Using industrial joists offers numerous advantages, including reduced structure weight, increased strength and durability, and improved performance against various loads. Moreover, since these joists are produced in a controlled factory setting, they are less prone to defects and execution problems. As a result, construction projects that utilize industrial joists are more efficient in terms of time and cost.
Here, we will review the stages of producing industrial joists in a factory, detailing each process from the selection of raw materials to the final stages of formwork and concreting.
Raw Materials Used in Joist Production
In industrial joist production, the use of high-quality, standard raw materials is crucial, as the final quality of the joist directly depends on the quality of these materials. The two main materials used in making joists are steel and concrete.
1. Steel
Rebars serve as the main framework of the joist and are responsible for bearing tensile forces. Typically, high-quality ribbed steel rebars are used to ensure a strong bond with the concrete and to increase the structure’s strength. The steel used must comply with national and international standards to guarantee the desired mechanical resistance and physical properties.
2. Concrete
Concrete acts as the compressive element of the joist and should have an appropriate mix of cement, gravel, sand, and water. The quality of the concrete determines the final strength of the joist. Standard, high-compressive-strength concrete is typically used, which during concreting, can flow easily and completely fill the form, and after curing, reaches the required strength.
3. Supplementary Materials
Sometimes, specific additives such as plasticizers or anti-freeze agents are added to the concrete to enhance its properties and help it withstand special environmental conditions.
Overall, precise selection and quality control of raw materials are key to the successful production of industrial joists. Therefore, factories strive to source materials from reputable suppliers and conduct necessary testing before use.
Design and Drafting of Industrial Joists
The design of industrial joists is one of the most important production stages, requiring high precision and consideration of the structural needs. In this stage, engineers analyze the loads applied to the joist and determine its dimensions and specifications to ensure it can withstand tensile, compressive, and bending forces.
The main steps in industrial joist design include:
· Load Analysis: Dead loads (the weight of the joist itself and other structural components) and live loads (operational loads such as people, equipment, and environmental forces) are assessed. These provide the basis for joist strength calculations.
· Choosing Joist Dimensions and Cross-Section: Based on the imposed loads and span length, the joist’s dimensions including length, height, and thickness are determined. The number and diameter of tensile rebars and stirrups are also specified.
· Preparation of Execution Drawings: Detailed drawings, including rebar placement, joist dimensions, and other specifics, are prepared. These are used as guides for cutting, assembly, and formwork in the factory.
· Use of Engineering Software: Specialized software such as ETABS, SAP2000, or joist design applications are often used in joist design, enhancing calculation accuracy and enabling load simulation and structural analysis.
Accurate and principled design of industrial joists guarantees quality and optimal performance in the finished structure, preventing potential issues like failure or cracking.
Cutting and Preparing Steel Components
After the joist is designed and detailed drawings are prepared, the next stage is preparing the steel components, which includes cutting and shaping the rebars. This phase is critical to the final quality of the joist since the dimensions and shape of the rebars must strictly adhere to the design drawings.
Main Steps in Cutting and Preparation
- Cutting the rebars
The rebars are cut to the specified sizes using advanced cutting machinery, usually automated to boost accuracy and production speed. - Bending and Shaping
Certain rebars, such as stirrups or hooked bars, require specific bending and shaping. This is done with specialized machines to ensure precise angles and bends with no cracking. - Quality Control of Components
After cutting and bending, the pieces are checked for dimensional accuracy and the quality of bends and cuts. Any defects or deviations from the drawings must be fixed. - Preparation for Assembly
The prepared steel components are gathered and organized in designated locations for ease of use during the assembly stage.
The use of advanced equipment and strict quality checks in this stage ensures the manufactured joists have high quality and meet necessary standards, providing optimal structural performance.
Joist Assembly
Following the cutting and preparation of steel parts, the assembly stage of the industrial joist begins. This step involves placing the rebars in their specified locations and connecting them to form the main skeleton of the joist.
The assembly steps of the joist include:
Arranging the rebars: The longitudinal and transverse rebars (stirrups) are placed as per the design drawings. This must be done with high precision so that all dimensions and spacing meet the standard.
Connecting the rebars: The rebars are typically joined using welding or mechanical couplers. Welding should be performed by skilled specialists and in accordance with required standards to guarantee the strength of joints.
Securing the stirrups: The stirrups or transverse rebars are systematically tied around the longitudinal rebars so that the joist can properly withstand shear forces.
Assembly Quality Control: Upon completion of assembly, a technical inspector reviews the work visually and with measuring tools for accuracy. Any defects or deviations must be corrected before concreting.
Preparation for Formwork: After assembly quality is approved, the joists are made ready for formwork and concreting and are transferred to the next production line section.
Accurate and standard assembly of industrial joists forms the foundation for joist strength and durability in the finished structure and plays a key role in improving the quality and safety of the building.
Quality Testing and Final Inspection of Joists
After completing the assembly processes, conducting thorough quality tests and final inspections is essential to ensure that joists meet the required standards of strength, dimension, and safety, and will perform properly in the structure.
The most important quality control and test steps include:
- Dimensional Inspection
Precise measurement of length, width, height, and other dimensions of the joist using calibrated tools to confirm compliance with design drawings. - Weld Testing
The welds made in the assembly stage are checked using non-destructive tests such as ultrasonic or penetrant testing to ensure their integrity and strength. - Tensile and Compressive Strength Testing
Samples of the rebars and concrete used in the joist are tested to verify that their strength meets the defined standards. - Concrete Quality Check
Concrete samples taken during concreting are tested for compressive strength and durability to confirm quality and curing. - Final Visual Inspection
A final check is performed to ensure there are no cracks, damage, or visual defects that could affect joist performance.
Thorough execution of these quality control and test steps boosts confidence in the joist’s durability and performance under real-world conditions while preventing potential structural issues.
Formwork and Concreting of Joists
After assembly and quality control of the steel parts, the next stage is formwork and concreting of the industrial joists. This step is especially important because the concrete is the main factor for the joist’s final strength, and proper formwork ensures the concrete takes the right shape and prevents leakage or cracking.
The steps for formwork and concreting include:
- Form Preparation: Forms are usually made of durable metal or plastic and must be completely clean and free of any contaminants to ensure the concrete surface is smooth and uniform after it sets.
- Positioning the Forms Properly: Forms are installed with precision according to the designed dimensions. The formwork must enable air to escape and the concrete to fully fill the space.
- Concrete Pouring: Concrete is poured into the forms using a precise mix and technical specifications. At this stage, concrete vibrators are used to remove air bubbles and compact the concrete.
- Concrete Curing: After pouring, the concrete must be kept under controlled conditions (humidity and temperature) for a specified period to reach the required strength. This step increases durability and quality.
- Removing the Forms: After sufficient curing, the forms are gently removed, and the ready joists are prepared for the next stage (storage or transport to the installation site).
Proper formwork and concreting are key to producing high-quality joists and are vital in extending the lifespan and functionality of structures built with these joists.
Storage and Warehouse Management of Joists in the Factory
After the production and concreting of industrial joists, the stage of storage and warehouse management becomes crucial to ensure joists remain in optimal condition and are not damaged before shipment to the project site.
Key considerations in joist storage and warehousing include:
- Proper Storage Location:
The joists should be stored in a dry, sheltered area with adequate ventilation to avoid direct exposure to moisture, rain, or intense sunlight. Excess humidity can cause rebar corrosion and concrete damage. - Correct Stacking of Joists:
Joists should be stacked so that no excessive pressure is applied and sufficient air circulation is allowed between them. Maintaining proper spacing prevents breakage and deformation. - Periodic Quality Inspections:
Joists should be regularly checked for cracks, corrosion, or any visible damage, so prompt corrective measures can be taken if issues are found. - Observing Safety Procedures:
Joist storage must minimize the risk of falls or sudden movement, and staff should observe all safety precautions while working. - Inventory Registration and Management:
For better production management and timely delivery, accurately recording the number, dimensions, and status of joists in storage is essential.
Adhering to proper storage and warehousing practices preserves joist quality and prevents financial and time losses in construction projects.
Conclusion
The production of industrial joists in the factory is a precise, multi-stage process, with each stage playing a crucial role in the final product’s quality and performance. From selecting high-quality, standard raw materials to precise design, steel component preparation, correct assembly, thorough quality control, proper formwork and concreting, and finally, appropriate storage and management—every stage must be executed with methodical care to yield durable, strong, and standard-compliant joists.
The use of industrial joists in construction projects not only speeds up execution and reduces costs but also ensures the quality and safety of the structure. Factory-controlled production allows for defect mitigation and adherence to standards, ultimately reducing execution problems and increasing the building’s useful life.
Therefore, attention to all production stages and strict adherence to technical and quality principles is the key to success in manufacturing high-quality industrial joists, which can play a significant role in advancing the construction industry.
