It considered CFST as a unified composite material, and one equivalent confining coefficient [[xi].
These data show that superposition method gives a conservative prediction of underestimating the specimens, while Unified Theory of CFST appears to overestimate the specimens.
From the epidemiologic perspective, it is interdependent (Greenland and Poole 1988) because for the binary outcome of the CFST model, each exposure causes an effect only if the other is absent.
In individuals of identical CFST type, if the effect of X is the same regardless of any simultaneous exposure to Z, then Z evidently has no effect on X; that is, there is no dependence of the effect of X on the effect of Z (or vice versa).
Complexity of estimating CFST columns carrying capacity lies in that their concrete cores and steel shells function in conditions of three-dimensional stress state, which constantly changes with increase of external loading level (fig.
At the first stage one calculates resistibility of short eccentrically compressed CFST column standard section.
Strength of short axially loaded CFST is usually calculated by the formula which was theoretically obtained by A.
It is known that concrete core of CFST with circular cross-section functions under triaxial compression of the type [absolute value of ([[sigma].
However, research related to strengthening of CFST
members using fibre are not widespread and also more tests are required to derive an optimal combination of fibre orientation, number of layers and sequence in applying CFRP layers.
columns have many advantages over reinforced concrete columns.
Porosity of concrete for centrifuged core of CFST
Porosity (%) Specimen Layer Average Single-layered -- 14,6 Double-layered 1st layer 12,8 14,0 2nd layer 15,1 Triple-layered 1st layer 10,0 2nd layer 10,8 11,6 3nd layer 14,2 Four-layered 1st layer 9,2 2nd layer 10,6 11,6 3rd layer 12,6 4th layer 14,3 Table 2.
Many researchers agree that CFST
members utilise the advantages of both steel and concrete .