CE227SAC

CE227SAC - FEMA Program to Reduce Earthquake Hazards in...

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Unformatted text preview: FEMA Program to Reduce Earthquake Hazards in Steel Moment-Frame Structures A New Paradigm for Design and Evaluation of Steel Moment Frame Buildings Stephen Mahin Nishkian Professor of Structural Engineering University of California at Berkeley Chair, Project Management Committee Steel Moment Frames Widely used – Construction ease – Architectural and functional versatility – Introduction of welding increased their efFciency and economy – Considered one of the best earthquake resisting systems available Typical Steel Moment Frame Structures Brittle Fractures Detected in Connections Following 1994 Northridge Earthquake The Pre-Northridge Connection Lateral loads resisted by moments developed in frame Beams welded and bolted to columns Complex joint Brittle Connection Damage • Generally confned to vicinity oF welds oF beams to column connections • Occurred in many types oF welded steel moment Frame buildings – New and old buildings – Tall and short buildings – Conventional and important buildings • Contrary to intent oF modern building codes A New Solution Approach ! Brittle nature oF damage invalidated basic assumptions used to design and evaluate steel moment Frames ! To fnd a reliable and practical solution to this problem, a new approach was utilized: • Integrating directed research, guideline development and training • Implemented perFormance-based engineering Framework • Mobilized expertise and resources covering an unprecedented array oF disciplines From throughout the US FEMA Program to Reduce the Earthquake Hazards of Steel Moment-Frame Structures – the design and construction oF new steel moment- Frame buildings, – the identifcation, inspection, evaluation and retroft oF existing at-risk welded steel moment-Frame buildings, and – the identifcation, evaluation, repair or upgrading oF damaged buildings Following earthquakes. Goal: Develop reliable, practical and cost-effective guidelines and standards of practice for: The Pre-Northridge Connection Lateral loads resisted by moments developed in frame Beams welded and bolted to columns Complex joint Brittle Connection Damage • Generally confned to vicinity oF welds oF beams to column connections • Occurred in many types oF welded steel moment Frame buildings – New and old buildings – Tall and short buildings – Conventional and important buildings • Contrary to intent oF modern building codes A New Solution Approach ! Brittle nature oF damage invalidated basic assumptions used to design and evaluate steel moment Frames ! To fnd a reliable and practical solution to this problem, a new approach was utilized: • Integrating directed research, guideline development and training • Implemented perFormance-based engineering Framework • Mobilized expertise and resources covering an unprecedented array oF disciplines From throughout the US FEMA Program to Reduce the Earthquake Hazards of Steel Moment-Frame Structures – the design and construction oF new steel moment-...
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This note was uploaded on 05/09/2008 for the course CE 227 taught by Professor Mahin during the Spring '06 term at Berkeley.

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CE227SAC - FEMA Program to Reduce Earthquake Hazards in...

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