Concrete Silos Research Articles

A Dual-Mode Hybrid System Combining Solar Thermal With Pumped Thermal Energy Storage

A hybrid system that delivers renewable electricity generation and electricity storage capabilities is introduced. This dual-mode hybrid system is based on Pumped Thermal Energy Storage (PTES) which uses a heat pump to convert electricity into thermal energy that is transferred to silica particles which are stored in concrete silos. The stored heat is later converted back to electricity in a heat engine. The heat pump and heat engine use a closed Joule-Brayton cycle and fluidized bed heat exchangers. If the PTES system is co-located with an array of concentrating solar mirrors and a particle receiver, then the silica particles may also be heated up by the concentrating solar power (CSP) system. The PTES heat engine may also be used to convert the stored solar heat into electricity, thereby sharing this system between the PTES and CSP systems and reducing costs. However, this requires careful management of the heat engine off-design parameters. A thermodynamic model is used to evaluate the performance of the dual mode PTES-CSP hybrid system. The model accounts for turbomachinery efficiency, and approach temperature and pressure loss in heat exchangers, as well as other sources of inefficiency, such as motor-generator losses, and air fan power. The hybrid system also requires the evaluation of the turbomachinery efficiency and pressure ratio at off-design conditions since the CSP system operates over different temperature ratios than the Carnot Battery. Several design variables and design modifications are investigated, such as pressure ratios and maximum temperatures.

Numerical investigation of the effects of soil-structure and granular material-structure interaction on the seismic response of a flat-bottom reinforced concrete silo

Numerical investigation of the effects of soil-structure and granular material-structure interaction on the seismic response of a flat-bottom reinforced concrete silo

A Study on the Impact of Low-Frequency Random Loading and Unloading on Silo Structures

To investigate the development of cracks in the walls of reinforced concrete silos under feeding–discharge cycle loading, their causes, and their fatigue life during dynamic loading, a study was conducted using a combination of in situ monitoring and numerical simulation analysis. The following conclusions were drawn: during the loading and unloading process of the silo, the time of occurrence of the minimum pressure points follows a 4:3 ratio; extreme points are approximately 15 min apart; the minimum pressure increases during material addition and decreases during material subtraction; and the load in the non-discharge area is 1.43 times that of the load in the discharge area. That is, at the same elevation, the load borne by the silo wall is uneven, with fluctuations and rotational effects occurring. Under such uneven load conditions, the silo wall experiences significant bending and torsional moments, causing excessive local tension and leading to cracking. Our analysis showed that the most unfavorable load condition occurs when discharge ports 5 and 7 are operating simultaneously, which causes the maximum tensile damage to the silo wall. For the first time, a fatigue life prediction model for reinforced concrete silos was proposed, and the accuracy of this prediction method was verified based on actual conditions.

Dynamic responses of reinforced concrete silo considering pile–soil‐structure–granular solid interaction

SummaryThe columned‐supported reinforced concrete silo models with different filling conditions considering soil‐structure dynamic interaction (SSI) are established based on the finite element program ANSYS to thoroughly investigate the complex interaction mechanism of the soil–pile–silo structure with granular solid. The dynamic characteristics and seismic responses of the SSI system and fixed‐base condition are analyzed and compared when the filling conditions are empty‐filled state, half‐filled state and full‐filled state. The numerical results reveal that the SSI effect reduces the seismic acceleration response of columned‐supported silos effectively. However, in terms of displacement, the SSI effect often amplifies the relative deformation of the supporting column and the cylindrical silos. Furthermore, the SSI effect often increases the relative dynamic lateral pressure of the storage material in the half‐filled silo condition. In the full‐filled silo condition, the relative dynamic lateral pressure at the top and bottom of the storage material is increased by the SSI effect; while it is decreased in the middle part of the granular solid, demonstrating that the SSI effect could change and increase the seismic responses of the silo structure in certain areas. Therefore, the investigation provides a comprehensive insight into the interaction mechanism of the pile–soil–silo structure with different filling conditions.

Current design of rectangular steel silos: limitations and improvement

This study proposes a modification for the current design approach for square and rectangular silos that accounts for silos’ wall flexibility. First, the authors investigated the effect of wall stiffness symbolized by the wall width-to-thickness ratio (a/t) and silo’s dimensions, on the wall-filling pressure using a recently validated 3D finite element model (FEM). The model was then employed to predict the pressures acting on silos’ walls accounting for the stress state in stored granular materials. Most design formulas and guidelines assume silos’ walls to be rigid. This assumption is acceptable for the case of rigid wall concrete silos; however, it is questionable for semi-rigid, flexible wall metal silos. Consequentially, it is crucial to determine the minimum wall stiffness necessary to secure the applicability of the current design rigid wall assumptions and to propose a way to deal with semi-rigid and flexible walls. To this end, several wall pressure distributions that correspond to filling steel silos with varied wall thicknesses were studied. A new adjustment to the Janssen technique was proposed for a better estimate of the wall-filling pressures for square and rectangular silos. In the case of prismatic silos, the Eurocode uses the Janssen equation together with an equivalent radius of a corresponding circular silo (with the same hydraulic radius) to determine the wall pressure. This method predicts pressure values that are practically accurate for rigid-wall silos, but its accuracy decreases for semi-rigid and flexible-wall silos. As an enhancement, the Janssen equation was modified in this research to generate more accurate pressure estimates based on the equivalent volume concept. The finite element results of several developed models with the same granular material were compared to the estimations of the newly established approach to verify the broad range of its applicability.

Failure analysis of underground concrete silo under near-field soil explosion

The underground concrete silo is commonly constructed severing as vertical transport passages in mining and emergency exits for buried structures like tunnels, which, however, is possible to encounter accidental or intentional soil explosions (e.g., blasting excavation). The purpose of this study is to reveal the failure mode and mechanism of an underground concrete silo (46 m in height) subjected to a near-field soil explosion. The Coupled Lagrangian-Eulerian (CEL) method, along with two well-developed material models respectively for soil and concrete, is employed to handle the violent interactions between the exploded soil and the concrete silo. The numerical framework is first validated by simulations of a soil explosion beneath a concrete slab, where the predicted crack patterns of the concrete slab accord well with the experimental results. Subsequently, comprehensive numerical simulations are conducted to investigate the failure of the concrete silo under various soil explosion scenarios. The results indicate that the concrete silo experiences successively or simultaneously tensile spalling failure, local compression-induced tensile failure, and bending-induced tensile failure, with one or two predominating. The prevailing failure mode of the concrete silo is highly dependent on the intensity of the shock wave and the loading area. Further investigations expose that with the scaled distance increasing from 0.12 to 0.4 m/kg1/3, the dominant failure mode of the concrete silo transforms from local compression-induced tensile failure to overall bending-induced tensile failure. The critical scaled distance is 0.2 m/kg1/3. Regardless of the dominant failure mode, three-dimensional fracture planes that split the silo structure are generated. Besides, the tensile spalling failure, arising from the reflected tensile stress wave, is severe on the internal surface of the silo structure, consequently, fragments with velocities up to 12 m/s are produced, posing potential risks to humans and facilities inside the silo if any. This is the first time, to the authors’ knowledge, the failure of the prototype of a large-scale underground concrete silo arising from a large-yield and near-field soil explosion has been investigated. The finding can benefit the research community and provide a reference for the protection of the underground concrete silo as well as the facilities inside it to withstand soil explosions.

Clinker storage silos: Validation of dynamic performance through measurements and finite element simulation

The paper describes the design and application of a structural health monitoring system aimed at analysing the dynamic response of reinforced concrete silos for the storage of clinker. The in-situ dynamic measurements, supported by finite element simulations to assess the structural safety, were prompted by reports from people working in facilities near the silos in question, who complained of strong vibrations. The proposed approach combines the advantages of theoretical and operational modal analysis based on monitoring during normal use of the silos, including their emptying. The measurements were performed automatically and continuously over time, and only significant events, like shocks caused by clinker masses falling off the side walls of the silos, were saved into the remote server as the acceleration-time waveforms. They were registered with 4000 Hz frequency by piezoelectric accelerometers mounted on the bottom of the silos within the support structure. The data management system with predefined post-processing algorithms allow to extract dynamic parameters of the structure, which were then used to validate the spatial finite element model (FEM). What is worth underlying, the analysis took into account different degrees of filling of the silos, as these directly affect the dynamics of the structure. The results described hereafter were the basis for providing expertise on structural safety. The presented case study is an example of how automatic monitoring over a specified period of time can assist engineers in making rational decisions.

Verification of ultimate limit state of reinforced concrete walls of rectangular tanks with use “sandwich model” according to abendment of Eurocode

In the paper the calculations of reinforcement area of exemplary reinforced concrete squat silo for coal are presented. The results of classical calculation and calculation executed with use of ”sandwich model” are compared. The last one is recommended in the amendment of EC2-1-1 code. The calculations are preceded with compilation of standard recommendations concerning the dimensioning of concrete membranes, shells and plates

Review of Aging Management for Concrete Silo Dry Storage Systems

Review of Aging Management for Concrete Silo Dry Storage Systems

Asset Assessment of Concrete Structure

Infrastructures which were constructed in the last century are approaching or have exceeded their design life. It is essential to maintain, repair and rehabilitate existing structures to ensure safety and develop a sensible rehabilitation plan. This paper suggests an inspection program for the condition evaluation of existing structures, particularly for structures that are approaching or exceeding their design/campaign lives. Cracking on concrete bridges is often induced by static and cyclic temperature loading. Throughout the service life of the structure, cracks will initiate, propagate, coalesce and form a greater damaged zone. Depending on the location and severity of the crack network; corrosion of reinforcement, debonding between concrete and reinforcement, and spalling of concrete may occur. The implementation of regular inspection or monitoring of structural condition is an essential component of asset management. Early detection of damaged zones can ease scheduling and reduce the cost of repair, which in turn also allows extension of structural lifespan without compromising safety. Similarly, for industrial properties, asset management and rehabilitation programs are paramount as they can significantly reduce capital expenditures in asset maintenance, if implemented prior to or at the early onset of structural degradation. This paper illustrates the use of NDT techniques for the condition assessment of a prestressed concrete bridge, as well as concrete storage silos. Both of which were either approaching or have exceeded their design campaign life and were needing a proper rehabilitation plan. The assessment included crack movement monitoring, crack depth determination, concrete strength estimation, and the detection of debonding between rebar and concrete.

Feed intake, digestibility, ruminal fermentation, growth performance, and carcass traits of lambs fed corn silage treated with Lentilactobacillus buchneri and stored for different times

Our objective was to investigate the impact of inoculation and storage length of flint corn silage on the metabolic and production responses of lambs. A flint corn hybrid was harvested with 315 g dry matter (DM)/kg and ensiled in concrete pipe silos without (control) or with Lentilactobacillus buchneri CNCM I-4323 at 1 × 105 cfu/g of fresh forage for 120, 240 and 360 d (n = 2 for each treatment). Such silages were used to formulate six different diets. Sixty non-castrated male Dorper × Santa Inês lambs were used in the feeding program (n = 10). Additionally, eight ruminally cannulated Dorper × Santa Inês crossbred lambs were used to measure the ruminal fermentation (n = 4). Extending the storage of corn silage from 120 to 360 d increased the contents of soluble protein (P = 0.030; 415–490 g/kg CP) and ammonia-N (P = 0.047; 82.5–114 g/kg total N). Compared to the control, inoculation resulted in higher (P < 0.05) concentration of lactic (+19.9 %) and acetic acid (+38.6 %), and lower butyric acid (–25.3 %), ammonia-N (–23.5 %), and DM loss (–36.2 %). The aerobic stability of corn silage was also improved by inoculation (P = 0.002; +160 h compared to the control). An interaction between storage length and inoculation was reported for feed intake, and lambs had increased DMI (P < 0.001) by feeding the inoculated silage stored for 120 d. Overall, the total-tract starch digestibility increased (P = 0.041) with longer storage (120 d = 94.4 %; 240 d = 95.7 %; 360 d = 96.5 %). However, the total VFA was unchanged (P > 0.05) while the ruminal molar proportion of propionate decreased from 22.8 to 20.7 mM/100 mM in lambs fed corn silage stored for 120 and 360 d (P = 0.004). Lengthening silage storage from 120 to 240 and 360 d tended (P = 0.06) to increase the ADG of lambs by 4.6 % and 10.2 %, respectively (120 d = 0.216 kg/d; 240 d = 0.226 kg/d; 360 d = 0.238 kg/d). Moreover, the feed efficiency was substantially improved (P = 0.008) by 5 % and 14 % when the silages were stored for 240 and 360 d compared to 120 d. In opposite, inoculation had no effect (P > 0.05) on ADG and feed efficiency of lambs. Final hot carcass weight (data ranged from 16.8 to 17.2 kg) and 12th rib longissimus muscle area (data ranged from 13.8 to 14.7 cm2) were not affected by treatments (P > 0.05). Overall, only few parameters of carcass and meat traits of lambs were altered by storage length and inoculation, but it were of minor biological importance. In conclusion, the productivity responses of lambs were enhanced by increasing the storage length of flint corn silage, but inoculation with L. buchneri did not contribute to improve animal performance.

A novel vertical waterproofing joint with trapezoidal steel plate connections for steel–concrete underground silos: Bending test and numerical simulation

Steel-concrete silo is a popular option in green grain storage project due to its pretty stiffness and better waterproof. However, the structural form and mechanical properties of vertical joints in the prefabricated steel–concrete silo are two key problems, which restrict its wide application. Consequently, a novel vertical waterproofing joint with trapezoidal steel plate (TSP) connections is proposed for steel–concrete underground silos. The TSP is welded laterally between the adjacent prefabricated silo walls, and it also needs to undertake part of the axial force transmission of underground silos. Firstly, the steel–concrete specimen of two-TSPs’ deformation, interior force, failure mode and mechanism are analyzed comprehensively. Secondly, two numerical model of the steel–concrete silo wall with non-TSP and two-TSP are established on ABAQUS. Finally, the effect of different parameters on mechanical properties are analyzed. Experimental results show that, compared with the specimens with non-TSP, the deflection of the proposed two-TSP connection is decreased by 270% and the yield load of internal waterproof steel plate is increased by 29%. When the internal waterproof steel plate is yield, the compressive strain of external waterproof steel plate and TSP in the upper part are similar, while its internal tensile strain in the lower part have a little gap. TSP can cooperative work with both internal and external waterproof steel plates. Numerical results are difference from test results by only 5.34% and 4.48% respectively, which verifies that the numerical model is effective and feasible. Meanwhile, it is also found that the proposed novel connection has the greatest strength enhancement effect on flexural bearing capacity of vertical joint, and the greatest effect on improving the flexural bearing capacity of vertical joint.

Performance of a superamphiphobic self-cleaning passive subambient daytime radiative cooling coating on grain and oil storage structures

The thermal performance of a novel exterior coating material for commonly used grain and food-grain oil structures was investigated. Grain structures included a concrete squat silo and a concrete warehouse while the edible oil structure was a concrete sided tank. The exterior coating provided excellent moisture runoff and solar reflectance properties and is best described as a superamphiphobic self-cleaning passive subambient daytime radiative cooling (SSC-PSDRC) coating. The coating exhibited a remarkable subambient daytime cooling effect in various structures in different climatic regions. Compared with the roof surface temperatures of a cool white-coated concrete grain silo and a gray carbon iron-based edible oil storage tank, those of the PSDRC coated top surfaces could be reduced by 37 °C and 33 °C, respectively. The roof surface temperature of a warehouse painted with a cool-white coating—with a solar reflectance of 0.9 and an emissivity of 0.85—and that of a warehouse with the roof installed with aluminised polymer waterproof membranes were 19 °C and 18 °C higher than that of the PSDRC warehouse, respectively. Consequently, the interior temperature of the wheat pile in the PSDRC grain silo was 10 °C lower than that in the control squat silo. With the inner loop flow temperature control system operating, the interior air temperatures of the PSDRC west-facing separate space were 6 °C and 3 °C higher than those of the cool-white coated and control west-facing separate spaces, respectively. Even after the application of PSDRC coating for only a few days, the interior air temperature of the PSDRC oil storage tank was reduced by 38 °C, and the interior temperature of the oil storage tank was reduced by 4 °C. Furthermore, in practical applications, the coating showed impressive superamphiphobic self-cleaning capabilities and super aging resistance. The wide applications of the coating would have far-reaching, global implications for maintaining grain and edible oil products, particularly in the sub-tropical climates.

Analysis and design of reinforced concrete silo by conventional method

Any industrial or organised storage facility needs bulk material storage structures, also referred to as bins, bunkers, silos, or tanks. The ratio of their various dimensions serves as the main defining characteristic between bunkers and silos. Silos are structures that are used for storing different types of granular material. Silos are architectural constructions made especially for storing different kinds of granular materials, such grains and cement. Silos are distinguished by their disproportionately tall lateral dimensions. For instance, massive silos are frequently used to store cement in cement mills and significant construction projects. The project's main goal is to analyse and design a silo made of reinforced cement concrete. The theory adopted for analysis of silo is Janssen’s theory. The silo is designed for storing the cement clinkers with a capacity of 5000 tonnes. The normal pressure calculation during emptying and filling, and maximum pressure calculation has performed. The hoop stresses and Temperature stresses are calculated and hoop tension is calculated for different heights. The assessment of the loads on silo was performed as per IS: 4995 (Part I) - 1974, and for design criteria IS: 4995 (Part II) – 1974 is used.

Experimental study on horizontal pressure of column-supported concrete group silos under earthquake force

ABSTRACT The overpressure of silo wall caused by granular materials under earthquake is one of the main reasons of silo damage. Two shaking table model tests were carried out with column supported silos and independent single silos, respectively. The seismic response of silo granular materials was analyzed first, and then the dynamic lateral pressure of silo wall under different levels of earthquake and overpressure coefficient were obtained. The results showed that the interaction between the granular materials and the silo wall in the group silos is related to the position of the individual silo. The seismic response of granular materials is linked with the spectral characteristics of seismic waves. The overpressure coefficients of the corner silo and the side silo are greater than that of the independent single silo with a 7% and 9% higher value, respectively. Apparently, the seismic response characteristics of the independent single silo are totally different from that of the group silos. It was concluded that when designing the wall of the group bin, the position of the bin should also be considered.

Seismic performance of column-bearing silo structure with granular materials considering SSI effect

This paper investigates the effects of different silo height-to-diameter ratios, different storage categories and different site soil categories on the seismic performance of column-bearing concrete grain vertical silo structures considering soil-structure dynamic interaction (SSI). The study reveals more comprehensive response mechanism of soil-pile-silo structure with grain storage system under earthquake actions. The numerical results indicate that for the full silo models with different height-diameter ratios, the SSI effect could reduce the absolute acceleration response, and the reducing rate at the top of the support column will be slightly larger than that of the top of the silo. In addition, the greater the height-diameter ratio, the more obvious the absolute acceleration damping effect of the SSI effect. The SSI effect has the greatest damping effect on the absolute acceleration response when the silo is filled with wheat. Moreover, the degree of softness and hardness of the soil affects the shock absorption effect of SSI on the absolute acceleration and elastic–plastic acceleration of the silo. The softer the soil, the more obvious the shock absorption effect of SSI. More interestingly, among the parameters of height-diameter ratio, storage material type and dynamic shear modulus of soil, the height-diameter ratio has the greatest influence on the seismic response and hysteretic energy dissipation performance of the column-bearing silo structure considering SSI effect, followed by the foundation soil. Dynamic shear modulus and the storage material category have the least influence.

Radon Exposure to Community Members Living Near a Uranium Procession Plant

Background: Members of the Fernald Community Cohort (FCC, N=9782) are persons who lived within 5 miles of the uranium processing plant at Fernald, Ohio, USA. From 1951 to 1989 the site processed uranium ore and recycled materials to make highly refined uranium metal products used in the United States Department of Energy nuclear weapons production. The aqueous raffinate or waste from the chemical digestion process was pumped into two large concrete silos for storage and were found to be sources of radon decay products. Vents in the protective dome covers were not sealed until 1979. Source terms and dosimetry algorithms for exposure to both uranium particulates and radon were developed by CDC. Methods: Based on the CDC prior work, we developed a mathematical model to estimate yearly outdoor radon exposure persons in the cohort from the K-65 silos during 1952-1988. We collected and verified residential history information from members of the cohort. We used the radon source terms developed by CDC, yearly wind speed and direction data, and applied the model to the residential history for each member of the cohort. Results: 9306 members of the cohort had sufficient residential history information to be used for radon dosimetry calculations for individual cohort members. The population mean value (sd) of total cumulative exposure (over the years 1952-1988) was 460.70 (508.84) pCi/m2-years, median 299.60 pCi/m2-years, with a large range of 0-4625.75 pCi/m2-years. Arithmetic median exposure also was calculated for each person, or the median of yearly exposure, with a population mean of 20.43 pCi/m2, also with a large range 0 to 200.57 pCi/m2. Conclusions: Using reliable data and well-developed algorithms we estimated environmental (outdoor) radon exposure for members of the FCC and found a wide range of cumulative outdoor radon exposure. Key Words: uranium, radon, community cohort

Study of RCC Silo structure for different Height/Dia. ratio

Abstract: This work shows the effect of height to diameter ratio on reinforced cement concrete circular silo. Janssen’s theory as per IS 4995:1974 part I &amp; part II is used to determine the load intensity and structural dimensions. The Response Spectrum Method along with Wind load Analysis is used for analysis of the reinforced cement concrete silo structures. In the present studies, the silo structures are considered to be in Zone V of IS 1893:2005 Part 3 and IS 875:2015 Part IV. SAP 2000 software is used for the modelling and analysis of silo structure. Two different heights to diameter ratios are used for getting results on four models in the form of horizontal pressure on the silo wall due to stored material, displacement and base shear. The displacement will be more at the top of the structure due to increase in height of the silo. For earthquake and wind load analysis, empty silo structure shows the maximum value of displacement and base shear.

Experimental and Numerical Investigation of Plastic–Concrete Waterproof Walls of an Underground Granary Subject to Combined Bending Moment and Water Pressure

To investigate the mechanical properties of plastic–concrete silo walls in practice, the mechanical properties and failure mechanism under the combined bending moment and water pressure were analyzed through the uniform loading test, water pressure test, and numerical analysis. The influence of the connecting plate spacing, radius, and the waterproof plate thickness on the water pressure-bearing capacity were analyzed. The test results show that the chemical adhesive force exists between the waterproof plate and concrete and can resist 20 kPa. The displacement and strain of the waterproof plate increases significantly with the increment in water pressure. When the water pressure reached 85 kPa, the specimen was damaged due to shear failure. The established numerical model was validated by the test results. The numerical analysis results show that the specimen failure mainly depends on the bolt strength when the thickness of the waterproof plate is greater than 14 mm or the radius of the connecting plate is greater than 60 mm. The relation between the design parameters and the water pressure-bearing capacity was proposed. Compared with the waterproof plate thickness, the connecting plate spacing and radius have greater influence on the water pressure-bearing capacity.

Buckling of cylindrical concrete tanks and silos due to prestressing — nonlinear approach

The buckling of concrete cylindrical tanks and silos is associated mainly with prestressing, which influences the meridional critical force. Higher compression produces a lower meridional critical force. For three-dimensional structures subjected to biaxial or triaxial loading, the simplified methods of stability analysis proposed in Eurocode standard for concrete structures are inappropriate. The authors try to answer which procedure may be helpful for the assessment of buckling possibility, which results from prestressing of cylindrical structures. The numerical analyses are performed with the use of “Simulia Abaqus system”, which allows the nonlinear stability analysis adopting the plasticity-based damage material model and assuming initial imperfections. Two variants of load distribution (constant and hydrostatic external prestress) and two variants of wall-foundation connection are considered. The results are presented with the use of two parameters. The first one constitutes the ratio of lateral pressure to vertical pressure on the upper edge. The second one describes the ratio of current vertical force – corresponding to real load – to the initial test value of the iterative process. The obtained relationships of critical vertical force and the level of external prestress for cylindrical tank of height twice the diameter can be the guideline for engineers in designing process.