4- detailing of steel elements
TRANSCRIPT
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Earthquake Resistant Design & Detailing Requirements for Steel Elements
Dr. Maguid H.M. HassanExt. 1413
Email: [email protected]
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
OUTLINE
• Seismic Behavior of Steel Systems
• Design Requirements & Detailing
– Beams
– Columns
– Connections
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Seismic Behaviour of Steel Elements
• Seismic behaviour of steel elements is affected by:
• Instability
• Ductility
• Connections
• Interactions with other elements
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Seismic Behaviour of Steel Elements
• Structural steel systems suitable for earthquake resistance:
• Moment resisting frames
• Tube Structures
• Structural Walls
• Concentrically & Eccentrically Braced Frames
• Hybrid Structures
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Seismic Behaviour of Steel Elements
• Design Criteria should reflect the following:
• Beams failing first
• Suppress instability to allow needed ductility
• Appropriate ductility ratio should be achieved
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Seismic Behaviour of Steel Elements
• Steel Grade Used should satisfy the following:
• Adequate ductility
• Consistent Mechanical Properties
• Notch ductility
• No Laminations
• Lamellar Tearing
• Weldability
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Seismic Behaviour of Steel Elements
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Beams
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Beams: Monotonic Vs. Cyclic
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Beams: Sample Design Requirements
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Ductility
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Effective Length
– Should be calculated according to type of column.
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Lateral Buckling
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Local Buckling
– Similar to Beam requirements
• Shear
– If large shear forces are present, proper interaction among normal and shear stresses shall be employed
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Concentrically Braced Frames
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Concentrically Braced Frames
– All lines of actions shall be concentric
– In any single line of framing at least 30% and no more than 70% of total lateral load shall be resisted by tension
– Limitations on compactness
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Concentrically Braced Frames
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Eccentrically Braced Frames
– When frames are under lateral loads, axial forces in braces induce flexure in beams.
– The portion of the beam intersected by the brace, link, is expected to experience ductile yielding.
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Eccentrically Braced Frames
– Short Spacing
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Eccentrically Braced Frames
– Best for column safety
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Eccentrically Braced Frames
– Minimum rotation for a given lateral displacement.
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Columns: Sample Design Requirements
• Eccentrically Braced Frames (Active Links)
– Are designed to dissipate energy in shear.
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections
• Butt welded connection
– Best performance in energy dissipation
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections
• Filet welded with flange plates
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections
• Bolted with flange plates
– Shows reduced hysteretic behaviour due to slippage
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections
• Panel zones
– Beam-column connections contribute to one third of inter-storey drift, half of these arise from shear deformation of panel zones.
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections: Detailing Requirements
• Connections shall be designed to be stronger than adjacent members
• Increase in strength beyond yield is allowed to account for strain hardening
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections: Detailing Requirements
• Welding
– Butt welds are the best method for load transfer
– Partial penetration welds should not be used in stress reversal locations
– Fillet welds are acceptable
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections: Detailing Requirements
• Bolting
– Over sized holes are not recommended
– Condition of faying surfaces and painting shall be considered
– Friction type bolts are preferred
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections: Detailing Requirements
• Cleats
– Shall be properly designed considering all eccentricities
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
Steel Connections
• Beam-Column Connections
– Hole reduction shall be considered
– Panel zone requirements shall be observed
– Diagonal stiffeners or double web plates shall be used to stiffen panel zones
Maguid H.M. Hassan, Ph.D. / Fulbright AlumnusDesign & Detailing Maguid H.M. Hassan, Ph.D. / Fulbright Alumnus
References
Some or all of the material is reproduced from the following resources
• Dynamics of Structures, Ray Clough & Joseph Penzein• Structural Dynamics for Structural Engineers, Gary Hart & Kevin Wong• USGS web site • Earthquake Resistant Design and Risk Reduction, David J. Dowrick• Seismic Design of Building Structures: A Professionals Introduction to
Earthquake Forces and Design Details , Michael R. Lindeburg PE (Author), Kurt M. McMullin PE
• Earthquake Engineering: From Engineering Seismology to Performance-Based Engineering, Yousef Bozorgnia (Editor), Vitelmo V. Bertero
• The Seismic Design Handbook, Farzad Naeim• Dynamics of Structures , Anil K. Chopra• Structural Dynamics: Theory and Computation, Mario Paz, William Leigh