Skip to content

formula_3_28

codes.eurocode.en_1992_1_1_2004.chapter_3_materials.formula_3_28

Formula 3.28 from EN 1992-1-1:2004: Chapter 3 - Materials.

Classes:

codes.eurocode.en_1992_1_1_2004.chapter_3_materials.formula_3_28.Form3Dot28RatioLossOfPreStressClass1 

Form3Dot28RatioLossOfPreStressClass1(
    rho_1000: PERCENTAGE, mu: DIMENSIONLESS, t: HOURS
)

Bases: Formula

Class representing formula 3.28 for the calculation of the ratio between loss of pre-stress and initial pre-stress of class 1.

[\(\frac{\Delta \sigma_{pr}}{\sigma_{pi}}\)] Ratio between loss of pre-stress and initial pre-stress for class 2 [\(-\)].

EN 1992-1-1:2004 art.3.3.2(7) - Formula (3.28)

Parameters:

  • rho_1000 (PERCENTAGE) –

    [\(\rho_{1000}\)] Value of relaxation loss at 1000h after prestressing at an average temperature of 20 degrees Celsius [\(-\)]

  • mu (DIMENSIONLESS) –

    [\(\mu\)] Ratio between initial pre-stress and characteristic tensile strength [\(-\)] = [\(\frac{\sigma_{pi}}{f_{pk}}\)] Use your own implementation of this formula or use sub_formula_3_28_39_30 class SubForm3Dot282930Mu.

  • t (HOURS) –

    [\(t\)] Time after prestressing [\(hours\)]

Returns:

  • None –
Source code in blueprints/codes/eurocode/en_1992_1_1_2004/chapter_3_materials/formula_3_28.py 
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
def __init__(
    self,
    rho_1000: PERCENTAGE,
    mu: DIMENSIONLESS,
    t: HOURS,
) -> None:
    r"""[$\frac{\Delta \sigma_{pr}}{\sigma_{pi}}$] Ratio between loss of pre-stress and initial pre-stress for class 2 [$-$].

    EN 1992-1-1:2004 art.3.3.2(7) - Formula (3.28)

    Parameters
    ----------
    rho_1000 : PERCENTAGE
        [$\rho_{1000}$] Value of relaxation loss at 1000h after prestressing at an average temperature of 20 degrees Celsius [$-$]
    mu : DIMENSIONLESS
        [$\mu$] Ratio between initial pre-stress and characteristic tensile strength [$-$]
        = [$\frac{\sigma_{pi}}{f_{pk}}$]
        Use your own implementation of this formula or use sub_formula_3_28_39_30 class SubForm3Dot282930Mu.
    t : HOURS
        [$t$] Time after prestressing [$hours$]

    Returns
    -------
    None
    """
    super().__init__()
    self.rho_1000 = rho_1000
    self.mu = mu
    self.t = t

codes.eurocode.en_1992_1_1_2004.chapter_3_materials.formula_3_28.Form3Dot28RatioLossOfPreStressClass1.latex 

latex(n: int = 3) -> LatexFormula

Returns LatexFormula object for formula 3.28.

Source code in blueprints/codes/eurocode/en_1992_1_1_2004/chapter_3_materials/formula_3_28.py 
60
61
62
63
64
65
66
67
68
69
70
71
def latex(self, n: int = 3) -> LatexFormula:
    """Returns LatexFormula object for formula 3.28."""
    return LatexFormula(
        return_symbol=r"\frac{\Delta \sigma_{pr}}{\sigma_{pl}}",
        result=f"{self:.6f}",
        equation=r"5.39 \cdot \rho_{1000} \cdot e^{6.7 \cdot \mu} \left( \frac{t}{1000} \right)^{0.75 \cdot (1 - \mu)} \cdot 10^{-5}",
        numeric_equation=(
            rf"5.39 \cdot {self.rho_1000:.{n}f} \cdot e^{{6.7 \cdot {self.mu:.{n}f}}} \left( \frac{{{self.t:.{n}f}}}{{1000}} \right)"
            rf"^{{0.75 \cdot (1 - {self.mu:.{n}f})}} \cdot 10^{{-5}}"
        ),
        comparison_operator_label="=",
    )