The quantities of the materials are calculated and cost of construction for slabs are determined and compared. Difference between one way slab and two way slab daily civil. The concrete slabs are modelled as threedimensional solid parts, whereas in. Slabs are structural members forming floors and roofs in buildings. A slab strip of unit width is analysed using simple beam theory. What is the formula for taking load from two way slab for.
Distribute moments transverse at critical sections to column and middlestrip and if. Abcd is a two way slab lb 3 design of rectangular beams and oneway slabs 12 h a 12 strip in a simply supported one way sl ab. Strengthening of twoway slabs using steel plates article pdf available in aci structural journal 991 january 2002 with 4,935 reads how we measure reads. Reinforced concrete design 1 design of slab examples. Twoway edge supported solid slab d twoway ribbed slabs. The basic design procedure of a twoway slab system has five steps. The choice between twoway and beamless slabs for more normal situations is complex. Under the general provisions of the 1995 code, chapter, the twoway joist portion may be combined with a solid column head or with solid wide beam sections on the column centerlines for uniform depth construction. On the other hand, when slab is supported on all four sides and bending take place in two directions are said to be two way slab. When zd is determined, the prestressing force required to balance an. Oneway and twoway slabs university of asia pacific. In two way slab, the ratio of longer span l to shorter span b is less than 2. Comparison of oneway and twoway slab behavior oneway slabs carry load in one direction.
First of all, it depends on the use of the structure. From the study it is considered that post tension slab is more economical than twoway slab. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. Direct design method, that could have been named the direct analysis method because it determines or prescribes moments for different parts of the slab panel without the need to conduct structural analysis, is explained in the following sections.
These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. Determination of load transfer in reinforced concrete solid slabs by. Difference between one way slab and two way slab system. When a reinforced concrete slab is supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. Load transfer in a oneway slab, b twoway slab nilson fig. Bending will take place in the two directions in a dishlike form. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Deflections of twoway slabs scholars mine, missouri.
In many cases the slabs are of such proportions and are. Solid slabs are fully customizable concrete slabs of varying width, length and thickness. This means that oneway concrete solid slab doesnt exist and all concrete solid slabs work as a twoway concrete slab. Which slab is better ribbed slab or solid slab one way or two way. In two way slabs, load will be carried in both the directions.
Slabs of uniform thickness bending and reinforced in two directions. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Comparison between one way joist slab structure using lightweight foam concrete and two way solid slab structure using normal concrete. Analysis of twoway slabs using direct design method. Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. For the love of physics walter lewin may 16, 2011 duration. In terms of economy of material, especially of steel, the twoway slab is often best because of the large effective depths of the beams. Oneway and twoway slabs oneway slabs transfer the imposed. The project comprises fullscale tests on simply supported square slabs with square openings. Oneway slabs normally design as a beam with cables running in the direction of the span at uniform centres.
Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. The determination of exact moments in twoway slabs with various support. Reinforcement detailing of reinforced concrete slabs. Verandah slab is a type of one way slab, where the slab is spanning in the shorter direction with main reinforcement and the distribution of reinforcement in the transverse direction what is two way slab. If a slab is supported on all the four sides but the ratio of longer span l to shorten span b is greater than 2, then the slab will be considered as one way slab. Slabs of uniform thickness bending and reinforced in one direction. Beams of width and depth are provided on all column lines. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. Slab resting on walls or sufficiently deep and rigid beams on all sides. The direct design method is an approximate method used to analyze two way slabs. Please read the lauses mentioned in the video while solving the problem. Learning outcomes at the end of this lecture, the student should be able to a classify all types of solid slabco1 b identify one way and two way solid slab co1 c use a relevant clauses in code of practice co1 d design oneway slabs co2 e details the slabsco1. Pdf reliability based design of reinforced concrete twoway.
The twoway slab will deflect in a dish or saucerlike form under the action of loads. From the slabs the loads are transferred to the beams, thereafter the loads from. Comparison of oneway and twoway slab behavior economic choices oneway slab on beams suitable span 3 to 6m with ll 35knm2. Total load is carried in the direction perpendicular to the supporting beam. Determine moments at critical sections in each direction, normally the negative moments. For flat plates and slabs the column connections can vary between.
Pdf strengthening of twoway slabs using steel plates. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. Traditionally, the term flat slab has represented a solid uniform depth slab with thicker drop panels supported upon mushroom head conical capitals with round columns or various prismatic brackets with square columns. Twoway slab analysis and design using equivalent frame method efm. Two way slab design by direct design method as per aci 31811. This is attributed to the considerable reduction in dead load as compared to other floor systems. The twoway slab is designed for both the directions as it bends in both directions. Accordingly, main reinforcement is required in the two directions. Solid slabs can be designed and produced with mild reinforcing or by adding prestressing strands. The distributed load is applied by means of an underlying airbag. They can be used in a variety of applications such as bridges, piers, building floors. Difference between one way slab and two way slab system the one way and two way slab systems are the most commonly used floor system in the reinforced concrete structure. In twoway slabs shorter direction strip carry greater %age of load.
Pdf in the design of twoway reinforced concrete slabs, e. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Twoway slab twoway slabs are surface members acting in a both directions. My graduation project with my mate ghassan faris, a two way ribbed slab of clear span of 18 x 25 m was designed by safe 2014, the building is 3storey concrete. Traditionally, the term flat slab has represented a solid uniform depth slab with thicker drop panels supported upon mushroom head conical capitals with. Can be used for larger spans with relatively higher cost and higher deflections oneway joist system suitable span 6 to 9m with ll 46knm2. It deals with the problem of openings in twoway concrete slabs. Article pdf available september 2014 with 128 reads. Reliability based design of reinforced concrete twoway solid slabs using eurocode 2. For uniformly distributed loads of w per square foot of the slab, each strip acts approximately like a simple beam uniformly loaded by its share of w. Analysis and design of slabs two way civil engineers pk. The slabs are loaded with uniformly distributed load up to failure. The waffle slab is capable of providing the largest spans of the conventional concrete floor systems and can be economically used for spans up to 12.
Economical for medium spans with intermediate to heavy loads. Twoway slab analysis and design using equivalent frame method efm aci 318 states that a slab system shall be designed by any procedure satisfying equilibrium and geometric. Design of reinforced concrete structures ii twoway slabs. They may be solid of uniform thickness or ribbed with ribs running in one direction or two directions waffles. One way slab is supported on two opposite side only thus structural action is only at one direction. Slab is a common term used to describe the structural elements such as floors and roofs where the thickness of the element is very small compared to the length and. In this video deisgn of two way slabs has been covered using is 456. Design of reinforced concrete structures ii twoway slabs 1 1. Corners of the twoway slab lift up if the slab is not cast monolithically with the supports wallsbeams. Aci 31811 code provides two methods for two way slab design one of which is direct design method. Which slab is better ribbed slab or solid slab one way. Twoway slabs have two way bending unlike oneway slab. The ratio of length to width of one slab should less than 2 otherwise oneway action is obtained, even though supports are provided on all sides. The slab has to carry a distributed permanent action of 1.
308 559 1352 674 1112 552 1381 928 832 1392 527 981 1609 800 1184 250 590 1109 1290 831 1580 1069 1093 734 148 51 783 1184 1286 1123 461 701 1237