contruss engineering company

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ConTruss system introduction Contruss engineering company

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Contents Introduction: ................................................................................................................... 2

1- introduction of double-sided voided slab ................................................................. 2

1-1- two-way voided slab with I-shaped section: ..................................................... 2

1-2- double-sided voided slab history: ...................................................................... 2

1-3- advantages of double-sided voided slab applied for spans beyond 7 meters . 5

2- Contruss filler introduction ....................................................................................... 7

3- Contruss system installation ...................................................................................... 8

4- Contruss system advantages .................................................................................... 11

4-1- economic advantages: ....................................................................................... 11

4-2- architectural advantages: ................................................................................. 13

4-3- technical advantages: ........................................................................................ 15

4-4- practical advantages: ........................................................................................ 18

5- comparison with the other systems ......................................................................... 25

5-1- comparison of the Contruss system with the rib and block slab tutorial: ... 25

5-2- comparison of the Contruss system with the metal deck ceiling: ................. 31

5-3- comparison of Contruss system with beam and slab floor system: .............. 37

5-4- comparison of Contruss system with prestressed slab system: .................... 41

6- projects constructed by the use of Contruss system .............................................. 45

7- Conclusion and ultimate comparison table: .......................................................... 58

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Introduction: Contruss system is a permanent filler that is created for constructing voided slabs, an innovative

system developed by Contruss engineering company. The patent was issued in 2014 in which, I-

shaped sections are created in the voided slabs along with mutually perpendicular ribs. It is a

composite filler that will provide more functional and technical advantages, compared to other

permanent ones because of special forming, material and components. The commercial named

Contruss, is consist of the words concrete+ truss, defined as a concrete truss, suitable for long

spans. In the following, the functional and technical advantages is elaborated.

1- introduction of double-sided voided slab

1-1- two-way voided slab with I-shaped section: Mutually ribs with I-shaped sections are so practical in constructions; Due to inclusion of high

moment of inertia, it will contribute the slab to operate properly in large spans, when subjected

to vibration and deflection. In addition, it is capable of providing openings in various dimensions

in the concrete slab, as regard to existence of much indeterminate degrees.

By involving of two concrete layers, I-shaped sections are appeared in two directions in the

double-sided voided slab system, which will enrich the rigidity and resistance of the ceiling. On

the other words, this system includes two concrete layers connected by orthogonal shear webs

in the ceiling, that is a so-called concrete truss which will result in high rigidity as well as lower

concrete consumption.

Figure 1.1. beam created in the Contruss voided slab

1-2- double-sided voided slab history: The concept is actually quite old. Based on the lack of structural benefit, all of the constructed

concrete systems were come up with a solution to eliminate unloadable concrete in structures

during previous centuries.

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Figure 1.2. the manners of creating voided slab

The origins of concrete voided slab applied in constructions, can be traced to the long-times ago,

as some samples belong to last century. The initial voided slab with I-shaped section, that is

known as a double-sided voided slab along with permanent fillers, first recognized in 1995 in

Europe. It was created by the use of spherical hollow fillers as permanent ones in the concrete

slab.

Figure 1.3. schematic image of spherical voided slab

In 2002, the exclusive companies initiated changing the manner of manufactured permanent

fillers, created them as rectangular cuboid ones. In comparison to the spherical as special

forming, the new fillers enriched them with a reduction in self-weight and concrete consumption.

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Figure 1.4. schematic image of rectangular cuboid formwork

With no structural benefit, the filler is aimed to eliminate unloadable concrete as well as creating

hollow zone inside the concrete, which is referred as permanent filler.

Besides the advantages issued for the permanent cuboid fillers, there are some possible defects

in the system. As seen in some projects, some of the possible defects are existence of stress

concentration on the connection band of shear web and flange in the ribs, fracture of the fillers

during installation, difficulty in concrete flowing to the bottom surface of fillers and considering

inadequate cover clearance for rebar.

Contruss engineering group, a pioneer company in creating and practicing innovative technology

for constructions, initiated activity on development of voided slabs created by permanent fillers

in 2008 in the Middle East, as the first one to extend this innovative system, locally and

internationally.

Based on conceptual technical knowledge upon voided slab systems, the research and

development department of company, locally and globally, began innovating in conjunction with

designing and manufacturing of permanent fillers in order to resolve the mentioned defects.

Subsequently, the company initiated manufacturing of its invented permanent fillers,

commercially named “Contruss”, issued in 2014. At the same time, by practicing the fillers in

constructions as voided slab system with permanent fillers, it was advocated by employers and

contractors.

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Figure 1.5. Contruss permanent formwork

1-3- advantages of double-sided voided slab applied for spans beyond 7 meters a) two-way function:

In many types of concrete slabs, the transfer of loads occurs in the plane of floor with straight

trajectory along one direction of the slab, that makes the transfer trajectory longer, which will

increase beams and columns dimensions as well as ceiling weight. On the contrary, the two-way

voided slab distributes the loads equally in two directions on supports.

b) elimination of beams:

As respect to the high moment of inertia and rigidity as well as lightened weight, the use of

voided slabs makes it possible to transfer dead and live loads directly on the supports; there is

no need to use beams. Although this function is the same as mushroom slabs, the lightened

weight of the voided slabs reaches 30 to 40 percent compared to the filled ones, with equal

rigidity. Therefore, it can be practiced for long spans as provides possibility of omitting beams

and creates a flat soffit (smooth bottom surface of the ceiling). This omission will result in

following advantages:

- achieving long spans without beams

- reduced height of structure as well as increased number of floors

- creating flat intrados floor without drops

Note that removing beams is totally depended on the structural system. By providing shear walls

or in the structures with total height less than 10 meters, the elimination is possible; Unless, the

presence of beams is essential.

c) lightening, fewer columns and high strength in earth quake:

- reduction in dead load that leads to involving of fewer columns; the result is less applied load

on the foundation that leads to less deep foundation excavation.

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- reduction in dead load applied on the ceiling that leads to decreased lateral force, ultimate shear

and consequently increased structural strength in earthquake.

- reduced deflection as well as increased slab rigidity

d) flexibility in architectural design:

Thanks to the use of voided slab with permanent fillers, creating long span will be possible. From

the architectural point of view, providing long span will allow suitable flexibility in scheme as

well as increasing useful space; additionally, it will provide possibility of using reallocation.

e) suitable operation as an acoustic subjected to noise, heat and vibration:

High rigidity due to the existence of two solid concrete layers and mutually perpendicular ribs,

contribute the slab to control vibration.

As covered by polystyrene up to 80 percent of slab surface, the Contruss system will operate

more properly in subjected to noise and heat, compared to the conventional filled slabs. With a

15-cm-thick as well as much lower heat and sound transmission coefficient compared to the

concrete, polystyrene functions suitably as insulation in transmission of noise and heat.

Note: concrete ceiling is not appropriate insulation in transmission of airborne noise; but the

double-sided voided slab is capable of acting as an acoustic system, since the presence of hollow

space inside the slab.

f) providing possibility of great openings in the slab:

Structural function of slab as a rigid diaphragm for distributing seismic loads among supports

does matter much. Creating openings, from the structural point of view, might disorder the loads

distribution in floors. The double-sided voided slab, due to the high moment of inertia and much

indeterminate degrees, will form a rigid and solid slab that act properly as a diaphragm, even

though in the presence of large openings.

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2- Contruss filler introduction Contruss filler is a composite combination with a middle core made of EPS material, along with

plastic plates, supports and piles made of PP material, that will provide more functional and

technical advantages, by use of a lightened weight filler compared to the other permanent ones.

Figure 2.1. the positioning manner of Contruss fillers

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3- Contruss system installation 3-1- ceiling formwork:

The entire surface of the ceiling is shuttered continuously with metal or wood deckings (or other

similar systems); then the scaffolds or jacks are positioned under it.

Figure 3.1. ceiling formwork

3-2- positioning of the lower rebar:

The lower rebar is positioned in two mutually perpendicular directions along with add rebar,

middle beam rebar and dowel rebar. Ceiling deflection must be controlled by a survey camera in

this phase.

figure 3.2. positioning of the lower rebar

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3-3- positioning of the Contruss fillers:

The Contruss fillers are placed on site according to the design, then attached together by the belts

so they can't move or float upward.

Figure 3.3. positioning of the permanent fillers

3-4- positioning of the upper rebar:

the upper rebar is positioned according to the design; then the slab is ready for concrete pouring.

figure 3.4. positioning of the upper rebar

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3-5- Concrete pouring, vibration and levelling:

The concrete pouring must be performed in one phase; and concrete slump must be adequate to

fill the lower layer totally. By adding of accelerating admixture, the concrete viscosity is

increased that will enhance the strength and performance quality of the ceiling. Once properly

performed, completely burying the Contruss filler. Then, the pouring is levelled and smoothed

in a traditional manner.

Figure 3.5. Concrete pouring, vibration and levelling

3-6- removing the formwork:

Once the concrete has been hardened, the formwork can be removed and a smooth surface with

flat soffit is created.

Figure 3.6. removing the formwork

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4- Contruss system advantages

4-1- economic advantages: a) reduced construction cost for long spans:

Most of ceiling slabs exerted in the constructions, function as a one-way system. According to

the increased deflection and vibration in the ceiling as well as using additional beams over spans

beyond 7 meters, the use of one-way slab is not practical, economically and practically. Based

on participating of two concrete layers and orthogonal webs, the Contruss system will form a

high rigid and two-way slab by which, achieving long spans up to 20 meters will be possible.

In general, one of the major difficulty related to the concrete structures is large dimensions of

columns, which can be solved by using of this system as omitting the middle columns.

Furthermore, the Contruss ceiling system will form a high rigid and resistant slab operating

properly subjected to lateral forces, due to the inclusion of two concrete layers along with

orthogonal webs. Additionally, providing long spans, from an architectural point of view, offers

better aesthetic.

Figure 4.1. increased effective span

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b) variability of filler dimensions:

The Contruss fillers are the only permanent ones in which, dimensions can be evaluated by

engineers to be slashed down in size in factory by means of CNC machine to fit the required

spaces when installing on site, that will simplify slab installation. In correspondence of

economically and functionally improvement, the Contruss filler is capable to be manufactured

with dimensions ranging from 45 to 60 cm, and 12 to 65 cm in height.

Figure 4.2. various dimensions of Contruss filler

c) increased number of parking lots:

Thanks to the use of Contruss voided slab system in terms of removing middle columns, the

numbers of provided parking lots are increased. beyond the financial aspect, this increase will

make the movement and turning of the cars easier.

In some cases, the increased number of parking lots will result in the elimination of a parking

floor as well as costs reduction.

Figure 4.3. increased number of parking lots

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4-2- architectural advantages: a) increased span length (the distance between columns):

It is known as the most considerable benefit by the architectures, as achieving long spans in

structural design will accompany by following advantages: larger spaces, increased number of

parking lots, facilitated use reallocation, retaining walls displacement and architectural freedom.

figure 4.4. increased effective span

b) creating a flat soffit by eliminating drops:

By the use of Contruss system, ceiling thickness will be decreased; for example, the ceiling will

be 35-cm-thick in a span with length of 12 meters, but a flat surface is created under of ceiling

that can be simply used for systems installation as well as plastering. Vice versa, creating beams

with 80 cm height, drops and uneven intrados surface will complicate the passage of systems by

use of other fillers.

Advantages gained by removing drops and creating a flat intrados floor:

- reduced construction costs because of decreased floor height

- simplified formwork, concrete pouring and rebar performance

- reduced dropped ceiling costs

- flexibility in architecture

- facilitated passage of systems

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Figure 4.5. creating a flat intrados floor

c) creating large irregular openings:

According to the high rigidity as well as two-way function, the Contruss system is capable of

creating large irregular openings in the rigid diaphragm, which matters much in reception halls,

villas, commercial and educational centers. Also, creating additional openings for passage of

systems will be possible even after completion of slab installation.

Figure 4.6. creating large irregular opening

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4-3- technical advantages: a) possibility of creating openings after slab construction:

As considering various reasons for creating openings after completion of installation, it is

prohibited in one-way systems, due to beams disrupting. The Contruss system, by involving of

two concrete layers and perpendicular webs, will form a high rigid and two-way slab, that is

capable of creating openings after slab installation.

b) fire resistant slab:

Since composed of flame retardant polystyrene, the Contruss ceiling will provide high quality

acoustic operation in transmission of heat, function more properly in burning compared to the

other systems, certified that is a non-flammable material.

The polystyrene used in the Contruss is a fire-retardant material, which is expanded and

manufactured by hot steam at 100 degrees C, that will be stable in volume per a week.

c) resistant subjected to noise and vibration:

Material strength in sound transmission is investigated in two segments: 1) airborne noise, 2)

percussion noise.

In general, the concrete resists properly in transmission of airborne noise; as consequence, the

Contruss slab operates suitably subjected to airborne noise, because of participating two concrete

layers.

Furthermore, by involving trap air bubbles inside the polystyrene, sound power level will be

reduced by passing of percussion noise through the slab. The use of polystyrene in the Contruss

filler will result in improved acoustic behavior.

With regard to the increased rigidity of Contruss voided slab, less ceiling vibration will be

transferred in comparison with the common concrete slabs, that will be a relief for residents.

Figure 4.9. schematic image of sound waves transmission in a building

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d) reduced ceiling weight:

Since the variability of Contruss filler dimensions, it will provide more reduction in weight and

cost of ceiling, compared to other voided slab systems. Slashing by CNC machine in the factory,

makes it possible to manufacture the fillers in various dimensions, according to the structural

design requirements. The dimensions of a prismatic formed Contruss filler can be 45 to 60 cm

with the height of 12 to 65 cm, that will provide the most optimum slab construction, technically

and economically.

Figure 4.10. variability of Contruss filler dimensions

The main goal in creating voided slab is referred to eliminating of unloadable concrete in the

middle spaces of ceiling. To come up with, it is highly influenced by the dimensions of the filler,

based on the variation of loading and span length. The Contruss filler is known as the unique

one, which is capable to be designed in any arbitrary dimensions according to the order of

builders in order to minimize ceiling weight and costs.

Table 4.1. filler size and height

Filler height Ceiling thickness(cm) Effective span(m)

Size 15 30 9

Size 20 35 11.5

Size 25 40 13

Size 30 45 14

Size 35 50 15.5

Size 40 55 17.5

Size 45 60 19

Size 50 65 20.5

Size 55 70 22

Size 60 75 25

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e) providing appropriate clearance for rebar:

Based on the design of trays placed over the fillers, rebar will be positioned in desired distance

as clearance is provided suitably in the Contruss system, which makes it possible to design the

steel mesh without restrictions.

Figure 4.11. providing clearance for rebar

f) controlling vibration and deflection of the ceiling:

Due to the inclusion of perpendicular I-shaped ribs, the double-sided voided slab will provide

high moment of inertia, compared to flat, prestressed and waffle slab, for the ceiling. Generally,

The Contruss ceiling can be known as a hollow concrete truss with much high rigidity, that will

transfer the lateral loads properly as a rigid diaphragm as well as suitably control vibration and

deflection.

g) lack of stress concentration in the shear web:

Providing I-shaped ribs is the major advantage of two-way voided slab. Due to the special

forming of Contruss filler, as depicted in figure 4.12, the connection zone between web and

flanges in the rib is curved and shear force will transfer properly, which prevent it from creating

stress concentration. Stress concentration is a main defect existed in plastic fillers, that is

resolved thanks to the innovative Contruss filler.

Figure 4.12. lack of stress concentration in the I-shaped ribs

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h) easy to be slashed:

By using of polystyrene, the Contruss filler can be slashed down easily by means of saw to fit

the required spaces in correspondence of irregular scheme with various span length. This unique

qualification will make it easy to position the fillers at the corner region on site.

figure 4.13. use of slashed filler

4-4- practical advantages: a) simplified implementation:

Due to the elimination of middle beams in the Contruss voided slab, the ceiling formwork will

be so simple that can be performed by conventional reinforcement workers. Additionally, by

removing beams, the numbers of rebar and stirrups practiced in the ceiling is decreased that will

permit quick installation.

b) construction speed:

The positioning of fillers, lower and upper rebar and concrete pouring are main steps to install

the Contruss ceiling. The speed of installation will increase as much as 25 percent compared to

other systems since performing continuous formwork, and also will be completed quicker than

the beam and slab floor system, due to a flat soffit.

c) no need for special advanced technology to install:

The use of advanced technology in building construction requires spending much time and cost

as well as protection and surveillance of instruments in some cases. Meanwhile, the Contruss

system is needed no special group to install that can be easily exerted by conventional workers

after simple training.

d) benefit during installation compared to the other permanent fillers:

Because the permanent fillers are maintained in the ceiling, the installation costs are highly

depended on the materials used in manufacturing process. As a consequence, recycled plastics

applied in previous fillers presented different resistance when subjected to cold and warm

conditions. High quality as well as competitive costs are superior advantages of the composed

Contruss filler.

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The innovative application of a combined polypropylene, compatible adhesive and a polystyrene

core is accompanied by the following advantages:

1 - being solid that leads to avoiding fracture and concrete penetrating inside the fillers during

installation:

As a hollow recycled plastic with lower strength in daily heat interactions, the previous

permanent fillers might be fractured during or before concrete pouring, which will allow the

concrete penetration inside the filler that result in increased ceiling weight.

Since a solid form, the Contruss filler is impossible to be fractured as well as exposing high

flexibility subjected to heavy loads.

Figure 4.14. Contruss system installation

2 - the fillers adapt to drilling in order to simplified concrete pouring:

By increasing dimensions of filler in the double-sided voided slab, consuming concrete will be

reduced, though it may cause honeycomb in concrete at lower regions. Thanks to the engineers

involved at the research and development department of Contruss company, an exhaust hole can

be drilled at the middle of Contruss filler in order to facilitate concrete pouring as well as

preventing from created honeycombing concrete.

Manufacturing in various dimensions and drilled forming are the unique superior benefits of the

Contruss filler that will make it possible to create the most optimized voided slab.

Figure 4.15. a perforated Contruss filler

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The advantages gained by the use of polypropylene trays:

a) increased filler strength subjected to tensions created by flexure acting on the middle of filler:

The Contruss filler has been qualified to resist over bending fracture, shear punch and

overturning in an experimental test subjected to a load as much as 150kg applied on a surface

with dimension of 8*8cm.

One of the main reasons that has satisfied the builders is mentioned as the strength of Contruss

filler during installation. Once loading applied on the filler during installation, the trays are

stretched as preventing the filler from being deflected; while the hollow fillers will be deflected

or fractured in similar circumstance.

Figure4.16. Contruss filler

b) providing appropriate clearance:

Most of the previous plastic cuboid fillers used in the voided slabs are manufactured in a form

that will provide rebar clearances at the middle of filler, which is known as a defect because the

rebar must be positioned on center of it. The task is not viable or not performed properly in many

projects. Thanks to the use of hollow trays on the Contruss filler, a 2-cm clearance will be

provided simply.

Figure 4.17. providing appropriate clearance

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c) piles applied to determine the thickness of lower concrete layer:

The filler piles are considered to set the thickness of lower concrete layer as well as preventing

it from floating upward.

Figure 4.18. Contruss piles

d) indicators applied to determine the thickness of upper concrete layer:

The concrete pouring of ceiling is going to be performed after the positioning of fillers and rebar,

while it is difficult to determine required concrete volume. Thanks to the use of indicators over

the upper tray, the concrete pouring level will be determined simply that permits accurate

concrete pouring.

Figure 4.19. indicators applied to determine concrete thickness

e) belts installation:

One of the efficient component engaged in the installation of the fillers is belt, which applied to

create perpendicular integrated ribs in two directions in the slab. Based on the technical concept,

the ribs must be formed integrated and orthogonal, that is achieved by preventing the fillers from

movement during installation. Meanwhile, it is difficult to achieve because of various

circumstances in construction workshop such as passing workers and systems over the ceiling.

The Contruss fillers are attached tightly and regularly by the practice of an integrated belt, which

will permit high quality installation.

While keeping the fillers, the belts are capable of supporting rebar up to size 32, which are

referred as the upper rebar belong to the ribs, that were impossible to be positioned in previous

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permanent fillers, due to the lack of belts. Consequently, the builders had been required to apply

prefabricated vaults that result in the use of unnecessary rebar in the slabs.

Prefabricated vaults contain shear rebar formed as W in which, one of the applied paired bar will

not be involved in the shear strength because the shear rebar must be positioned perpendicular

to the shear flow to help for strength of slab. Furthermore, there is no need to apply rebar in

many parts of the slabs such as middle, due to lack of shear loads. Therefore, the use of

prefabricated vaults is not recommended in the slabs because of involving unnecessary rebar.

Thanks to the use of belts in the Contruss fillers, the upper rebar of ribs is maintained in the

position; there is no need to use highly cost prefabricated ribs.

figure 4.20. belt on the Contruss filler

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figure 4.21. fillers maintenance during execution

Figure 4.22. positioning of upper rebar over the belts

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f) easy to store and transport:

By using piles, the Contruss fillers are attached totally upon each other, which will simplify

storing as well as transporting to site.

Figure 4.23. the attached fillers Figure 4.24. storing the fillers

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5- comparison with the other systems

5-1- comparison of the Contruss system with the rib and block slab tutorial: a) flexibility in architecture:

Great architectures have dreamed to design over large spaces without columns and long

cantilevers over the history. The Contruss voided slab system will create a space without middle

columns in order to provide architectural freedom as well as facilitated use reallocation.

In the rib and block slab tutorial system, span created will be as much as 7-meters long, while

beyond, it is difficult to be exerted because of increasing deflection and vibration as well as

double ribs required. As regard to the inclusion of two concrete layers and perpendicular webs,

the Contruss ceiling will form a high rigid slab that can be constructed over span up to 20-meters

long.

Figure 5.1. ceiling exerted by the Contruss voided slab

b) one-way slab and seismic function:

The concept in applying rib and block is based on regarding of T-shaped elements, which will

transfer the loads to the supports in one single direction, and also allow elimination of tensioned

concrete that leads to reduced ceiling weight.

Figure 5.2. schematic section of Contruss voided slab Figure 5.3. schematic section of ribs and block

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By supplying permanent composite fillers in the concrete, the unloadable concrete in the slab

with no structural efficiency will be omitted in the Contruss system, that will permit creation of

I-shaped ribs with two-way function. Due to creating two integrated concrete layers as well as

perpendicular mutually ribs, the slab will provide much bearing capacity.

Figure 5.4. two-way Contruss voided slab Figure 5.5. one-way rib and block

The Contruss voided slab is constructed continuously in two layers that will form a rigid

diaphragm slab in earthquake which transfer lateral forces suitably on supports. It will operate

much more properly compared to the rib and block slab tutorial, in which, just a few centimeters

of tensioned rebar are involved in the ceiling.

Figure 5.6. Contruss system construction Figure 5.7. rib and block construction

c) ceiling thickness:

In the Contruss system, total thickness of ceiling is lower than the rib and block slab tutorial

system. for example, the ceiling will be 35-cm-thick in a span with 12-meters long, but it will

create a flat soffit that can be used for simple passage of systems. While in the rib and block slab

tutorial ceiling, creating beams with 80 cm height, drops and uneven intrados surface along with

the passage of systems will create a ceiling much thicker than the Contruss ceiling.

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Figure 5.8. Contruss ceiling thickness compared to the rib and block slab tutorial

d) creating large openings:

Impossible to adapt to openings, from the architectural point of view, is one of the main

restriction in use of the rib and block slab tutorial system. As regard to the one-way attribute of

the rib and block slab tutorial system, cutting ribs will disrupt load transfer, which will cost much

to create openings in the ceiling.

On the contrary, according to one of the most major property, the Contruss system is capable of

creating large irregular openings, which matters much in reception halls, villas, commercial and

educational centers.

Figure 5.9. large opening created in the Contruss ceiling

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e) ceiling weight:

For spans beyond 7 meters along with heavy loads such as parking floor, applying the rib and

block slab tutorial system will be required to accompanied by double ribs as well as much costs.

Although for shorter spans the Contrus system weighs more, it will provide much savings for

spans up to 7-meters long, due to high moment of inertia.

f) final cost:

Because the Contruss system formwork is performed continuously, a flat intrados floor will be

appeared; while there is no need for integrated formwork in the rib and block slab tutorial system,

the costs will be reduced but it will present an uneven surface for the ceiling.

Additionally, due to the existence of uneven surface, large soffit (uneven bottom surface of the

ceiling because of thick beams) and drops, dropped ceiling will be required in buildings. By

representing a flat soffit in the Contruss system, there will be no need for dropped ceiling that

makes the Contruss system costs approximately equal to the traditional rib and block slab tutorial

system.

Figure 5.10. chassis of dropped ceiling

g) simplified installation:

the Contruss system is so easy to be installed that can be performed by conventional parties with

a simple training. no need for special advanced technology to install, the Contruss system is

similar to the rib and block slab tutorial, from constructional point of view.

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Figure 5.11. the rib and block slab tutorial execution Figure 5.12. the Contruss system execution

h) construction speed:

As required integrated formwork in the Contruss ceiling, construction duration will be increased

as much as 5 percent, that is not considerable.

Required construction duration is same as needed for the rib and block slab tutorial execution,

in both, every floor will be completed in 15 days.

Figure 5.13. Contruss execution compared to the rib and block slab tutorial

i) ceiling deflection and vibration:

Once creating voided slabs via the Contruss system, the slab moment of inertia will remain stable

while dead load will be reduced. As ceiling vibration and deflection is highly depended on the

moment of inertia, the Contruss voided slab system will operate more suitably than the rib and

block slab tutorial.

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j) adapt to highly irregular supports:

The Contruss system will be able to adapt to irregular supports schemes, as regard to the

integrated mutually function. Consequently, it will provide possibility of changing the columns

scheme as well as positioning the columns in the retaining walls, that is impossible in the rib and

block slab tutorial.

k) fire resistance:

Concrete structures will endure better than the steel structures in fire, generally. Due to existence

of two concrete layers, the Contruss ceiling will function properly in transmission of heat when

subjected to fire, provide more strength than the other ceiling systems. The polystyrene used in

the Contruss filler has been certified that is a flame retardant material.

Figure 5.14. slower transmission of heat in the Contruss system

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5-2- comparison of the Contruss system with the metal deck ceiling: a) cash flow:

The major issue considered as a distinction between the Contruss and metal deck system is

referred to financial subject. In general, steel structures construction will cost much higher than

concrete structures by 35 to 50 percent, as applying metal deck will increase the costs.

Moreover, concrete structure will offer a better opportunity for builders, who are willing to spend

money upon construction segments by segments as regard to project progress. Because of using

metals in steel structures, it is required to spend much cash at the beginning of project.

Figure 5.15. comparison of concrete structure cash flow to steel structure

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b) ceiling thickness:

By providing shear walls, the Contruss ceiling formwork will be performed continuously, that

result in creating a flat intrados floor. On the contrary, metal deck ceiling performance is

accompanied by thick girders that will reduce useful height due to executing dropped ceiling.

For large spans up to 10-meters, the Contruss system will come up with a lower total thickness

of ceiling.

Figure 5.15. passage of systems above girders

Figure 5.16. thick girders in metal deck system

In the metal deck ceiling, by passing of systems over the girders, floor useful height will be

reduced.

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Figure 5.17. increased thickness and costs as dropped ceiling execution

c) adapt to openings:

As a one-way system, cutting ribs will disrupt load paths, that will make it so difficult to create

openings in metal deck system. In order to create openings (for systems passage) after

construction, the decking must be slashed initially as well as reinforcing cutting beams, then the

ceiling is ready for creating opening.

According to the high rigidity and two-way function, the Contruss system is capable of creating

large irregular openings in the rigid diaphragm, which matters much in reception halls, villas,

commercial and educational centers. Also, creating additional openings for the passage of

systems will be possible even after completion of slab installation.

d) fire resistance:

Inefficiency in fire is considered as one of the most prominent defect about metal deck system.

Figure 5.18. fallen apart metal deck system because of fire

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Due to existence of two concrete layers, the Contruss ceiling will function properly in

transmission of heat when subjected to fire, provide much more strength than metal deck ceiling.

The polystyrene used in the Contruss filler has been certified that is a flame retardant material.

e) construction speed:

Although steel structures are capable of being constructed as much as 30 percent quicker than

concrete structures, but there are two subjects to be considered:

1) By constructing concrete structures over two times per day as a so-called Fast-track project,

it will be completed quicker than the steel structures and at the same time it is more economical

even by two times working per day.

2) After constructing a few bottom stories in tall concrete structures, it is allowed to begin the

brickworks and systems installation in mentioned stories and keeping formwork in upper stories

simultaneously, that will make construction speed of concrete structures equal to steel structures.

Figure 5.19. Contruss system compared to metal deck

35

f) strength subjected to noise and vibration:

Sound resistance of materials is investigated in two segments: 1) airborne noise, 2) percussion

noise.

In general, the concrete ceilings operate properly in transmission of airborne noise; once by

involving polystyrene, acoustic function in percussion noise will be improved. As a result, the

Contruss slab will function more properly than metal deck when subjected to both airborne and

percussion noise

Figure 5.20. percussion noise

On the other hand, resistance in transmission of vibration regarded to ceiling is known as one of

the most essential property for the residents. Providing such strength will cost much in steel

structures. On the contrary, due to the high rigidity of Contruss voided slab, it will operate more

properly subjected to vibration, which is a relief for residents.

Figure 5.21. noise and vibration transmission in floors

36

g) ceiling weight:

The Contruss voided slab weighs more than metal deck which will be acceptable by considering

lower costs, adapt to large spans, less ceiling thickness in large spans, high rigidity and the other

superior related to the Contruss system.

h) providing large span:

Metal deck can be performed simply for spans up to 8 meters; while beyond, it will require much

cost as well as increased ceiling thickness. As inclusion of two concrete layers along with

perpendicular webs, the Contruss ceiling form a high rigid slab that will provide a rigid

diaphragm subjected to lateral forces as well as provide spans up to 20-meters long.

Figure 5.22. ceiling created by the Contruss voided slab

In general, from an architectural point of view, one of the major defect related to concrete

structures is the large dimensions of columns, which can be solved by removing the middle

columns and creating large spans, thanks to the Contruss system. Providing large spans will

result in numerus efficiency such as greater exposed spaces, increased the number of parking

lots, partitions reallocation and architectural freedom.

37

5-3- comparison of Contruss system with beam and slab floor system: a) ceiling thickness:

Large soffit and drops will be accompanied by following defects:

1- increased total height of structure due to increased floor height

2- increased costs as well as difficulty in formwork, concrete pouring and rebar performance

3- additional costs respect to dropped ceiling

4- architectural restrictions

5- difficulty in passage of systems

Figure 5.23. easy to install systems due to a flat soffit

Figure 5.24. better aesthetic by omitting drops

38

b) increased construction costs for spans up to 8 meters:

The Contruss voided slab has been come up to develop the conventional beam and slab system,

based on the elimination of unloadable concrete in middle spaces with no structural benefit. The

Contruss voided slab system weighs less compared to solid slabs, that will reach up to 50 percent

with equal rigidity in some cases.

Due to high rigidity and low weight as well as two-way function, the voided slabs will be able

to create large spans along with low ceiling thickness. For example, in a double-sided voided

slab with 35-cm-thick, the concrete is poured in 22-cm height that will demonstrate optimized

concrete consumption. Afterwards, a 22-cm-thick flat slab will provide a maximum 7-meters

span, which express the voided slab advantages.

Moreover, the loads are transferred to secondary beams, main beams and then the columns in

the beam and slab floor system. In the Contruss system, vice versa, the loads are transferred

directly to the columns because of two-way function. Therefore, the Contruss ceiling system will

offer better function and lower costs in large spans; however, for spans beneath 7 meters, as

reduced bending moment at the middle of slab, the conventional beam and slab floor system will

cost less.

Figure 5.25. two-way function of Contruss system

Similar to flat slabs, the Contruss system formwork will provide a flat intrados floor. Due to

existence of beams and large soffit in the beam and slab floor system, dropped ceiling will be

required which will increase construction duration and formwork costs.

c) construction speed:

As creating a flat soffit, a flat integrated formwork will be required for the Contruss system

which permit easy and quick construction.

39

Figure 5.25. the beam and slab floor system figure 5.26. the Contruss voided slab system

d) adapt to large and irregular openings:

The loads are transferred to supports through I-shaped mutual ribs in the Contruss system. In the

beam and slab floor system however, such transfer is accomplished by secondary beams which

makes it difficult to crate openings in the slab because of disrupting in beams.

e) easy to install:


as well as protection and surveillance of the instruments during construction in some cases.

Meanwhile, the Contruss system is needed no special group for installation in spite of known as

innovative engineering technology, that can be exerted easier than the beam and slab floor

system.

Figure 5.27. positioning the Contruss fillers to perform a voided slab

40

f) fire resistance:

Concrete structures will endure better than steel structures in fire, generally. Due to existence of

two concrete layers, the Contruss ceiling will function properly in transmission of heat when

subjected to fire, provide more strength than the beam and slab floor systems. In addition,

polystyrene used in the Contruss filler is a slow burning certified that is a flame retardant

material.

g) strength subjected to noise and vibration:

Material resistance in sound transmission is investigated in two segments: 1) airborne noise, 2)

percussion noise.

In general, the concrete ceilings resist properly in transmission of airborne noise; as consequence,

the Contruss slab operates suitably as well as the beam and slab floor system when subjected to

the airborne noise. However, the difference is appeared over percussion noise.

By involving trap air bubbles inside the polystyrene used in the Contruss system, sound power

level is reduced by passing of percussion noise through the slab. Polystyrene is known as the

second available materials that represents best acoustic function in sound transmission according

to the building codes. Overall, applying polystyrene along with two concrete layers in the

Contruss fillers have provided proper resistance subjected to airborne and percussion noise

transmission.

Figure 5.28. noise transmission through walls and ceiling

Furthermore, with regard to the increased rigidity of Contruss voided slab, it will transfer less

ceiling vibration in comparison with the beam and slab floor system, that is a relief for the

residents.

41

5-4- comparison of Contruss system with prestressed slab system: a) required advanced technology and specialist parties to construct:


as well as protecting of instruments during construction. As regard to scientific and technical

complication, the prestressed system is accompanied by special complicated pre-tensioning, high

advanced technology materials and difficult performance which will discourage the builders to

use unless for bridges or large spans up to 30 meters. Consequently, the Contruss system is more

acceptable, from the technical and economical point of view.

Figure 5.29. instruments of the prestressed system

One example about complexity of the prestressed system is releasing of post-tensioning cables,

which is required to be inspected that is not viable in buildings, though it can be controlled after

a while in bridges.

Figure 5.30. pre-tensioning process

Another example about complexity of the prestressed system is occurred when opening is needed

after slab installation. As providing much resistance subjected to forces applied on the slab via

such cables, it will be required high accuracy to protect the cables for creating openings in the

ceiling after slab construction.

42

Figure 5.31. post-tensioning cables

Positioning of cable pods according to the curvature of scheme is another difficulty in the

prestressed system installation, which is required specialist parties to position, tension and cover

the cables.

On the contrary, installing the Contruss ceiling is followed by positioning of the fillers, lower

and upper rebar and concrete pouring that is as simple as conventional ceiling system but it is

capable of providing large spans up to 20 meters.

Figure 5.32. positioning of the Contruss fillers Figure 5.33. performing pre-tensioned arch cable

pods

b) construction speed:

Based on the following reasons, the prestressed system will require more time to complete than

the Contruss system:

1- concrete must be hardened before pre-tensioning:

Concrete is required to be hardened before applying the pre-tensioning force in the post-

tensioned system, so the executive party has to complete the process after hardening. Then the

formworks are removed to use for next ceiling.

2- In many prestressed slabs, in addition of integrated ceiling formwork, drops and large soffit

formwork is needed which will increase the construction duration and costs.

3- Because of involving specialist parties, delay in presence of parties will increase total

construction duration.

43

c) existence of drops and large soffit in most of prestressed ceilings:

As the cables must be restrained in two directions in the slab, around beams will form a thick

and large section in the prestressed systems that leads to creating large soffit.

Figure 5.34. structure exerted by prestressed system Figure 5.35. structure exerted by Contruss system

There will be more difficulties related to the prestressed ceilings constructed by pre-tensioning

method such as creating flaw in the ceiling, architectural restrictions and installation problems.

As regarding of such difficulties, pre-tensioning manner is usually applied for industrial ceilings.

Figure 5.36. ceiling exerted by prestressed system

d) weight of used materials:

By involving total concrete section under compression, the neutral axis is conducted upward that

will result in decreased materials consumption as well as reduced concrete section in the

prestressed ceiling. On the other side, because of creating middle voids in the ceiling, moment

of inertia is increased and concrete consumption is reduced in the Contruss system that will

present a lower weight ceiling by 5 to 15 percent compared to the prestressed system.

44

e) cost:

Due to simplified performance, the Contruss system will cost less by 5 to 10 percent than the

prestressed system.

f) adapt to openings:

Because of disrupting the cables trajectory, it is so difficult to create openings in the prestressed

slab system, and also impossible to implement special formed openings in many cases.

In the Contruss system however, creating large irregular openings in ceilings will be so simple

that matters much in reception halls, villas and commercial and educational centers.

g) acoustic function of ceiling:

By involving middle polystyrene cavities, the Contruss voided slab system is a suitable insulation

in transmission of airborne noise which is so important in religious and educational centers.

h) fire resistance:

Due to existence of two concrete layers along with flame retardant polystyrene between them,

the Contruss ceiling will function properly in transmission of heat when subjected to fire, provide

more strength than the prestressed ceiling systems. The polystyrene used in the Contruss filler is

has been certified that is a flame retardant material.

The major defect related to the prestressed ceiling when subjected to fire is releasing of the post-

tensioning cables. As regard to providing much resistance for total strength of the slab by the

cable, it will be expanded and fail in fire that leads to collapse of the ceiling.

45

6- projects constructed by the use of Contruss system

Pratham residential complex:

Effective

span (m)

Filler size

(cm)

Story

numbers use Area (m)

6.5*10.5 24*55 8 residential 2731

46

Vaikunth official complex:

Effective

span (m)

Filler size

(cm)

Story


6.5*10.25 20*55 7 official 1470

Sivanta residential project:

Effective

span (m)

Filler size

(cm)

Story


10*12 13 22 residential 14334

47

Anandvan residential project:

Effective

span (m)

Filler size

(cm)

Story


11.5*10 20 9 residential 5422

Diamond commercial project:

Effective

span (m)

Filler size

(cm)

Story


13*8 24 10 commercial 3200

48

Asha residential project:

Effective

span (m)

Filler size

(cm)

Story


11*9 13 7 residential 1875

Soham Residential project:

Effective

span (m)

Filler size

(cm)

Story


12.5*10 24 8 residential 2731

49

Kalpvan residential project:

Effective

span (m)

Filler size

(cm)

Story


9.5*8 20 4 residential 1000

Ashirward residential project:

Effective

span (m)

Filler size

(cm)

Story



50

Snakalp residential project:

Effective

span (m)

Filler size

(cm)

Story


11.5*9.5 19 7 residential 1442

Venus tower project:

Effective

span (m)

Filler size

(cm)

Story


10.5*10 20 14 residential 11000

51

Chamatkar villa project:

Effective

span (m)

Filler size

(cm)

Story


10.5*7.5 19 5 residential 1315

Kalpana terminal project:

Effective

span (m)

Filler size

(cm)

Story


12 25 5 terminal 1300

52

Ranjit residential project:

Effective

span (m)

Filler size

(cm)

Story


19*16 32*19 2 residential 1394

Preet project:

Effective

span (m)

Filler size

(cm)

Story


10 25 7 residential 35000

53

Sukharm project:

Effective

span (m)

Filler size

(cm)

Story



Arpan complex project:

Effective

span (m)

Filler size

(cm)

Story


12 25 8 residential 11000

54

Daya residential project:

Effective

span (m)

Filler size

(cm)

Story


11.5*10 20 11 residential 3600

Vivanta residential project:

Effective

span (m)

Filler size

(cm)

Story



55

Mannat villa project:

Effective

span (m)

Filler size

(cm)

Story


12*9.5 15 2 villa 425

Sumel reception hall& commercial complex:

Effective

span (m)

Filler size

(cm)

Story


13.5*10 32 10 commercial 900

56

Surabhi residential project:

Effective

span (m)

Filler size

(cm)

Story



Ahand shopping project:

Effective

span (m)

Filler size

(cm)

Story


11.5*15 19 10 commercial 5370

57

Doctors building complex:

Effective

span (m)

Filler size

(cm)

Story


13.5*10 24 8 official 6497

Rajhans project:

Effective

span (m)

Filler size

(cm)

Story


10*13 24 12 residential 4595

58

7- Conclusion and ultimate comparison table: Thanks to the use of modern Contruss voided slab system, technical advantages along with

simple performance are provided as well as much economic benefits for large spans. Due to

providing two concrete layers and mutually I-shaped ribs, the system presents high rigidity

subjected to gravity and lateral loads that will provide possibility of creating spans up to 20

meters. Because of inappropriate function of one-way ceiling over spans beyond 7 meters, the

integrated two-way function of Contruss voided slab will be so practical in such spans. The

following table is illustrated the attributes and advantages of the Contruss system compared to

the other constructional ceiling systems.

59

Comparison table of Contruss voided slab system with the other ceiling systems:

Contruss

Rib and

block slab

tutorial

Beam and

slab

system

Prestresse

d system

Metal

deck

Adapt to large spans

and cantilevers

Resistant in sound

transmission

No need for dropped

ceiling

Construction speed

Simplified

implementation

Lack of large soffit

and drops

Fire resistance

Construction costs

for spans beneath 8-

meters

Construction costs

for spans beyond 8-

meters

Reduced vibration

and deflection

Reduced weight of

structure

No need for special

parties to install

Adapt to irregular

large spans

Adapt to irregular

supports

Complete points:

contruss engineering company

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