Concrete Silos Research Articles

The Wound of Time

The Wound of Time

Seismic Analysis of Reinforced Concrete Silos under Far-Field and Near-Fault Earthquakes

Silos are strategical structures used to stockpile various types of granular materials. They are highly vulnerable to earthquake excitation and have been frequently reported to fail at a higher rate than any other industrial structure. The seismic response of silos within the near-fault region will suffer a complex combination of loadings due to the unique characteristics of the near-fault ground motions; which are usually associated with a large amplitude pulse at the beginning of either the velocity or the displacement time histories. This study aims to numerically evaluate the seismic response of reinforced concrete cylindrical silos under near-fault ground motions (NFGM) and far-field ground motions (FFGM). The assessment investigates the impact of the slenderness ratio and the parameters’ influence on the seismic behavior of reinforced concrete silos. The validity of the Eurocode provisions in the structural safety of silos will also be inspected. The nonlinear time history analysis is carried out through the finite element approach by examining four silos with different slenderness ratios. The concrete damage plasticity model is assigned to the silo wall to simulate the nonlinear behavior of concrete in the plastic zone; while, the behavior of the stored material is represented by the Drucker-Prager plastic model. The wall-granular material interaction is considered and defined by coulomb’s friction theory. The results of the near-fault records reveal a growth up to 72.8% in the hoop stress and 160.4% in the vertical stress compared to the far-field earthquakes. Consequently, the seismic response of reinforced concrete silos is highly sensitive to the type of ground motion, and slender silos tend to impose greater structural demand under the NFGM. Additionally, The Eurocode-8 seismic provisions were adequate in the conventional far-field ground motions and less effective in the near-fault zone.

Crack and strength assessment of reinforced concrete cement plant blending silo structure

Cracks have occurred at the slab of a cement plant blending silo structure after the 2004 megathrust earthquake and tsunami in Aceh Province, Indonesia. In order to repair and strengthen the structure, an assessment was conducted to evaluate the crack and remaining strength of the structure. Ultrasonic pulse velocity and hammer test were then performed. The site assessment results showed that the dynamic elastic modulus at the crack section was only 0.39 of that at the uncracked ones. Meanwhile, due to the cracks, the average compressive strength of concrete was reduced from 26 MPa to 11.74 MPa. Static and dynamic analysis of the structure with the current building code showed that the remaining flexural capacity of the structure cannot withstand the applied loads, therefore a strengthening of the structure is needed. The combination of epoxy resin injection and carbon fiber reinforced polymer (CFRP) wrapping was proposed for the retrofitting of the structure.

An objective assessment strategy for industrial reinforced concrete structures – Case study

Due to the booming construction wave between the 60´s and 80´s, a lot of reinforced concrete structures are now approaching their intended service life design. Concerning the industrial sector, an unforeseen shutdown of production processes due to urgent maintenance or repair actions of reinforced concrete structures can have major consequences for owners and managers. Therefore, it is important that they get a clear view of the current state of their structures in order to shift towards a more proactive maintenance. In order to recognize and assess both classic and more complex damage phenomena, a scientific approach to translate collected field data towards a service life and inherent repair strategies for the concrete structure is adopted by means of an in-house developed data analysis tool DIMCoSt (Durability Information Model for Concrete Structures). The objective assessment strategy is described in this paper by means of a case study. The subject of the case study is concrete storage silos. Although the applied methodology is mainly universal, each case has its own emphasis that must be considered regarding the decision-making process based on the owner’s or manager’s requirements. By means of this case, a scientifically based approach is presented which leads to objective decision-making regarding asset management and planning of maintenance or renovation activities.

Causes of Failures in Circular Concrete Silo Walls, Particularly Under Environmental Influences

Abstract The paper reports the results of a case study for achieving longer service life and increasing the environmental sustainability of concrete silos. Damage mechanisms in concrete silo walls, and respectively in cylindrical structures (e.g., chimneys, cooling towers, and tanks), are widely diverse. The common causes of failures include those due to poor design considerations, construction deficiencies, non-compliance with operational rules and regulations, lack of maintenance, and insufficient and/or corroded reinforcements, together with the environmental conditions affecting the walls. In addition to the ultimate limit state design, temperature-induced cracking may often be underestimated in the design of reinforced concrete silos, leading to premature deterioration and losses in serviceability. Cracks from environmental or service conditions facilitate the ingress of moisture and corrosive agents. Therefore, there is an increased interest in reducing the appearance of cracks and limiting their width. The aim of this paper is to highlight the synergistic effects in the design, construction, and operation of silo walls, particularly under varying environmental influences. The research undertaken indicates that systematic errors can be identified and corrected.

Preliminary Component Design and Cost Estimation of a Novel Electric-Thermal Energy Storage System Using Solid Particles

Abstract Energy storage will become indispensable to complement the uncertainty of intermittent renewable resources and to firm the electricity supply as renewable power generation becomes the mainstream new-built energy source and fossil fuel power plants are phased out to meet carbon-neutral utility targets. Current energy storage methods based on pumped storage hydropower or batteries have many limitations. Thermal energy storage (TES) has unique advantages in scale and siting flexibility to provide grid-scale storage capacity. A particle-based TES system is projected to have promising cost and performance characteristics to meet the future growing energy storage needs. This paper introduces the system and components required for particle TES to become technically and economically competitive. The system integrates electric particle heaters, particle TES within insulated concrete silos, and an efficient air-Brayton combined-cycle power system to provide power for storage durations up to several days via low-cost, high-performance storage cycles. Design specifications and cost estimation of major components in a commercial-scale system are presented in this paper. A techno-economic analysis based on preliminary component designs and performance indicates that particle TES integrated with an air-Brayton combined-cycle power system has a path to achieve the targeted levelized cost of storage of 5 ¢/kWh-cycle at a round-trip efficiency of 50% when taking low-cost energy-specific components and leveraging basic assets from existing thermal power plants. The cost model provides insights for further development and economic potentials for long-duration energy storage.

Shaking table test and horizontal torsional vibration responseanalysis of column-supported vertical silo group silo structure

Reinforced concrete vertical silos are universal structures that store large amounts of granular materials. Due to the asymmetric structure, heavy load, uneven storage material distribution, and the difference between the storage volume and the storage material bulk density, the corresponding earthquake is very complicated. Some scholars have proposed the calculation method of horizontal forces on reinforced concrete vertical silos under the action of earthquakes. Without considering the effect of torsional effect, this article aims to reveal the expansion factor of the silo group considering the torsional effect through experiments. Through two-way seismic simulation shaking table tests on reinforced concrete column-supported group silo structures, the basic dynamic characteristics of the structure under earthquake are obtained. Taking into account the torsional response, the structure has three types of storage: empty, half and full. A comprehensive analysis of the internal force conditions under the material conditions shows that: the different positions of the group bin model are different, the side bin displacement produces a displacement difference, and a torsional effect occurs; as the mass of the material increases, the structure

The Future and Prospects of Periwinkle Composites in Reinforced Concretes: A Review

The choice of building materials and the rising cost of construction materials have continued to plaque the building and construction industry without an immediate solution. Industrialists and scholars are investigating several naturally occurring materials for concrete composite reinforcements. The article chronologically reviewed the growth and development of periwinkle shell powder (PSP) and periwinkle ash powder (PSA) as composite materials in concretes. Findings showed that 28 days of curing age are required for lightweight concretes reinforced with PSP or PAP at 10-30% optimum. Produced lightweight concretes were susceptible to acidic medium and induce lower compressive strength which eventually leads to concrete/structure disintegrate and collapse. Research challenges and funding hamper the application of PSP/PAP in the concrete formulation and are unable to drive innovations and economic benefits as a composite. Advances in concrete technology showed that PSP/PSA mollusk shells achieve pillar strength grade and weight/load bearing status for the improvement of PSP/PSA blended concretes. Also, the composite potential showed that the functionalization of PSP/PSA, sustainability, and nano modification of cementitious materials and concretes are promising. Future studies are required to develop periwinkle reinforced concrete silos, sewers, and smart concrete materials with improved mechanical, thermal, and aesthetic properties.

Seismic Damage Assessment of Reinforced Concrete Grain Silos

This paper deals with seismic performance and damage assessment of concrete grain silos. An existing large silo is taken as a case study to conduct the numerical analyses. A global damage index based on target displacement is proposed to quantify numerically different damage states of the structure. To this aim, the classical N2 method is extended to adaptive multimodal to evaluate seismic performance of the structure for increasing pic ground acceleration levels with taking into account degradation of stiffness and modification of modal characteristics. The seismic capacity of the silo is evaluated, as an averaged curve, by conducting pushover and several incremental dynamic analyses using artificial and recorded accelerograms. The seismic demand is derived from the design spectrum of the Algerian seismic code (RPA 2003). The target displacement is determined by taking into account both the participation of the dominant modes, and the degradation of the structure’s modal characteristics. The nonlinear behavior of the structure’s walls is modeled by using nonlinear multilayered shell elements. The effect of the stored granular material is included through distributed equivalent masses. It is found that when the structure modal characteristics are updated as its stiffness is degraded, the target displacement is correctly computed. Whereas, it wrongly grows indefinitely, with increasing PGA, when constant modal characteristics of the intact structure are assumed, as usually done. The proposed global damage index is compared to three existing reliable indices. It better reflects the different damage states of studied silo.

Analysis of the structural response of Beirut port concrete silos under blast loading

Analysis of the structural response of Beirut port concrete silos under blast loading

Research on concrete temperature control measures in deep hole area of super high arch dam

The deep hole area is a key part of the dam during the construction period, and its temperature field and stress field changes are the focus of the current research on temperature control and crack prevention in the deep hole area. Based on the traditional three-stage and nine-stage temperature control standard, this paper uses three-dimensional finite element temperature stress simulation analysis to study the three major research ideas of shortening the medium-term cooling, shortening the second-stage cooling, and shortening the two at the same time. The concrete silo with a relatively lagging temperature control phase reaches the arching temperature at the same time. The simulation results show that the three temperature control measures can not only keep the stress in the area within a safe range, but also effectively shorten the construction period, providing new ideas for temperature control measures in the deep hole area of the arch dam.

Comment on Maraveas, C. Concrete Silos: Failures, Design Issues and Repair/Strengthening Methods. Appl. Sci. 2020, 10, 3938

Current silo analysis and design methods developed from Janssen’s theory focus mainly on the flow of the granules inside the silo by assuming that the overall silo structure is infinitely rigid. A silo structure during discharge is technically a time varying mass dynamic problem, where the properties of the overall silo structure and the discharge rate and material properties also contribute to the development of the load. The physics of a silo system requires equilibrium between the granules inside the silo, the silo structure as a whole and the surrounding air. The established scientific principles and experimental data require fulfilling such equilibrium to accurately predict the dynamic loads during discharge. This correspondence explains how the equilibrium between the granules inside the silo, the silo structure as a whole and the surrounding air can be achieved to better predict and control the dynamic loads generated by the silo discharge process.

Condition Assessment of an Early Thin Reinforced Concrete Vaulted System

ABSTRACT For the analysis and conservation of architectural heritage a multi-disciplinary approach is required. In the specific case of early concrete buildings, survey and experimental investigations constitute a fundamental source of information for verifying the actual structural behavior and the residual safety levels. This paper reports the direct experience acquired from an extensive experimental campaign conducted on the Paraboloide in Casale Monferrato. The study aims to be an example of how condition assessment of the structural heritage of the early 1900s, with an apparently simple geometric shape and composition, can actually contribute in understanding hidden structural complexity. Moreover, this work may provide useful information to researchers and practitioners who are approaching this specific structural typology (e.g., the industrial heritage represented by parabolic concrete silos). In more details, results are presented regarding the in-situ investigations, and the laboratory tests carried out to analyze the mechanical performance inherent to both (i) local aspects of the structure, such as the quality of the materials and connections, and (ii) global aspects, such as the modal response of the structure. Furthermore, considerations are made on the results of the experimental campaign, also through the corroboration of numerical models.

Some Aspects of the Work of Silos as Cellular Structures with Static and Temperature Effects

This work is devoted to studying the behavior of silos as cellular structures during their work on static and temperature effects. The paper presents the characteristic differences in the operation of metal and concrete silos, identifies their advantages and disadvantages, and considers the conditions of their work connected with the difficulty of storing “living” material backfill. The reasons for the destruction of metal silos are given. The work also evaluated the effect of surface tension of the moisture in the backfill at natural humidity and a backfill humidity higher than honest. The nature of the backfill behavior is shown depending on its moisture content. Information is given on the temperature distribution in the silo type cellular structure for seasonal and ten-day fluctuations in outdoor temperatures. It is proposed to consider the influence of these parameters in further research and design of cellular structures, including silos. It is also recommended to use the data given in the development of regulatory materials.

The use of composite materials for the manufacture of grain silos

Relevance and methods. One of the main tasks of grain production in Russia is the storage of harvested grain crops. The growth of grain capacity in recent years has been mainly due to the construction of metal grain storage facilities. This is due to lower capital costs and shorter installation times compared to reinforced concrete silos. The use of polymer composite materials (PKM) and, in comparison with traditional alloys, provides for a reduction in the weight of the metal structure, an increase in its resource, a reduction in the labor and energy intensity of manufacturing parts by up to 50%, an increase in the strength properties of the structure, a reduction in labor costs during the preparation of production, as well as an increase in the terms of exportation. Results. The purpose of this study was to review Russia’s grain complex and the tasks it faces, in particular the problems of storage and processing of crops. The main storage method — silos and their structural characteristics — was considered. A comparative analysis of traditional materials with composite ones was carried out and the advantages of the latter were concluded.

İzmir İlinde Bulunan Hastalıktan Ari Sütçü Sığır İşletmelerinin Yapısal Özellikleri*

Bu araştırmanın amacı, İzmir ili merkez ve ilçelerinde bulunan hastalıktan ari süt sığırı işletmelerinin yapısal özel-liklerini belirlemektir. Bu amaçla hastalıktan ari sertifikası olan süt sığırı işletmesi sahipleriyle anket çalışması yapılmış-tır. Anket formunda; işletme yapısına ve personele yönelik bilgilerle, yemler ve yemleme yöntemlerine dair sorular yer almıştır. Çalışmada, işletme sahiplerinin %58.8’inin 50 yaş ve üzerinde olduğu belirlenmiştir. İşletme sahiplerinin önem-li bir kısmının lisans veya lisansüstü (%54.7) eğitime ve 10 yıl veya üzeri (%57.8) deneyime sahip oldukları saptanmış-tır. İşletmelerin %82.6’sı modern ahırlara sahip olup, %70.2’sinde buzağı kulübesi kullanılmaktadır. Ayrıca işletmelerin %93.5’inin silajını kendi imkanları ile yaptığı ve silajların havuz tipi beton silolarda hazırlandığı belirlenmiştir. İşletmele-rin %40.5’inde yonca ekildiği ve yonca hasadının genellikle çiçeklenme başlangıcında (%64.7) yapıldığı tespit edilmiş-tir. Bunun yanında işletmelerin %60.5’inde silajlık mısır ekimin yapıldığı ve hamur olum (%48) veya sert dane (%44) döneminde hasat edildiği belirlenmiştir. Kaba yemler hayvanlara genel olarak parçalanmış halde ve iki öğünde veril-mektedir. Yemler, hayvanlara genellikle ölçülü olarak verilmekte olup, işletmelerin %59.5’inde verilecek yem miktarı süt verimi göz önüne alınarak belirlenmektedir. Sonuç olarak, İzmir merkez ve ilçelerinde bulunan hastalıktan ari süt sığırı işletmelerinin genel olarak ortalamanın üzerinde standartlara sahip oldukları söylenebilir.

Proposal for Modular Precast Bulk Warehouse for Brazilian Agricultural Frontier Farms

Brazil is one of the largest agribusiness producers in the world, however, Brazilian competitiveness is impaired when the agricultural product, at lower costs, reaches its destination at higher costs than global competitors due to the deficiency of the grain storage system and transport infrastructure. A viable alternative is the construction of a storage silo on the rural property, with low-cost prefabricated parts that can be transferred to other locations, with easy demobilization and assembly, if necessary. This paper has the objective to design a precast concrete silo with low weight, modular, structurally analyzed by the SAP 2000 V20 software, and presented the cost estimated at 15.6% of the cost of a conventional precast bulk silo, with the same storage capacity.

Seismic analysis on reinforced concrete group silos through shaking table tests

AbstractThe main objective of this research is to explore the seismic performance of the group silos through the shaking table tests and the finite element analysis. The 1/16 scaled model of reinforced concrete silos supported by supporting wall was designed and constructed. The shaking table tests were carried out with gradually increasing table‐input acceleration amplitudes. The dynamic characteristics, seismic responses, cracking patterns and failure mechanism of the model under empty and full conditions were analyzed. The finite element model was established and verified by experimental results. This article is aimed to provide guide for engineering design of group silos.

Concrete Silos: Failures, Design Issues and Repair/Strengthening Methods

The review article investigated failure, design issues, repair and strengthening of reinforced concrete (RC) silos, primarily in agricultural set-ups. The durability of RC structures was influenced by the nature of the bulk solids, materials used in the reinforcement of the structures. Traditionally, high-grade steel has been used in silo wall reinforcement because it is affordable and readily available. However, it is susceptible to corrosion. In contrast, fiber-reinforced polymers (FRP) have better mechanical properties (tensile strength, elastic modulus, and Poisson’s ratio) and are not corroded. Additionally, there are limited scalable and facile methods for commercial production. The low ductility elevates the risk of brittle fracture in external pre-stressing concrete repair/strengthening. Beyond the material factors, the existing silo design codes such as BS EN 1991-4:2006, Australian Standard AS 3774-1996, and American Society of Agricultural Engineers ANSI/ASAE EP433 DEC1988 (R2011), and American Concrete Institute ACI 313-97 are limited by simplified characterization of loading/unloading scenarios and exclusion of specific hopper geometries and configurations. The funnel and mass flow scenarios and accumulation of bulk materials contribute to silo failure. In brief, the present repair/strengthening strategies (external pre-stressing, insertion/removal of inserts, shear columns, and FRPs alternatives to steel) do not adequately address the diverse variables that elevate the risk of material failure.

Smart cooling-aeration guided by aeration window model for paddy stored in concrete silos in a depot of Guangzhou, China

A smart cooling-aeration (SCA) system was developed and tested for cooling bulk paddy stored in concrete silos in a south-subtropical depot of Guangzhou, China. Besides lowering the grain temperature with natural cold air during winter months, the cooling-aeration operation was also required to minimize grain moisture content loss, as well as the fan noise nuisance to nearby residents. Based on the grain and ambient air condition, the SCA system used the collected information in Aeration Window Model (AWM) for optimal control of aeration fans. The AWM was based on the CAE adsorptive equation and equilibrium absolute humidity curve. The SCA system was tested in two concrete silos of 650 tonnes in Guangzhou (22°44′N, 113°30′E) from 7 December 2018 to 5 March 2019. The system was set to turn on the fans when the temperature of grain bulk was 3 °C higher than the ambient air temperature and the equilibrium absolute humidity of grain for adsorption was above the absolute humidity of the ambient air. The grain temperature in one silo decreased by 10.3 °C after 97.8 h of aeration. The unit energy consumption by one 5.5-kW centrifugal fan was 0.063 kWht∙°C-1. The grain temperature was lowered by 9.2 °C in 106.5 h in the second silo with the unit energy consumption of 0.031kWht∙°C-1 by a 2.2-kW centrifugal fan. The unit energy consumption for both silos were 52−77% lower than the lowest “typical” value (0.132 kWht∙°C-1) in similar type of silos in the region when cooling aeration is manually controlled. Compared to the 650 tonne paddy rice in the control silo with a 15 kW aeration fan, the grain moisture content, the total milled rice yield and grain processing quality was unchanged by the smart cooling aeration with smaller kW aeration fans.