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Flow chart for simplified calculation method for beams and slabs

Finish Is the element a

simply supported? Is M_{Ed, fi}. ≤ ^M_{Rd, fi}^?

Are the support moments exceeded?

Calculate the support design moment of resistance,

MRd, fi, support

‘Fit’ the ‘free’ bending moment so that M_Ed,fi = M_Rd,fi

Redesign section or use alternative methods Start

Calculate M_{Rd, fi} Calculate M_{Ed, fi}.

Determine k_s(y) from Figure 12

Determine y, using temperature profiles in Annex A of Part 1-2.

Yes

No No

Yes

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Coefficient, ks (ycr) or kp (ycr)

Reinforcing steel

Prestressing steel (bars)

Prestressing steel (wires and strands)

Temperature,y( C)^o

12. Structural fire design

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c) Fire exposure on four sides (beam or column) 500 C^o

a) Fire exposure on three sides with tension zone exposed

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Compression Tension

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Finish

Is M_Ed,fi≤ M_Rd,fi? Redesign section or use

alternative methods Start

Calculate M_{Ed, fi} (see simplified calculation method for beams and slabs)

Check the minimum dimensions exceed the values in Table 7

Determine reduced section size (b_fi d_fi) using Figure 13 and temperature profiles in Annex A of Part 1–2

No

Yes

Determine y, using temperature profiles in Annex A of Part 1–2

Determine k_s (y ), from Figure 3 or Figure 4

Calculate M_u, using stress distribution shown in Figure 15. M_u = M_u1 + M_u2

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Finish Does the section also resist torsion?

Calculate the reference temperature at points P along

the line A–A − see Figure 20

Calculate the torsion resistance and interaction with shear using section 6.3 of Eurocode 2, Part 1–1 Start

Determine the reduced cross-section using either 500°C isotherm or zone methods

Calculate the compressive and tensile concrete strengths:

For isotherm method, f_cd,fi = f_cd,fi(20) = f_ck and f_ctd,fi = f_ctd,fi(20) = f_ctk For zone method, f_cd,fi = k_c(y_m) f_cd,fi(20) and f_ctd,fi = k_ct(y m) f_ctd,fi(20), where k_c(y_m) and k_ct(y_m) may be taken as k_c(y ) and can be determined

from Figure 2

Determine position P, the point at which the reference temperature, y_p is calculated. P is located along section A–A, which is

determined from h_c,ef (see Figure 19)

Yes

No

Determine y_p using temperature profiles in Annex A of Part 1–2

Calculate the reduced design strength of the shear reinforcement, f_sd,fi, from: f_sd,fi = k_s(y) f_sd(20) = k_s(y) f_ywd

where k_s(y) can be determined from Figure 3 or Figure 4

Calculate the shear resistance using the methods given for ambient temperature design, see Chapter 4 Beams¹¹

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y

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In document EC2 - How to Design Concrete Structures (Page 111-114)