Concrete Silos Research Articles

Influence of physical properties of solid biomass fuels on the design and cost of storage installations

The aim of this work consists on determining biomass fuels properties and studying their relation with fixed and variable costs of stores and handling systems. To do that, dimensions (length and diameter), bulk density, particle density and durability of several brands and batches of wood pellets and briquettes were tested, according to international standards. Obtained results were compared with those in literature. Bulk density tests were applied for several other biomass fuels too, and later used to determinate which ones of all the biomass-fuels tested are economically more profitable for a typical transport/store system made of a screw conveyor and a concrete bunker silo.

滑模施工混凝土筒仓结构的缺陷原因分析

混凝土筒仓采用滑模施工相对简便快捷，模板投资较低，可连续作业，该施工方法普遍用于混凝土烟囱、冷却塔、广播电视发射塔等高耸体形且截面规则壳体结构的浇注成型，多年来,作为专项成套技术在国内外得到了广泛应用。近年的国内工程调查表明，滑模施工混凝土筒仓的筒壳易出现以下缺陷：表层强度不同程度低于内部及设计强度,混凝土粘结握裹配筋状况较差,不规则与环向水平裂缝，对结构各项性能有明显不利影响。为此，对混凝土筒仓因滑模施工可能导致质量劣化的问题进行了分析研究，提出了相关技术建议，可供结构设计与施工人员参考。 For the slipforming construction to built reinforced concrete silos, it is not only faster and easier relatively than that in usual, but also less template investment and it brings about continuous operation. The method is still widely used to built this kind of tall and regular cross-section concrete shells, such as chimneys, cooling towers, radio and TV towers etc. and it is token as special sets of construction technology at home and abroad for many years. In recent years, a number of engineering surveys in the domestic showed that the following shell defects appeared easily in slipforming construction and affected them badly, such as surface concrete strength which was less generally than that of the internal and the design requirement, poor concrete adhesive around reinforcements, more irregular and annular cracks on silo walls. To resolve these problems, careful analysis and research are done for the quality deterioration of reinforced concrete silos due to slipforming techniques, and then some improved suggestions are proposed to the reference for relative structural designers and workers.

Design forces for groups of six cylindrical silos by artificial neural network modelling

A huge amount of various granular materials can be stored in and between the cells of grouped reinforced concrete cylindrical silos. The determination of design forces for reinforced concrete groups of six cylindrical silos requires significant computational effort owing to structural continuity and force transfer between adjacent silos. In this study, the efficiency of artificial neural network models in predicting the design forces and moments of groups of six cylindrical silos due to interstice loadings was investigated. Previously obtained finite-element analysis results in the literature were used to train and test the artificial neural network models. Each parameter (silo wall thickness, intersection wall thickness and the central angle spanning the intersection walls of the groups of six cylindrical silos) affecting design forces and moments was included in the input vector. The outputs of the artificial neural network models are the bending moments, hoop forces and shear forces at the supports and crowns of the interstice walls owing to interstice loadings. All artificial neural network models were trained and tested using 11 different three-layered back-propagation methods widely used in the literature. The results obtained demonstrated that all the back-propagation methods are capable of predicting the design forces and design moments at the interstice walls of the groups of six cylindrical silos.

Design and Construction of Fly Ash Silo with Inverted Cone

A coal and biomass power plant was built at Maasvlakte near Rotterdam in the Netherlands. For the storage of fly ash which is a residual product of the coal combustion process, a 24 m diameter reinforced and prestressed concrete silo having a height of 65 m was designed. The silo has a central inverted cone composed of precast concrete elements which forces the fly ash to be discharged from eight openings around the perimeter of the silo. This paper presents the process of designing the foundation, the cylinder wall and the central cone and discusses the engineering challenges. It deals with the characterization of the load cases resulting from filling and discharging the silo, and explains the way thermal loads resulting from the high-temperature fly ash were allowed for in the analysis of the structure. Finally, it summarizes the main issues regarding the construction of the silo structure.

Cylindrical shell bending theory for orthotropic shells under general axisymmetric pressure distributions

The axisymmetric linear bending theory of shells is treated for thin-walled orthotropic cylindrical shells under any smooth axial distribution of normal and shear pressures. The equations are developed, solved and explored in this paper. The derivation is presented in terms of a generalised Hooke’s Law with coupling between the axial membrane stress resultant and axial bending moment. This formulation permits the shell to be alternatively treated as a composite isotropic cylinder with axial stiffeners, rendering it useful for many practical problems. A linear kinematic relationship is assumed between the generalised strains and displacements. Expressions for the linear axial bending half-wavelength are presented for special cases of the stiffness matrix.The equations developed here are simple enough to be applied to the analysis of anisotropic thin-walled cylindrical shells using basic spreadsheet tools, removing the need to perform an onerous finite element analysis. Engineering applications potentially include corrugated metal, axially-stiffened or reinforced concrete silos under granular solid pressures, tanks under hydrostatic pressures, tubular piles under earth pressures, gas-filled cisterns and chimneys.

Theoretical Analysis and Research of Large Diameter Silos

In this paper, through analyzing the differential element of silos wall suffering from axially symmetric load according to their actual working status, the author applies the theory of taking account of moment to getting silos internal forces and displacements ,and gives the differences in the calculation results gotten respectively using nonmoment theory and the theory of taking account of moment through an example. What to be thought, during the course of designing to code for design of reinforced concrete silos, is brought.

Efficacy of Heat Treatment for Disinfestation of Concrete Grain Silos

Field experiments were conducted in 2007 and 2008 to evaluate heat treatment for disinfestations of empty concrete elevator silos. A Mobile Heat Treatment Unit was used to introduce heat into silos to attain target conditions of 50 degrees C for at least 6 h. Ventilated plastic containers with a capacity of 100 g of wheat, Triticum aestivum L., held Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). Polyvinyl chloride containers with a capacity of 300 g of wheat held adults of Liposcelis corrodens (Heymons) (Psocoptera: Liposcelididae) and Liposcelis decolor (Pearman), which were contained in 35-mm Petri dishes within the grain. Containers were fastened to a rope suspended from the top of the silo at depths of 0 m (just under the top manhole), 10 m, 20 m, and 30 m (silo floor). When the highest temperature achieved was approximately 50 degrees C for 6 h, parental mortality ofR. dominica and T. castaneum, and both psocid species was 98-100%. Progeny production of R. dominica occurred when there was parental survival, but in general R. dominica seemed less impacted by the heat treatment than T. castaneum. There was 100% mortality of L. corrodens at all depths in the heat treatments but only 92.5% mortality for L. decolor, with most survivors located in the bioassay containers at the top of the silo. Results show wheat kernels may have an insulating effect and heat treatment might be more effective when used in conjunction with sanitation and cleaning procedures.

Analysis and Design Recommendations for the Collapse of a Concrete Silo

Accidents of the cement manufacturers’ reinforced concrete silo structures frequently occurred currently in China, because of quality problems, causing enormous losses. The collapse status of a cement raw meal silo is investigated. Combined with the test results of the location and spacing of silo wall’s reinforcing bars, concrete strength, cracks and defects, the reasons for collapse of silo wall are analyzed and design recommendations for concrete silo structures are made. This can give reference to reinforced concrete silo structure design and construction in the future.

Performance Analysis of Concrete Silo Structure Strengthened with Carbon Fiber Reinforced Polymer Laminate

Due to the low design standards when constructed, limited construction materials, corrosion damage from natural environments and degeneration in normal use process, some reinforced concrete silos put up in the 1980s and 1990s are facing the troubles like decrease of bearing capacity, cracks and component damages, which are seriously affecting their normal use and bring certain security risks. Thus, the strengthening of these silos should be taken into account. In this paper, the positions that should be paid more attention when strengthened are obtained through finite element method analysis of a silo. Then the silo is strengthened with carbon fiber sheet through three different reinforcement conditions. The structure performances after being strengthened are analyzed, and the factors that affect the reinforcement effects are summarized.

The Experimental Study on Prestress Losses of Steel Stranded Wire in Non-Coherent Prestressed Concrete Silos

In this paper, non-coherent prestressed steel stranded wire being introduced in one concrete silo model of 10m inner diameter is tensed at both ends. The prestress losses of wires are tested. Based on the tested result, the trend of prestress losses and prestressing wires strain is educed.

Dynamic Response Analysis of Column-Supported Silos

In consideration of the deficient study on dynamic response of reinforced concrete silos, especially group silos at home and abroad, taking the silos of one grain storage for instance, the dynamic response analysis of a single column-supported silo and that of group silos are carried out and contrasted through finite element method. Then the analysis results are contrasted with corresponding standards as well as academic studies.

Design Formulas for the Groups of Six Cylindrical Silos Due to Interstice Loadings

Different and huge amounts of granular materials can be stored in and between the cells of the grouped reinforced concrete cylindrical silos. The determination of design forces acting on these grouped silos requires significant computational effort due to structural continuity and the force transfer between the adjacent silos. In this conjunction, the present study carried out a series of two-dimensional linear elastic analyses for various groups of six cylindrical silos to examine their behaviors against interstice loadings. A detailed parametric study was performed by varying the silo-wall thickness, intersection wall thickness and the intersection wall lengths of the groups of six cylindrical silos in order to confirm their effectiveness on the resultant design forces. Bending moments, hoop forces and shear forces occurring at the interstice walls due to interstice loadings were computed with finite element analyses. Based on the results of the present numerical analyses, the design formulas were introduced and the design coefficients were proposed to compute the design forces without necessitating any finite element analyses.

Seismic Behavior of Reinforced Concrete Silos Considering Granular Material-Structure Interaction

Silos are structures that are used for storing different types of granular materials. Due to nonlinearity of reinforcedconcrete walls of silo and incrementally nonlinear behavior of granular material, overall seismic behavior of reinforced concrete silos is very complex, in this paper we have used ABAQUS finite element package for modeling of earthquake effect on a reinforced concrete silo, reinforced concrete silo walls are modeled by shell elements and their nonlinear behavior is considered by concrete damaged plasticity model, seismic behavior of granular material inside silo is highly nonlinear and requires a complex nonlinear description of the granular material, the behavior of granular material is incrementally nonlinear even at low strains. The hypoplasticity theory describes the stress rate as a function of stress, strain rate and void ratio. It can model the nonlinear and inelastic behavior of granular materials due to its rate-type formulation. Granular material inside silo is modeled by solid elements and its nonlinear behavior is considered with a hypoplastic constitutive model, for modeling of interaction between silo walls and granular material, surface to surface contact with coulomb friction law is considered between silo walls and granular material. After modeling, the behavior of reinforced concrete silo under earthquake excitation is compared with a model without considering granular material-structure interaction.

Structural Integrity: Key to Reliability of Waste Containment Systems

Fernald site produced over 500 million pound of uranium metal products from 1952 to 1989 resulting in a huge quantity of hazardous waste to be stored, treated and transported for final disposal. The structural integrity evaluation of specific types of waste containers used in the Fernald Closure Project are briefly presented in this paper. Metal containers of various shapes and sizes, concrete silos, gondola rail cars were successfully used for storage and disposal of low-level waste. Computer solutions were obtained using finite element analyses techniques, destructive and non-destructive tests were used to get a realistic response to complex loading conditions. Structural integrity is evaluated for concrete silos built in the fifties, unique metal containers and fiberglass rail car lid. A failure modes and effects analysis was also made for the railcar lid to identify the weak link for postulated failure mechanisms. Establishing the structural integrity was a key to the reliability of the various containment systems for a successful storage, transportation and final disposal of the low-level radioactive wastes.

Design of Pre-Weakening and Evaluation of Structural Safety for Explosive Demolition of Concrete Silo

Recently the demand for demolition of unnecessary cylindrical silo structure is increasing due to the deterioration and malfunctional conditions and the issue of demolition is in the limelight. To minimize environmental hazards caused during the process of demolition, the explosive demolition method has been applied increasingly. The concrete silo structure is often built by the slip-form method which is a continuous concrete casting operation. As a result, the structure does not have expansion joints or other structural weaknesses that can be used to assist in the demolition process. This study presents the pre-weakening of explosive demolition of the cylindrical concrete silo structure by overturning method. Pre-weakening for the explosive demolition of the structure is usually conducted based on the field experience without technical guideline for the pre-weakening procedure. Hence, there always exist safety-related concerns. To demolish the structure by blast effectively and safely, rational approach to the pre-weakening and evaluation method of the load carrying capacity of the pre-weakened structure should be established. To do this, mechanical properties of concrete are estimated by experiment prior to structural analysis. Based on the result of investigation, design or operation methods of pre-weakening for the blast demolition are discussed.

Computer Aided Design of Circular Reinforced Concrete Silos

"ENGINEER", established in 1973 by The Institution of Engineers, is a Journal for dissemination of Engineering knowledge, published quarterly.If you are interested in contributing an Original Technical Paper based on research by the author(s) (intended for Section I) or an Original Article of Professional or Technical interest related to Engineering. (Section II) to this journal please go through the publication checklist which can be downloaded from here.Cover DescriptionCover images show a few views of the Maduru Oya reservoir and construction of right bank canal. The Institution of Engineers, Sri Lanka, acknowledges Eng. L.D. Amila Sanjeewa of the Department of Irrigation for providing images and related information of the project.

Cause of Damage and Failures in Silo Structures

Silos are special structures subjected to many different unconventional loading conditions, which result in unusual failure modes. Failure of a silo can be devastating as it can result in loss of the container, contamination of the material it contains, loss of material, cleanup, replacement costs, environmental damage, and possible injury or loss of life. Silo damage and failures that occurred in different regions of the world are presented in the paper using illustrative photos. Also provided are a review and discussion of the common or spectacular silo failures due to explosion and bursting, asymmetrical loads created during filling or discharging, large and nonuniform soil pressure, corrosion of metal silos, deterioration of concrete silos due to silage acids, internal structural collapse, and thermal ratcheting. Silo damage and failures from several earthquakes are also presented.

Efecto del Almacenamiento de Granos de Maíz (Zea mays) sobre la Calidad del Aceite Extraído

The effect of storage time on grains of yellow maize (Zea mays) was evaluated on the quality of the oil obtained. The quality parameters detected at the reception of the maize were: indexes of acidity, peroxide and the color of the oil extracted from grains stored in a concrete silo for 0, 30, 60 and 90 days, using the procedures described in the patterns in Venezuela. Adverse significant effects (P<0.05) of the storage time on the indexes analyzed were found. These were caused by the moisture and impurities of the grains, as well as a deficiency of 704 m 3 min -1 of fresh air fed to the silo, which affects storage. The grain of maize stored during 90 day produced increases in the index of acidity, index of peroxide and color of the extracted oil.

Numerical Modeling of the Gas Migration Test at the Grimsel Test Site (Switzerland)

The Gas Migration Test (GMT) at the Grimsel Test Site underground laboratory in central Switzerland was designed to investigate gas migration through an engineered barrier system (EBS). The EBS consists of a concrete silo embedded in a sand/bentonite buffer emplaced in a silo cavern that intersects a shear zone in the surrounding granite host rock. The experiment was performed in a series of stages: (a) excavation of the access drift and silo cavern, (b) construction and instrumentation, (c) saturation of the EBS, (d) water tests, (e) long-term gas injection at different rates, (f) postgas water testing, (g) gas injection with a “cocktail” of gas tracers, and (h) depressurization and dismantling. A numerical model was developed for the design and analysis of the different stages and to describe the relevant phenomena associated with gas migration from a potential repository for transuranic waste.A numerical model of the GMT was implemented with the two-phase-flow code TOUGH2, representing the GMT silo with a multilayered radially symmetric mesh and the surrounding water-conducting granite shear zone with a two-dimensional vertical feature. The different stages of the experiment were simulated in sequence using the results of the previous stage as initial conditions for the subsequent stage. Two-phase-flow parameters for the EBS were derived from laboratory experiments on core samples of the different materials that comprise the EBS, while hydraulic properties of the sand/bentonite and of relevant interface zones were calibrated to the pressure responses in the silo and selected piezometers in the sand/bentonite. The results of the numerical modeling of the GMT experiment show that the main features and processes of the different stages of the experiment could be reasonably well reproduced. Following the initial calibration of effective properties from the water test response during stage 4, property changes during the subsequent test phase were calibrated as stress-or pressure-dependent permeability changes. During the gas injection phases, the pressure-dependent permeability change could be related to the minimum effective stresses along interfaces. The inferred coupled hydromechanical phenomena were implemented using pressure-dependent permeability relationships on interfaces at the top of the silo and between the sand/bentonite and the granite host rock. During the recovery sequence following the first injection gas phase, the calibrated decrease in permeability of the sand/bentonite above the silo was related to the pressure decline in the upper cavern, but there was no apparent stress change. However, the calibrated permeability reduction in the sand/bentonite was in the range of values measured during the EBS excavation. In addition, time-dependent permeability relationships were calibrated for the tunnel seal to account for the gradual decrease in water inflow from the upper cavern into the access tunnel and the drift.

Study of the Durability of OPC versus GGBS Concrete on Exposure to Silage Effluent

Ordinary portland cement OPC has been traditionally used in the construction of concrete silos in Ireland. However, the aggressive nature of the effluent produced by silage leads to severe degradation of the concrete. GGBS is a common addition to PC composites. It has been demonstrated that GGBS improves the general performance of PC concrete, decreasing chloride diffusion and chloride ion permeability, reducing creep and drying shrinkage, increasing sulfate resistance, enhancing ultimate compressive strength, and reducing heat of hydration and bleeding. It has also been suggested that GGBS may increase concrete durability in the aggressive environment of silos. In order to investigate this theory, a simulation study was carried out by immersing samples of mortars incorporating increasing amounts of GGBS in a silage effluent solution and a magnesium sulfate solution. Over the course of an experiment consisting of three, 28-day cycles of immersion in the silage effluent, the sample performance was evaluated by testing permeability, porosity, water absorption, capillary suction, compressive strength, and mass loss. According to the results obtained, the OPC samples suffered the highest rise in permeability and porosity, and the greatest loss in both mass and compressive strength. In addition, the durability of the mortars, when subjected to both salt crystallization and silage effluent cycles, increased with increasing amounts of GGBS. The significant rise in capillary suction, water absorption, and permeability over the course of the experiment indicates that the damage induced by the effluent is not as superficial as previously reported. Loss in mass and increase in permeability were found to be the most reliable indicators of corrosion, as they gave the most dramatic and uniform results.