Inner page

Failure of three Hammerhead Cranes in Miami and Fort Lauderdale, Florida


Quiz Questions

1. As stated in the SK315 Hammerhead Tower Crane Operating Manual, the maximum permissible in-service wind speed that the SK315 cranes were designed to bear is ___________?
45 mph
55 mph
2. According to Figure 18, the circulation in the wake region is described as?
Failure of three Hammerhead Cranes in Miami and Fort Lauderdale, Florida 1
Laminar
Turbulent
3. The full form of CFD
Computational Failure Dynamics
Computational Fluid Dynamics
4.

From the summary of observations, which of the following is false?

  1. Prior to the storm, the cranes were not lowered by two tower sections
  2. Allsectionsofthejibs remainedconnectedafterthe collapses.
  3. The maximum height of the tower cranes above the uppermost tie-in was less than the maximum allowable free-standing height of the cranes.
Only 1
1 and 2
5.

Under actual wind loads section, wind data obtained from the National Weather Service was recorded at five locations
True
False
6. The A-frame of the crane involved in the third failure was found deformed: the right hand post bent at about the mid-height.
True
False
7. Based on mode analysis of jib, a mode with a large, effective mass is usually a significant contributor to the response of the system to _________________ excitation.
Dynamic
Static
8. According Table 4, a Mode number of 22 is seen under which direction?

  TransversDirection VerticalDirection
  Mode
No. 		Frequency
(Hz) 		Participation
Factor (%)		 Mode
No. 		Frequency
(Hz) 		Participation
Factor (%)
1st failure 9 3.819 53 4 1.354 81
1 0.466 14 10 4.349 6
22 12.083 10 7 3.033 2
2st failure 8 3.906 52 4 1.423 82
1 0.67 13 10 4.516 6
22 14.329 10 15 8.956 2
3st failure 6 4.051 52 4 1.462 82
1 0.759 11 8 4.39 6
22 14.341 11 17 10.466 3
Vertical
Transverse
9. What does TVS stands for?
Tornadic Vortex Signature
Tornadic Velocity Signature
10. According to figure 8, how many high rise buildings are existing?
Failure of three Hammerhead Cranes in Miami and Fort Lauderdale, Florida 2
3
2
11.

The equation of motion of the rotating part of the crane is given as?
Iθ+μš¹š‘Ÿš‘–š‘š‘”š‘–š‘œš‘›θ=Tš‘¤š‘–š‘›š‘‘(x,y,z)
Iθ+μš¹š‘Ÿš‘–š‘š‘”š‘–š‘œš‘›θ=Tš‘¤š‘–š‘›š‘‘(t)
12. It is concluded that the design of the crane, model SK-315 generally met the U.S. and ____________ standards.
Australian
European