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Marcus's method is a structural analysis used in the design of reinforced concrete slabs.The method was developed by Henri Marcus and described in 1938 in Die Theorie elastischer Gewebe und ihre Anwendung auf die Berechnung biegsamer Platten. [1]
The underside of a waffle slab, showing the grid like structure. A waffle slab or two-way joist slab is a concrete slab made of reinforced concrete with concrete ribs running in two directions on its underside. [1] The name waffle comes from the grid pattern created by the reinforcing ribs.
A two-way slab has moment resisting reinforcement in both directions. [24] This may be implemented due to application requirements such as heavy loading, vibration resistance, clearance below the slab, or other factors. However, an important characteristic governing the requirement of a two-way slab is the ratio of the two horizontal lengths.
Compared to traditional solid slabs, the reduced self-weight of biaxial slabs allows for longer spans and/or reduced deck thickness. The overall mass of concrete can be reduced by 35–50% depending on the design, [ 1 ] as a consequence of reduced slab mass, as well as lower requirements for vertical structure and foundations.
The precast concrete slab has tubular voids extending the full length of the slab, typically with a diameter equal to the 2/3–3/4 the thickness of the slab. This makes the slab much lighter than a massive solid concrete floor slab of equal thickness or strength. The reduced weight also lowers material and transportation costs.
Waffle slab foundations adhere to International Building Code requirements. By 2008, most states put into effect the changes adopted in the 2006 IBC and, in regards to foundations, the on-grade mat foundation has become a more attractive design because, as an engineered system, it already accommodates the 2008 design recommendations, and required no major modifications to bring it into compliance.
Since the 1950s there have been several attempts to develop theories for arching action in both one and two-way slabs. [5] [6] [7] One of the principal approaches to membrane action was that due to Park [8] which has been used as a basis for many studies into arching action in slabs. Park's approach was based on rigid plastic slab strip theory ...
Formulas in the B column multiply values from the A column using relative references, and the formula in B4 uses the SUM() function to find the sum of values in the B1:B3 range. A formula identifies the calculation needed to place the result in the cell it is contained within. A cell containing a formula, therefore, has two display components ...