I have used the word flat slab and by that i mean the slab that has leveled surface from both top and soffit. Analysis and design of slabs two way civil engineers pk. In addition to general ultimate and serviceability limit state design issues, practical design considerations such as the formation of holes in the slab, support details, fire protection, and attachments to the slab are discussed. Sandwich slab reinforcement details in reality, sandwich slabs are ribbed slabs with a slab placed both to their upper and lower surface. We would be restricting ourselves to understand the waffle slab used as roof. If slab is supported on all four sides and r shorter side longer side slab. Jul 02, 20 introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs. Now here i need to clarify that this article will not treat waffle slab foundation which is another building element used in high cyclonic and windy areas but that is out of the scope of this article. Slabs having supports on less than four sides can be designed as oneway.
Pdf investigating the effect of solid and lightweight hollow block. As support for these types of applications, dsf conducted numerous screw withdrawal tests. Genrally construction of building members like coulmns beams and slabss etc. The works shall be performed as mentioned in this procedure and the quality assurance requirements shall be consistent with the relevant sections of quality system procedure manual of name of the contracting company as well with the project quality plan. In the design of reinforcedconcrete buildings, solid and lightweight hollow block slabs are. Mar 02, 2016 design of solid slabs part 1 solid slab 15 ts. Accordingly, main reinforcement is required in the two directions. Hordy slabhollow block slab hollow blocks are used to fill portions of the slab thickness. Tests showed only slight variation in the force required to remove a variety of. Structural steel composite slab 1 of 7 rev design project. For 1m slab width, moment, shear force, oneway continuous slab for continuous slab, moment and shear force can be obtained from table 3. It is also available in different measures, sizes and lengths, reaching up to length of 4m.
The design procedure separately incl udes determining thickness of slab under wall load. Chapter 3 design of rectangular beams and oneway slabs 12 h a 12 strip in a simply supported one way sl ab h. The espac precast ribhordi roof system is intended primarily for houses, low rise. Analyses are for a onebaywide strip using the equivalent frame analysis method of the aci code. The ratio of the total costs was found to be within the range 1. Experiments on fibre reinforced concrete twoway slabs. The blocks are considered as nonstructural element as they do not contribute to strength of.
Analyze and design flat slab or waffle slab floors. Designing a one way ribbed concrete joist floor system per. Design of slab for flexure 067 m unit width of slab. In twoway slabs shorter direction strip carry greater %age of load. Introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs. L center to center distance between the support b depth of slab. Design of reinforced concrete structures ii twoway slabs. The slab is propped at the centre during construction stage. Flat slabs may have drop panels at columns and columns may have capitals. A civil engineer must know all the aspects regarding the flat floor system. Oneway simply supported slab analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. Dec 09, 2006 the factory produces hordi blocks from polystyrene which is available in all dimensions starting from 1020 kg.
But crcm uses concrete a material used more than 3,000. The hourdi blocks manufactured by al manaratain is used to create floors and roofs. Chapter 3 design of rectangular beams and oneway slabs 12. Shopdesign drawing to be strictly complied with at the site. Design of rectangular beams and oneway slabs continued. In these tests, screws of various sizes and thread design were evaluated for resistance to withdrawal when pulled out of the face of diamond snapties.
Rectangular beams and oneway slabs page 5 of 9 maximum permissible steel ratio, max an overreinforced beam will fail in a brittle manner while an underreinforced beam will. Concrete rib construction method, crcm uses the engineering technology to design the elements structurals to handle the loads originated by climatic and or geographical location of the project. Its not like a flat slab which is here and there i. What is waffle slab and hordy slabhollow block slab.
Rectangular beams and oneway slabs page 3 of 9 design of rectangular beams and oneway slabs continued a. Reinforced concrete sk 33 section through slab showing stress due to moment. Flat slab analysis, design and detailing pdf civil engineering. Recommendations for finite element analysis for the design of. The strip may have up to 20 spans and may have cantilevers at the ends. The factory produces hordi blocks from polystyrene which is available in all dimensions starting from 1020 kg. Pdf in the design of reinforcedconcrete buildings, solid and lightweight hollow block slabs are commonly. Flat slab system is an important division of concrete floor system. Ribbed slabs oneway joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. Sep 03, 2011 reinforced concrete sk 33 section through slab showing stress due to moment. Department of mechanics, materials and structures english.
The cross section of the profiled sheeting is shown in fig. The saving of materials tends to be offset by some. In both of them, the shear resistance has to be determined by means of slab tests, however the total number of test can be considerably reduced, because once the longitudinal strength. Twoway slabs have two way bending unlike oneway slab. In case of hollow block slab voided blocks are placed to reduce the total weight of the slab. The design procedure set forth in that publication had at that time been in use by the author for about 15 years.
The distribution of slab moments into column strips and middle strips is to be made in the same manner as specified in direct design method. Effective span of slab shall be lesser of the two 1. Slabs are constructed to provide flat surfaces, usually horizontal in building floors, roofs, bridges, and other types of structures. Reinforced concrete slab design and detailing guidelines for depth of slab, loads on slab, reinforcement guide for oneway and twoway slabs as per is 456. Oct 21, 2016 csi etabs 2016flat slab design, strip design and punching shear check duration.
This thesis is a part of a project carried out at lulea university of technology. The design procedure includes determini ng slab thickness based on moving live loads and then checking adequacy of slab thickness for stationary live load. Remove all minor protrusions, nails, deposits, masking tapes, paint marks p. You have asked this question because waffle slab is not that common throughout the world. Polystyrene slab hourdi slab concrete slab ceiling. Find the following parameters for design moments in step 2 per unit width step 4 note. Structural design practice for residential buildings in. Analysis of two way ribbed and waffle slabs with hidden beams. Csi etabs 2016flat slab design, strip design and punching shear check duration. These materials are originally located at different websites.
Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. Dec 27, 2016 dec 27, 2016 hordy slab hollow block slab. Slabs are usually used in floor and roof construction. Chip off the loose concrete slurry at edges of rib beams and polystyrene hourdi. Both methods use the same procedure to divide the moments so found between the middle strip and column strips of the slab and the beams if any.
The cost is managed by supervision of non skilled laborers, following the recommendations in this manual. The finite element method is commonly used to design the reinforcement in concrete slabs. The slab system used is limited to hordi slabs and solid slabs on beams. These blocks generally rest over on a reinforced concrete tbeam for support. Design project calculation sheet checked by pu date 080800 check the adequacy of the continuous composite profiled deck slab with spans of 3. Only the conditions at the centre of the span in the width of slab under consideration should be considered to influence deflection. Analysis and design of slabs one way civil engineers pk. The design of composite slabs and beams is discussed in detail in relation to the eurocodes and bs 5950. The first step is to make a couple of design assumptions regarding the thickness of the slab and the clear spacing between ribs. As the nature of these blocks is hollow with greater resistance, they are generally used in creating roofs which are more comfortable under a hot climate. Please practice handwashing and social distancing, and check out our resources for adapting to these times.
The slab may be supported by walls or by reinforced concrete beams usually cast monolithically with the slab or by structural steel beams or by columns, or by the ground. Following are the rcc slab design and detailing guidelines. The appropriate ratio may be obtained from table 3. Flat slab analysis, design and detailing pdf civil. Hourdi blocks hourdi block in uae hourdi block in dubai. So i am glad that you have asked me what a waffle slab system is.
Concrete floor slabs on grade are subjected to a varie ty of loads and loading conditions. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes. Chapter 3 design of rectangular beams and oneway slabs. Design of reinforced concrete structures ii twoway slabs 1 1. Al manaratain produces hourdi roof rak and light weight blocks in 7, 9. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Investigating the effect of solid and lightweight hollow block slabs on. After this publication, it was subsequently adopted by the uniform building. The concrete centre provides material, design and construction guidance. Composite slab worked example 1 made by sssr date 140500 structural steel design project calculation sheet checked by pu date 080800 check the adequacy of the continuous composite profiled deck slab with spans of 3. In order to simplify the analysis and to be able to use the superposition.
Bending will take place in the two directions in a dishlike form. The clear distance between ribs cannot be greater than 30 inches per aci code 31811 section 8. Reinforced concrete slab design and detailing guide is456. The spanning oneway slab includes oneway spanning solid slab and oneway spanning hourdi block slab. Sandwich slabs may have the disadvantage of a larger weight compared to the ribbed ones but on the other hand, they have the advantage that their spans and supports behave in the same proper way. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. A 120mmthick slab with a minimum rib thickness of 125 mm for continuous ribs is required to achieve a 2hour fire rating. In design of twoway slabs, the possibility to redistribute the load between the different loading directions is used in plastic design methods. Oct 20, 2016 whenever we use the term precast it simply means construction of any member of the building outside the site premises. Crcm manual 4 crcm means concrete rib construction method, the word method, can create confusion, because the icc ibc uses such word in the section 1701.