249399169 bubble deck technology

8/18/2019 249399169 Bubble Deck Technology

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Bubble Deck Technology

1. Introduction

1.1Concrete Floor Systems

Reinforced concrete slabs are components commonly used in floors, ceilings, garages,

and outdoor wearing surfaces. There are several types of concrete floor systems in use today,

and are shown in Figure 11!

• Twoway flat plate "bia#ial slab$ There are no beams supporting the floor between the

columns. %nstead, the slab is heavily reinforced with steel in both directions and

connected to the columns in order to transfer the loads.

• Twoway flat slab with drop panels This system differs from the twoway flat plate

system by the drop panel used to provide e#tra thickness around the columns. This

strengthens the column to floor connection in consideration of punching shear.

• &neway beam and slab This is the most typical floor system used in construction.

The slab loads are transferred to the beams, which are then transferred to the columns.

• &neway 'oist slab The 'oists act like small beams to support the slab. This floor system

is economical since the formwork is readily available and less reinforcement is re(uired.

• &neway wide module 'oist slab This system is a variation on the oneway 'oist slab with

wider spaces between the 'oists.

• Twoway 'oist slab "waffle slab$ This floor system is the stiffest and has the least

deflection of those mentioned since the 'oists run in two directions ")oncrete Reinforcing

*teel %nstitute$

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.

Figure 1-1: Types of Reinforced Concrete Floor Systems (Concrete Reinforcing Steel Institute)

Reinforced concrete has many advantages for floor systems it provides resistance to

high compressive stresses and to bending stresses it is relatively cheap to produce and

construct and it can be molded into virtually any shape and si-e. Disadvantages include a

high weightto strength ratio and difficulty in structural health monitoring "Reinforced

)ement )oncrete Design$.

1.2Hollo-Core Sl!"s

%n the mid/th )entury, the voided or hollow core floor system was created to reduce

the high weighttostrength ratio of typical concrete systems. This concept removes and0or

replaces concrete from the center of the slab, where it is less useful, with a lighter material in

order to decrease the dead weight of the concrete floor. owever, these hollow cavities

significantly decrease the slabs resistance to shear and fire, thus reducing its structural

integrity.

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This floor system typically comes in the form of precast planks that run from 2 ft to

1 ft wide and consist of strips of hollow coring with prestressed steel strands in between.

Figure 1 illustrates several types of hollowcore planks used in the industry. They are

combined on site to form a oneway spanning slab and topped with a thin layer of surfacing.

Figure 1-2: Types of Hollo-Core #l!n$s


%n the 133/4s, 5orgen Breuning invented a way to link the air space and steel within a

voided bia#ial concrete slab. The BubbleDeck technology uses spheres made of recycled

industrial plastic to create air voids while providing strength through arch action. 6s a result,

this allows the hollow slab to act as a normal monolithic twoway spanning concrete slab.

These bubbles can decrease the dead weight up to 789 and can increase the capacity by

almost 1//9 with the same thickness. 6s a result, BubbleDeck slabs can be lighter, stronger,

and thinner than regular reinforced concrete slabs "BubbleDeck:;$.

)urrently, this innovative technology has only been applied to a few hundred

residential, highrise, and industrial floor slabs due to limited understanding. For this

investigation, the structural behavior of BubbleDeck under various conditions will be studied

in order to gain an understanding on this new techni(ue and to compare it to the current slab

systems. This technology will then be applied to create lightweight bridge decks since a

significant portion of the stress applied to a bridge comes from its own selfweight. By

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applying the knowledge gathered during the behavioral analysis, a modular deck component

for pedestrian bridges that is notably lighter but comparable in strength to typical reinforced

concrete sections will be designed.

2. %&%%' C*

2.1+!teri!ls

BubbleDeck is composed of three main materials steel, plastic spheres and concrete,

as see in Figure 1.

• *teel The steel reinforcement is of higher o plastici-ers are necessary for the concrete mi#ture. "BubbleDeck

%nternational$.

Figure 2-1: Components of ! %u""leec$ (Stu""s)

2.2Sc,em!tic esign

BubbleDeck is intended to be a flat, twoway spanning slab supported directly by

columns. The design of this system is generally regulated by the allowed ma#imum

deflection during service loading. The dimensions are controlled by the span "?$ to effectivedepth "d$ ratio "?0d$ as stated by B*@ 11/ or =). This criterion can be modified by applying

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a factor of 1.8 that takes into account the significantly decreased dead weight of the

BubbleDeck slab as compared to a solid concrete slab.

%n addition, larger spans can be achieved with the use of post tensioning as the L/d

ratio can be increased up to 7/9. "BubbleDeck:;$

L/d A 7/ for simply supported, single spans

L/d A 21 for continuously supported, multiple spans

L/d A 1/.8 for cantilevers

There are five standard thicknesses for BubbleDeck, which vary from 7/ mm to 28/

mm, and up to 510 mm and // mm for specific designs pending ;&C& certification. The

varieties of BubbleDeck can be found in Table 1.

T!"le -1: ersions of %u""leec$/ (T,e %i!0i!l Hollo dec$- T,e !y to ne solutions)

2.Types of %u""leec$

6ll of the BubbleDeck versions come in three forms filigree elements, reinforcement

modules, and finished planks. They are depicted in Figure . For all types of BubbleDeck,

the ma#imum element si-e for transportation reasons is 7 m. &nce the sections are connected

on site however, there is no difference in the capacity.

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2..1 Type - Filigree lements

BubbleDeck Type 6 is a combination of constructed and unconstructed elements. 6

/ mm thick concrete layer that acts as both the formwork and part of the finished depth is

precast and brought on site with the bubbles and steel reinforcement unattached. The bubbles

are then supported by temporary stands on top of the precast layer and held in place by a

honeycomb of interconnected steel mesh. 6dditional steel may be inserted according to the

reinforcement re(uirements of the design. The full depth of the slab is reached by common

concreting techni(ues and finished as necessary. This type of BubbleDeck is optimal for new

construction pro'ects where the designer can determine the bubble positions and steel mesh

layout.

2..2 Type %- Reinforcement +odules

BubbleDeck Type B is a reinforcement module that consists of a preassembled

sandwich of steel mesh and plastic bubbles, or bubble lattice. These components are

brought to the site, laid on traditional formwork, connected with any additional

reinforcement, and then concreted in place by traditional methods. This category of

BubbleDeck is optimal for construction areas with tight spaces since these modules can be

stacked on top of one another for storage until needed

2.. Type C- Finis,ed #l!n$s

BubbleDeck Type ) is a shopfabricated module that includes the plastic spheres,

reinforcement mesh and concrete in its finished form. The module is manufactured to the

final depth in the form of a plank and is delivered on site. :nlike Type 6 and B, it is a one

way spanning design that re(uires the use of support beams or load bearing walls. This class

of BubbleDeck is best for shorter spans and limited construction schedules "BubbleDeckE

:;$.

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Figure 2-2: T,ree Types of %u""leec$- Type % 3 C

2.4d5!nt!ges of %u""leec$

2.4.1 +!teri!l !nd 6eig,t Reduction

The dominant advantage of a BubbleDeck slab is that it uses 7/8/9 less concrete

than normal solid slabs. The bubbles replace the noneffective concrete in the center of the

section, thus reducing the dead load of the structure by removing unused, heavy material.

Decreased concrete material and weight also leads to less structural steel since the

need for reinforcement diminishes. The building foundations can be designed for smaller

dead loads as well. &verall, due to the lighter floor slabs, the several downstream components

can be engineered for lower loads and thus save additional material "rap$.

2.4.2 Structur!l #roperties

Due to the lower dead weight of the slab and its twoway spanning action, load

bearing walls become unnecessary. BubbleDeck is also designed as a flat slab, which

eliminates the need for support beams and girder members. 6s a result, these features

decrease some of the structural re(uirements for the columns and foundations.

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6dditionally, BubbleDeck slabs can be designed and analy-ed as a standard concrete

flat slab according to research performed on its strength and ductility. 6s summari-ed by

Table , the dead loadtocarrying capacity of a solid slab is 7!1 while a BubbleDeck of the

same thickness has a 1!1 dead loadtocarrying capacity ratio "rap$.

T!"le 2-2: %u""leec$ 5s. Solid Sl!" (!d!pted from %u""leec$/-&*)

2.4. Construction !nd Time S!5ings

&n site construction time can be shortened since BubbleDeck slabs can be precast.

Type 6 includes a / mm precast concrete plate as the base and formwork for the slab. This

type of slab would eliminate the need for on site erection of formwork, thus significantly

cutting down construction time. *imilar to modem precast concrete flooring modules,

BubbleDeck can be fully shop fabricated and transported on site for installation as well.

Time savings can also be achieved through the faster erection of walls, columns and

C=+s due to the lack of support beams and load bearing walls for this innovative flat slab.

6ddition time may be saved from the (uicker curing time since there is less concrete in the

slab.

2.4.4 Cost S!5ings

%n relation to the savings in material and time, cost reductions are also typical with the

BubbleDeck system. The decreased weight and materials mean lower transportation costs,

and would by more economical to lift the components. ith less onsite construction from

the full and semiprecast modules, labor costs will decrease as well. %n addition, money can

be saved downstream in the design and construction of the building frame elements "columns

and walls$ for lower loads.

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There is a slight rise in production costs for the BubbleDeck slab due to the

manufacturing and assembly of the D+= spheres. owever, the other savings in material,

time, transportation and labor will offset this manufacturing price increase "*tubbs$.

2.4.7 8reen esign

The number of owners, designers and engineers who desire green alternatives is

growing e#ponentially. BubbleDeck is a fitting solution for lowering the embodied carbon in

new buildings. 6ccording to the BubbleDeck )ompany, 1 kg of recycled plastic replaces 1//

kg of concrete. By using less concrete, designers can save up to 2/9 on embodied carbon in

the slab, resulting in significant savings downstream in the design of other structural

members. )arbon emissions from transportation and e(uipment usage will also decrease with

the use of fewer materials. 6dditionally, the bubbles can be salvaged and reused for other

pro'ects, or can be recycled.


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. STR&CT&R' #R9#RTIS SI8

.18ener!l

Research has been performed at several institutions in Denmark, etherlands on the mechanical and structural behavior of BubbleDeck. *tudies include

bending strength, deflection, shear strength, punching shear, fire resistance, and sound

testing.

.2%ending Strengt,:

Bubble Deck where compared to a solid decks both practically and theoretically. The

results showed that for the same deck thickness the bending strength is the same for

BubbleDeck and for a solid deck and that the stiffness of the Bubble Deck is slightly lower.

.S,e!r Strengt, !nd #unc,ing S,e!r:

The results of a number of practical tests confirm that the shear strength depends on

the effective mass of the concrete. The shear capacity is measured to be in the range of G

319 of the shear capacity of a solid deck. %n calculations, a factor of /. is used on the shear

capacity for a solid deck of identical height. This guarantees a large safety margin. 6reas with

high shear loads need therefore a special attention, e.g. around columns. That is solved by

omitting a few balls in the critical area around the columns, therefore giving full shear

capacity.

.4Sound

6 comparison was made between Bubble Deck and oneway prefabricated hollow

deck of similar height. The noise reduction with Bubble Deck was 1 db higher than the one

way prefabricated hollow deck. The main criterion for reducing noise is the weight of the

deck and therefore Bubble Deck will not act otherwise than other deck types with e(ual

weight.

The Bubble Deck construction is following every usual criteria, and can be calculated

according to usual principles. The construction is not deviating, in any way, from what is

already known and used. The construction is analogous to an e(uivalent solid deck.

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.7eflection:

Due to the bubbles a Bubble Deck slab is not as stiff as a solid slab H but this effect is

small. *tudies and tests have shown that Bubble Deck has appro#imately @G9 of the fle#ural

stiffness of a solid slab. %f no other measures were taken, this would mean marginally higher deflections at *?* than in an e(uivalent solid slab in direct proportion to this ratio. owever,

the effect can be compensated for by adding a modest amount of steel even though the

deflection is significantly mitigated by the fact that Bubble Deck is lighter and in long term

*?*, where fre(uently the load combination comprises 1//9 permanent load and a

proportion such as 779 imposed load, the permanent weight saving ma#imi-es Bubble

DeckIs effect. ?ong term *?* is fre(uently the governing criteria for flat slab designs.

.;ur!"ility

The durability of Bubble Deck slabs is not fundamentally different from ordinary

solid slabs. The concrete is standard structural grade concrete and combined with ade(uate

bar cover determined in accordance with =) or B*@11/ is what provides most control of

durability commensurate with normal standards for solid slabs. hen the filigree slabs are

manufactured, the reinforcement module and balls are vibrated into the concrete and the

standard and uniformity of compaction is such that a density of surface concrete is produced

which is at least as impermeable and durable, arguably more so, to that normally produced on

site.

Bubble Deck 'oints have a chamfer on the inside to ensure that concrete surrounds

each bar and does not allow a direct route to air from the rebar surface. This is primarily a

function of the fire resistance but is also relevant to durability.

)racking in Bubble Deck slabs is not worse, and probably better, than solid slabs

designed to work at the same stress levels. %n fact Bubble Deck possesses a continuous mesh,

top and bottom, throughout the slab and this ensures shrinkage restraint is well provided for

and that cracking is kept to a minimum whether it is intrinsic or e#trinsic cracking.

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sway reversals should be properly considered as well as amplification of the punching shear

due to the vertical component of ground acceleration.

%n computing the buildingIs response, the seismic designer should be closely engaged

with determination of the mass and the effect of this on modal spectrum. :sing Bubble Deck

a significant reduction of mass in the floor plate may be reali-ed together with an increase in

modal fre(uency and reduction in the sway forces due to lateral acceleration.

.= 'o!d C!rrying C!p!city

6 solid slab can only carry load one third of its own weight, and have problems with

long spans due to its high weight. Bubble DeckIs bia#ial deck solves this problem by

eliminating 78 9 concrete, while maintaining strength. ence, a Bubble Deck slab has thesame applied load capacity with only 8/ 9 of the concrete re(uired for a solid slab, or with

the same slab thickness has twice the load capacity using 8 9 of the concrete.

*hear capacity is more than 8 9 of a solid deck with same height. %n calculations are

used a factor /.. %n critical areas "around columns$, balls can be omitted to achieve full

capacity

.>Cont!ct %eteen %u""les nd ReinforcementThe potential for any contact is only theoretical because the balls do not perfectly fit

between reinforcement bars and moves slightly during assembly 0 site concrete compaction so

that some grout surrounds it and provides a measure of passivation. owever, even if there

were contact between the ball and the steel, the environment inside the void is very dry and

protected there is also no breach "apart from micro cracking$ of the concrete to the outside

air. %t is a better situation than e#ists with inclusion of plastic rebar spacers within solid slabs

that create a discontinuity within the concrete between the outside air and the rebar in solid

R.). slabs. e therefore have a situation that is better than e#isting with plastic rebar spacers

and these have been permitted for many years. e have had balls cut open in olland and

Denmark and there has been no sign of significant corrosion.

.1?ffect of %u""le oids &pon Stiffness

:nlike hollow core units, Bubble Deck voids are discrete balls and not prismoidal

voids running the length of the span. This makes a huge difference to the performance

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compared to hollow core sections. Tests carried out in Denmark,


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4. SIT RCTI9 IST''TI9

4.1St!ge 1- rect Tempor!ry #ropping

During erection each slab must be placed on suitable temporary propping beams

arranged in parallel rows mounted on props sufficient to ade(uately support the weight of the

precast filigree elements plus the loose reinforcement fi#ed on site, concrete poured on site

and all other site construction loads applied during final pouring of the concrete topping and

curing of the slab.

Typic!l !rr!ngement of props !nd propping "e!ms

4.2St!ge 2@ eli5ery 'ifting !nd #l!cing lements

Site eli5ery: The elements are delivered on flatbed trailers typically between 1m to 17.m

long, e#cluding drivers cab. The filigree elements will be stacked on top of each other up to a

ma#imum .8 m overall height. For e#ample, with BD@/ slabs there will be ma#imum G

layers of slabs, with a transport height of 8/mm each plus wooden packers typically 8/mm

deep separating each element, making an overall height of .1m above the trailers bed. =ach

individual load will be planned so the weight of a load will be a ma#imum 3 Tonnes and you

must provide suitably hard and level access for our delivery transport to reach the offloading

position you have determined.

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'o!ded tr!ilers !rri5ing on site

'ifting !nd #l!cing Filigree lements: The filigree elements must &>?K be lifted by the

lattice beam girder reinforcement. ?ifting hooks must 6?6K* be attached under the upper

angles of the girder reinforcement diagonal web bars. ?ifting hooks must >=L=R be attached

to the upper reinforcement mesh as this would be unsafe.

'ifting element into position 'ifting ,oo$s under girder di!gon!l e" "!rs

4.St!ge @ Fi0ing 'oose Site Reinforcement

*ite installation drawings are provided for loose site reinforcement "supplied by others$ fi#ed

at the bottom of the slab "directly on top of the precast concrete filigree permanent formwork

without spacers or on top of site shuttering on spacers$ and reinforcement fi#ed at the top of

the slab "directly onto top mesh reinforcement$, together with accompanying bar bending

schedules. These must be studied and closely followed at all times.

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4.4St!ge 4 @ Constructing S,uttering

&nce the perimeter loose reinforcement has been installed work on erecting perimeter

and construction 'oint shuttering can commence. Temporary works are our responsibility to

determine.

4.7St!ge 7 @ #rep!r!tion for Concreting

The precast concrete permanent formwork edges are manufactured to a high

accuracy and care taken to get a tight 'oint during laying the elements can render 'oint filling

unnecessary. hen 'oints between slab elements have not been closely butted they must be

filled to prevent grout seepage. *hould this be re(uired 'oint filling can be undertaken with

either mortar grout or a small bead of silicone sealant inserted at the bottom of the splay 'oint

between elements. This is most easily undertaken prior to installing the loose splicereinforcement.

4.;St!ge ; @ %u""le ec$ Site Inspection

The technical representative will visit the site and undertake a full inspection of the

BubbleDeck element and loose reinforcement installation. Following inspection, the technical

representative will issue you with an inspection record listing any work that needs to be

undertaken prior to site concreting, or confirming the installation is ready for concreting and

the work is to our approval.

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#ouring i"r!ting 3 Flo!ting Site Concrete

4.=St!ge = @ Remo5ing Tempor!ry #ropping

During construction planning the minimum period for removal of propping before

backpropping is confirmed. This is usually between 7 to 8 days from pouring of the site

concrete as long as the early concrete test results have confirmed the site concrete has

reached at least /9 of its final design strength, but can vary dependant upon our floor slab

design, strength of site concrete, and ambient temperatures.

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7. A+#'S 9F %&%%' C* TCH9'98B

7.1+illennium Toer Rotterd!m

The first high rise building erected with BubbleDeck filigreeelements and the secondhighest building in >etherlands, 72 stories and 171 meter high. BubbleDeck was chosen, in

spite of being a completely new product, because of its advantages in cost, construction time

and fle#ibility and because of environmental issues. Beams could be e#cluded resulting in

two more stories than planned in the beginning for the same building height. Built in 133@

///.

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7.2C!r p!r$

)ar park built with BubbleDeck in Frankfurt


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;. C9C'&SI9

Bubble Deck will distribute the forces in a better way than any other hollow floor

structures.

Because of the threedimensional structure and the gentle graduated force flow the

hollow areas will have no negative influence and cause no loss of strength.

Bubble Deck 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 e#perience shows a positive effect in the process of

concreting H the balls cause an effect similar to plastici-er additives.6ll tests, statements and engineering e#perience confirm the fact that BubbleDeck in

any way acts as a solid deck H and therefore will follow the same rules0regulations as a solid

deck "with reduced mass$, and further,leads to considerable savings.

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249399169 bubble deck technology

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