One way ribbed slab pdf

The oneway slabs are economical up to the span of 3. Ribbed or waffle slab is a slab system which consists of series of parallel reinforced. For the love of physics walter lewin may 16, 2011 duration. Mathcad program and show its impact on teaching the analysis and design of twoway ribbed slabs. Reinforced concrete design 1 design of slab examples. Ribbed or waffle slab is a slab system which consists of series of parallel reinforced concrete t beams framing into reinforced concrete girders. 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. The minimum thickness needed for the whole plan is the worst case. In two way slab, the slabs are supported on all the four sides. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab.

Twoway joist concrete slab floor waffle slab system. The thickness of oneway slab varies between 100mm to 150mm or even more depending upon the span and based on the deflection considerations. The ribs are tapered in crosssection in its lower part. Design of reinforced concrete structures ii twoway slabs. Mathematical structural analysis of one way ribbed slabs was introduced in this paper. These modifiers, available through assign area stiffness modifiers, should be applied relative to the local axes and the desired direction of oneway action. In sap program, the model has been divided to frame elements to represent ribs and beams and shell elements to represent the slab and solid part. Ribbed slab system which consists of a series of parallel reinforced concrete t beams framing into reinforced concrete girders. Determine moments at critical sections in each direction, normally the negative. One way slabs are available on concrete slab floors risafloor es. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. One way slab design procedure with example design of one. The blocks are considered as nonstructural element as they do not contribute to strength of. Difference between one way slab and two way slab slab.

Ribbed slabs types and its advantages in construction. The results of this analysis are compared with the results of the finite element method by sap program. One way ribbed slab manual mechanical engineering building. Total load is carried in the direction perpendicular to the supporting beam. Oneway joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. Design of reinforced concrete structures ii twoway slabs 1 1. The oneway slab is a simple wide shallow rectangular beam as. Twoway joist waffle slab design approach and methodology twoway joist slab often called twoway ribbed slab or waffle slab is an economical floor system when the spans are long andor loads are high.

Reinforced concrete ribbed slabs with widebeam lajes. When one says ribbed slab it is actually a one way spanning system with ribs where as in waffle slab the joists form a two way system. Rectangular beams and oneway slabs page 3 of 9 design of rectangular beams and oneway slabs continued a. Design of continuous one way slabs checks, detailing. Designed as a series of parallel tbeams and economical for medium spans with light to medium live loads.

Ribbed and waffle slabs types, advantages, disadvantages. Cost optimization of reinforced concrete oneway ribbed slabs using harmony. Cost optimization of reinforced concrete oneway ribbed slabs using. Teaching twoway ribbed slab analysis and design using. The one way slab floor will act like a beam supported floor distributing the loads onto the beams in onedirection. To enforce oneway action, assign small m11 or m22 stiffness modifiers to the slab. Introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need.

The ribbed slab was analyzed exactly by finite element theory through sap 2000 program. Difference between one way slab and two way slab daily civil. Ribbed and waffle slabs types, advantages, disadvantages civil. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. One way slab is supported on two opposite side only thus structural action is only at one direction. Twoway joist concrete slab floor waffle slab system analysis and design. Oneway and twoway slabs university of asia pacific.

Structural ribbed concrete slabs the cupolex floor slab can be fully or partially suspended on piles, stem walls or gradeedge beams. The service live load is 100 psf and 4000 psi concrete is specified for use with steel with a yield stress equal to 60000 psi. One way slab being supported on two opposite sides only leads to the structural action in single direction. Ribbed slab design spreadsheets to eurocode engineering. Two bays one way ribbed slab is analyzed by both traditional and finite element methods to determine the induced moments of the rib. Cost optimization of reinforced concrete oneway ribbed slabs using harmony search algorithm. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Twoway joist waffle slab design approach and methodology. Two slabs were supported on both edges of the x direction only. In a oneway slab, this lateral expansion is resisted by adjacent slab strips, which tend to expand also. Shear in oneway slabs under concentrated load close to support article pdf available in aci structural journal 1102. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes.

The result is a slight strengthening and stiffening in the span direction, but this effect is small and can be disregarded. In one way slab, the slabs are supported by the beams on the two opposite sides. The model provides the actual behavior for ribbed slab by analyzing the structure as oneunite in two dimensions. Ribbed slab grid slab, solid slab, filler slab, folded plate 6 basis of spanning directions. Analysis and design of slabs one way civil engineers pk. One way shear in slab structural engineering general. Normally it works fine but this time after carrying out the calculations the slabs fail in shear because of there are some huge point loads near the support. One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. The slab is the flange of the beam and the extended part is the web.

For example, when parallel walls connect to either side of a continuous slab, oneway action results. The ratio of steel in a slab can be determined by dividing the sectional area of. Difference between one way and two way slab in terms of their structural behaviou for one way slab. The spacing between the ribs should be in general 2030 inch. The slab may be supported by walls, by reinforced concret. Lb2 is one way slab lb oneway solid slabs and oneway ribbed slabs.

Difference between one way and two way slab in terms of. Design of reinforced concrete structure one way slab presented by md. May182017 twoway joist concrete slab floor waffle slab system analysis and design design the concrete floor slab system shown below for an intermediate floor with. This paper presents an experimental and computational study on ribbed slabs with widebeam, two oneway slabs and two twoway slabs, with. Ribbed slab floors are most economical for buildings such as hospitals, schools, hotels, and. Introcduction slab in which the deflected surface is predominantly cylindrical termed as oneway slabs spanning in the direction of curvature. With accurate to temperature and shrinkage, minimum of. Slabs are usually used in floor and roof construction. As they are oneway slabs i treat them as wide beams. Two way slabs are normally supported from four sides. Difference between one way slab and two way slab simple. Pdf cost optimization of reinforced concrete oneway. One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. Pdf shear in oneway slabs under concentrated load close.

Oneway and twoway slabs oneway slabs transfer the imposed. Slab cast integrally with a series of closely spaced joist which in turn are supported by a set of beams. In the one way ribbed slab where the ribs are in one direction, it is assumed that the loads are distributed in the direction of the ribs only. In one way slab, the loads are carried along one direction. The simplest routine structural element for illustration of design provisions in the code is the oneway slab. In case of ribbed slab the blocks are not permanent.

One way ribbed slab manual free download as word doc. This paper presents an experimental and computational study on ribbed slabs with widebeam, two oneway slabs and two twoway slabs, with variable depths were tested to evaluate their resistance. Current study, such as lau and clark 4, assesses the performance of one and twoway ribbed slabs with widebeams by analyzing the structural. Analysis of two way ribbed and waffle slabs with hidden beams. In case of hollow block slab voided blocks are placed to reduce the total weight of the 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. The basic design procedure of a twoway slab system has five steps. I am doing oneway slabs and hope you can clean up my doubts about the one way shear in slab. Mention the parameters governing slab moment coefficients and explain their effects on moment. Here ratio of longer span of slab to the shorter span of slab is greater than 2. Loads modeled are attributed to the beams and the beams transfer the loads through the floor framing to walls and.

The slab has to carry a distributed permanent action of 1. Analysis of two way ribbed and waffle slabs with hidden beams ibrahim mohammad arman international journal of civil and structural engineering volume 4 issue 3 2014 343 four slabs are taken in this study to show the moments distribution in two way ribbed slab. Pdf cost optimization of reinforced concrete oneway ribbed. Keywords reinforced concrete slab oneway joist floor harmony search. They may be supported on two opposite sides only fig. 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. The waffle slab is also sometimes termed as ribbed slab system but you would find it interesting to know that ribbed and waffle slab are somehow two different things. The ratio of longer span l to shorter span b is equal or greater than 2, considered as one way slab because this slab will bend in one direction i. Chapter 3 design of rectangular beams and oneway slabs.