Eurocode EN Eurocode 3: 3 Design of steel structures. Part 1-1: General rules and rules for buildings

Transcription

1 Eurocode EN Eurocode 3: 3 Design of steel structures Part 1-1: General rules and rules for buildings

2 Eurocode EN Eurocode 3 applies to the design of buildings and civil engineering works in steel. It complies with the principles and requirements for the safety and serviceability of structures, the basis of their design and verification that are given in EN 1990 Basis of structural design. EN gives basic design rules for steel structures with material thicknesses t > 3 mm. The following subjects are dealt with in EN : Section 1: General Section 2: Basis of design Section 3: Materials Section 4: Durability Section 5: Structural analysis Section 6: Ultimate limit states Section 7: Serviceability limit states

3 Member axes Convention for member axes. The convention for member axes is: x-x along the member, y-y axis of the cross-section, z-z axis of the cross-section. Generally: y-y - cross-section axis parallel to the flanges, z-z - cross-section axis perpendicular to the flanges. (detiles: Figure 1.1 EN )

4 Materials Part 3 of EN 1993 covers the design of steel structures fabricated from steel material conforming to the steel grades listed in Table 3.1. The nominal values of the yield strength f and the y ultimate strength f u for hot rolled structural steel shall be taken from Table 3.1.

5 Materials Nominal values for structural hollow sections.

6 Design values of materials coefficients The material coefficients to be adopted in calculations for the structural steels covered by this Eurocode Part should be taken as follows: modulus of elasticity E = N/mm 2 shear modulus G = N/mm 2 Poisson s ratio in elastic stage v = 0.3

7 Classification of cross sections The role of cross section classification is to identify the extent to which the resistance and rotation capacity of cross sections is limited by its local buckling resistance. Four classes of cross-sections are defined: Class 1 see p EN Class 2 see p EN Class 3 see p EN Class 4 see p EN Classification of cross section Table 5.2 EN

8 Maximum width-to-thickness ratios for compression part

9 Maximum width-to-thickness ratios for compression part

10 Maximum width-to-thickness ratios for compression part

11 Maximum width-to-thickness ratios for compression part

12 Maximum width-to-thickness ratios for compression part

13 Ultimate limit states The partial factors γ M should be applied to the various characteristic values of resistance: resistance of cross-sections whatever the class is: γ M 0 resistance of members to instability assessed by member checks: γ M 1 resistance of cross-sections in tension to fracture: γ M 2 resistance of joints: see EN The following numerical values are recommended for buildings: γ M 0 = 1,00 γ M 1 = 1,00 γ M 2 = 1,25

14 Resistance of cross-sections - Tension The design value of the tension force N Ed at each cross section shall satisfy: N Ed N trd 1,00 For sections with holes the design tension resistance N t,rd taken as the smaller of: should be The design plastic resistance of the gross cross-section The design ultimate resistance The design ultimate resistance of the net cross-section at holes for fasteners N plrd = A f y γ M0 N urd = 0.9 A net f u γ M2

15 Resistance of cross-sections - Compression The design value of the compression force N Ed at each cross section shall satisfy: N Ed N crd 1,00 The design resistance of the cross-section for uniform compression N c,rd shall be determined as follows: for class 1, 2 or 3 cross-sections for class 4 cross-sections N crd = A f y γ M0 N crd = A eff f y γ M0

16 Resistance of cross-sections Bending moment The design value of the bending moment M Ed at each cross-section shall satisfy: M Ed M crd 1,00 The design resistance for bending is determined as follows: for class 1 or 2 cross sections M crd =M plrd = W pl f y M crd for class 3 cross sections M crd =M elrd = W el f y M crd for class 4 cross sections see p EN

17 Resistance of cross-sections Shear The design value of the shear force V Ed at each cross section shall satisfy: In the absence of torsion the design plastic shear resistance V crd is given by: V Ed V crd 1,00 V crd =V plrd = A v (f y / 3) γ M0 A v is the shear area and for rolled I and H sections, loading parallel to web, may be taken as: A v =A 2 b t f +(t w +2 r) t f