For a groundbearing slab, the formwork may consist only of side walls pushed into the ground. Load chara c t e r istics must obv i ously va r y with the decking configurations and thickness, span re i n f o r cement, concrete stre n g t h and concrete thickness. Twoway concrete floor slab with beams design and detailing design the slab system shown in figure 1 for an intermediate floor where the story height 12 ft, column crosssectional dimensions 18 in. There are 16 different types of slabs in construction. Suspended concrete slab is referred to a cement slab that is not in contact with the ground. Jun 29, 2019 theres no single method for design of nonsuspended slab. The prestandard env for ec2 has now been available since 1992.
The manual and advisory safety code of practice for concrete pumping67. This type of concrete slab construction requires different concrete slab design from the one we normally see that is cast on the ground. Design of slab examples and tutorials by sharifah maszura syed mohsin. Sep 03, 2011 reinforced concrete sk 33 section through slab showing stress due to moment. If its a cip concrete slab, then they sound much worse. A two way spanning concrete slab roof typically supported on concrete columns. The slab has to carry a distributed permanent action of 1. The depth of a concrete slab floor is very small compared to its span. Indicate only tensile and shear reinforcement and label clearly.
Design of slab for flexure 067 m unit width of slab. According to the 1995 aci code, all twoway reinforced concrete slab systems, including edge supported slabs. Twoway joist concrete slab floor waffle slab system analysis and design design the concrete floor slab system shown below for an intermediate floor with partition weight of 50 psf, and unfactored live load of 100 psf. For slabonground floors it provides an understanding of the footingslab selection, design, detailing and construction requirements contained in as 2870 and. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. Twoway joist concrete slab floor waffle slab system. Tm 580912 concrete floor slabs on grade subjected to heavy. A second video shows how the shear resistance of the slab and its deflection are checked. How does a suspended slab work, in a new home construction suspended reinforced concrete slabs are used in many applications in the construction industry. This slab will have significant bending acting in both directions.
The main objective of this project is to analyze and design a multistory building 3ddimensional reinforce concrete frame, the design of reinforced concrete slabs, beams, columns, footings and. Floor width must be greater than zero for all loads. Reinforced concrete slabs, at least those designed to span in one direction, are no different conceptually from any other beams, with the following three caveats. Tolerances for the floors placed on these suspended systems are often misunderstood. The structural design of a concrete floor slab on grade is primarily controlled by the stresses caused by moving live loads and in some cases the. The design of suspended floors should conform to requirements of aci 318 and aci 421. Find the following parameters for design moments in step 2 per unit width step 4 note. Concrete slab rest ing on grade cont aining steel reinforcement which consists of either a welded wire fabric or deformed reinforcing steel bars. Concrete slab design procedure7 design of continuous slab basics of reinforced concrete slab design slabs are generally designed on the assumption that they consists of a number of beams of breadth one. How to design concrete structures using eurocode 2.
Theres no single method for design of nonsuspended slab. A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. The design procedure includes determini ng slab thickness based. Concrete slab design procedure7 design of continuous slab basics of reinforced concrete slab design slabs are generally designed on the assumption that they consists of. The advantage of a suspended reinforced concrete slab is that it is possible to get high strength, but at the same time keep the weight low. The posttensioning institute pti design manual6 gives recommended spantothickness ratios for slabs and spantodepth ratios for beams. With some limitations, reinforcement for slabs can be sized using the subgrade drag theory in order to increase the spacing of control or construction joints. In order to simplify the design of the slab and columns, there was an assumption that shear walls would. Materials used for this redesign is normal weight concrete with compressive strength of 4ksi and steel rebar with a yield stress of 60 ksi. Confusedsuspended concrete slabs, tensile and shear.
Oneway and twoway slabs oneway slabs transfer the imposed. It depends on purposes and location, but there several construction and design methods for nonsuspended slab. The slab depths in the tables are m e a s u red from the top of the slab to the bottom of the ribs in the decking. Suspended slab cracking structural engineering general. Precast suspended slabs design solutions included in this booklet, designers and engineers will find a design guide, load tables, and construction details for heldenfels enterprises inc. A one way slab will only have significant bending moments in the short direction. Vibration design of concrete floors for serviceability1 bijan o aalami2 this technical note covers the design of concrete floor systems for vibration, with an emphasis on simple and expeditious first estimates for a floors vibration response. I have a situation where a recently poured suspended slab has some severe cracking in my opinion.
I would like to know if somebody knows of a method suggestions, text or resources to design a cantilevered concrete slab that is going to be supported on masonry shearwalls. Refer to aci 223 for special procedures recommended for the design and construction of shrinkagecompensating concrete slabs on. Floor slab thickness was determined by aci 31802 table 9. The first reinforced concrete design manual formerly titled aci design handbook was developed in. Concrete slab floors come in many forms and can be used to provide great thermal comfort and lifestyle advantages. Decisions required for the preliminary design of a floor system that are not discussed in this article, but are covered in other literature, include establishing slab and beam dimensions and concrete cover. The most common application of suspended slab in residential construction is used at garage floor where below the garage floor is a storage. The assembly is designed for seismic zone 2 and may be used for structures up to 8 storeys. Manual for design and detailing of reinforced concrete to the september 20 code of practice for structural use of concrete 20 2.
The reinforced concrete design manual sp1711 is intended to provide guidance and assistance to professionals engaged in the design of castinplace reinforced concrete structures. A 2 2area 2 a c 2 2 posttensioned concrete design table 11 list of symbols used in the aci 31808 code cp area enclosed by the outside perimeter of the section, in a g gross area of concrete, in a 2 l total area of longitudinal reinforcement to resist torsion, in a o area enclosed by the shear flow path, sqin a oh area enclosed by the centerline of the outermost closed. Ascc concrete contractors will work with all parties in addressing these issues. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. General overview of posttensioned concrete design instructor. Cantilevered concrete slab design structural engineering. Twoway concrete slab with beams spanning between supports. Reinforced concrete slab design using the empirical method bridgesight solutions for the aashto lrfd bridge design specifications bridgesight software tm creators of effective and reliable solutions for the worlds bridge engineers. The formwork shall be designed to withstand construction loads such as fresh concrete pressure and weight.
The design of slabs on ground should conform to the recommendations of aci 360r. If you have any questions, contact your ascc concrete contractor or the ascc technical hotline at 800 3310668. A two way spanning concrete slab floor typically supported on concrete columns. Suspended concrete slab, suspended slab, cement slab. In this paper a design method developed for structural design of this slab system is presented. What you see is a series of steel frames with cross braces holding them together. Nonsuspended slab is a slab that cast on the ground. For a suspended slab, the formwork is shaped like a tray, often supported by a temporary scaffold until the concrete sets. Istructe ec2 concrete design manual 9 foreword the eurocode for the design of concrete structuresec2 is likely to be published as a euronorm en in the next few years. L center to center distance between the support b depth of slab.
Foreword the reinforced concrete design manual sp1711 is intended to provide guidance and assistance to professionals engaged in the design of castinplace reinforced concrete structures. Design the roof slab, beam and column of house given in figure 1. Concrete floor slabs on grade are subjected to a varie ty of loads and loading conditions. Reinforced concrete design 1 design of slab examples and. To facilitate its familiarisation the institution of structural engineers and. The posttensioning institute pti design manual6 gives recommended spantothickness ratios for slabs and. In design of nonsuspended slab, youve to consider environmental factors, an.
Manual for the design of reinforced concrete building. Aci318 code provides two design procedures for slab systems. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. When a slabs length is more than twice its width l 2w then the slab can be considered a oneway slab. Not trying to check your design, but cracks can mean. Manual for design and detailing of reinforced concrete to. Rc slab design ec2 worked example bending reinforcement. Effective span of slab shall be lesser of the two 1. It has been the most common material used in slabs but several new. For slab onground floors it provides an understanding of the footing slab selection, design, detailing and construction requirements contained in as 2870 and. Roof width must be greater than zero for all loads. It is a horizontal structural component, with top and bottom surfaces parallel or near so. Direct design method ddm for slab systems with or without beams loaded only by gravity loads and. Flexibility of future use with due consideration to long term deflections.
On the right is the slab formwork for a suspended concrete slab to a multi story building, but this system of concrete formwork could just as easily be used on an owner builder house. The result is a lightly reinforced slab designed to offset the effects of temperature and shrinkage of the concrete. For slabs spanning in both directions published tables and charts should be used to find bending moment and shear per unit width of slab. Reinforced concrete design 1 design of slab examples. This guide covers the design and construction of composite slabs and beams, and addresses. They can be insulated, both underneath and on the edges. The attached excerpted resource materials have been made. Reinforced concrete slab design using the empirical method.
Manual for design and detailing of reinforced concrete to the. A short tutorial showing how the main reinforcement in a simply supported slab is designed using ec2. Feb 07, 2014 a short tutorial showing how the main reinforcement in a simply supported slab is designed using ec2. Refer to aci 223 for procedures for the design and construction of shrinkagecompensating concrete slabsonground. The lateral loads are independently resisted by shear walls. Sci p300, composite slabs and beams using steel decking. Tm 580912 concrete floor slabs on grade subjected to.
Steelreinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs may be used for exterior paving see below. When designing and building suspended slabs, this guide should be used in conjunction with aci 318 and 302. This document supplements information contained in the aci 360r and 302. The cupolex floor slab can be fully suspended on reinforced concrete piles. Reinforced concrete slab an overview sciencedirect topics. However, the procedure for the lateral distribution of the moments is the same for both design methods. Posttensioned concrete design table 11 list of symbols used in the aci 31808 code m bal design moment resistance of a section with tendons and the necessary mild reinforcement to reach the balanced condition, nmm m u factored moment at section, lbin n c tension force in concrete due to unfactored dead load plus live load, lb p. Reinforced concrete sk 33 section through slab showing stress due to moment. When the ratio between the long to short side doesnt exceed 2, a twoway slab is present. The formwork is commonly built from wooden planks and boards, plastic, or steel. Reinforced concrete slab systems on steel decks decking can serve as form, shoring and finished surface 18 gage 20 gage 22 gage slab thickness, simple continuous simple continuous simple c o n t i n u o u s. Additional reinforced internal ribs are used in the slab by additional reinforced internal ribs are used in the slab by introducing pontex, the structural cupolex accessory to provide a structure capable of spanning between stem walls or piles.
The structural design of a concrete floor slab on grade is primarily controlled by the stresses caused by moving live loads and in some cases the stationary loads. The first reinforced concrete design manual formerly titled aci design handbook was developed in accordance with the design provisions of 1963 aci 318 building code by aci committee 340, design. Guide for concrete slabs that receive moisturesensitive. Concrete slab, a very common and important structural element, are constructed to provide flat, useful surfaces. Concrete floor slab construction process includes erection of formwork, placement of reinforcement, pouring, compacting and finishing concrete and lastly removal of formwork and curing of concrete slab. Slabs may be supported on two sides only or have beams on all four sides. Some of them are outdated and many of them are frequently used everywhere. Structural redesign two way slab drop panels my redesign of fordham place will comprise of a 9 flat slab with 5. Even with the best floor designs and proper construction, it is unrealistic to expect.
1048 521 1547 415 89 1268 44 349 995 161 1428 810 229 703 132 743 432 432 1541 832 973 4 1204 163 520 893 651 108 22 381 468 482 412 1093 1153 581