Steel Buildings in Europe

Part 10: Technical Software Specification for Composite Beams 10 - 24 6.2.3 Minimum degree of connection The minimum degree of connection,  min , is calculated according to EN 1994-1-1 § 6.6.1.2, as follows: If L  25 m:  min = 1 – (355/ f y ) (0,75 – 0,03 L ) But  min  0,4 Otherwise:  min = 1 where: L is the span length in meters f y is the yield strength in N/mm 2 6.2.4 Verification of the degree of connection At the point of maximum bending moment, if the degree of connection is lower than the minimum degree of connection (  <  min ), the plastic theory does not apply (EN 1994-1-1 § 6.1.1(7)). In this case, the following message should display: “Insufficient degree of connection: you should increase the resistance of the shear connection”. 6.3 Cross-section resistance 6.3.1 General Different criteria are calculated at each design point along the beam. A criterion is the ratio of a design force to the relevant design resistance. Therefore the verification is satisfactory when the criterion, denoted  , does not exceed the unity:   1,0 Verification OK 6.3.2 Classification of the cross-section It is reminded that the field of application of these specifications is limited to the plastic design of the cross-section. So it shall be checked that each cross- section is class 2 (or class 1). The class of the cross-section is the maximum of the class of the compressed flange (upper flange) and the class of the web. The limit of slenderness depends on the material parameter  as defined in Section 3.1 of this guide. The first step is to determine the position y pl,a of the Plastic Neutral Axis in the structural steel section, measured from the bottom of the section. For the calculation of y pl,a , refer to Section 6.3.7 where no influence of the shear force is taken into account (i.e.  = 0 in the expressions of y pl,a ). Class of the compressed upper flange If y pl,a > h – t f The upper steel flange is not fully in compression. So the flange has not to be classified.