Week 5: Save on Foods Collapse

Question 1

What two modes of failure were involved in the roof collapse?

Answer 1

• Beam failure: primary cause of failure - beam was under strength for imposed bending loads (negative bending over column), and laterally unsupported lower compression flange of the beam buckled at supporting column
• Column failure: vertical beam-column assembly buckled simultaneously - though probably not primary cause

Question 2

T/F: The recommendations made by the Closkey report were implemented right aways

Answer 2

False: Many took decades to implement

Question 3

What 5 categories can the 19 recommendations made by the report be put into?

Answer 3

• Implementation (task force)
• Technical
• Building regulations and inspectors
• Construction industry procedures
• Engineering standards

Question 4

List 5 of the 9 actions that led to the roof collapse

Answer 4

• change in slab thickness
• extra concrete in walkway
• smaller beam used
• mill coupon certificates incorrectly done (from web and not flange)
• no buckling resistance in beam and column

Question 5

List the sequence of collapse of the beam/column assembly

Answer 5

• column head displaces laterally
• lower beam flange yields
• web begins to buckle
• joists begin to disconnect
• displacement and buckling increase until joists fail
• collapse immediate

Question 6

What are 3 of the 19 recommendations made in the Closkey report?

Answer 6

• Structural engineers to pass special exam
• monitoring of structural drawings and calculations as part of building permit application
• register engineering companies