Cost Estimating Tutorial

# How To Design Two Way Slab System of Reinforced Concrete

This construction video offers detailed information on How to design Two Way Slab Systems of Reinforced Concrete adhering to ACI 318-11. In this video discussion is made on designing two-way slabs for one-way & two-way shear because of moment transfer as well as shear strength in two-way action delivered with concrete, conventional shear reinforcement, and headed shear stud reinforcement. Besides, discussion is made on what should be assessed in the design for preclude shear failure prior to flexural failure and how to circumvent catastrophic failure.

A one-way slab spreads amid parallel line supports like walls or beams. At each point, the axis of bending is equivalent to the supports. One-way slabs are basically wide beams and are designed on the basis of the similar principles that is used to any beam. One-way slabs transfer loads to beams, which, sequentially, convey the loads to columns

A two-way slab spreads in two directions and bends about two axes. The orientation of the principle axes of bending modifies all through the slab.

Two-way slabs belong to the types of construction forms made with reinforced concrete. It is an effective, inexpensive, and extensively recognized structural system. In fact, two-way slabs adopt different forms. For comparatively light loads found in apartments or similar buildings, flat plates are applied.

For longer distances, the thickness necessary for transmitting the shear of vertical loads to the columns, surpasses that is essential for flexural strength. Because of this, the concrete at the center of the panel can’t be applied competently. To lighten the slab, minimize the slab moments, and save material, the slab at midspan is substituted with intersecting ribs. Remember, adjacent to the columns, the complete depth is held for shear transfer of loads from the slab to the columns. This type of slab is called as a waffle slab (or a two-way joist system) and is developed with fiberglass or metal “dome” forms. Waffle slabs are applied for distances covering 25 to 40 ft. To deal with heavy industrial loads, the flat slab system is applied. Here, the transmission of shear to the column, is completed by thickening the slab adjacent to the column with drop panels or by flaring the top of the column to develop a column capital. Drop panels generally expand about one-sixth of the distance in each direction ahead of the column, providing additional strength and rigidity in the column region whereas reducing the amount of concrete at midspan. Flat slabs are useful for loads surpassing 100 psf and for distances of 20 to 30 ft.