One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. Difference between one way slab and two way slab simple. The choice of decomposition is set in the slab item properties. Tekla tedds contains two modules for simple, quick design of oneway or twoway spanning slabs. There are several methods by which twoway slabs can be designed. This spreadsheet undertakes these calculations and returns design moments for use during detailed design. The load on the slab is carried by the short span in one direction. If slab is supported on all four sides and r shorter side longer side 8. 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 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. In the absence of advanced analysis software, like fem modelling, it was necessary to idealize the slabs, oneway or twoway slabs, to use direct methods for the design. Before going to this topic, please read it there are two types of slab classification based on the direction of bending occurs in these slabs. The coefficient method may be the simplest, easiest and the quickest approach for the design of twoway slab supported by edge beam on all slab sides.
A one way slab is a slab in which its length divided by its breadth is greater than or equal to 2. 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. If slab supported by four side of beams or walls, the slab is considered one way if ratio of long span ly to short span lx greater than 2. Structural analysis and design with tekla software. I have no problem performing local area calculations like punching shear. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. However main reinforcement bar and distribution bar in transverse direction. This condition occur if the slab supported by two side of beam or walls. Design procedure steps for one way slab slab design steps. For the simplicity in design, one way slabs are designed in per meter strips. I know that there is aashto for deck design using one axle or point loads, but these point loads a are smaller. Step 2 design forces draw panel of slab and indicate maximum design moments, shears and in plane loads, if any, per unit width of slab.
Plan view of floor system assume partitions will not be damaged by deflections. When a slab is supported on all four sides and the ratio of long span to short span is equal or greater than two, it will be considered as one way slab. The necessary bars derive from the calculated required reinforcement. How to model one way span slabs thanks rafascudo, i have a situation where the roof slab is deck slaboneway, but its edges are connected to the supporting walls below, despite the fact that it is acting one way, theres a certain portion of the loads attracted to the supporting walls parallel to. What is the design of a one way slab and a two way slab. When a slabs decomposition is set as oneway it is assumed that it is some form of precast slab presumably designed by safe load tables. Ce 433, fall 2006 slab design example 1 6 design a oneway slab for an exterior bay of a multistory office building using the information specified below. How to modify the direction of loads transfer for a fe slab where the applied panel calculation model contains a one way simplified transfer of loads.
I wanted to see if anyone has any good literature on twoway slab design for point loads. A flat slab panel always uses twoway load decomposition. How to model one way span slabs autodesk community. Reinforced concrete slab and beam design software adaptrc 2017 product overview an easytouse and learn software for the design, analysis, and investigation of reinforced nonprestressed concrete beams, beam frames, slabs and floor systems a must have production tool in every structural engineering office.
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. Here ratio of longer span of slab to the shorter span of slab is greater than 2. Two way slabs are normally supported from four sides. Quick design of one way spanning slabs in tekla tedds. Hello, today i am introducing to you an excel spreadsheet program specially created to help design one way continuous reinforced concrete slabs. Total load is carried in the direction perpendicular to the supporting beam. Powered by the equivalent frame method of analysis and design per latest american aci 31814 and canadian csa a23. Twoway concrete slab with beams spanning between supports. This can be used in conjunction with a structural analysis program such as our beam analysis spreadsheet or our slab analysis tool. The ratio lb which is less than 2 is known as two way slab. Guidelines for a oneway concrete flooring system brewer. These modifiers, available through assign area stiffness modifiers, should be applied relative to the local axes and the desired direction of oneway action.
Slab are considered as oneway if the main reinforcement is designed only in one direction. I frequently am posed with the problem of concentrated loads on oneway and twoway slabs. Twoway spanning or oneway spanning although for certain slab types the value is fixed as follows. One way slab one way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. Reinforced concrete slab and beam design software adaptrc. Oneway load decomposition in tekla structural designer is a simple procedure that does not determine slab design forces. The two classifications are oneway slab and twoway slab. Oneway spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. One way slabs are the easiest to design as the direction is simple and are usually designed as set of beam strips spanning in one direction. For those who do not know what are the des ign requirements of a slab. This brief will provide guidance to architects and structural engineers during the concept phase of the design for selecting a suitable oneway flooring system. On the other hand oneway slabs span in shorter direction and is designed for one way bending. All methods are viable provided that the safety and serviceability of the elements are within the acceptable limits.
One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. This can be used in conjunction with a structural analysis program such as our. This spreadsheet is an extremely efficient tool and allows to quickly design two way slabs to aci code. Some of these loads are vertical point loads and some are concentrated moments through a baseplate. Two way slab design to aci free download and software. Slab design, bs 8110 slab design, how to determine ultimate load for slabs, how to check for deflection in slabs, how to calculate for dead load, how to calculate for lever arm, basics of slab design, how can i design a 2 way spanning slab. However, a slab with length breadth ratio of not less than 1. Slabs are usually used in floor and roof construction. A oneway slab is supported on two opposite sides, so structural action is only ever in one direction. This spreadsheet allows user to design a one way spanning reinforced concrete slab in accordance with the british standard bs 8110. Concrete slab design aspects tekla structural designer. What im wrestling with is the bendingtorsion calcs i. To enforce oneway action, assign small m11 or m22 stiffness modifiers to the slab. Bars that are currently loaded after model generation are not the correct ones.
In a oneway slab the need for reinforcement appears mainly in the span and along the bending direction. How twoway spanning concrete slabs are represented in. For example, when parallel walls connect to either side of a continuous slab, oneway action results. One way slab being supported on two opposite sides. Every example ive ever seen on twoway slab design is for uniformly distributed loads. Here are the steps for the design procedure for one way slab in steps. In other words, it can be said that, twoway slabs span in both directions. How to modify direction for one way simplified transfer of. The chosen option is applied to all slab items in the same slab two options are available.
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