1. Understanding Causes of Structural Failures by Fred Nelson, P. E. , S
Understanding Causes of Structural Failures by Fred Nelson, P.E., S.E., Vice President, Gervasio & Associates, Inc. ASCE/ASHE Conference – Sept. 2016

2. SECTION SUMMARY Lessons Learned from Historic Failures
Design and Agency Errors
Defective Construction
Material Deficiencies
Excessive Loadings
Deterioration and Degradation
Maintenance and Operation Errors
Terrorist Acts
Bonus Presentation – Mudslide Deployment in Oso Washington

3. Lessons Learned from Historic Failures: Sources of Information are: (1) ASCE Failure Case Studies in Civil Engineering, c. 2013; and (2) Google Website

4. Leaning Tower of Pisa

5. Background and Lessons Learned from Tower of Pisa
The tower was built in phases: the first four floors were built from 1173 to 1178; the next three floors were built between 1272 and 1778; and the third construction phase for the bell tower was between 1360 and 1370.
Foundation failure (resulting in tower rotation) has occurred continuously for over 800 years.
The 200 ft. high tower reached a horizontal tilt of 17 ft. by 1993, with an south inclination of almost 5.5 degrees.
Despite extensive investigations and analyses over the past 60 years, there is still no consensus on the failure.
Finally, after 8 centuries, the tower has been stabilized, via the use of a soil extraction method.

6. 1976 Teton Idaho Dam Failure

7. Background and Lessons Learned from Teton Dam Failure
Zone-filled earth dam, 300 ft. high - reservoir filling commenced in November 1975.
Dam failed on June 5, 1976, when water level was 30 ft. below crest.
Breaching was preceded by a period of two days with increasing quantities of seepage.
At 10:30 A.M., the seepage was approximately 15 cfs in a 6 ft. tunnel. By 11:00 A.M. a vortex was observed in the reservoir, and the crest was breached at 11:55 A.M.
It was the tallest dam to have failed.
The failure helped engineers to learn (1) the need for instrumentation; (2) protective filters to prevent seepage erosion; (3) design of cut-off trenches; (4) the effect of frost action; (5) the importance of adequate compaction control criteria and methods.

8. Tacoma Narrows Bridge - 1940

9. Background and Lessons Learned from Tacoma Narrows Bridge Failure (Evaluated by the “Board of Engineers”)
Bridge was well designed and built to safely resist all static forces.
Its failure resulted from excessive oscillations made possible by the degree of flexibility of the structure…its deck/span ratio was an unprecented 1:350.
During its service, under steady winds of an estimated 25 to 35 mph, the bridge experienced gentle amplitudes of 4 ft. that were considered to be normal and not dangerous.
The solid plate girder and deck acted like an “aerofoil”, creating both “drag” and “lift” via the Karmon Vortex effect.
The initial failure was the slippage of the cable band on the north side of the bridge, which may have initiated torsional oscillations.
After this failure, more studies were needed done on future bridges to (1) consider the aerodynamic effects of wind; and (2) to eliminate the aero-elastic instability that pushed Galloping Girtie to failure.

10. Kansas City Hiatt Regency Failure

11. Failure resulted from a change in a hanger detail that was not fully evaluated by the Engineer of Record…resulted in 4 times the design stresses. In addition, there was no redundancy in hangers

12. Background and Lessons Learned from Hyatt Regency Failure
The technical reason was easy to understand.
There is a need for all parties to understand their responsibilities and to perform their assignments properly.
The structural engineer is responsible for the overall structural integrity, including the performance of connections was firmly established in this case…the structural engineer did not evaluate the loads on the connections.
The failure also reinforced the need for practices such as project peer review and constructability checks.

13. Hartford Civic Center Roof Collapse in 1978

14. Roof Section and Inverted Pyramid Module

15. Three Dimensional Drawing of Roof Space Truss Module

16. Top Chord Bracing Issue…One of Three Conflicting Collapse Theories…the other Two were Torsional Buckling and Inadequate Welding

17. Background and Lessons Learned from Hartford Civic Center Roof Collapse
With clear spans of 210 and 270 ft. between four pylon supports, the “inverted pyramid” space structure was near record size.
The roof collapsed before dawn on January 18, 1978 after a snowstorm (15 to 18 psf) and just hours after fans left a well-attended basketball game.
Although the design assumed that the compression members were braced at mid-span, they in fact were not…these members buckled.
The use of struts without cross bracing did not provide diaphragm action for bracing the top chords.
The roof dead loads were also seriously underestimated at 40 psf, when they were actually 53 psf…a 20% reduction.
The investigation revealed that excessive deflection occurred during the construction phase…and the engineer of record dismissed this information.
This case is a lesson that computer software is a tool, and not a substitute for sound engineering experience and judgment.

18. Boston’s Big Dig Ted Williams Tunnel Ceiling Collapse

19. Background and Lessons Learned from Boston’s Big Dig Ceiling Collapse
The ceiling collapse occurred on July 10, 2006 when a concrete panel and debris weighing 26 tons and measuring 20 ft. by 40 ft. collapsed.
The failure began with the simultaneous creep-type failure of several anchors embedded in epoxy in the tunnel’s roof slab…this became a progressive collapse.
Not only were the bolts too short, but the epoxy was not of the type that could sustain continuous tension loads.
The “Powers Fasteners” epoxy used to hold the bolts in place cost $1, The cost of repair was $54 million.

20. The I-35 Bridge Mississippi River Collapse

21. Background and Lessons Learned from I-35 Bridge Collapse
The bridge was built in 1967 and collapsed on August 1, 2007, resulting in 13 fatalities and 145 injuries.
At the time of the failure, loads on the bridge, including added loads during service (thicker road beds) and construction loads (staged sand and gravel for making concrete and equipment) exceeded design loads.
The failure was determined to be at 24 gusset plates that were ½ the required thickness for the original design…consistent with tears in the gussets observed in the collapse debris.
The bridge was poorly rated and had been on MnDOT’s radar for many years. The “design error” escaped discovery during numerous inspections and repair operations over the years, including the last “in depth” inspection in June 2006.
The failure was formally evaluated by NTSB and Wiss Janney Elstner and Lichtenstein & Associates.

22. A “Blue Ribbon” Committee and Dedicated Contractor Combined to Construct a New Bridge and win the Public’s Confidence, which opened on September

23. Design and Agency Errors from G&A Files

24. Two Design Failures of MSE (Mecanically Stabilized Earth) Walls

25. MSE Wall Failure at Overpass

31. MSE Wall Failure after Water Leak

38. Flyash Tank Design and Material Failure: Engineer’s Assumptions resulted in design for only one half of the actual hoop stresses, and fabricator used undocumented foreign bolts of less strength than specified by engineer

39. Flyash Tank Failure

42. Failed Bolt Taken from Debris

43. Bolt Failed by Laboratory Torsion
Bolt Failed by Laboratory Shear

44. Dairy Tank Failure…Due to Failed Pipe Delivering Sulfuric Acid

47. Design Failure: Engineer did not Account for Thermal Concrete Shrinkage Stresses in Large (20 Million Gallon) Reservoir. After initial Filling in December with CAP water, Tank Lost 1 ft. of Water (1 million Gallons) of Water Daily for Seven Days before Problem was Realized. Simpson Gumpertz and Hager Study verified 1/32 inch cracks would pass water more than that which was lost.

48. Large Underground Water Storage Tank Leakage

49. Partial Floor Plan of 20 million Gallon Concrete Water Tank (20 ft
Partial Floor Plan of 20 million Gallon Concrete Water Tank (20 ft. High)

50. No Joint between Columns
Footing Restrains Slab Movement

53. Agency Error: Mill Avenue (Construction) Bridge Collapse under a flood of 125,000 to 140,000 cfs, when the Agency required it to be designed for only 30,000 cfs

64. Severe Wind Damage to Poorly Supported Glass Masonry

69. Field Notes showing Missing Glass Masonry

70. Underdesigned Concrete Wastewater Tank

73. Defective Construction (From G&A Files)

74. Grain Dryer Collapses: Caused by (1) Lack of Design; and (2) Defective Construction

80. Empty Grain Bin Failure during Strong Winds

81. Contractor Drilled Through Concrete Pipe while Installing Sheet Piling

83. Boring into Existing Water Main

85. HARDESTY, ALBERTA, CANADA RAIL TERMINAL COLLAPSE DURING WIND STORM

93. Maintenance and Operation Errors From G&A Files

94. Concrete Formwork Failure

95. Concrete Formwork Failure

96. Material Deficiencies From G&A Files

97. Truss Failure During Reroofing

99. Airplane Speared by Debris from Failed Canopy During Wind Storm (defective column base plate welds)

102. Overload Failures from G&A Files

103. Two Case Studies in Overload Failures, involving Concrete trucks and Bridges

104. Concrete Truck Overloaded Old Bridge

107. Out-of-Control Concrete Truck Impacts Bridge

113. Roof Collapse due to Ponding from Inadequate Drainage

115. Deterioration and Degradation Examples from G&A Files

116. 1925 Water Tank Evaluation and Repairs

121. Repair Drawing of 1925 Water Tank

122. Finished Tank now an Attractive Part of Gilbert AZ Landscape

123. Precast Concrete Cylinder Pipe Failure

128. Arizona Dam Spillway Repairs
Recipient of the
ICRI Award of Excellence
for Outstanding Concrete Repair Projects
2003

132. The engineer……… just hanging around!

133. Wall pier with huge delamination.

136. Rope access to identify delaminated concrete.

137. Chipping on delaminated concrete to verify extent of damage

138. Rigging access to bottom of the spillway slab

140. Investigation of bottom of the spillway slab
Investigation of bottom of the spillway slab. An extremely difficult place to access.

141. Preparations during the repairs for shotcrete.

142. Dry shotcrete repair process.

143. for Outstanding Concrete Repair Projects
Sports Stadium
Recipient of the
ICRI Award of Merit
for Outstanding Concrete Repair Projects
2007

144. Steel floor beam below.
Project started with trip and fall concerns on the concourse floors.

145. Heavily corroded steel floor beams.

146. As much as one half of top flange thickness was lost
As much as one half of top flange thickness was lost. Over 5/8” in some cases.

147. Shoring from structure above.
Concourse floor beam repairs.

148. Carbon Fiber Rod Reinforcement

149. Prestress tendons completely corroded away

150. Hollow core concrete plank repair
Prestress tendons

151. Cable Roof Structure Repair

153. Lost Tension in Roof Cable

155. Old Swimming Pool Floatation Failure

159. Dome Failure

161. What evidence do we look for at the scene?
The mechanical equipment
Cable damages
Damage to fabric
Foundations
Damage to small doors
Damage to overhead doors at vehicle entry
Fabric quality
Wind damage to outside equipment

162. Does the mechanical equipment work properly?

163. The cables were slack, but there was no failures or damage.

164. A lot of perimeter tears

165. This drawing shows the major fabric tears.

166. Major tears occurred at the towers.

167. No damage to foundation.

168. Small doors overturned.

169. One door did not overturn, but had moderate base damage.

170. At the vehicle entry, the outside door was upside down.

171. The upside down door became the focus of the investigation.

172. The six panels had bend outward at the middle and came off tracks.

173. A protocol for testing the door was established and lab testing was done to determine the failure pressure.

174. The company that furnished the air inflated dome, came to the scene, and repaired the damages, reinserted the perimeter into the foundation and reinflated the dome…at night. They were from Canada and could not endure our Arizona heat.

177. Terrorist Acts FEMA Urban Search and Rescue Deployments

178. Murrah Building Bombing: April 19, 1995

179. Large Explosion - Crater & E Q
Next
1.1-9c

180. Exterior Explosion Loading
over
pressure
over
pressure
spherical
shock
wave
reflected
pressure
Explain:
Spherical shock wave
Initial reflected pressure
Over pressure
Drag forces
drag
over
pressure
stand-off 1v 1s

181. Exterior Explosion Loading
Exterior walls,
columns & windows A
Roof & Floor slabs B
Successive Loading of structure - in milliseconds
Also mild EQ
Frame C
Ground shock 1s

182. Note that the Murrah Building was designed in 1970
Note that the Murrah Building was designed in The beams were designed with positive (bottom) reinforcing steel between columns and negative (top) reinforcing steel over the columns.

185. World Trade Center: September 11, 2011

187. The Pentagon was also attacked in coordinated attacks by our enemies on September 11, 2011

188. September 11, :43 am.

190. “E” RING LEAN-TO COLLAPSE, SMOLDERING

191. Bonus Presentation – March/April 2014
Oso, Washington Mudslide Presentation

192. OSO WASHINGTON (ROUTE 530) MUDSLIDE

202. SUMMARY COMMENTS All of us represent more than just ourselves.
Each person has special talents. Develop them and appreciate other’s talents.
When we do “1” and “2” very well, we have an aura about ourselves, which others notice and which motivates others to do good.
This whole business of Performing Forensic Engineering is a Process, not an Event. What we learn takes time and experience.