Fargo+Grain+Elevator

Fargo Grain Elevator (1955) Tyler Strange, BAE, Penn State, 2010toc

=Introduction= The Fargo Grain Elevator was constructed during the summer and autumn of 1954, two miles west of Fargo, North Dakota. That autumn and winter there was only a small amount of grain stored in the elevator. In April of 1955 the majority of the filling began. The collapse and utter destruction of the elevator occurred on the morning of June 12, 1955 (Nordlund and Deere, 1970).

=Key Words= Grain Elevator, Settlement, Soil Strength, Bearing Capacity Failure

=Grain Elevator Construction= Joseph Dart invented the grain elevator in Buffalo, New York in 1842. At the time, Buffalo’s grain receipts increased almost 20 fold, a faster and more efficient method of loading, unloading, and storing the grain was needed. The term elevator originated from the processes of unloading the grain, it elevated the grain from the ship and stored it in bins (“Grain Elevators: A History”, 2006).

The Fargo Grain Elevator consists of 20 circular bins and 26 smaller interstitial bins, all reinforced concrete. At one end a combined head-house, bin-house, and work-house is located. The circular bins, with an inside diameter of 19 ft., are arranged in two rows of 10 bins. The bins have a height above ground of 122 ft. and are capped with a 6 in. thick roof slab (See Figures 1 and 2). The foundation is a 2’-4” thick reinforced concrete raft, the bottom of this raft is 6’-0” below grade (Nordlund and Deere, 1970). Figure 1: Fargo Grain Elevator Plan (Based on Figure from Nordlund and Deere, 1970)

Figure 2: Fargo Grain Elevator Elevations (Based on Figures from Norlund and Deere, 1970)

=Causes of the Failure= On June 12, 1955 the grain elevator collapsed northwards, early in the morning. Filling the elevator began in early May and steadily continued until the collapse at a rate of roughly 1 ksf in ten days. Prior to the collapse, the elevator suffered from significant settlement, readings were taken of seven elevation benchmarks and are shown in Table 1. There was also a 6 foot ground heave on the south side of the elevator. The average net pressure on the foundation at the time of the collapse was 4.75 ksf. Despite the extraordinarily high settlement reading no one took a closer look at the load and settlement data. If a plot of load versus settlement had been analyzed the imminent collapse would have been blatantly obvious and unloading the elevator would have prevented its collapse (Nordlund and Deere, 1970).

Table 1: Settlement Readings Prior to Collapse (Based on Nordlund and Deere, 1970)
 * Date of Observation ||||||||||||||= Settlement, in inches ||
 * ^  || BM 1 ||= BM 2 ||= BM 3 ||= BM 4 ||= BM 5 ||= BM 6 ||= BM 7 ||
 * May 10 ||= 0.00 ||= 0.00 ||= 0.00 ||= 0.00 ||= 0.00 ||= 0.00 ||= 0.00 ||
 * May 18 ||= 0.60 ||= 0.12 ||= 0.72 ||= 0.96 ||= 1.20 ||= 1.56 ||= 1.44 ||
 * May 25 ||= 1.92 ||= 1.08 ||= 2.04 ||= 2.28 ||= 2.88 ||= 3.49 ||= 3.00 ||
 * June 1 ||= 4.92 ||= 4.68 ||= 5.40 ||= 5.52 ||= 5.89 ||= 6.00 ||= 5.89 ||
 * June 8 ||= 9.48 ||= 8.75 ||= 10.42 ||= 10.92 ||= 11.52 ||= 12.13 ||= 11.30 ||

The Fargo area soil consists of glacial lake silts, sands, and clays to a depth of 150 feet (Anderson, 2006). The soil is stratified which means it consists of layers of differing soil textures. The failure here is unmistakably a full-scale bearing capacity failure and more specifically a local shear failure, Figure 3 depicts a local shear failure (Day, 2005). The soil could only support a maximum of 4.11 ksf based on unconfined compression tests while the foundation pressed down with a force of 4.75 ksf. With a minimum acceptable factor of safety of 1.5 the maximum allowable working pressure would have been 2.74 ksf. Based on the compression tests the grain elevator’s weight was well beyond what could safely be supported by the soil. Errors in soil strength calculations as well as incorrect assumptions about soil characteristics might have been the reason the computed compression strength of the soil was so much larger than the allowable working pressure (Nordlund and Deere, 1970). If borings would have been taken prior to construction the collapse could have been averted. This collapse also could have been prevented if the elevation benchmark readings were plotted against the loading.

Figure 3: Local Shear Failure (Based on Figure from Day, 2005)

=Lessons Learned from this Failure= Bearing capacity failures like the Fargo Grain Elevator and the Transcona Grain Elevator give an opportunity for geotechnical theories to be verified. The Transcona Grain Elevator suffered from the same problems as the Fargo Collapse and made it possible for theorists of the 1950s to verify the concept of zero internal friction for saturated clays. This concept was first explored in the 1920s but didn’t have any failures to test the theory until Robert Peck verified the theory in the 1940s (Morley, 1996).

Preconstruction soil tests or more accurate calculations could have prevented the Fargo collapse. Despite advances in technology and techniques, the soil’s maximum stress is still difficult to predict (Delatte, 2009). Prior to the Fargo collapse, the Transcona Grain Elevator failure, also located in the Red River Valley, occurred due to unstable foundation soils as well (Anderson, 2006). These types of failures have motivated engineers to come up with new and innovative ways of building on poor soils. One solution as explained by Jelsing in "A City on Stilts"; where buildings are supported by piers and caissons.

Unfortunately, even after these 2 failures the engineers have not learned the lesson. The Ocean Tower on South Padre Island, TX started to collapse and was demolished due to soil conditions. There was also a bearing capacity failure in Shanghai, China on June 26, 2009. The 13-story apartment tower collapsed due to excavation done on one side of the building for a parking garage (Transcona Grain Elevator).

=Conclusion= As with failures like the Transcona failure, the Fargo Grain Elevator collapse could have been prevented. Since Transcona and Fargo have similar soils, both being in the area of Glacial Lake Agassiz, geological engineers should have considered the instability of the alluvial sediments (Anderson, 2006). It is unclear what caused the engineer to calculate an allowable stress so much higher than the maximum determined from laboratory tests. Potential causes of this failure include calculation errors, absence of boring prior to construction, absence of a geotechnical study, and a general lack of awareness. The collapse has allowed the geological theories in use to be verified and if necessary refined for future engineers (Morley, 1996).

=Bibliography= Nordlund, R.L, and Deere, D.U. (1970). “Collapse of the Fargo Grain Elevator.” ASCE Journal of the Soil Mechanics and Foundations Division, 96(SM2), 585-607.  []

"Grain Elevators: A History." The Buffalo History Works: 2010. Web. November 10, 2010. <[]>.  This website explains the history of the grain elevator starting with the first elevator invented by Joseph Dart.

Day, Robert W. "Chapter 6: Bearing Capacity of Foundations." Foundation engineering handbook design and construction with the 2006 international building code. New York: McGraw-Hill, 2005. Digital Engineering Library. Web. 10 Feb. 2010.  <[]>

Morley, J. (1996). “’Acts of God’: The Symbolic and Technical Significance of Foundation Failures.” ASCE Journal of Performance of Constructed Facilities, 10(1), 23-31.  []

Anderson, F. J. (2006). “A highlight of environmental and engineering geology in Fargo, North Dakota, USA.” Environment Geology, 49(7), 1034-1042.  [] Describes the various geological conditions in Fargo, North Dakota including elastic deformation of clayey soils, shrink-swell, inadequate bearing capacities, and mass movements. It is also discussed how these conditions caused the failure of the Fargo Grain Elevator.

 Delatte, N. J. Jr. (2009). “Soil Mechanics, Geotechnical Engineering, and Foundations.” Beyond Failure: Forensic Case Studies For Civil Engineers., (7), ASCE, Reston, VA., 221-256.[| http://matdl.org/failurecases/Other%20failures/transcona_and_fargo_grain_elevat.htm]  Case study of the Fargo Grain Elevator collapse.

 Jelsing, C., (2005). "A City on Stilts". <[]> (Sept. 25, 2010)  Shows a successful solution to the soil conditions at the Fargo grain elevator.

Annin, English, Judge, and Stein. (2010). "Transcona Grain Elevator". https://failures.wikispaces.com/Transcona+Grain+Elevator Discussion of a similar grain elevator collapse that occurred before the Fargo collapse.