Nonlinear Modeling and Analysis of RC Buildings using ETABS (v 2016 and onwards)
This document compiles the basic concepts of inelastic computer modelling and nonlinear analysis of building structures. It also presents a step-by-step methodology to construct the nonlinear computer models of RC building structures (for their detailed performance evaluation) using CSI ETABS 2016.
NUST Institute of Civil Engineering (NICE)
School of Civil and Environmental Engineering (SCEE)
National University of Sciences and Technology (NUST)
H-12, Islamabad, Pakistan
Summary
The computer model of a structure is a compromise between the real structure and its mathematical representation. For the purpose of structural design, an understanding of these models, their underlying assumptions and analysis procedures is very important in order to arrive at an adequate and efficient design solution. With the advent of performance-based seismic design methodology, the use of inelastic computer modeling and nonlinear analysis has rapidly increased in recent years. This document compiles the basic concepts of inelastic computer modelling and nonlinear analysis of building structures. It also presents a step-by-step methodology to construct the nonlinear computer models of RC building structures (for their detailed performance evaluation) using CSI ETABS 2016. For the purpose of an example demonstration, the following modeling scheme is followed in this document.
The RC girders are modelled with moment-rotation hinges at both ends. The ASCE 41-17 modelling parameters are used for this purpose. The RC shear walls are modelled with nonlinear (concrete and steel) fiber elements throughout their lengths. The RC columns are modeled as a combination of nonlinear fiber elements at plastic hinge zone and elastic frame element at mid-section. For concrete fibers, the Mander’s stress-strain model is used with expected material strength properties. For the steel fibers, the bilinear elasto-plastic model is used with expected yield strengths. The shear and torsional responses of beams, columns and shear walls are modelled as elastic. The slabs are modeled using elastic thin shell elements. The mass of floors are lumped at each floor. No nonlinear action is considered in RC retaining walls. No effects of soil-structure interaction are considered and the base of all columns and shear walls are assigned with idealized fixed or hinge support conditions.
CE - 416: Earthquake Engineering
Description and Rationale
Pakistan is located on a highly earthquake-prone and seismically active part of the world. The country lies on a tectonically active Himalayan orogenic belt developed as a result of slow collision (extended over last 30-40 million years) among the Indian, Arabian, and Eurasian tectonic plates. This geological setting has resulted in a number of active seismic sources and faults in the region which are capable of producing moderate- to large-magnitude earthquakes. Besides having a high level of seismic hazard, the country is also confronted over the years with high rate of population increase and rapid growth of urbanization. With all these challenges and high seismic risk, there is an urgent need of equipping the civil engineering students with state-of-the-art information about seismic hazard, risk and its mitigation. This course aims to develop basic expertise and skill among UG students about various practical aspects of seismic design of buildings and structures.
This course aims to develop basic expertise and skill among UG students about various practical aspects of seismic design of buildings and structures.
Course Contents
1) Introduction to Earthquake Engineering. Understanding the Seismic Hazard: Introduction to Seismology, Seismic Hazard Assessment
2) Introduction to structural dynamics: Equations of motions for SDF Lumped mass system, free vibrations, rigid body assemblages, Response of SDF system to harmonic, periodic and general dynamic loadings, Direct integration solution of SDF systems using time-stepping methods, MDF lumped mass system: shear building, classical modal analysis (Eigen-value analysis), calculation of natural frequencies, time periods and mode shapes of MDF systems
3) Seismic Analysis and Design of Structures: Equivalent static lateral force procedure and Calculation of base shear for given building frame system, Response spectrum analysis of buildings, Time history analysis of buildings, Seismic design of reinforced concrete structures, according to provisions of ACI, UBC/IBC. Detailing of reinforced concrete structures for earthquake resistance as per Code), General seismic design considerations: common mistakes in practice, regularity, lateral force resisting mechanisms and ductility.
4) Term Project: Seismic Design of a Multi-story Building: Use of any FEM software (ETABS 2016 or SAP 2000) for seismic design of structures
Textbooks, References and Reading Material
Textbooks: Lecture notes provided by instructor
Reference Books
1) W. F. Chen and C. Scawthorn (2003), Earthquake Engineering Handbook
2) P. M. Shearer (1999), Introduction to Seismology
3) S. L. Kramer (1996), Geotechnical Earthquake Engineering
4) A. Coburn and R. Spence, (2002), Earthquake protection
5) B. Bolt, Earthquakes
6) C. H. Scholz, The Mechanics of Earthquakes and Faultings
7) H. Tiedemann, Earthquake and Volcanic Eruptions: A Handbook on Risk Assessment
8) W. Hays, B. Mohammandioun and J. Mohammadioun, Seismic Zonation
9) T. Pauley and M. J. N. Priestley, Seismic Design of Reinforced Concrete and Masonry Buildings
10) R. W. Clough, and J. Penzien, (1993): Dynamics of Structures, McGraw-Hill, New York, 2nd Edition.
11) A. K. Chopra, (1995): Dynamics of Structures-Theory and Applications to Earthquake Engineering, Prentice Hall, New Jersey.
12) J. W. Smith, (1988): Vibration of Structures: Applications in Civil Engineering Design, Chapman and Hall, London.
13) T. R. Tauchert, (1974): Energy Principles in Structural Mechanics, McGraw-Hill, ISE.
14) H. Bachmann, and W. Ammann, (1987): Vibrations in Structures-Induced by Man and Machines, Series: Structural Engineering Documents. Vol. 3e. International Association for Bridge and Structural Engineering (IABSE), Zurich, Switzerland.
15) D. E. Newland, (1993): An Introduction to Random Vibrations, Spectral and Wavelet Analysis, Longman, 3rd Edition, London.
16) S. H. Crandall, and W. D. Mark, (1963): Random Vibration in Mechanical Systems, Academic Press, New York.
International Standards/Guidelines
1) TBI (2010): Guidelines for Performance-Based Seismic Design of Tall Buildings – PEER
2) FEMA 356 (2000): Pre-standard and Commentary for the Seismic Rehabilitation of Buildings
3) ATC-40 (1996) Seismic Evaluation and Retrofit of Concrete Buildings, USA
4) ASCE/SEI 41-13 (2014): Seismic Rehabilitation of Existing Buildings (ASCE/SEI 41-13)
5) Council on Tall Buildings and Urban-Habitat (2008): Recommendations for the Seismic Design of High-Rise Buildings.
6) PEER/ATC-72-1 (2011): Modeling and Acceptance Criteria for Tall Buildings, USA
7) ASCE 7-16 (2017): Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-16)
Research Journals:
1) Earthquake Engineering & Structural Dynamics, Wiley
2) Engineering Structures, Elsevier
3) The Structural Design of Tall and Special Buildings
4) Soil Dynamics and Earthquake Engineering, Elsevier
5) Journal of Structural Engineering, ASCE
6) ACI Structural Journal, ACI
7) Structural Engineering International Journal, IABSE
8) Magazine of Concrete Research, ICE
Internet Resources
Useful Websites
1) http://peer.berkeley.edu/
2) https://www.fema.gov/
3) www.ctbuh.org
4) www.structuralengineering.info
5) https://earthquake.usgs.gov/
6) http://www.iris.edu/hq/
7) http://ds.iris.edu/ieb/
Major Ground Motion Databases
1) USGS Earthquake Catalog: https://earthquake.usgs.gov/
2) PEER Ground Motion Database: https://ngawest2.berkeley.edu/site
3) British Geological Survey Database: http://quakes.bgs.ac.uk/
4) COSMOS Ground Motion Data Center: http://www.cosmos-eq.org/
5) K-NET and KiK-net, the NIED Strong-motion Seismograph Network Database: http://www.kyoshin.bosai.go.jp/
Magazines/Articles
http://www.structuremag.org/
https://www.istructe.org
http://ctbuh-korea.org/ijhrb/index.php
https://www.express.pk/story/968021/
http://www.technologyreview.pk/the-science-of-earthquakes/
http://www.technologyreview.pk/12-years-october-earthquake-pakistan-prepared-handle-another-big-one/
Some Useful Video Playlists
1) Nonlinear Modeling and PERFORM 3D Seminar by Graham H. Powell
Description: Four valuable sessions on nonlinear modeling of structural components + Hands-on training sessions PERFORM 3D.
Link: Click Here
2) Title: “PBD Seminar and Workshop” – AIT Solutions (Youtube Channel)
Description: International Seminar and Workshop on Performance Based Design of Reinforced Concrete Buildings – 27-28 August 2013 – Hosted by the Asian Center for Engineering Computations and Software (ACECOMS) in collaboration with AIT Consulting.
Link: Click Here
3) Computers and Structures, Inc. (Youtube Channel)
Description: CSI Watch and Learn Video Tutorials
Link: Click Here
ETABS: Click Here
PERFORM 3D: Click Here
4) International Seminar on Design of Tall Buildings – November 2016 (Bangkok)
Description: Hands-on training sessions of different finite element modeling and analysis software (SAP, ETABS, SAFE and PERFORM 3D)
Day 1 (Training on Other CSI Software):
Link: Click Here
Day 2 (Training on PERFORM 3D):
Link: Click Here
5) Lecture Series on Performance Based Design: State of Practice for Tall Buildings
Description: A full playlist (presentations) from the 2014 Earthquake Engineering Research Institute (EERI) Technical Seminar Series – “Performance Based Design: State of Practice for Tall Buildings”.
Link: Click Here
6) Talk and Group Panel Discussion on Performance-based Design
Description: Special Talk on PBD by Mr. Ron Klemencic at the Asian Institute of Technology (AIT), Thailand, November 2017.
Link: Click Here
7) Ashraf Habibullah Talks
Description: CSI founder and CEO Ashraf Habibullah talks during a one-day seminar titled “The theory and practice of Performance-Based Design: The Future of Earthquake Engineering.”
Links:
i. The 4 performance levels in PBD
ii. Nonlinear analysis and energy dissipation
iii. Animations in structural engineering
iv. Strength and deformation of tall structures
v. The Advantage of a Ritz Analysis over an Eigen Analysis in Dynamics
vi. The Power of Virtual Work in Deflection Control of Structures
vii. Optimization in Design of Large Steel Structures
8) IRIS Earthquake Science (Youtube Channel)
Description: Official YouTube channel of Incorporated Research Institutions for Seismology
Link: https://www.youtube.com/user/IRISEnO
Grading Scheme
Assignments + Quizzes: 20%
OHT Exams: 30%
Term Project: 10%
End Semester Exam: 50%
Total: 100%
Instructor
Dr. Fawad Ahmed Najam
Assistant Professor (Structural Engineering)
NUST Institute of Civil Engineering (NICE)
School of Civil and Environmental Engineering (SCEE)
National University of Sciences and Technology (NUST)
H-12 Islamabad, Pakistan
Cell: 92-334-5192533, Email: fawad@nice.nust.edu.pk
Office No: 118, 1st Floor, NIT Building, SCEE, NUST
Recent Posts
Some of our recent posts are shown below.
Why the Location of Center of Rigidity Changes for Each Story Even for Symmetric Structures?
By fawadnajam|2020-07-18T12:21:04+00:00July 18th, 2020|FAQs, Structural Engineering|0 Comments
The Definition of Design Basis Earthquake Level and the Retrofit Need for Structures Designed for Older Codes
By fawadnajam|2020-06-21T05:53:22+00:00June 21st, 2020|FAQs|0 Comments
Why building codes require a base shear scaling for the RSA procedure?
By fawadnajam|2020-05-13T18:34:40+00:00May 13th, 2020|FAQs|0 Comments