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Within the trades rebar is known by a shorthand utilizing the bar diameter as descriptor, such as "four-bar" for bar that is four-eighths (or one-half) of an inch. The cross-sectional area of a bar, as given by πr², works out to (bar size/9.027)², which is approximated as (bar size/9)² square inches. For example, the area of #8 bar is (8/9 ...
Concrete cover, in reinforced concrete, is the least distance between the surface of embedded reinforcement and the outer surface of the concrete (ACI 130). The concrete cover depth can be measured with a cover meter. The purpose of concrete cover is to protect the reinforcement from corrosion, fire, and other potential damage.
A waffle slab is flat on top, while joists create a grid like surface on the bottom. The grid is formed by the removal of molds after the concrete sets. This structure was designed to be more solid when used on longer spans and with heavier loads. [3]
The roof is also a dead load. Dead loads are also known as permanent or static loads. Building materials are not dead loads until constructed in permanent position. [8] [9] [10] IS875(part 1)-1987 give unit weight of building materials, parts, components.
Specific modulus is a materials property consisting of the elastic modulus per mass density of a material. It is also known as the stiffness to weight ratio or specific stiffness. High specific modulus materials find wide application in aerospace applications where minimum structural weight is required.
If the slab is to be reinforced, the rebars, or metal bars, are positioned within the formwork before the concrete is poured in. [26] Plastic-tipped metal or plastic bar chairs, are used to hold the rebar away from the bottom and sides of the form-work, so that when the concrete sets it completely envelops the reinforcement.
Reinforcing rebar is placed axially in the column to provide additional axial stiffness. Accounting for the additional stiffness of the steel, the nominal loading capacity P n for the column in terms of the maximum compressive stress of the concrete f c ' , the yield stress of the steel f y , the gross cross section area of the column A g , and ...
Generally, 1–2 wt. % of [Ca(NO 2) 2] with respect to cement weight is needed to prevent corrosion of the rebars. The nitrite anion is a mild oxidizer that oxidizes the soluble and mobile ferrous ions (Fe 2+ ) present at the surface of the corroding steel and causes them to precipitate as an insoluble ferric hydroxide (Fe(OH) 3 ).