# Earthquake Engineering and the Design of Tall Buildings

```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 Bracing
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
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 1st 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
• &quot;Einstein of structural
engineering&quot;
• His &quot;tube concept,&quot;
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
```