Undergraduate seismic design competition 2013 EERI Student Chapter

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! Building Front View Building Top View Non-symmetric Bracings 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!

Topic #2: Structural Systems for Tall Buildings

Tall Buildings • Skyscraper is the greatest architectural invention of America • Steel frame structure for the 1 st time used in England in 1792 14

Problem of Size • Increase in size: reduction in strength – The Euler buckling of the columns – Cannot directly employ the existing models and magnify them 15

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 16

Structural Systems 17

Example of Bundle Tubes 18

Truss Tube Mode shapes 19

Connections • Optimum seismic connection 20

Failure Mechanism 21

Failure Mechanism 22