One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. One way shear in slab structural engineering general. Accordingly, main reinforcement is required in the two directions. Twoway concrete slab with beams spanning between supports. If a slab is supported on all the four sides but the ratio of longer span to shorter span is greater than two, the slab will be considered as a one way slab. Oneway and twoway slabs one way slabs transfer the imposed loads in one direction only. The design bending moment of two way restrained slab can be calculated as follows. Slab panel is supported in the short direction of oneway slab on two opposite sides.
Here ratio of longer span of slab to the shorter span of slab is greater than 2. One way slab is supported by beams in only 2 sides. In flatplate floors, slab column connections are subjected to high shear stresses produced by the transfer of axial loads and bending moments between slab and columns. One way shear in slab mrhershey structural 20 nov 17 15. The following simplified design is valid when length2width of slab and for 15ft or 4. The ratio of longer span panel l to shorter span panel b is less than 2. How to provide steel bar in one way and two way slab. Pdf oneway shear strength of thick slabs and wide beams. One way concrete slab bends or deflects in a direction perpendicular to the supporting edges. For better view, please read this post in landscape mode if you are on the mobile device.
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. Twoway concrete floor slab with beams design and detailing. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. If the ratio of longer span to shorter span is equal to or less than 1. Assume partitions cannot be damaged by deflections.
A slab is supported only one direction that is one way slab now tha loads are transferred only this two supports. 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. One way slabs are those supported continuously on the two opposite sides so that the load sare carried along one direction only. Two way slab is supported by beams in all four sides. The flexural reinforcement calculation for the beam strip of end span interior negative location is provided below. Oneway slab on beams suitable span 3 to 6m with ll 35knm2. A rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and. One way slab design simplified online design of concrete. One way slab is supported on two opposite side only thus structural action is only at one direction.
Comparison of one way and two way slab behavior economic choices one way slab on beams suitable span 3 to 6m with ll 35knm2. Difference between one way slab and two way slab simple. The basic design procedure of a two way slab system has five steps. The ratio lb which is less than 2 is known as two way slab. Types of one way slab one way slab may be solid hollow ribbed 6. In case of one way slab, the main reinforcement of the slab, span along the width of the room while the distribution bars, laid at right angles to the main reinforcement, lie parallel to the length of the room. One way slab one way slabs are those slabs with an aspect ratio in plan of 2. The slab has to carry a distributed permanent action of 1.
Two way restrained slab if the slabs consist more than one panel or corner of the slab are prevent against lifting it is define as two way restrained slab. Moments are obtained using coefficients and the formula m cwl2. Design calculation design of one way slab slab s1 span of one way slab l 2m section provided d mm d 105 mm loads on slab self weight of slab 3. Slabs having supports on less than four sides can be designed as one way. What is the formula for taking load from two way slab for. The other half span rebars are formed with a straight length.
Two way 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 compatibility, provided that strength and serviceability criteria are satisfied. Slab support condition solid slabs continuous at one end solid slabs continuous at both ends simple span solid slabs cantilever. 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 slab is supported on all four sides and r shorter side longer side one way slab.
Oneway and twoway slabs oneway slabs transfer the imposed. The one way slab is supported on two beams and then to the columns of the building. Two way reinforced concrete slab design clear longer span of slab please enter the longer span dimension of slab panel. The load on the slab is carried by the short span in one direction.
In practical, one way slab is supported by only two parallel beams or walls. The minimum required reinforcement in the support areas is provided in two alternative ways. Two way slab design by direct design method as per aci 31811, step by step procedure and limitations of direct design method for two way slab is presented. Deflection calculations from nilson and nawy the deflection of a uniformly loaded flat plate, flat slab, or two way slab supported by beams on column lines can be calculated by an equivalent frame method that corresponds with the method for moment analysis. 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. One way slab is supported by two parallel beams or walls. Design procedure steps for one way slab slab design steps. Due to the huge difference in length, load is not transferred along the longer direction. How to calculate quantity of steel in one way slab. Two way slab design by direct design method as per aci 31811. They may be supported on two opposite sides only fig. In two way slab, the ratio of longer span l to shorter span b is less than 2.
Analysis and design of slabs one way civil engineers pk. One way slab here i solve a probleam based on the one way slab, the diamentions are provided in the probleam 1st determine the aspect ration and with respect to. The one way slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. In this post, we are going to explain how to calculate steel quantity for the slab. The design uses the program adapt floor pro release 20092010 featuring the hong kong code. Guidelines for a oneway concrete flooring system brewer. What is the difference between one way and two way slab.
Shear strength in one and twoway slabs according to the. Pdf design calculation design of one way slab slab s1. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. 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. Difference between one way slab and two way slab system.
In two way slabs, load will be carried in both the directions. 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. A new punching shear equation for two way concrete slabs reinforced with frp bars conference paper pdf available november 2005 with 1,171 reads how we measure reads. However main reinforcement bar and distribution bar in transverse direction. Distribute moments transverse at critical sections to column and middlestrip and if. A one way reinforced slab may be stronger than a two way nonreinforced slab, depending on the type of load. The basic design procedure of a twoway slab system has five steps. Oneway and twoway slabs university of asia pacific. The bars we use in the tension zone of the slab is called bent. For b oth one way and two way slab with an example. The one way slab steel quantity calculation is done according to its supporting conditions. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Bending will take place in the two directions in a dishlike form. While the basic expression for one way shear in aci 31805 is the same for narrow beams, wide beams, and slabs, an engineer is permitted to design to higher shear stresses in the latter two cases.
One way slab being supported on two opposite sides only leads to the structural action in single direction. Generally, there are two types of slab which are one way and two way slabs. Slabs are usually used in floor and roof construction. In two way slabs, the width of the critical shear crack is assumed proportional to the slab rotation. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. Total load is carried in the direction perpendicular to the supporting beam. No redistribution is allowed when method 1 or method 2 of analysis in section 3. One way slabs are typically 150 to 400 mm in depth and cover spans of 3 to 12 m. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Can be used for larger spans with relatively higher cost and higher deflections one way joist system suitable span 6 to 9m with ll 46knm2. One way slab is the slab having ratio of longer span to shorter span equal to or more than 1.
The slab size is 3 by 4 reinforcement is 16 email protected mm and 10 email protected mm cc shorter and longer span direction respectively. This condition occur when the slabs are connected monolithically with support. Please select the grade of concrete for twoway slab construction. If the length to breadth ratio of the room is less than 2, the slab is designed as a two way reinforced slab. Before calculating the quantity of steel in one way slab it is very important to clear the basic concepts. Difference between one way slab and two way slab daily civil. Slab panel is supported in the short direction of one way slab on two opposite sides the thickness of the one way slab varies between 100mm to 150mm based on the deflection consideration and span swot analysis. However, the impact for the floor system reported herein is small, since the one way system is small.
Oneway slabs transfer the imposed loads in one direction only. Based on the stiffness requirement assume suitable depth and calculate the effective span. 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. A new punching shear equation for twoway concrete slabs. One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab.
Design of a two way rcc slab structural engineering. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. One and two way slab quantity excel sheetfree download. Thus, lb one way slabs page 3 of 9 design of rectangular beams and one way slabs continued a. Load transfer in a oneway slab, b twoway slab nilson. The direction in which the load is carried in one way slab is called the span. Calculate factored moment and shear force by considering the onemeter width of the slab. Design of reinforced concrete structures ii two way slabs 1 1. Their spandepth ratio is roughly constant at low loadings i. Reinforced concrete design 1 design of slab examples. The ratio of longer span panel l to shorter span panel b is equal or greater than 2. Design of two way floor slab system comparison of one way and two way slab behavior one way slabs.