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The derivation of the maximum arching moment of resistance of laterally restrained concrete bridge deck slabs utilised Rankin's [21] idealised elastic-plastic stress-strain criterion for concrete, valid for concrete cylinder strengths up to at least 70N/mm 2, which he had derived on the basis of Hognestad, Hanson and McHenry's [23] ultimate ...
The modified compression field theory (MCFT) is a general model for the load-deformation behaviour of two-dimensional cracked reinforced concrete subjected to shear. It models concrete considering concrete stresses in principal directions summed with reinforcing stresses assumed to be only axial.
ACI 318 Building Code Requirements for Structural Concrete provides minimum requirements necessary to provide public health and safety for the design and construction of structural concrete buildings. [6] It is issued and maintained by the American Concrete Institute. [7] The latest edition of the code is ACI 318-19.
Once the slabs have been raised to their desired height the lifting collars are welded to the columns, along with shear blocks to support the slab from beneath. To assure the security of a structure during the raising of the slabs, the hydraulic jacks , attached to the top of the columns, use synchronized consoles to lift the slabs at an even rate.
The ACI Building Code Requirements put the following restrictions on amount of spiral reinforcement. ACI Code 7.10.4.2: For cast-in-place construction, size of spirals shall not be less than 3/8 in. diameter. ACI Code 7.10.4.3: Clear spacing between spirals shall not exceed 3 in., nor be less than 1in.
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
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The humidity content of concrete is one of the main influencing factors of CO 2 diffusion in concrete. If concrete pores are completely and permanently saturated (for instance in submerged structures) CO 2 diffusion is prevented. On the other hand, for completely dry concrete, the chemical reaction of carbonation cannot occur.