ENR calls the TBI Guidelines “A Big Step Forward”
Engineering News-Record has released a news story about the newly released Guidelines for Performance-Based Seismic Design of Tall Buildings. Read the article by Nadine Post.
Now available: PEER’s Guidelines for Performance-Based Seismic Design of Tall Buildings
The PEER Center is pleased to announce the release of the “Guidelines for Performance-Based Seismic Design of Tall Buildings” that was developed by PEER’s Tall Buildings Initiative.
The Guidelines present a recommended alternative to the prescriptive procedures for seismic design of buildings contained in standards such as ASCE 7 and the International Building Code (IBC). They are intended primarily for use by structural engineers and building officials engaged in the seismic design and review of individual tall buildings.
Properly executed, the Guidelines are intended to result in buildings that are capable of achieving the seismic performance objectives for Occupancy Category II buildings intended by ASCE 7. Alternatively, individual users may adapt and modify these Guidelines to serve as the basis for designs intended to achieve higher seismic performance objectives.
The Guidelines were developed considering the seismic response characteristics of tall buildings, including relatively long fundamental vibration period, significant mass participation and lateral response in higher modes of vibration, and a relatively slender profile. Although the underlying principles are generally applicable, the Guidelines were developed considering seismic hazard typical in the Western United States.
The Working Group members that prepared the guidelines include:
- Yousef Bozorgnia (PEER, UC Berkeley)
- C.B. Crouse (URS Consultants)
- Ronald Hamburger (Simpson Gumpertz & Heger
- Ronald Klemencic (Magnusson Klemencic Associates)
- Helmut Krawinkler (Stanford University)
- James Malley (Degenkolb Engineers)
- Jack Moehle (PEER, UC Berkley)
- Farzad Naeim (John A. Martin & Associates)
- Jonathan Stewart (UC Los Angeles)
Request a Free Copy of the TBI Guidelines
As a part of the launch of the new Guidelines document, PEER is offering one free copy of the printed Guidelines to engineering offices located in the United States (while supplies last). To receive your free copy, please submit a request via PEER’s online request form.
Online Request Form for TBI Guidelines – PEER IS NO LONGER SENDING FREE HARD COPIES OF THIS REPORT. PEER sent over 150 copies of the report from this online report offer. To download an electronic copy, free of charge, visit the link above. You can buy a hard copy of any PEER Report by completing this PEER Report Order Inquiry Form .
Task 7 PEER/ATC 72-1 report released about nonlinear modeling of tall buildings
The Tall Buildings Initiative, coordinated by the Pacific Earthquake Engineering Research (PEER) Center, has just released its Task 7 Report, “Modeling and acceptance criteria for seismic design and analysis of tall buildings.” This report is jointly published by PEER and the Applied Technology Council as PEER/ATC 72-1.
The goal of this task in the Initiative was to develop practical guidance for nonlinear modeling of tall buildings (buildings that exceed 160 ft) constructed with reinforced concrete, steel, and composite construction. The project coordinated a workshop that identified critical issues in tall buildings modeling and acceptance values, gathered researcher/practitioner teams to review the literature, and conducted analyses to identify appropriate procedures.
This report represents a compilation of the latest available information on analytical simulation, system and component behavior, material properties, and recommendations specific to the seismic design of tall building structural systems.
PEER/ATC 72-1 is intended to serve as a resource document for the “Guidelines for Seismic Design of Tall Buildings,” which will be published later this year by PEER.
The report is available for download from the TBI Publication and Reports page
Applicability of UBC-97 Eqn. 30-7 to Drift Calculations
Design of buildings in California currently falls under the provisions of the 1997 Uniform Building Code (UBC-97). Among its provisions, UBC-97 prescribes minimum base-shear strength requirements (PDF file – 105.5 KB). In addition to satisfying strength requirements, UBC-97 establishes maximum drift limits. In addition to satisfying strength requirements, UBC-97 establishes maximum drift limits. For tall building designs satisfying the prescriptive provisions of UBC-97, an important question is whether Equation 30-7 should be used to calculate the drift demand. This subject has been addressed in a SEAOC Seismology Committee Background and Position Regarding 1997 UBC Eq. 30-7 and Drift (September 2001) (PDF file – 146.5 KB), where it is stated that the Seismology Committee position is that Eq. 30-7 should be used for drift demands.
The meeting resulted in development of a consensus on the following position:
For performance-based design, it is acceptable for the design to not apply Equation 30-7 to the calculation of drift demands, provided there is a peer-reviewed performance check at MCE level that demonstrates, using a nonlinear dynamic analysis with appropriate ground motions, that the drift demand does not exceed 0.03. This position is intended to be used in conjunction with a performance-based approach such as the one being developed by an ad hoc task group of SEAONC for the City and County of San Francisco. See draft document (PDF file – 293.3 KB). Note that this is a draft document, not an official position of SEAONC or any other organization.
Some jurisdictions currently permit performance-based seismic designs of tall buildings in which exceptions are taken to some of the prescriptive provisions of the code. A question that arises in these designs is whether it is acceptable for one of the exceptions to be an exemption to the drift checks using Equation 30-7. To help develop a position on this question, PEER conducted a two-hour WebEx meeting on 23 February 2007. The agenda (PDF file – 63.5 KB) provided opportunities for prepared presentations and open discussion by the meeting participants (listed below).
During the discussion it also was noted (PDF file – 36 KB) that we only have one recording close to a magnitude ~8 earthquake – the Pump Station 10 recording of the Denali, Alaska earthquake – so we do not know much about such ground motions. From a theoretical point of view, we would expect a magnitude ~8 earthquake to have quite large demands. Ground motion selection and scaling should include these effects if warranted.
- Agenda (PDF file 144 KB)
- Seismology Committee Background and Position Regarding 1997 UBC Eq. 30-7 and Drift September 2001 (PDF file – 60 KB)
- Near-Source Factors – History – Kircher (PDF file – 316 KB)
- Design Drift Requirements For Long-Period Structures – Searer and Freeman (PDF file – 100 KB)
- Unintended Consequences Of Code Modification – Searer and Freeman (PDF file – 80 KB)
- Poorly Worded, Ill-Conceived, And Unnecessary Code Provisions – Searer (PDF file – 180 KB)
- P-Delta and Minimum Base Shear a – Krawinkler (PDF file – 224 KB)
- P-Delta and Minimum Base Shear b – Krawinkler (PDF file – 480 KB)
- Code Minimum Base Shear Requirements – Maffei (PDF file – 7.4 MB)
- Minimum Base Shear – Graphics – Maffei (PDF file – 36 KB)
- Selected Near Field Motions – Hamburger (PDF file – 128 KB)
- Thoughts On Minimum Strength & Stiffness Requirements For Seismic Design – Deierlein (PDF file – 140 KB)
- Expected characteristics of near fault magnitude 8 ground motions – Somerville (PDF file – 36 KB)
- Draft SEAONC Recommended Version 13 February 2007 (PDF file – 212 KB)
- Norm Abrahamson
- Yousef Bozorgnia
- Greg Deierlein
- Dave Fields
- Sigmund Freeman
- Michael Gemill
- Ron Hamburger
- Helmut Krawinkler
- Marshall Lew
- Joe Maffei
- Steve Mahin
- Neville Mathias
- Jack Moehle
- Mark Moore
- Farzad Naeim
- Paul Somerville
- Jeff Taner