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Equivalent T-stub in compression is in general calculated according to EN 1993-1-8 and its chapter 6.2.5 with respect to dissertation of Patrícia Medeiros Amaral: Steel column bases under biaxial loading conditions.
The design bearing strength of the joint fjd should be determined according to EN 1993-1-8 Article 6.2.5 (7) as:
As given by the EN 1992-1-1 Article 6.7:
By combining the two formulas above the bearing strength of concrete fjd is calculates as:
with:
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βj |
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fcd |
design compressive strength of concrete |
| Ac0 | area of the base plate Ac1 = a*b |
| a | base plate length |
| b | base plate width |
| Ac1 | maximum spread area Ac1 = a2*b2 |
| a2 | maximum spread length a2 = max (a+h, 3*a,a1) |
| b2 | maximum spread width b2 = max (b+h, b*a,b1) |
| a1 | foundation block length |
| b1 | foundation block width |
| h | foundation block height |
| α | coefficient which accounts for the concrete bearing strength enhancement due the diffusion of the concentrated force within the foundation |
If the foundation dimensions are known, set of foundation dimensions is defined in the concrete data dialog and dimensions are used for direct calculation of α.
If the foundation dimensions are unknown, it is recognized that usual foundation sizes relative to that of the base plate justify α ≥ 1,5. Value of 1,5 is used as a default in such case.
The final formula for bearing strength of concrete fjd use in SCIA Engineer :
Additional bearing width c is defined by EN 1993-1-8 Article 6.2.5 (4) as:
with:
|
t |
thickness of base plate |
|
fyk |
characteristic strength of base plate material |
| fjd | bearing strength of concrete |
| γM0 | partial safety factor for material |