IJSRD - International Journal for Scientific Research & Development Vol. 4, Issue 02, 2016 ISSN (online):

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1 IJSRD - International Journal for Scientific Research & Development Vol. 4, Issue 02, 2016 ISSN (online): Structural Behaviour of Bubble Deck Slabs and Its Application: Main Paper Neeraj Tiwari 1 Sana Zafar 2 1,2 Madan Mohan Malviya University of Technology, Gorakhpur Abstract The Bubble Deck slab is a newly designed slab made by reinforcement mesh, hollow HDPE ball, reinforcement mesh again at bottom.it is based on the patented integration technique thai is the connection of steel and air. It is a hollow deck in which HDPE sphere ball acte the purpose of reducing concrete that has no carrying effect. By adapting the mesh width & the geometry of the sphere, a unique and optimized concrete construction is obtained, with regular maximum use of both moment and shear zones. The reinforcement mesh catches, distributes & fixes the spheres at exact position point, while the spheres shape the air volume.it controls the level of reinforcement mesh and also stabilizes the spatial lattice. Key words: Structural behaviour, Bubbledeck slab, Reinforcement mesh, HDPE sphere balls spanning slab supported by columns.it generally regulates to allow maximum deflection during service loading. It consist of plastic spheres that is sandwich between two steel meshes.these members are brought to site,placed on formwork and concreting is done by technical methods. This type of slab is optimal for construction area with compact spacing because these modules can be stacked on top of one another for storage until required. A. Standard Deck Types Bubble deck is cast in six standard deck types.(the marked standards are recommended): Deck thickness(mm): I. INTRODUCTION Bubble deck slab is the slab in which some amount of the concrete is replaced by the plastic hollow bubbles which are made by the waste plastic material, which reduces the selfweightof thestructure.the main effect of the plastic sphere is to reduce the dead load of the deck by1/3 in compare to solid slab having same thickness without effecting its deflection behavior & bending strength It locks spheres between the top and bottom reinforcement meshes, thereby creating a natural cell structure, acts like a solid slab. The slab is cast with the same capabilities as a solid slab, but with considerably lesser weight due to elimination of excessive concrete. Currently, this innovation technology has been applied to a few hundred residential high rise buildings, and industrial floor slab due to limited understandings. For this investigation, the structural behaviour of Bubble Deck under various condition will be studied in order to gain an understanding on this few technique and to compare it to the current slab system. This technology will then be applied to create lightweight bridge deck since a significant portion of the stress applied to a bridge comes from its own self-weight. By applying the knowledge gathered during the behaviroal analysis. Modular deck components for pedestrian bridges that is notably lighter but comparable in strength to typical reinforcement concrete section will be designed.this floor system is designed to reduce the strength to weight ratio of typical concrete slab.it replaces or removes concrete from center of slab,where not or less useful.in place of that concrete,this design system uses hollow HDPE spheres to decrease the dead load of concrete floor.however it also reduces the slab resistance to fire and shear. II. SCHEMATIC DESIGN The simple bubbledeck slab is made over the prefabricated `bubble-lattice` on traditional frame.in this slab system,the bottom of the slab is furnished with a pre-cast concrete layer on which the building horizontal part is replaced.bubbledeck is intended to be a flat slab,two way Fig. 1: Types of Bubble deck 1) Compostion The spheres are placed in the centre of the cross section of the slab.here concrete has less effect while maintaining the solid section in top & bottom where high stresses can exist.hence the slab is fully workable with regards to both positive & negative bending. FiG. 1: In this principle,bubble deck slabs acts as asolid slab just with reduced load due to the less amount of concrete. For the design mould,the required quantity of material are given below- Type Cement Sand Aggregate water Bubble deck Solid deck Table All rights reserved by 433

2 2) Difference Between Traditional Building & Bubbledeck Building 1) Preaparation Of Reinforcement Mesh As we know that the steel bars are provided in Bubbledeck for tension zone and concrete are provided for compression zone.the mesh of steel bars is given below. Fig. 2: 80 % OF THE NEW WORLD FROM THECARRY OUTSIDE 20 % OF THEMETHOD BY WORLD USE JORGEN PRECAST THE OUT THE SLABS BREUNING: BUIlDINGS DECK IN SITU THE LOOK CHOICE OFBubbleDeck SIMILAR SUPPORT IS SUPERIOR CASTED TIED TOIN EVERY WALLS ORWAY BUT THE CHOICE OF BEAMS CHOICE OF CONSTRUC SUPPORT IS TIONS ARE CAUSING AN SUPPORT IS DIFFERENT ARBITRARY - UNCHANGE ABLE AND ARBITRARY - BUT SPAN IS UNFLEXIBLE AND SPAN IS SHORT BUILDING LARGE Table 2. B. Material Used BubbleDeck slab is madeup of three materials-plastic spheres,concrete and steel,as seen in Figure, 1. STEEL-Steel reinforcement having grade Fe60 strength or more is used.two steel meshes for lateral supports are used. PLASTIC HOLLOW SPHERE-It is a hollow sphere made up of high density polythene or HDPE. CONCRETE-Concrete is made up of standard portland cement,sand and fine aggregates Fig. 2: Fig. 3: Reinforcement Mesh The size of the steel bars in horizontall direction is 50cm and in vertical direction is also 50cm.The spacing provided between is 6.5cm.The diameter of steel bar is 8mm and the diameter of HDPE sphere is 7.3cm.The combination of mesh and sphere is shown in below figure. 2) Combination Of Hdpe Sphere With Mesh Fig. 4: HDPE sphere-mesh combination 3) Hdpe Sphere Property Detail a) Production Designation Product marketing PE-HD Chemical Designation Polyethene(high density) Table 3. b) Formulation Detail About Ingredients Usual chemical designation Polyethene(high density) Chemical formula (-CH2-CH2-)n Genus Polyolefin Hazardous additional substances none CAS No Table 4. c) Physical & Chemical Properties Physical condition Solid(at+20ᵒc Colour Choosen by manufacturer Odour Weakly of parafin ph Not applicable Relative density kg/m3 Melting point ᵒc Softing point ᵒc Solubility in water insoluble Table 5. Polymer characteristics All rights reserved by 434

3 Decomposition temperature >300ᵒc Flashpoint >355ᵒc Spontaneous ignition temperature >355ᵒc Table 6. Safety characteristics 4) Benefits And Advantages Of Bubble Deck a) Material And Reduced Weight Its main advantage is that it uses 30-50% less concrete than other conventional,normal slab. Plastic Spheres Replaces The Uneffective Concrete In The Centre Of The Section. Since It Reduces The Overall Dead Load Of Structure By Deducing Unused Heavy Material. Reduces In Material Of Concrete Weight Also Leds To Less Requirement Of Steel. Building Foundation Will Be Designed With Smaller Dead Loads. b) Advantages Reduced weight Increased strength Larger span Fewer columns No ribs or beams under the ceiling, pillars have no capital c) Production and Carrying Out Less work insitu, unskilled labours may be used. Simple & easier simple erection. Less space for storage. Light & cheap lifting equipment. Higher quality of production of fabricated unit. These slabs can be precast at site,so reduces on site construction time. Less time consumption can also be achieved by faster erection of columns,walls & MEPs because of lack of load bearing walls & support beams for this new flab slab. Lesser curing time also save time since there is less concrete in bubble deck slab Fig. 6: Lifting Section of Bubbledeck Slab 7) Cost Savings Due to reduction in time & material, cost also reduces. Reduced material and weight, lowers the cost of transportation & more economical to lift the material. Cost also reduces in construction & design of frame elements like columns & walls. There is slight increase in cost of production due to assembly & manufacturing of HDPE spheres. Fig. 5: 5) Structural Properties Because of lesser dead weight of slab and its two way spanning action load bearing walls become unrequired. It is also designed as flat slab,which neglects the requirement for girder members and support beams. These properties reduces some of the structural needs for the foundation and column. Bubble deck slabs can be analyzed and designed as a standard concrete flab slab on behalf of its ductility and strength. 6) Time And Construction Savings The transportation of material is considerably reduced with lower cost & environment improvement. Fig. 7: Spheres Mesh System 8) Deflection & Bending Stiffness The bottom reinforcement steel and the top compressive portion of stress block contributes to flexural stiffness in bending. Fig. 8: Standard stress block 9) Shear Strength The shear strength & punching shear are tested. This test is performed on test elements with slab thickness 180mm.The All rights reserved by 435

4 shear capacity was calculated by a/d (distance from imposed force to support divided by deck thickness). Shear capacity(in % of solid slab) a/d=2.23 Solid slab 100 Bubbledeck slab 75 Table 7. It is calculated to 81% compared to solid slab. Shear strength of slab mainly depends on effective mass of concrete. due to use of plastic bubbles, the shear resistance of bubbledeck greatly reduces in comparison of solid slabs 10) Bending Strength and Deflection Behaviour In % of a solid deck Same strength Bubbledeck vs solid slab Same bending Stiffness Same concrete volume Strength Bending stiffness Volume of concrete Table 8. 11) Punching Shear The average punching shear is calculated to 91% in comparison to solid slab It must be firstly analysed that whether the applied shear is lesser or greater than the shear capacity of bubbledeck slab. Firstly it is determined by the designer whether the applied shear is greater or less than the bubbledeck capacity.if it is found to be lesser than no futher check is required.but if its founds to be greater,the spheres should be omitted surrounding the column & then check the shear in newly solid section.then if shear resistance of solid concrete portion is lesser than applied shear,than shear reinforcement is required. C. Application in Pedestrian Bridge Decks Since the bubble deck slab has significantly less shear capacity in comparison to solid slabs,a pedestrian bridge is choosen over a vehicular bridge. Punching shear is also another important matter for bridge deck with HDPE spheres. In case of floor slab, if shear is too large near to column, spheres may be left out & that space filled with concrete. The vehicles wheel apply point load during travel along deck with varing speed instead of being stationary, distributed load as in building 1) Safety Having fire proof construction. Earthquake-due to weight reduction, it is less destructible. Moisture-condensation safe design. III. OBSERVATIONS A. Solid Deck Slab Slab dimension of solid slab: Length-500mm,Width- 500mm,Depth-180mm L o a d ( m m ) load vs deflection of solid deck slab Deflection(mm) Fig. 11: Load Vs Deflection Curve Of Solid Deck Slab IV. RESULT Maximum shear load taken by normal solid slab is observed to be 160 KN Cracks in the slab is observed at 75.2 KN as shown in figure Fig. 9: Punching shear failure Fig. 10: Floor to Column connection modification Fig. 12: Pattern of crack in solid slab (at 75.2 KN) All rights reserved by 436

5 A. Bubble Deck Slab Slabdimension:Length-500mm,Width-500mm,Depth- 180mm verifies the prior analysis & experiments. however the performance of bubble slab is not as successful in pedestrian deck. this does not reduces the use of bubble deck in bridge deck, but requires more studies to completely analyse the feasibility of slab in bridge. ACKNOWLEDGEMENT This work has been carried out in civil engineering department of Madan Mohan Malaviya University of Technology, Gorakhpur, India. The author presents its heartiest gratitude towards Sana Zafar,Mrinank Pandey for constant encouragement, guidance and support. Fig. 13: V. RESULT Maximum shear load is taken by bubble deck slab is observed to be 156KN Cracks have been seen at load of 59.6KN as in figure shown Fig. 14: Pattern of Cracks In Bubble Deck Slab (At 59.6KN) REFERENCES [1] "Bubble deck design and detailing,bubbledeck Voided Flat Slab Solutions- Technical Manual and Documents (2007). [2] "BubbleDeck Slab properties " Bubble Deck Voided Flat Slab Solutions- Technical Manual and Documents (2006). [3] " BubbleDeck-UK". "Lighter Flat Slab Structures with Bubble Deck." (2006). [4] "BubbleDeck Engineering Design & Properties" Overview." Bubble Deck Voided Flat Slab Solutions- Technical Manual and Documents (2007). [5] " BubbleDeck International. "The Light weight Biaxial Slab." Bubble Deck(n.d):1-4. [6] "BubbleDeck Tests and Reports summary. " BubbleDeck Voided Flat Slab Solutions- Technical Manual and Documents!(2006) [7] "Concrete Reinforcing Steel Institute".Structures:The Sum of their parts April 2010 [8] "DR.B.C.Punmia,A.K.Jain",Soil Mechanics & Foundations,16th Edition 2005 [9] "Ashok Kumar Jain",Reinforced Concrete,6th Edition,2002. VI. RESULT DISCUSSION The shear strength of concrete slab mainly depends on effective mass of concrete in the slab. Due to presence of HDPE spheres,the shear resistance of Bubbledeck slab is largely decreased in comparison to normal solid slabs(as shown by graph) BubbleDeck performs better than normal conventional solid slabs. The internal forces & maximum stresses in the voided deck were upto 40% lesser than solid slab due to reduced dead weight by use of HDPE spheres. The deflection was little greater by 10% since the stiffness reduces from presence of bubbles. These results say that this type of slab will provide better long durable floor slab with better long term result under a dominant gravity and uniform load. VII. CONCLUSION This analysis proves that BubbleDeck technology is more useful and efficient than a solid conventional slab in office floor system.the models of the slabs created for the analysis All rights reserved by 437