Undergraduate seismic design competition 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 #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

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

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

16 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

17 Structural Systems

18 Example of Bundle Tubes

19 Truss Tube Mode shapes

20 Connections Optimum seismic connection

21 Failure Mechanism

22 Failure Mechanism