One-day CPD Seminar at Dr. Fawad A. Najam Department of Structural Engineering NUST Institute of Civil Engineering (NICE) National University of Sciences and Technology (NUST) H-12 Islamabad, Pakistan Cell: 92-334-5192533, Email: [email protected]Swedish College of Engineering and Technology (SCET), Wah Cantt Seismic Design Philosophies – From Prescription to Performance
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Seismic Design Philosophies From Prescription to Performance
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One-day CPD Seminar at
Dr. Fawad A. NajamDepartment of Structural Engineering
NUST Institute of Civil Engineering (NICE)
National University of Sciences and Technology (NUST)
Ground Shaking Hazard: Yogyakarta Earthquake (2006), Indonesia
Magnitude = 6.2
Final Comprehensive Examination 17
Surface Rupture Hazard: The 1999 Chi-Chi earthquake, Taiwan
Final Comprehensive Examination 18
The 1999 Chi-Chi earthquake, Shih-Kang Dam
Final Comprehensive Examination 19
Overturned building in Adpazari, Turkey in the 1999 Kocaeli EQ
A building in Dagupan,
Philippines after the
1990 Luzon EQ
Soil Liquefaction HazardLoss of Bearing Capacity
Final Comprehensive Examination 20
Tokachi-oki EQ, Hokkaido (2003)
Final Comprehensive Examination 21
Underground Pipe Failure in Baguio, Philippines (Luzon Earthquake, 1990)
Final Comprehensive Examination 22
Earthquake-induced Landslide in Wenchuan County, China(Wenchuan Earthquake, 2008)
Introducing AIT SolutionsFinal Comprehensive Examination 23
Bhuj earthquake 2001 Irrigation Dams
Introducing AIT SolutionsFinal Comprehensive Examination 24
Tsunami generated by an Earthquake
Generation
Propagation
Inundation
Final Comprehensive Examination 25
Maximum Water Level
Khao Lak, Phang-Nga
Final Comprehensive Examination 26
Fires resulting from Earthquakes (Kobe EQ, 1995)
Final Comprehensive Examination 27
Fires resulting from the
Earthquake (Kobe EQ, 1995)
Final Comprehensive Examination 28
Seismic Design Philosophies – From Prescription to Performance
29
Why Buildings
Collapse under
Earthquakes?
31Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
Future ground
shaking
Structure
Linear/Nonlinear
Analysis Model
Characterization of
Seismic Ground
Motions
Estimation of Linear/Nonlinear
Seismic Demands
• Global-level Responses
• Inter-story Responses
• Component-level
Responses
The Earthquake Problem
Seismic Waves
Soil
Epicenter
Hypocenter
(Focus)
Fault
AttenuationSeismic waves lengthen and diminish in strength
as they travel away from the ruptured fault.
Site ResponseGround motion can
be amplified by soil
Site
Seismic WavesHypocenter
(Focus)
Fault
Soil
Site
Site ResponseGround motion can
be amplified by soil
Attenuation
Epicenter
32Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
Global Seismic Hazard Map
33Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
Evolution of Structural Design Approaches against Earthquakes
Intuitive Design
Code-based Design
Performance-based Design
Consequences and Risk Based Design
Resilience Based Design
Focus of this talk
34Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
The First Building Code: Code of Hammurabi (1792 BC to 1750 BC)
Clause 229:
If a builder builds a house for someone, and does not construct it properly, and the house
which he built falls in and kills its owner, then that builder shall be put to death.
35Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
Ancient Building Code: Laws of Moses
“In case you build a new house, youmust also make a parapet for your roof,that you may not place bloodguilt uponyour house because someone fallingmight fall from it”.
- The Bible, Book of Deuteronomy, Chapter 22, Verse 8
36Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
“Structural Design is the process of proportioning the structure to safely
resist the applied forces in the most cost effective and friendly manner”
A systematic investigation of the stability,
strength and rigidity of structures
Where Safety is a prime concern
37Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
Capacity > Demand
𝑪
𝑫= 𝑭𝒐𝑺 𝐶 = 𝐷 × 𝐹𝑜𝑆
𝐶
𝐹𝑜𝑆= 𝐷
𝐶
𝐹𝑜𝑆1= 𝐷 × 𝐹𝑜𝑆2
Ensuring Safety through Factor of Safety!
38Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
Development of Formal Buildings Codes
“Rebuilding of London
Act” after the “Great Fire of
London” in 1666 AD.
In 1680 AD, “The Laws of
the Indies” Spanis
h Crown
London Building Act of
1844.
In USA, the City
of Baltimore first building
code in 1859.
In 1904, a Handbook of the Baltimore
City
In 1908 , a formal
building code was drafted
and adopted.
The International
Building Code (IBC) by (ICC).
European Union,
the Eurocodes.
39Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
The General Code Families
UBC, IBC
ACI, PCI, CRSI, ASCE,
AISI,
AASHTO
British, CP and BS
Euro-codesChina, USSR,
Japan
40Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
The Modern Codes – With “intent” to make buildings safe for public
(ACI 318 – 11)
Extremely detailed prescriptions
and equations using seemingly
arbitrary, rounded limits with
implicit meaning
(IS 456-2000)
41Seismic Design Philosophies – From Prescription to Performance (Fawad A. Najam)
Design for Seismic Resistance and Extreme Events
• Force/stress based design
• Assume reduced forces, limit the stresses.
• Displacement based design
• Allow force D/C to exceed, as long as displacements can be limited.
• Capacity based design
• Put “fuses” in the structure limit the force capacity, hence the demand.
• Energy based design
• Total energy input is collectively resisted by kinetic energy, the elastic strain energy and energy dissipated through plastic deformations and damping.
42
The Elastic
Behavior of
Structures
Strain
Stre
ss
fy
0.5fy
Unused Strength and Ductility
43
The “Real
Behavior” of
Structures
Introducing AIT SolutionsFinal Comprehensive Examination 44
Progression of Seismic Resistance Design
Historical Approach:Earthquake forces proportional tobuilding mass (Vdes = 5 - 10% of Wt),