Introduction to Seismic Essentials in Groningen
7.2 Steel Structures By Prof Milan Veljkovic MSc PhD – TU Delft
Design Codes for New Steel Structures Eurocode 3 Eurocode 8 EN 1998-1 December 2004 ICS 91.120.25 Eurocode 3: Design of steel structures - Part 1-1: General Eurocode 8: Design of structures for earthquakes resistance - Part 1: rules and rules for buildings General rules, seismic actions and rules for buildings Eurocode 3 & 8 | permission granted by CEN CENELEC NPR 9998:2015 | permission granted by NEN - Delft 8 Eurocode 3: Design of steel structures - Part 1-8: Design of joints December 2015
Selection Table for Steel Grades Nominal thickness of the element t [mm] Standard and t ≤ 40 mm 40 mm ≤ t ≤ 80 mm Steel Grade f y [N/mm 2 ] f u [N/mm 2 ] f y [N/mm 2 ] f u [N/mm 2 ] EN 10210-1 S 235 H 235 360 215 340 S 275 H 275 430 255 410 S 355 H 355 510 355 490 Table 3.1 S 275 NH/NLH 275 390 255 370 S 355 NH/NLH 355 490 335 470 “Nominal values of yield strength f y and ultimate tensile strength f u for S 420 NH/NLH 420 540 390 520 S 460 NH/NLH 460 560 430 550 structural hollow sections” EN 10219-1 Eurocode 3 & 8 | permission granted by CEN CENELEC S 235 H 235 360 S 275 H 275 430 S 355 H 355 510 S 275 NH/NLH 275 370 S 355 NH/NLH 355 470 S 460 NH/NLH 460 550 S 275 MH/MLH 275 360 S 355 MH/MLH 355 470 S 420 MH/MLH 420 500 S 460 MH/MLH 460 530
Design Codes for New Steel Structures Eurocode 3 | permission granted by CEN CENELEC When there is no danger for earthquake actions, there is only need for at least low ductility, although even in those cases the preference is to have at least medium ductility.
Brittle Type Failure End plate beam to column and beam to beam connection | Steel Beam to beam construction steel frame | Detalles constructivos | CCO Construction Institue via steelconstruction.info | CCO
Examples of Ductile Behaviour types of beam-to- hysteresis loops of beam-to- column connections column connections
Farm Buildings, Industrial Halls and Offices Spinder stalinrichting | Hollema Bouw | Permission to be aksed Exchange Tower | Kallserve | CCO
Structural Schematisation pitch roof frame two story office building
Pitch Roof Frame braced direction Splinder stalinrichting | Hollema Bouw | Permission granted
Pitch Roof Frame unbraced direction Splinder stalinrichting | Hollema Bouw | Permission granted
Two Story Office Building
Energy-dissipative Bracing System
Storage Rackings Storage Rackings | Constructor Group | Public Domain
Possible Structural Solutions Unbraced direction Determine ductility class via a nonlinear push-over analysis and calculate the Determine ductility class via a nonlinear push-over analysis and calculate the q-factor q-factor When the ductility is low (DCL) in the unbraced direction: - Strenghten the frame to take the horizontal forces when necessary When the ductility is medium (DCM) or high (DCH) in the unbraced direction: - Strenghten the frame to improve the energy dissipation when necessary
Possible Structural Solutions Braced direction Determine ductility class via a nonlinear push-over analysis and calculate the Determine ductility class via a nonlinear push-over analysis and calculate the q-factor q-factor When the ductility is low (DCL) in the braced direction: - Add sufficient bracings to take the horizontal forces when necessary - If not possible, than improve the existing bracing in terms of energy dissipation When the ductility is medium (DCM) or high (DCH) in the braced direction: - Improve the existing bracing in terms of energy dissipation when necessary
Concluding Remarks Determine the actual behaviour of the existing steel structure Analyse what is necessary to adapt the structure to the effects of earthquake actions Steel is an adequate material to resist seismic actions
Thank you for your attention!
References and further reading NPR 9998 (2015). Assessment of buildings in case of erection, construction and 7.2 disapproval – Basic rules for seismic actions: induced earthquakes. Published by NEN, Delft. EN 1993 - Eurocode 3 (2005). Design of steel structures - Part 1-1: General rules and rules for buildings, Part 1-8: Design of joints and Part 1-10: Material toughness and through-thickness properties . Published by CEN/CENELEC, Brussels. EN 1998-1, Eurocode 8-part 1 (2005). Design of structures for earthquake resistance – Part 1: General rules, seismic actions and rules for buildings . Published by CEN/CENELEC, Brussels. TNO report (2015), Push-over analyse stalen 3 scharnierspant – tbv NPR 9998:2015.
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