Analysis and design of silos by the post-tensioned method

. This design focuses on the analysis and design of silos exercising the post-tensioned system, aiming to facilitate these critical storehouse structure's structural effectiveness and safety. Silos are extensively used in colourful diligence to store bulk accoutrements, and their structural integrity is of consummate significance to ensure dependable and secure operations. The study involves a relative analysis between conventional silo designs and those employing the post-tensioned system. The geste of silos under different loading conditions is simulated and evaluated. The assessment considers key performance indicators such as load-bearing capacities, deflection, cracking behavior, and overall stability. The findings indicate that post-tensioning significantly enhances the structural performance of silos. The post-tensioned method offers a sustainable and cost-effective alternative to traditional silo construction by reducing cracking and improving overall stability. The results contribute valuable insights to the optimization of silo design, offering engineers and stakeholders in the industry a practical and efficient solution for industrial storage requirements. In conclusion, the analysis and design of silos using post-tensioning techniques provide a promising approach to enhancing the effectiveness and safety of silo structures. Implementing these innovative methods can improve performance and reduce maintenance costs, making them an attractive option for future silo construction systems.


Introduction
Silos serve as vital infrastructure in various industries, facilitating the storage of bulk materials such as grains, cement, minerals, and chemicals.The structural integrity and performance of silos are critical factors in ensuring these materials' safe and efficient storage.To meet the demands of modern industrial applications, it becomes imperative to explore innovative engineering solutions that can enhance the durability, stability, and costeffectiveness of silo structures.This project aims to investigate the potential advantages of using the post-tensioned method in silo design and analyse its impact on the structural behavior of these essential storage facilities.Though widely employed, the conventional approach to silo construction may present certain limitations in terms of cracking, deflection, and long-term maintenance costs.By introducing post-tensioning techniques into the design process, we aim to address these challenges and optimize the overall performance of silos.The post-tensioning method involves using high-strength steel tendons that are tensioned after the concrete has been cast, effectively compressing the concrete and countering the tensile stresses that can lead to cracking.This innovative approach has demonstrated success in various structural applications, and its application to _____________________________ Silos holds the potential for significant improvements in their structural integrity and Longevity.In this study, we will comprehensively analyse conventional silo designs and compare them with post-tensioned silo designs.We will simulate the behavior of silos under different.We are loading scenarios to assess their performance under various conditions.The project aims to provide valuable insights into the benefits of implementing the post-tensioned method, offering practical guidance to engineers and stakeholders involved in silo construction and maintenance.Through this investigation, we hope to contribute to the advancement of silo design practices, promoting adoption of more efficient and durable storage solutions in the industrial sector.By enhancing the structural performance of silos, we anticipate a positive impact on safety, operational efficiency, and overall costeffectiveness, ultimately leading to more sustainable and reliable storage facilities.The structure of Post Tensioned silo is as shown in Fig 1. Vishal SapateandTrushaliJagtapet(2021) [1] Reinforced chimneys are crucial in power plants, transporting hot and toxic flue gas to significant heights while withstanding lateral forces like wind, earthquakes, and thermal stresses.This study aims to investigate the lateral deflection variation at the chimney's top by altering its height above 275 m.For this purpose, five different models with heights of 275m, 285m, 295m, 305m, and 315m are selected and analyzed.The lateral deflection of each model is carefully calculated using the Code of Practice for the design of reinforced concrete chimneys (Third revision of I.S. 4998:1992 [Part I]) as a reference for the analysis.The STAAD PRO software is employed to conduct the analytical study for all the selected models.The main focus of the analysis is to understand how the lateral deflection at the chimney's top varies with changing heights.This investigation is crucial in ensuring the structural stability and safety of the chimney, especially under the influence of external forces like wind.By evaluating the lateral deflection for different heights, valuable insights can be gained to optimize the design and performance of reinforced concrete chimneys.BogremSasidhar and C.Sashidhar (2021) [2] this study aims to evaluate the performance of a silo subjected to Corresponding Lateral Force (CLF) in all four seismic areas.The investigation involves comparing multiple concrete silo models under earthquake conditions.Various parameters are thoroughly analysed, including nodal displacement, stress distribution, and vertical/horizontal pressure on the walls.By examining the behavior of these silo models under seismic forces, the study aims to assess their potential and applicability in accurately understanding such structures' actions.The obtained similar outcomes can provide valuable insights into the seismic response and structural integrity of silos, helping engineers and designers make informed decisions to enhance their performance and safety.Through a comprehensive analysis of the concrete silo models in different seismic zones, this research contributes to advancing seismic design principles for such structures.The findings are expected to guide the development of more resilient and robust silos capable of withstanding seismic events in diverse geographical regions.This study serves as a valuable reference for professionals involved in the design and construction of silos, ultimately ensuring the reliable and sustainable operation of these critical industrial facilities.Byeon H., Jeong G.Y, and Jaeyeong Park (2021) [3] this study focused on modelling the waste package under the expected pressure from backfilling material.The reference model displayed plastic behavior at pressures below 6%, subjecting the waste to direct stress from the lid.A similar behavior was observed in the waste with 4 MPa compressive strength, irrespective of Young's modulus when compressed directly.However, enhancing the waste's compressive strength to 10 MPa resulted in elastic behavior, regardless of Young's modulus.Taking creep into account with a safety factor of 4/3, a compressive strength exceeding 15 MPa was recommended.A reinforced waste package was suggested considering the operator's burden in enhancing compressive strength.The fully reinforced design demonstrated the highest stability, with increased stability observed with additional reinforced stacks.The reinforced model experienced significantly lower stress, making the creeping effect negligible.However, the study did not investigate safety factors for dynamic forces, emphasizing the need for future work to consider modelling under dynamic force conditions.

Materials Used in Design
The concrete grade M30 is specifically designated for the construction of slabs and vertical walls; high-strength steel bars or strands are employed as reinforcement to enhance the tensile strength of the concrete and prevent cracking, High-strength steel tendons are used as post-tensioning elements to apply compressive forces to the concrete, increasing its resistance to external loads and stresses, Grout is used to encase the post-tensioning tendons and provide protection against corrosion, Specialized anchorages are employed to secure and tension the post-tensioning tendons within the concrete and Couplers are utilized to connect the reinforcing steel bars, ensuring continuity and integrity of the structure.

Method of Construction
This project's construction method involves using post-tensioning to construct the silo.The selected method aims to enhance the structural integrity and performance of the silo while ensuring it can withstand various loading conditions.The post-tensioning technique involves tensioning high-strength steel tendons within the concrete to provide added strength and reduce potential cracking.This construction approach offers increased stability and improved resistance to lateral forces, such as wind and seismic activities.The specific method of post-tensioning used will be determined based on project requirements, site conditions, and other relevant factors to ensure a successful and efficient construction process.

Input Data Taken Into Account in Design
The material to be stored in the silo is clinkers, The weight of the material stored in the storage silo is 5000 tons, The elevation of the bottom of the deck slab above ground level (G.L.) is 10 meters, The elevation of the top of the roof slab above ground level (G.L.) is 36.30meters, The internal diameter of the storage silo is 14 meters, In the design, the strand named "4K15" is used.The nomenclature indicates that "4" represents the number of strands, and "15" represents the diameter of each strand in millimetres (mm), The nominal breaking strength for a single strand with a diameter of 15.2mm is 260.7 kilonewtons (K.N.),The thickness of the top wall is 300 millimetres (mm),

Loads considered and Calculations
When constructing conventional structures in compliance with the relevant standards, loads like dead, live, wind, seismic, and temperature loads are frequently considered.However, while designing silos, it is also important to consider the additional load brought on by the stored materials and the loads that act on ordinary structures.[22] The total load for a silo in full condition, which means it is filled to capacity with material, is 81268.04KN, The total load for a silo in an empty state, meaning the silo is devoid of any material, is 31205.08KN

Pressure calculations
The Hoop Tension in post tensioned silo is shown in Table 1 , The Pressure Variation in   ∴ Friction loss, Px = 328.8kN.

Loss due to Crêpé of Concrete:
The loss of prestress due to creep of concrete under load shall be determined for all the permanently applied loads, including the prestress.

Results
Hoop reinforcement details of Post-Tensioning in the top wall of Silo is as shown in Table 2.

Conclusions
Based on the analysis and findings of the post-tensioned silos project, the following conclusions have been drawn:  Enhanced Structural Performance: Post-tensioning methods significantly improve the structural performance of silos.The application of high-strength steel tendons imparts prestress to the concrete, resulting in increased load-carrying capacity and reduced deflection under various loading conditions.
 Improved Durability: Post-tensioned silos exhibit enhanced durability and resistance to cracking.The post-tensioning tendons help to distribute stresses more efficiently, mitigating the risk of concrete cracking and ensuring the long-term integrity of the structure.
 Optimal Load Distribution: Post-tensioning assists in achieving a more uniform load distribution across the silo walls and base.This effect minimizes stress concentrations and enhances the overall stability of the silo during filling and emptying operations.
 Cost-Effectiveness: Although post-tensioning requires additional initial investment, it proves to be cost-effective in the long run due to the reduced maintenance and repair expenses.The extended service life and improved performance outweigh the upfront costs. ,

Fig. 2 :
Fig.2: Pressure changes along the depth while filling and emptying

Table 1 :
Hoop Tension in Top Wall