Choosing Storage Options - geapsangola.com

1 4/17/20171 Choosing Storage OptionsPART I: CONCRETE VS. STEEL BINSM ichael BloughProject Engineer, Clear Creek & AssociatesPresentation OverviewStorage History Brief SummaryDesign and Planning Site Layout Design & Applied Loading Cost4/17/20172 Presentation OverviewConstruction Concrete Construction Process Steel Construction Process Time Lapse VideosPresentation OverviewGrain Management Filling and Unloading Flow of Materials Aeration4/17/20173 Presentation OverviewStructural Maintenance Corrosion Damage Repair Methods Life ExpectancyStorage History4/17/20174 History of Grain Storage Facilities that handled over 2 million bushels used to be concrete clusters Grain bin Storage was maxing out at 750k bushels per bin Conveying at 40k

2 Bph was high speed Filling large dia. bins took days to weeks Soil loads at 4000psf allowable bearing pressure were great to build Facilities Today Facilities can have over 2 million bushels in 2 corrugated bins A single grain bin is capable of storing million bushels Conveying has moved toward 100k bph Now able to fill large diameter bins in hours, not days. Geopiers, pilings, soil additives, & soil with 5000psf allowable bearing pressure is being required. 4/17/20175 Grain Facilities Today Grain facilities have evolved to a highly complex operation compared to the past. More automation for high volume incoming & outbound grain. Higher level of consideration to operations, safety, cleanliness, & maintenance.

3 Design and Planning4/17/20176 Design and Planning:Site LayoutSite Layout Concrete Located in areas with limited space Built taller than steel bin structures Towers often not required for conveying equipment 4/17/20177 Site Layout Concrete Circular bin layout Capacity increased by using the interstice bins (star bins)Site Layout Concrete Hexagonal bin layoutReference: Layout Steel Located throughout the site to allow space for vehicular traffic, flow of materials, and rail lines Don t require soil to be as firm (lower bearing capacity) as concrete in order to support the weight of the structureDesign and Planning:Design & Applied Loading4/17/20179 Typical Grain Bin Loads Filling Unloading Temperature Cables Wind Seismic (Earthquake) Snow AerationDesign & Applied LoadingConcrete Able to withstand more intense filling and unloading cycles Better for resisting high impact loading Typically able to better resist wind and snow loading4/17/201710 Design & Applied LoadingSteel Flexible structural behavior Empty steel bin generally provides better behavior in seismic event than concrete silo Provides poor resistance for lateral bracing for towers or equipmentDesign and Planning.

4 Costs4/17/201711 Costs The current difference in cost per bushel for construction is low as compared to historical differentials. Steel silos generally provide a greater Storage capacity per dollar and tend to be more cost-effective as compared to to Consider Increasing diameter larger foundation, larger and/or greater capacity roof, increased catwalk length Increasing height longer bucket elevator, larger tower foundations4/17/201712 Cost per Bushel vs. Bin CapacityReference: Kenkel, P. Oklahoma State UniversityConstruction4/17/201713 Construction:Concrete Construction ProcessConstruction Process Concrete silos are typically constructed by jump-forming or slip-forming.

5 Slip-forming Complicated process requiring extensive supervision because it is continuous. Rebar placement and concrete affect the quality of the final of Materials Concrete is batched in a controlled environment, but variability of strength is introduced with variations in ingredients size and quantity. Individual strength tests of concrete can fall below up to 10% of f c (compressive strength) as long as the average of tests equal or exceed f c. Reference: ACI 318-11, Sec. Storage Before Installation Concrete is greatly affected by delivery time and weather. Concrete produced must be placed very soon after arriving on site. In general, concrete starts to lose its optimal characteristics after 2 hours (From time of production at batch plant).

6 4/17/201715 Concrete Silos Time LapseConcrete Silos Time LapseReference: , Trupointe Cooperative, Inc. YouTube channel4/17/201716 Construction:Steel Construction ProcessConstruction Process Erection of bin can be done with minimal supervision. Installation of openings in bins ( doors) and accessories ( ladders) are easy to of Materials Steel bin components are manufactured in a controlled environment . Slight variance of quality. ASTM specifications require minimum yield and ultimate steel strength used in design To meet the ASTM specification ( A36, A992) the steel is produced to be greater than or equal to minimum yield and ultimate steel strength.

7 Site Storage Before Installation Steel bin components that are not installed immediately maintain structural strength over a long period of time on site. Moisture between galvanized sheets4/17/201718 Steel Bin Time LapseSteel Bin Time LapseReference: , Grass Roots Media YouTube channel4/17/201719 Grain ManagementGrain Management:Filling and Unloading4/17/201720 Filling and Unloading Concrete Concrete has the rigidity to withstand the effects of eccentric loading Concrete wall thickness Bracing against other binsFilling and Unloading Steel The sheets and stiffeners of steel bins are susceptible to damage and/or collapse if they experience off-center unloading or loading4/17/201721 Filling of Grain Bins Center Fill Vertical DropOff-Center Loading4/17/201722 Maintaining Unloading Conditions Free Flowing Clean Dry In ConditionIssues with Poor Conditions Grain develops clumps Foreign items end up in the conveyors Grain goes out of condition and becomes non-free flowing

8 Gates plug4/17/2017231. Core bin from center gate2. Unload from center gate until grain stops flowing3. Unload from intermediate gates, moving out from bin centerCorrect Unloading - Floor GatesOff-Center Unloading4/17/201724 Concrete Hopper Bottoms The construction process lends itself to hopper bottoms underneath making complete cleanout possible without sweep augersFilling and Unloading Steel Large bins require quality, commercial-grade sweep auger for complete cleanout4/17/201725 Steel Hopper Bottom Hopper bottoms typically 36 ft. diameter or less Require structural columns to elevate tank Generally 10 rings tall or lessGrain Management:Flow of Materials4/17/201726 Flow of MaterialsReference: ASABE EP 433 Dec.

9 1988 (R2006)Funnel FlowReference: Jenike & Johanson ( )4/17/201727 Mass FlowReference: Jenike & Johanson ( )Flow of MaterialsFunction of: Finish of the interior surface (smoothness) Angle of the hopper Height/Diameter ratio Grain material properties4/17/201728 Flow of Materials Concrete Higher coefficient of friction of grain Mass flow difficult to achieve, likely funnel flow Funnel Flow = First-In, Last-Out (FILO)Flow of Materials Steel Lower coefficient of friction of grain Mass flow or funnel flow Mass Flow = First-In, First-Out (FIFO)4/17/201729 Grain Management:AerationAeration The horsepower required to operate an aeration system is a non-linear function of grain depth Often impossible or impractical to provide the same airflow in concrete silos that could be achieved in shorter, wider steel MaintenanceStructural Maintenance.

10 Corrosion4/17/201731 Corrosion Corrosion is a concern for both concrete and steel Concrete protects steel in concrete silos Sheets on steel bin are exposedCorrosion Concrete Silos4/17/201732 Exposed Reinforcing SteelExposed Reinforcing Steel4/17/201733 Concrete CrackingConcrete Cracking4/17/201734 Moisture InfiltrationMoisture Infiltration4/17/201735 Moisture InfiltrationCorrosion Steel Bins4/17/201736 Steel CorrosionSteel Corrosion4/17/201737 Steel CorrosionSteel Corrosion4/17/201738 Stiffener Buckling Caused by CorrosionSteel Material Loss Bins are not designed with a corrosion allowance. Many older bins were not designed using current, typical grain loads (ASABE 433).