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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
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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 ‘Soft-story’ formation • Avoid ‘soft-story’ ground floors! • Maintain uniformity throughout height • Provides braces at all storeys
Basic Design Concepts #2 ‘Soft-story’ formation • Avoid ‘soft-story’ upper floors! • Maintain uniformity throughout height • Provides braces at all storeys
Basic Design Concepts #3 Building Top View Building Front View Non-symmetric Bracing Bracings Symmetric Bracing Avoid non-symmetric bracing!
Basic Design Concepts #4 Avoid discontinuities is stiffness and resistance
Basic Design Concepts #5 • Provide slender structural walls! • Structural walls along principal directions • Be as symmetric as possible
Basic Design Concepts #6 • Avoid short column! • Short columns often fail in shear
Basic Design Concepts #7 Protect your foundations!
Basic Design Concepts #8 Strong column weak beam theory!
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!!
Basic Design Concepts #9 • Bracings and damping devices • Will be covered tomorrow!
Tall Buildings • Skyscraper is the greatest architectural invention of America • Steel frame structure for the 1st time used in England in 1792
Problem of Size • Increase in size: reduction in strength • The Euler buckling of the columns • Cannot directly employ the existing models and magnify them
Imhotep to FazlurRahman 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
Truss Tube Mode shapes
Connections • Optimum seismic connection