Steel Buildings in Europe

Part 4: Detailed Design of Portal Frames 4 - 20 4 SERVICEABILITY LIMIT STATE 4.1 General The Serviceability Limit State (SLS) analysis should be performed using the SLS load cases, to ensure that the deflections are acceptable at ‘working loads’. 4.2 Selection of deflection criteria No specific deflection limits are set in EN 1993-1-1. According to EN 1993-1-1 § 7.2 and EN 1990, Annex A1.4, deflection limits should be specified for each project and agreed with the client. The relevant National Annex to EN 1993-1-1 may specify limits for application in individual countries. Where limits are specified’ they have to be satisfied. Where limits are not specified, Appendix A of this document presents typical limits. If the structure contains overhead travelling cranes, the spread of the columns at the level of the crane is likely to be an important design criterion. In many cases, it will be necessary to provide stiffer steel sections than are necessary for the ULS design, or to provide some fixity in the base and foundation. An alternative is a tied portal (when second order analysis must be used) or a truss. 4.3 Analysis The SLS analysis is normally a first-order (elastic) analysis. The designer should verify plastic hinges do not form at SLS, simply to validate the deflection calculations. 4.4 Design summary The Serviceability Limit State (SLS):  Is assessed by first order analysis  Uses deflection criteria defined in the relevant National Annex or agreed with the client.