It doesn't offer a large span. A flat slab is one of the most popular types of slab constructed in the world due to its advantages when compared to the other types of slabs. Slabs that have span greater than 16m can make use of a waffle slab design. One Way Slab Vs Two Way Slab: Deflection Deflection in a one-way slab gives it a cylindrical shape. The construction time is also lesser when compared to the normal reinforced concrete slab. Namely, there are as follows. What are the disadvantages of solid slabs? HOW TO CALCULATE CEMENT, SAND AND COARSE AGGREGATE QUANTITY IN CONCRETE? Curving this type of slab is lower than any footing slabs. The slabs are lighter: - Ribbed slabs can be formed with a lesser amount of concrete equaling less cost. A flat slab stands for a one-way or two-way system with solidities in the slab at the columns and load bearing walls are known as ?drop panels? Not suitable for 2. When the load is heavy, and the span is long, a two-way joist or grid system, commonly known as a waffle slab, may be used. Previous Post Next Post Required fields are marked Drop panels act as T-beams over the supports. High slab bulkiness. 2. They avoid the enclosure of the triangular space. From floor to floor height will increase the height of the building. Shear reinforcement is not required at the columns. Compared to typical reinforced concrete two way slab system, the thickness of flat plate slabs are higher. Minimum And Maximum Spacing Of Beam, Column, Stirrups, Slab & Footing, MINIMUM SIZE OF CONCRETE SLAB, BEAM & COLUMN, HOW TO CALCULATE THE QUANTITY OF STEEL IN COLUMN (BBS), ALL YOU WANT TO KNOW ABOUT MASON TOOLS BEFORE BUYING IT, Copyright 2022 lceted. It doesnt offer a large span. 3. 3. The bands or wide beams are provided 1.5 to 2.0 times as deep as the slab and as wide as necessary up to the width of the column strip. 12. It can save approx 10% of the vertical member. ii) Large spans cannot be constructed. PROCESS OF INSTILLATION :-. The fact that solid slabs need drop beams greatly limits the [interior designer and / or tenant] ability to place the partitions wherever they want or change them in the future. 11. It increases the bending and shear resistance. Drop panels play a significant role here as they augment the overall capacity and . Domes Advantages And Disadvantages. Partition walls can be set anywhere wanted. Waffle Slabs Or Grid Slabs: Benefits and Drawbacks of Flat Slabs . Use extensive table formwork to provide faster construction. Beams disturb light and air circulation in the building. Considering the possible load transfer mechanisms. Create optimum design of the structure. Minimum thickness of The column strips function as shallow beams within the slab thickness. Flat roofs are not always advantageous. When it is required to resist higher shear forces at the column head, and there are higher bending moments, the construction of a column head are many advantages. Windows . Calculate the bending reinforcements. Higher Slab Thickness. Minimum structural depth. 9. Drawbacks of flat slab: 1. No beams. An increase in the wall load could increase the cost of construction significantly. The use of zero beams helps to have underfloor spaces and more service areas. 8. The column strips, in turn, transfer the loads to the columns by one-way action. The zones near columns are subjected to high negative moments and shear forces. In Waffle slab or Flat Grid very less amount of steel is used. Reinforcement Is Provided In A Form Of Beam Within The Gap. Share this: Facebook Telegram WhatsApp Twitter Reddit Step 2 :- Hardy Blocks Are Placed On The Shutter With One Brick Gap On The Entire Shutter. This can prove gainful in case of lower building height, decreased cladding expense and pre-fabricated services. The column heads may be provided with any angle from the consideration of . How Does it Work? Structurally it creates a spanning problem, as spans for structural support are in a right angle to each other. There are methods to determine the slab thickness. In a two-way slab, the load is transferred in both directions. have discussed in addition to other aspects. on the slab by minimizing clear or effective spacing. Select the load combinations to be considered. Select the suitable cover for the reinforcement based on the durability requirements and fire resistance. The economical span L of a reinforced concrete flat slab is approximately D x 28 for simply supported, D x 32 for an end span and D x 36 for an interior span. Rolled fill does not require to use in Waffle slab. Not Suitable For Supporting Masonry Partitions. An increase in the wall load could increase the cost of construction significantly. This is the usual type of slab type. 5. Required fields are marked *. Vibration control capacity is higher. 998 Words4 Pages. The Waffle slab system can be called as a two - way joist slab system which comprises of ribs constructed in perpendicular direction. A flat slab is a one-way or two-way system with thickenings in the slab at the columns and load bearing walls called 'drop panels'. Places where beam projections are not desired and where the need of aesthetics view. The overall depth of the drop panel is typically taken as 1.75 to 2 times the depth of the slab, again rounded to suit timber sizes or the nearest 25 mm. A reinforced concrete slab that generally does not use beams and transfers the load directly to the supporting column refers to the flat slab. There are several methods for design. Stiffness consideration usually controls the thickness of the flat slab, represented in the ratio of span to effective depth. It minimizes the moment in the with the curtailment of the clear or effective span. The load is transferred directly from slab to column in the flat slab. Flat slabs or plain ceiling Element designs with notes and discussions have added to get comprehensive knowledge. However, the depth of the column head is higher than the drop panels. 2. Disadvantages of Flat Slab. The two main constraints for using flat slabs in high . Disadvantages of Flat Slab Utilized during a flat plate system, it's impossible to possess a sizeable span. What liquid do you put in sensory bottles? What is an HVAC System? It stiffens the flat slabs, consequently reduces deflection. What is the benefit of flat slab?Flexibility in Room Layout Flat slabs allows Architect to introduce partition walls anywhere required, this allows owner to change the size of room layout. 13. A drop panel is an area around the column having increased the slab to improve the structural capacity of the slab. It is not effective for supporting fragile partitions (masonry) 3. Solid Slabs can be designed and produced with mild reinforcing or by adding prestressing strands. It uses drop panels that may interfere with oversized mechanical ducting. Reduction in the floor-to-floor height reduces the cost of construction. 1.1 CONVENTIONAL BEAM SLAB SYSTEM . The thickness of the flat plate slab is greater than that of the typical RCC two-way slab. Disadvantages of Flat Slab. They are also used where uses of beams are not required. The main disadvantages of flat slab systems are; they are not suitable for supporting brittle (masonry) partitions, higher slab thickness, Chance for progressive collapse is more in flat slab due to the punching shear failure, in flat slabs, the middle strip deflection may be critical. Your email address will not be published. The major disadvantages are given below. Minimizes the risk of earthquake hazards. These cores reduce slab self-weight and . They increase the shear capacity and the stiffness of the floor system under vertical loads, thus increasing the economical span range. Which is the most critical action for flat slab? 1.the floor system requires lesser depth and thus there will be a reduction in storey height 2.there is a reduction in the dead load and foundation loads since the overall weight and storey height are decreased. Column heads help to increase the shear strength of the slab. The use of a drop panel can interfere with large mechanical ducting. Advantages. 6. These slabs are directly held on a suitably spaced column with or without drop panel and column heads. Save our Whatsapp contact +919840140396 as LCETED and Send us a message JOIN, How to Calculate Cement, Sand and Coarse Aggregate Quantity in Concrete?/mix design. They provide a better appearance and offer better diffusion of light. Uncategorized. However, where the column heads are given, the part of a column head that lies within the most significant pyramid with a vertex angle of 90 or right circular cones can be included entirely within the column. In flat plate system, it is not possible to have large span. The precast concrete wall is known for its durability and superior strength. The flat plate floor system requires simple formwork. Load-bearing capacity is more than a flat slab. Disadvantages of Bubble Deck Slab The thickness of the slab is limited. This is connected with the flat slab design. because it reduces formwork. The construction of column heads in flat slabs is very common. In flat plate system, it is not possible to have large span. Flat roofs have limited options. The minimum thickness of the drop panel slab is usually taken 1.25 times the thickness of the slab. 4. Larger or storey height shorter & pleasing appearance. ADVANTAGES AND DISADVANTAGES OF FLAT SLABS AND STANDARD. 2. The negative moment capacity of slab is also raised c. This tightens the slab and thus decreases the deflection Flat slab construction can deeply reduce floor-to -floor height especially in the absence of false ceiling as flat slab construction does act as limiting factor on the placement of horizontal services and partitions. In Flat Grid trench mesh can be used. Comparatively higher slab thickness is required. For lateral loads, all columns may have significant moments. They require a specific level of thickness to maintain their strength - usually at least 4 inches for a slab-on-grade foundation. of the slab increased. Purpose, Importance, Advantages & Disadvantages. 5. MINIMUM SIZE OF CONCRETE SLAB, BEAM & COLUMN MINIMUM SIZE. Use of flat slab allows choice of omitting false ceiling and finish soffit of slab with skim coating. Higher slab thickness. Skilled labor required. When the being and shear forces extend beyond the column head, we could provide the drop panels to cater to the increase in the bending and shear stresses. More availability of the height of the room. Critical section for shear in case of flat slabs is, The main difference between flat slab & conventional slab-beam system is that. Not suitable for supporting fragile (masonry) partitions. There is modern software that we can use to design the slab completely and get the reinforcement drawings. Cracks in Concrete Slab Why do they develop after casting? Since flat slabs dont need beams, floor height can be minimized, reducing the building height. It offers faster construction provides economy in the overall cost of the building. d) Places where beam projections are not desired and where the need of aesthetics view. Beams are not used (Therefore under floor services outside the drops are simple). iii) Brittle partitions like the brick masonry are not suitable for flat slabs. 3: Use of drop panels may interfere with larger mechanical ducting: 4: Critical middle strip deflection In flat slabs, the middle strip deflection may be critical. Two-way flat slab: Suitable for applications with a span of 6 - 9 meters and with a live load of 4 - 7 kN / m2. One Way Slab Vs Two Way Slab: Cost One-way slabs are economically less expensive than two-way slabs. The major disadvantages are given below. Focusing on the disadvantages now, pitched roofs cost more and they also take longer to install. Material for flat roofsis a bit scarce. Generally, the column head size should keep approximately one-fifth of the span. 4. For carrying heavy loads, the thickness of the slab over columns increases, and the thickened part of the slab is recognized as a drop panel. The formwork is difficult. It can be imagined that the domain 1-1-1-1, described as the middle stripe (MS), caries load in two ways action with column strips (CS) 2-1-1-2 and 3-1-1-3 providing supports. 2. It's a form of the precast slab with cores running through it. 3. Advantages & Disadvantages Sunken Slab. 3. Source: www.civilengineersforum.com . Disadvantages of flat roofs than sloped roofs. Use of drop panels may interfere with larger mechanical ducting. When the span increases slab thickness needs to be increased. It increases the cost of construction otherwise, other slab types could be used. The edges of the slab are thicker (as wide as 24") in order to allow for extra strength around the perimeter. For reading the article. Reduction in the Floor to Floor Height. A few noteworthy are enumerated . In flat plate system, it is not possible to have large span. ADVERTISEMENTS: ii) Smaller thickness of deck thereby reducing the height of fill and consequently the cost of the approaches. Disadvantages: Medium spans. It has span limitations. The system can pose a problem to the whole organization when the ratio of employees to managers become too out of proportion. Shear reinforcement is not required at the columns. By contrast, a crawl space costs about $7 per square foot and a basement about $18 per square foot. It uses drop panels that may interfere with oversized mechanical ducting. Drop panels function as T-beams over the supports. Disadvantages of System: Medium spans Limited lateral load capacity as part of a moment frame May need shear heads or shear reinforcement at the columns or larger columns for shear Long-term deflection may be controlling factor May not be suitable for supporting brittle (masonry) partitions May not be suitable for heavy loads. Structural loads, structural analysis and structural design are simply explained with the worked example for easiness of understanding. You want to clean out the drains as needed and . Thickness of Waffle slab is 85 to 100 mm. Comparatively higher slab thickness is required. Flat slab with Both Drop Panel and Column Head, Difference between One Way Slab and Two Way Slab, What is Spalling of Concrete causes and repair, Compressive Strength of Concrete and Concrete Testing, 6 Factors Affecting Curing Time of Concrete, Cantilever Beam - Design and Construction Aspects, Cold Joint in Concrete | Why Important to Know, Concrete Column Forms [Design & Construction], Concrete Crack Repair - Methods & Procedures, Construction Joints in Concrete Structures, Control Joints in Concrete [a deep study], Destructive Testing of Welds | Detail Study, Excavation for Foundation [shallow and deep], Key Factors Affecting Strength of Concrete, Lintel [a comprehensive study on types of lintel], Non-Destructive Testing of Welds | Structural Guide, Pile Foundation Construction Problems and Solutions, Shear key [ Purpose, types, design, construction details], Slab Types - deep review on types, design and construction, Slump Test of Concrete | Measure of Workability of Concrete, Types of Concrete Joints [ A Detailed Study], Welding Inspection - What it is and How it done. 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