According to DS-EN 1992-1-2 (Danish annex to EN1992-1-2), Annex B2.

The thickness of the damaged zone, for beams, is

1590583172234-464.png

The thickness of the damaged zone for columns and walls with 2nd-order effects is

1590583192762-957.png

If 1590583248644-758.pngwe set thickness wy = h/2, otherwise we set wy = h

If 1590583331123-677.png we set thickness wx = b/2, otherwise we set wx = b

The mean value of the concrete compressive strength for the reduced cross-section is determined by

1590583406248-215.png and

1590583421944-881.png

The cross-section is divided into equal cross-section parts. n is an even number greater than 6. For rectangular cross-sections n = 60 are selected.

1590583618029-944.png

Where

θ4,b,h(0, yj, t) is the temperature in the middle of layer j and

θ4,b,h(xj, 0, t) is the temperature in the middle of layer i.

Factor (1 to 0.2 / n) takes into account the uncertainty of a few divisions.

1590583744781-725.png

For cross-sections with flanges we use the same calculation method as for rectangular sections, with the determination of a damaged zone for both body and flanges.

The cross-section is divided during the calculation, according to Section properties, into a body of width b (body width) and height h (original cross-section height) and a flange with width bf and height hf.

For circular cross-section, we divide it into n circle rings, each with thickness D / (2n-1), except that the inner circle has a diameter of D / (2n-1). For circular cross-sections n = 20 are selected.

1590583955089-893.png

Where

1590584005195-470.png is the temperature in the center of circle ring i.

1590584314371-381.png

 

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PRE-Stress Documentation