PREVENTING PROGRESSIVE COLLAPSE OF MULTI-STORY BUILDINGS

1
PREVENTING PROGRESSIVE COLLAPSE OF MULTI-STORY
BUILDINGS
Yahia Tokal Civil Engineering Seminar, Lawrence
Technological University, Southfield, Michigan
Analysis Methods
Abstract
The progressive collapse of the World Trade
Center towers has generated a worldwide concern
of the risks of progressive collapse in
multi-story buildings. The prevention of
progressive collapse lies primary in the proper
and effective analysis of the structures having
high potential to progressivity. Different
analysis methods are presented herein such as
linear elastic static, non-linear static, linear
elastic dynamic, and non-linear dynamic analysis.
To minimize the progressive collapse risks, The
structural system of the building should be able
to tolerate the removal of one or more structural
members and redistribute their load on the
surrounding members, so that disproportionate
collapse would not take place.

• Linear Elastic Static Analysis .
• Analysis is done based on the static removal of a
  major structural element.
• This method is approximate, and hence, design
  loads are conservative.
• The main advantages of this method lie in its
  simplicity.
• Non-Linear Static Analysis
• The main advantages of this method is that it
  accounts for the non-linear behavior of the
  members.
• The ductility of the structure can be evaluated
  using this non-linear approach.
• Non-Linear Dynamic Analysis
• This is the most accurate method to express the
  behavior of the structure following the removal
  of one or more structural elements.
• This method is more realistic as it accounts for
  the ductility, yielding, cracking, and damping
• It is very complicated and time consuming.

Progressive Failure of Multi-story Building
Proper Design against Progressive Collapse
(Rittenhouse, and Smilowitz, , 2004)
Progressive Collapse Chain Reaction Phenomenon
(9-11 Review, 2003)
Prevention of Progressive Collapse
Introduction

• Progressive collapse occurs when local failure of
  primary structural element leads to a chain
  reaction of structural element failures, and
  resulting in the collapse of all or
  disproportionately large part of the structure.
• The interest in progressive collapse can be
  tracked back to the collapse of the 22-story
  Ronan Point apartment building in England 1968,
  when a gas explosion in the 18th floor caused the
  floors above to collapse.

• The total prevention of progressive collapse may
  not be feasible as it is uneconomic. Yet, proper
  designing and detailing can significantly reduce
  its possibility.
• The alternate load path method focuses on
  providing a redundant load path following the
  loss of an individual structural member, so that
  a disproportionate collapse will not take place.
• Integrity, continuity, and energy-dissipating
  capacity in the structural members are essential
  to transfer the loads from the locally damaged
  region to adjacent regions capable of sustaining
  these additional loads without collapse.

(a) Ordinary Design
(b) Alternate Load Path Design
Behavior of Beam after removal of the Middle
Column Alternate Load Path Design (Baldridge and
Humay, 2003)
The weight and impact of the collapsed upper
floors caused a series of progressive failures of
the corner bay of the building, which collapsed
from top to bottom all the way to the ground.
Conclusion
References

• Rittenhouse, T. and Smilowitz, R., (2004).
  Building Protection on Main Street, USA,
  Design-Build Dateline
• Burns, J., Abruzzo, J., Tamaro, M. (2003).
  Structural System for Progressive Collapse
  Prevention
• GSA (2003), Progressive Collapse Analysis and
  Design Guideline for New Federal Office Buildings
  and Major Modernization Projects General Service
  Administration, Washington, D.C.
• Marjanishvili, S. M., (2004). Progressive
  Analysis Procedure for Progressive Collapse,
  Journal of Performance of Constructed
  Facilities-ASCE, May, pp. 79-85.
• Shankar, R., (2004). Progressive Collapse
  Basics, Modern Steel Construction, pp. 37-41.
• Baldridge and Humay (2003) Preventing
  Progressive Collapse in Concrete Buildings
• 9-11 Review website (2003) www.911review.com

• The analysis of multi-story buildings subjected
  to progressive collapse can be preliminary
  started using a simple method such as the linear
  elastic static method. If further analysis is
  necessary, more advanced analysis approaches can
  be used such as the non-linear elastic static and
  the non-linear dynamic analyses (Marjanishvili,
  2004).
• The size, shape, and importance of the building
  are the major factors used to determine the most
  suitable analysis approach for each building
• To prevent progressive collapse, the structural
  system of the building should be able to tolerate
  the removal of one or more structural members and
  redistribute their load on the surrounding
  members, so that disproportionate collapse would
  not take place

Progressive Collapse of the Ronan Point apartment
building in England 1968 (Shankar, 2004)