undergraduate seismic design competition -2013 eeri student chapter – rice university topic #1:...
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Undergraduate seismic design competition -2013
EERI Student Chapter – Rice University
Topic #1: Basic Earthquake Engineering Concepts
What happens during an Earthquake?
• Ground motion characteristics:– How long?– How strong?– Frequency content?
• Building response:– Strong vibrations – Large stresses and strains– Local Failure – Many local Failures Progressive Collapse
Building Collapse
Basic Design Concepts #1
• Avoid ‘soft-story’ ground floors!– Maintain uniformity throughout height – Provides braces at all storeys
‘Soft-story’ formation
Basic Design Concepts #2
• Avoid ‘soft-story’ upper floors!– Maintain uniformity throughout height – Provides braces at all storeys
‘Soft-story’ formation
Basic Design Concepts #3• Avoid non-symmetric bracing!
Bracings
Building Front View Building Top View
Non-symmetric Bracing
Symmetric Bracing
Basic Design Concepts #5
• Provide slender structural walls!– Structural walls along principal directions – Be as symmetric as possible
Basic Design Concepts #9
• Avoid resonance!– We will need this at the
analytical/computer model building stage– We have to check and confirm that
dominant earthquake frequency and building frequency are different to avoid resonance
– Mention this point in the proposal!!
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Tall Buildings
• Skyscraper is the greatest architectural invention of America
• Steel frame structure for the 1st time used in England in 1792
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Problem of Size
• Increase in size: reduction in strength– The Euler buckling of the columns– Cannot directly employ the existing
models and magnify them
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Imhotep to Fazlur Rahman Khan
• "Einstein of structural engineering"
• His "tube concept," using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design