar height were compared.The noise reduction with BubbleDeck was 1 dB higher than hollow core.

    The main criteria for reducing noise is the weight of the deck and therefore BubbleDeck evidently willnot act otherwise than other deck types with equal weight.

    German Test Certificate Number P-SAC 02/IV-065 concerning solid and live load Sound insulation Enclosure F2.

    The German "Materialforschungs- und Prfungsanstalt fr das Bauwesen Leipzig e.V." has issued theGerman Test Certificate Number P-SAC 02/IV-065 concerning solid and live load Sound insulation accordingto DIN EN ISO 140 / DIN ISO 717.

  • Page 7 of 10

    The results for 230 and 340 mm decks are:

    Soundinsulationdimension

    Additional spectrum adaptation values (DIN ISO 717-1)Standard

    impact soundlevel

    Deck Rw (C;Ctr) C50-3150 Ctr50-3150 C50-5000 Ctr50-5000 C100-5000 Ctr100-5000 Lc,w (C1;C50-3150)mm dB dB dB dB dB dB dB dB

    230 55 (-2 ; -7) -2 -8 -1 -10 -1 -8 78 (-11 ; -12)

    340 57 (-2 ; -7) -3 -9 -2 -7 -2 -9 76 (-13 ; -13)

    Test Report from Adviesbureau Peutz & Associes b.v.: Sound Resistance. March 2004 - Enclosure F3.

    Field tests in a raw building in Leiden, the Netherlands, concerning Air and Contact Noise-resistance.The slabs were BD 230 mm with a fixed floor layer of 30 mm.The measurements and ratings were carried out in regulation with ISO 717-1:1996 and NEN5077:2001

    Weighted Sound Reduction (vertical) Rw (C;Ctr) = 54 (-1; -14)Reduction Index for Airborne Sound llu = + 3Impact Resistance Level (vertical) Ln,Tw (C1) = 72 (-14)Reduction Index for Impact Sound lco = + 2Impact Resistance Level (horizontal) Ln,Tw (C1) = 63 (-13)Reduction Index for Impact Sound lco = + 10

    Test Report from Ian Sharland Ltd : Airborne and Impact Sound Insulation. Nov 2005 - Enclosure F4.

    Field tests in Le Coie Housing Development in St. Helier, Jersey, concerning Airborne and ImpactSound Insulation. The slabs were BD 285 mm, part of a standard party floor with ceiling and screed.The measurements and ratings were carried out in regulation with ISO 140-4:1998, ISO 140-7:1998,ISO 717-1:1997 and ISO 717-2:1997.

    The Vertical Impact (mean) was measured to: LnTw = 44 dBThe Vertical Airborne (mean) was measured to: DnTw = 59 dB

    The results show that the floor structures tested meet and significantly exceed the requirements of the BritishBuilding Regulations (2000)

    G. In General

    Report from the Eindhoven University of Technology / the Netherlands -Broad comparison of concrete floor systems. December 1997 Enclosure G.

    The advantages of BubbleDeck were not known at this early stage but nonetheless, BubbleDeckended on the top of the list.Afterwards it is recognised that "Flexibility", "Execution" and "Environment" are at a higher level (givingBubbleDeck at least 4 more points in this comparison).

    H. Comparison of Cost Price

    Report from the Eindhoven University of Technology / the Netherlands Enclosure H1.

    In connection to the general tests, a total cost price calculation of the Town Hall in den Haag is carriedout. The Town Hall was built with pre-stressed monolithic elements. The complete construction hasbeen evaluated in order to make a reliable comparison.

    Two types of comparisons were made:

  • Page 8 of 10

    1. BubbleDeck and a solid deck was compared in three various arrangements - alteration of placement ofcolumns. The calculations were made for increasing spans in the x-direction. For a given combination ofspan and deck thickness, BubbleDeck was 5 16 % less expensive than a solid deck.

    It is important to emphasize that the optimal combination of deck thickness and placement of columnswith BubbleDeck differs from a solid deck. A correct comparison must take this fact into consideration,which was made in the second comparison:

    2. Two variants of BubbleDeck were entered into the comparison.The result was clear the BubbleDeck building was significant less expensive than the traditionalsystem. The total savings was in the order of 20 %.

    Report from AEC Consulting Engineers Ltd. / Professor M.P. Nielsen - The Technical University ofDenmark Enclosure H2.

    Comparisons are made between BubbleDeck and solid decks.Only differences in materials concerning the slabs are considered. Advantages in the building designand building process are not taken into account.

    For the same amount of steel and concrete, BubbleDeck has 40 % larger span and is furthermore 15% cheaper.

    For the same span, BubbleDeck reduces the amount of concrete with 33 %, and reduces the price with30 %.

    Miscellaneous

    SavingsSavings can be expected in many respects. In the case of Weena Tower, the experience shows a reductionof 35 % in necessary time using the cranes. A very important aspect, especially concerning tall buildings,because of the large amount of downtime due to wind.

    Furthermore, the erection-cycle was reduced from 5 to 4 days per storey. This is confirmed through thefollowing projects where reductions of 1-2 days per storey were obtained.

    Subsequent works are simplified. Savings can also be expected throughout the buildings lifetime due to thehigh degree of flexibility.

    Approval by Authorities

    Dutch Standards

    From November 2001, BubbleDeck is incorporated in the Dutch Standards (by CUR CivieltechnischCentrum Uitvoering Research en Regelgeving) under CUR Recommendation 86 BubbleDeck slabs.

    UK Standards

    BubbleDeck can be treated as a normal flat slab supported on columns (BS 8110) according to CRIC(Concrete Research & Innovation Centre under the Imperial College of Science, Technology & Medicine),1997.

    Danish Standards

    BubbleDeck can be calculated from recognized principles and within existing standards - Directorate ofBuilding and Housing, Municipality of Copenhagen, 1996.

  • Page 9 of 10

    German Standards

    BubbleDeck can be used according to existing technical standards according to Deutsches Institut frBautechnik, 1994.

    Conclusion

    BubbleDeck will distribute the forces in a better way (an absolute optimum) than any other hollow floorstructures.Because of the three-dimensional structure and the gentle graduated force flow the hollowareas will have no negative influence and cause no loss of strength.

    BubbleDeck behaves like a spatial structure - as the only known hollow concrete floor structure.

    The tests reveal that the shear strength is even higher than presupposed.This indicates a positive influence of the balls. Furthermore, the practical experience shows a positive effectin the process of concreting the balls cause an effect similar to plastification additives.

    All tests, statements and engineering experience confirm the obvious fact that BubbleDeck,

    in any way act as a solid deck and consequently

    will follow the same rules/regulations as a solid deck (with reduced mass), and further

    leads to considerable savings

    BubbleDeck UKUK Office4 Firs Close, Ellesmere Road,St Martins, Nr Oswestry,Shropshire, SY11 3LTTelephone: +44 (0)1691 774242Facsimile: +44 (0)1691 774294E-Mail: [email protected]

    Channel Islands, Ireland & Head OfficeWhite Lodge,Wellington Road,St. Saviour, JERSEY, C.I., JE2 7TETelephone: +44 (0)1534 725402Facsimile: +44 (0)1534 739115E-Mail: [email protected]

  • Page 10 of 10

    Appendix 1 - Tests and Reports References

    A1 Report from the Eindhoven University of Technology / the Netherlands

    A2 Test Report (Biegung) from the Technical University of Darmstadt / Germany

    A3 Darmstadt Concrete (Annual journal on Concrete and Concrete Structures)

    B1 Report from AEC Consulting Engineers Ltd. / Professor M.P. Nielsen - The Technical University ofDenmark

    B2 Report from A+U Research Institute / Professor Kleinmann - the Eindhoven University ofTechnology / the Netherlands

    B3 Darmstadt Concrete (Annual journal on Concrete and Concrete Structures)

    B4 Report "Optimising of Concrete Constructions" - The Engineering School in Horsens / Denmark

    B5 Report "Punching Shear Strength of BubbleDeck" - The Technical University of Denmark

    C1 Test Report by Koning & Bienfait b.v. / The Netherlands

    C2 Report BYGDTU R-074 2003 - Ph.D. Gudmand-Hyer - Technical University of Denmark

    D1 TNO-Report for the Weena Tower / Rotterdam / the Netherlands

    D2 TNO-Report for 230 mm deck - fire-safe in 120 minutes

    D3 German Test Certificate Number P-SAC 02/IV-065 according to DIN 4102-2

    D4 A draft calculation over the internal pressure from heated air

    E1 Report from the Eindhoven University of Technology / the Netherlands

    E2 Darmstadt Concrete (Annual journal on Concrete and Concrete Structures)

    F1 Report from Adviesbureau Peutz & Associes b.v.: Comparison of BubbleDeck vs. Hollow core

    F2 German Test Certificate Number P-SAC 02/IV-065: Solid and live load Sound insulation

    F3 Test Report from Adviesbureau Peutz & Associes b.v.: Sound Resistance. March 2004.

    F4 Test Report from Ian Sharland Ltd : Airborne and Impact Sound Insulation. Nov 2005.

    G1 Report from the Eindhoven University of Technology / the Netherlands -Broad comparison of concrete floor systems. December 1997

    H1 Report from the Eindhoven University of Technology / the Netherlands

    H2 Report from AEC Consulting Engineers Ltd. / Professor M.P. Nielsen - The Technical University ofDenmark

  • Technical Paper

    BubbleDeck Slab Properties

    April 2006

    BubbleDeck LighterSlab Solutions

  • Page 2 of 4

    This BubbleDeck Technical Paper has been written to provide more detail on commonissues raised by Engineers covering 1) BubbleDeck slab thickness, 2) Shear propertiesnear columns, 3) Rebar quantity, and 4) Deflections.

    1. BubbleDeck increases slab thickness over and above alternative solutions

    In fact BubbleDeck consistently realises thinner overall structural zones than alternative structuralsolutions. Given equivalent spans and loadings BubbleDeck consistently realises a thinner slabcompared to a solid flat slab. The properties of a BubbleDeck slab compared to other slab typesshould be considered in terms of a) flexural strength, b) deflection, and c) shear which are eachconsidered below:-

    Flexural strength: BubbleDeck is conceived to omit a significant volume of concrete (comparedto a solid slab) in the central core where the slab is principally un-stressed in flexure. Whendesigning for flexural resistance, the depth of the stressed concrete in compression (often calledthe stress block) is concentrated within the solid concrete between the outermost extent of thebubble and the slab surface, whether the designer considers the stress block to be rectangular,recto-parabolic or other shape in accordance with accepted design methodology expounded inEC2 and BS8110. Sometimes, in heavily stressed slabs, the stress block will encroach slightlywithin the bubble zone but studies and tests have demonstrated this has an insignificant effect onthe resistance of a BubbleDeck slab in normal design situations and, to control this criterion, theBubbleDeck design guide gives a check to test whether the design is within this valid range.Therefore a BubbleDeck slab is equivalent, in terms of concrete stress, to a solid slab under allnormal building loadings.

    It is important to note the voids formed by the bubbles are not prismatic as in hollow core systems they are discrete volumes in a 2 dimensional array so they do not detract from the slab strengthand stiffness in the way that a prismatic void would.

    In a section at or approaching flexural ULS, the section will be fully cracked and the concretebelow the plastic neutral axis will be ineffective in any slab. Therefore this cannot be a source ofsupposed disadvantage. If the Engineer plots a stress and strain diagram through a typicalBubbleDeck slab section, it will be seen the redundant concrete (i.e. that which is not stressed)occurs wholly or almost wholly in the bubble zone. Since typically 30% or more of the weight ofthe slab has been omitted, this can be used in the design to justify either higher applied loadingsor longer spans so, in terms of the slab system, BubbleDeck is substantially more effective than asolid slab flat slab or otherwise.

    Deflection: Due to the bubbles a BubbleDeck slab is not as stiff as a solid slab but this effect issmall. Studies and tests have shown that BubbleDeck has approximately 87% of the flexuralstiffness of a solid slab. If no other measures were taken, this would mean marginally higherdeflections at SLS than in an equivalent solid slab in direct proportion to this ratio.

    However, the effect can be compensated for by adding a modest amount of steel even though thedeflection is significantly mitigated by the fact that BubbleDeck is lighter and in long term SLS,where frequently the load combination comprises 100% permanent load and a proportion such as33% imposed load, the permanent weight saving maximises BubbleDecks effect. Long term SLSis frequently the governing criteria for flat slab designs.

    Calculated long-term SLS combinations therefore favour BubbleDeck and frequent combinationimposed-load-only deflections can, if they are critical, be dealt with by a modest addition of steel(or even be ameliorated by rigorous design). It is therefore apparent BubbleDecks substantial

  • Page 3 of 4

    reduction of permanent load, considering deflection criteria, gives a substantial advantagecompared with alternative solid slab.

    Final design of BubbleDeck projects almost always incorporates rigorous deflection checkingusing FE modelling with modified element properties to take account of cracked sectionproperties and long-term material effects. This technique is well known to produce more accurateresults and these generally produce more favourable results for BubbleDeck slabs compared withsimplistic calculations.

    Shear: In any flat slab, design shear resistance is usually critical near columns. The shearstresses remote from the columns diminishes rapidly and outside the column zones it has beendemonstrated by testing and calculation the transverse and longitudinal shear stresses are withinthe capacity of the BubbleDeck system.

    Near the columns, bubbles are left out so in these zones a BubbleDeck slab is designed exactlythe same way as a solid slab. The BV girders incorporated within a BubbleDeck slab add to thelongitudinal shear resistance of the slab and it has been demonstrated the rate of change inbending moment near supports does not induce shear stresses in excess of the interface shearcapacity. This is part of the design process in critical cases.

    2. How is shear accounted for & calculated near columns.

    This follows on from the answer to the last issue. Bubbles are omitted around the columns in anarea, rectangular circular or oval as convenient, which is defined by the punching shear perimeterwhere the applied shear stress is exceeded by the capacity of the BubbleDeck voided slab. Theshear capacity of the voided slab has been shown to be approximately 2/3 the capacity of anequivalent solid section in design a conservative factor of 60% is usually employed.

    It must be noted again that the voids formed by the bubbles are not prismatic.

    Within the perimeter so defined, BubbleDeck is left solid without bubbles and the shear resistanceis calculated on the basis of a solid slab in the code dependent customary way. Shearreinforcement may be added, exactly as in a solid slab. Given equivalent spans, BubbleDeck hasthe capacity to produce lighter column loads and alleviate shear stresses. However, theadvantages of BubbleDeck are usually employed to maximise spans well beyond what can beachieved with a solid slab.

    As stated above, in critical situations, the interface shear is checked and the interface can bereinforced more heavily by adding additional girders if necessary. The applied shear is obtained,as explained in EC2 or BS8110, by calculating the forces each side of the interface from the rateof change of bending moments at each end of the segment considered and averaging this todeduce a longitudinal force per unit length. Both BS8110 and EC2 have methods for determiningthe shear resistance of interfaces between concrete poured at different times.

    3. BubbleDeck needs more rebar than alternative solutions

    One of the greatest advantages of BubbleDeck is that it removes the need for much, often poorlycontrolled, site operations by fabricating a large proportion of the slab off site in a factory undercontrolled conditions and using production techniques that are, through organised process, farmore productive than site work. This leads to large units that are simply transported to site, liftedinto position and the concrete poured.

  • Page 4 of 4

    However, for practical manufacturing, handling and transport reasons there is a limit to the size ofthe units and part of the BubbleDeck system is the splicing together of elements across the joints(retaining BubbleDecks 2 way spanning characteristic) along the sides and ends of the precastindividual elements, which is done using straight rebar and mesh. This does represent a modestincrease in rebar use over that strictly required for overall slab strength and stiffness. HoweverBubbleDeck, through its weight saving and rigorous design, is relatively frugal with steel and veryfrugal with concrete and this more than compensates for the small addition of splice bars.

    With BubbleDeck PT very modest rebar content can be realised as the advantages of posttensioning combined with weight saving are a winning combination.

    4. Deflections justify modifying the BS8110 span/depth criteria

    The modification of span / depth ratios given in BubbleDecks product literature and presentationsis only used for preliminary design scoping, to reflect the longer achievable spans resulting fromBubbleDecks lower slab dead weight. We do point out the adjusted ratios are only anapproximate guide, useful at feasibility stage for determining appropriate spans for a givenBubbleDeck slab depth. Experience has shown this rule of thumb adequately reflects the resultsfollowing full engineering calculation of a BubbleDeck slab.

    Beyond preliminary design scoping we do not rely on span-depth ratio methods (as is the case forflat slab design) except for slabs of minor importance or for cursory checks. A BubbleDeck slabshould be calculated in the normal way as far as deflection is concerned. Certainly, anyirregularity of spans in a flat slab design would largely invalidate span-depth ratio methods. Testscarried out at the full scale Cardington European Concrete Building Project demonstrate the poorcorrelation of results from various methods of deflection calculation with measurements on a realstructure.

    Again it must be noted the voids formed by the bubbles are not prismatic so one must notassume that the second moment of area of the un-cracked section is significantly depleted by thepresence of prismatic voids.

    During calculation of a BubbleDeck slab there is no modification to the span depth ratiosrecommended in BS8110 or EC2 except that the normal span depth ratio should be adjusted toreflect the 87% reduction in flexural stiffness (EI stiffness). In BS8110, the basic ratios are usedwith modifiers for overprovision of tensile and compressive reinforcement which affect the steelservice stress. In EC2, the basic ratios are also used and the modifiers obtained from equations7.16a & 7.16b which operate on the reinforcement ratios and concrete modulus implied by thecharacteristic concrete strength.

    When calculating deflection rigorously, it should be noted that the recommended level of crackingmoment in BubbleDeck is slightly lower (80%) than in an equivalent solid slab. This does notaffect ULS calculation since the section is fully cracked in that case.

    Eur Ing R A Beeton BSc CEng MICE, BubbleDecks Design Engineer, April 2006

    UK OfficeTelephone: +44 (0)1691 774242E-Mail: [email protected] Office, Channel Islands & IrelandTelephone: +44 (0)1534 725402E-Mail: [email protected]

  • BubbleDeck AcousticTests and Reports

    June 2006 Issue 3

    BubbleDeck UK Head OfficeWhite Lodge,Wellington Road,St. Saviour, JERSEY, C.I., JE2 7TETelephone: +44 (0)1534 725402Facsimile: +44 (0)1534 739115E-Mail: [email protected]

  • Page 2 of 3

    Acoustic Tests and Studies

    Tests have been carried out in Denmark, the Netherlands, Germany and in UK (Channel Islands).The conclusions are unambiguous:

    BubbleDeck performs acoustically in a better way than any other hollow or solid floor structures. Because ofthe three-dimensional structure and the gentle graduated force flow, the hollow spheres have a positiveinfluence on sound insulation.

    The tests reveal that airborne sound insulation is even higher than expected. This indicates the bubbles havea positive influence. Furthermore the combination of in-situ concreting on site with the semi pre-castelements produce a seamless finished slab without any joints, avoiding joint discontinuity associated withfully pre-cast planks (such as hollowcore) that can seriously impair sound insulation performance.

    BUILDING REGULATIONS CRITERIA

    Approved Document E, 2003 Edition: Floor Types 1 or 2 requires a concrete slab (cast in-situ or withpermanent shuttering) to have a minimum mass of either 365 kg/m2 (Clause 3.29 Floor Type 1.1C), or 300kg/m2 (Clause 3.67 Floor Types 2.1C and 2.1C(b)).

    Our thinnest BubbleDeck 230mm slab with a mass of 390 kg/m2 (95% full bubblepattern) exceeds Approved Document Part E requirement for Floor Types 1 or 2.All thicker BubbleDeck slab types have increased mass, exceeding Approved Document Part E requirementfor Floor Types 1 or 2, as follows:-

    Slab Type Thickness Mass kg/m2

    BD230 230mm 390BD280 280mm 484BD340 340mm 573BD390 390mm 694BD450 450mm 820

    TESTS AND REPORTS

    Report from Adviesbureau Peutz & Associes bv: Comparison of BubbleDeck vs.Hollow core Enclosure F1.

    A comparison was made between BubbleDeck and hollow core deck prior to the construction ofWeena Tower. Deck types of similar height were compared.The noise reduction with BubbleDeck was 1 dB higher than hollow core.

    The main criteria for reducing noise is the weight of the deck and therefore BubbleDeck evidently willnot act otherwise than other deck types with equal weight.

    German Test Certificate Number P-SAC 02/IV-065 concerning solid and live load Soundinsulation Enclosure F2.

    The German "Materialforschungs- und Prfungsanstalt fr das Bauwesen Leipzig e.V." has issued theGerman Test Certificate Number P-SAC 02/IV-065 concerning solid and live load Sound insulation accordingto DIN EN ISO 140 / DIN ISO 717.

  • Page 3 of 3

    The results for 230 and 340 mm decks are:

    Soundinsulationdimension

    Additional spectrum adaptation values (DIN ISO 717-1)Standard

    impact soundlevel

    Deck Rw (C;Ctr) C50-3150 Ctr50-3150 C50-5000 Ctr50-5000 C100-5000 Ctr100-5000 Lc,w (C1;C50-3150)mm dB dB dB dB dB dB dB dB

    230 55 (-2 ; -7) -2 -8 -1 -10 -1 -8 78 (-11 ; -12)

    340 57 (-2 ; -7) -3 -9 -2 -7 -2 -9 76 (-13 ; -13)

    Test Report from Adviesbureau Peutz & Associes b.v.: Sound Resistance. March 2004 -Enclosure F3.

    Field tests in a raw building in Leiden, the Netherlands, concerning Air and Contact Noise-resistance.The slabs were BD 230 mm with a fixed floor layer of 30 mm.The measurements and ratings were carried out in regulation with ISO 717-1:1996 and NEN5077:2001

    Weighted Sound Reduction (vertical) Rw (C;Ctr) = 54 (-1; -14)Reduction Index for Airborne Sound llu = + 3Impact Resistance Level (vertical) Ln,Tw (C1) = 72 (-14)Reduction Index for Impact Sound lco = + 2Impact Resistance Level (horizontal) Ln,Tw (C1) = 63 (-13)Reduction Index for Impact Sound lco = + 10

    Test Report from Ian Sharland Ltd : Airborne and Impact Sound Insulation. Nov 2005 -Enclosure F4.

    Field tests in Le Coie Housing Development in St. Helier, Jersey, concerning Airborne and ImpactSound Insulation. The slabs were BD 285 mm, part of a standard party floor with ceiling and screed.The measurements and ratings were carried out in regulation with ISO 140-4:1998, ISO 140-7:1998,ISO 717-1:1997 and ISO 717-2:1997.

    The Vertical Impact sound reduction (mean) was measured to: LnTw = 44 dBThe Vertical Airborne sound reduction (mean) was measured to: DnTw = 61 dB

    The results show that the floor structures tested meet and significantly exceed the requirements of the BritishBuilding Regulations (2000)

    BubbleDeck UKUK Office4 Firs Close, Ellesmere Road,St Martins, Nr Oswestry,Shropshire, SY11 3LTTelephone: +44 (0)1691 774242Facsimile: +44 (0)1691 774294E-Mail: [email protected]

    Channel Islands, Ireland & Head OfficeWhite Lodge,Wellington Road,St. Saviour, JERSEY, C.I., JE2 7TETelephone: +44 (0)1534 725402Facsimile: +44 (0)1534 739115E-Mail: [email protected]

  • Technical Paper

    Disproportionate Collapse

    Resistance Properties

    January 2006

    BubbleDeck LighterSlab Solutions

  • Page 2 of 5

    This BubbleDeck Technical Paper has been written to provide more detail about theinherent properties of BubbleDeck slabs in resisting Disproportionate Collapse.

    Buildings must always be designed to be stable, robust and resistant to a reasonable degree ofabuse, whether during construction or in use, regardless of their size. This is explicit in all of thedesign codes and Building Regulations. For buildings of medium to large size, there are specialprovisions to limit collapse, in accidental situations, to a limited area of the structure so that thedamage is contained and the occupants or those around the building may survive and so thatrescue and fire-fighters have a reasonable chance of entering the building after a damagingevent. This is known as the avoidance of disproportionate or progressive collapse and is arequirement in the Building Regulations intended to limit collapse so that it is not disproportionateto the cause.

    The history of this provision is vague but, for those in the UK it, is punctuated by an importantaccident that occurred in the 1960s the Ronan Point collapse which will be remembered by allthose of around 50 or more. In this incident a simple domestic gas explosion provoked thecollapse of an entire corner of a block of flats. Gas explosion is probably one of the causesuppermost in the mind of the designer of buildings but there are also many other events that candamage a building seriously enough for it to collapse if it is not robust enough fire, terrorism andvehicular collision being also of concern. The result of the bombing of the Murrah building inOklahoma in 1995 is an, admittedly extreme, example of progressive collapse.

    Generally speaking designers of modern buildings seeks to simplify the system of structuralsupport in the interests of economy and to enable rational design methods to be used. This oftenresults in buildings with relatively few load paths from any part to the ground. In more complexbuildings, such as older buildings that may be more highly compartmentalized with partitions andwalls, there may be many unintended load paths from any one part of the structure to thefoundations that is to say; parts of the building not intended to bear load will take a share ofload if some other, perhaps primary, part of the structure is removed or seriously damaged.

    Typically, the modern building will comprise a frame of steel or concrete beams and columns ormay be formed by flat slab construction on columns. Sometimes it may have load-bearingmasonry instead of columns. Here there would be relatively few primary structural components.For example, a column may be removed by an accidental event and that column may havesupported an entire bay for the full height of the building if the structure above the column werenot capable of spanning to the adjacent intact columns, a large volume collapse would occur.

    To avoid the catastrophic effects of removal or damage to primary structural elements, thebuilding may be designed to either span over such localized damage or it may be designed withalternative load paths to the ground. The latter solution militates against economy and use ofspace inside the building so it is more common to adopt the former approach. Another approachis to provide what are termed protected key elements, which are supports designed to resist allreasonably foreseeable accidental damaging events.

    Spanning over damaged areas can be accomplished in a number of ways:

    Firstly, we may assume that the structural elements, such as beams and slabs, remainisolated and not integrated or interconnected. The means that the framework of thebuilding, i.e. columns, walls, beams or parts of slab, must remain largely intact and bridgethe damaged area by forming a temporary structure akin to a truss, Veerendeel frame orsome kind of space frame. This will require that the primary structural elements mustremain attached together and, to this end, the codes require that effective tying isprovided around each floor of a building, across each floor, and up the height of thebuilding. The ties so formed, usually in the form of steel bars, straps, or structural steelsections, form a framework that can support the superstructure over a damaged area,even if the deflection in the accidental event would be alarming in normal use.

  • Page 3 of 5

    Pre-cast floors have an inherent disadvantage in respect of these provisions as they areisolated elements that require tying together in various directions on site after erection.Some part filigree/in-situ systems, which are fundamentally one way spanning, have tobe provided with tying across the main span to achieve the requisite tying in eachdirection and this also is added on site.

    An extract from Stability of Modern Buildingsi is given below:

    2.3 Effective ties

    The general principles of conserving stability against unforeseen hazards have been setout in Section 1 when discussing the concept of providing an alternative path for carryingthe load to the ground.

    The basic requirement of this concept is to contain the local damage that develops in onesection of the structure within a condition of partial instability and ensure that this does notlead to the total collapse or full instability of the building. This implies a capability in thestructure of bridging or stringing over the damaged area of the work.

    To satisfy the basic requirement, the structure should be effectively tied together at eachfloor level on the longitudinal and transverse axes along the main column grid lines,combined with effective continuity of the vertical load-carrying members. The mainconstituent elements of the floors and walls should also be anchored into the main-tiesystem where they are not themselves used to form the main tie.

    Emphasis has been placed on the need for an effective tie. The magnitude is obviouslyrelated to the span of the floor and beam components and should be capable of sustainingpractical catenary effects. It is also essential that the tie should be of a continuous form.Unless the joints in the tie are firmly bonded into the mass of the connected componentsthey should be of an interlocking type. In this respect, tests on continuous floor slabs overtwo bays when loaded without the central support have shown a considerable increase inloading capacity in this emergency condition when the bottom reinforcement is fully lappedover the missing support.

    Storey-height posts in the outside walls and particularly at the corners are alwaysrelatively vulnerable, and where these occur the bridging capacity of the supported beamand members should be correspondingly improved. Reference has also been made to thepotential capacity of storey-height walls to bridge across the damaged sections of theirsupport when properly tied in their own plane at the floor level (see Section 1).

    A second method of providing resistance to disproportionate collapse is to tie spanstogether so that a catenary is formed by the steel if an intermediate support is removed.The sag of the slab or beam in such an arrangement may be dramatic but the intention isthat it will just remain intact. This form of catenary action is difficult to realize in pre-castconstruction as the necessary embedment and joining of the steel in all directions is oftencomplex especially where the elements must be anchored to vertical ties.

    Unfortunately the catenary effect does not really work at building corners and verticalsupport to exterior corners are often vulnerable in many buildings due to explosion, orvehicle collision combined with the fact that windows often leave only an isolated pier orcolumn at the corner.

    A third method is to provide a reserve of conventional spanning capacity of the horizontalelements such as floor slabs or beams. A slab may be designed to perform satisfactorilyin the conventional way but also to have reserve strength to span across damaged orremoved supports even if the deflection or sag is large - this is an intermediate stagetoward the catenary effect mentioned above but the slab remains intact and deformsmuch less.

  • Page 4 of 5

    The provision of alternative load paths was mentioned above. Providing extra beams andcolumns has obvious disadvantages. However, in-situ slab structures are inherentlyrobust in this respect since reinforcement is usually provided in at least two directionsand, even if the slab is primarily intended to span one way only, it has the ability to spanthe other way and across a wide band so it may, with little or no need for modification,span onto other vertical elements if the primary vertical support is removed.

    Consider for example a corner room of a building supported on four sides: If the cornercolumn or a wall were removed so that the end support to a span was removed, such asat Ronan Point, an in-situ slab could span across the remaining walls. The span mayform between remaining opposite walls or across adjacent walls meeting at a corner. Notonly can the span remain intact but it can, since it is usually tied into the rest of the flooracross the whole width in both directions, provide lateral restraint to the remaining wallsor columns to prevent buckling or bursting outward. Even non- structural infill wall mayform a temporary support when primary walls are removed although the designer wouldhave to bear this in mind when specifying the infill materials and form of construction.

    Protected key elements are a viable option in most buildings but usually employed whenall else fails. They are required to resist very intense loadings applied directly to themand through anything attached to them so they can become inevitably complex or largeand costly. The load to be applied to them as prescribed in current codes is largelyderived from tests on contained gas-air explosions. Designing for vehicle impact can becomplex and onerous exercise if economic sizes are to result.

    BubbleDeck is fundamentally an in-situ RC slab and its benefits in respect of disproportionatecollapse are realised in all of the four mechanisms described above. No other floor system exceptsolid in-situ floor construction has this as an inherent feature. The filigree elements are relativelywide and are joined together with splice bars that are designed to develop the full moment ofresistance required at any joint and, in this way, are functionally equivalent to an ordinary in-situtwo way spanning slab.

    One way spanning systems, with or without filigree soffits must be made to fulfil the secondaryspanning function by adding components such as tie bars. Such secondary reinforcement may beintended to provide catenary action described above or may be intended to provide true spanningaction in the secondary direction. However, despite the superficial similarity to the BubbleDeckjointing, since the added bars are placed on top of the relatively narrow filigree units, thespanning capacity is limited by the reduced effective depth to the reinforcement across the wholeslab width.

    The BubbleDeck slab is not greatly affected by the reduced effective depth of the splice bars anddeflection performance is only marginal affected, since these bars are at infrequent intervals andthe increased curvature due to reduce effective depth takes place of a very short distance local tothe joint. The curvature contributing to flexural deflection therefore would comprise a very smallproportion of span length corresponding to the joints and a very large proportion of the spanremote from the joints with full effective depth.

    [For the technical reader, the deflection can be expressed as a function of the double integral ofthe curvature on the member length a method of calculating deflections is to integrate thecurvature twice upon the span length and add this to the support tangent. The reader may verifythat that the length over which the curvature is effective is fundamental to the result so resultingdeflection will be dominated by curvature over the majority of the span length rather thanproportionally very small lengths of high curvature. For a more detailed exposition of the theory,see the classic text in Timoshenkoii or other of the various treatments of the subject.]

  • Page 5 of 5

    The splice bars in a BubbleDeck slab are usually given sufficient lap length, often the full tensionlap, to ensure that full tying and spanning is obtained. Since the slab is reinforced in bothdirections across its whole width it can span over damaged areas in one direction or another andcan, in major damage, form part of a catenary system.

    The BubbleDeck slab can be locally reinforced with higher concentrations of rebar to enable wallsto be supported on it and this can also be enhanced by leaving out rows of balls at strategicpositions. Since effective tying is continuous, walls and slab may be designed compositely to formdeep beams or employ tied arching to span across larger opening formed by removal of supportbelow.

    BubbleDeck slabs can be designed in the conventional way to resist sagging or hoggingmoments with equal facility. In terms of disproportionate collapse this can be utilised to assist inthe support of support corners by cantilevering diagonally as well as orthogonally.

    Eur Ing R A Beeton BSc CEng MICE

    BubbleDeck UK Senior Engineer, January 2006

    i Stability of Modern Buildings, Institution of Structural Engineers, September 1971.ii Strength of Materials, Timoshenko, Van Nostrand Co Inc, 1956.

    UK OfficeTelephone: +44 (0)1691 774242E-Mail: [email protected] Office, Channel Islands & IrelandTelephone: +44 (0)1534 725402E-Mail: [email protected]

  • BubbleDeck Voided Slabs

    Fixings & Holes Manual

    Edition 1, Revision B: September-06

    BubbleDeck StructureSolutions

  • Page 2 of 6

    Introduction

    The information in this document is given in good faith and is believed to be correct at time ofpublication.

    This document has been published by BubbleDeck C.I. Ltd. For further details, please contact us. When using Hilti equipment and products it is important that standard safety procedures are

    observed and regulations adhered to. For further information please refer to Hilti technical andsafety documents

    Fixings into BubbleDeck slabs

    Lightweight FixingsThere is a minimum of 20mm concrete below the centre of each bubble, but just a short distance awayfrom the bubble centre the concrete depth quickly increases to 70mm plus up the side of each bubble.Therefore fixings for attaching light and medium weight articles can be made using normal methods(plug & screw / expanding anchors, etc.) to provide adequate fixings for wiring conduits, small cabletrays, small ventilation ducts and the like.

    Heavy Weight FixingsWhere stronger fixings are required to resist higher pull out (downward) forces from heavy loads to besuspended from the soffite we recommend our Bubble layout drawings are inspected to determinewhere fixings will occur directly below or close to the edge of a bubble. Where fixing locations andlengths are likely to project into a bubble void we recommend Hilti HIT HY20 Injection Resin Anchorwith HIT sieve, item no. 00068613, are used. Hilti also produce a range of other fixing systemsdesigned for fixing through into voids.

    Hilti Fixings into BubbleDeck Voids

    HKD-S AnchorThis is a shallow embedment depth anchor with an internal thread suitable in thread forms M6, M8 andM10. The fixing is flush with the surface after setting. The anchor is placed in a drilled hole in theprecast unit and set by driving a central expansion cone into the the anchor with a purpose designedsetting punch. The setting tool leaves a visible impression on the end of the anchor to enable easyinspection to see that the fixing has been correctly installed.

    This fixing is commonly used with set screws or threaded rod for plumbing, heating, air conditioning andventilation installations, pipe suspension, air ducts, etc, and also for securing channels, rails, plates,brackets and suspended ceilings. Variations in thickness fastened can be accommodated usingdifferent length set screws or threaded rods. It can be loaded as soon as it has been installed. A firerated fixing can be achieved by using HKD-S anchors.

  • Page 3 of 6

    HUS Screw AnchorThis screw fastening is made straight into theconcrete without using a separate plug. A 6mmdiameter hole is drilled into the concrete slaband the HUS screw is driven straight into thehole using an appropriate tangential impactscrewgun.This fixing is available with the following headtypes:

    Flat head for fixing timber and soft materials. Hexagon head used for fixing for instance

    light duty installation channels, light dutysteel angles, mechanical installationcomponents and parts for interior panellingor cladding.

    Metric connection thread for fastening lightduty pipe rings. This fixing can be loaded assoon as it has been installed. The HUSScrew fixing comes in a range of lengths toallow for variations in thickness fastened. Afire rated fixing can be achieved by usingHUS Screw fixings.

    HUS Universal HUS-H