Design problem circular bunker Working stress method

Summary

This video provides a detailed step-by-step guide for designing a cylindrical bunker to store coal, using the Limit State Method of design. It covers essential calculations, including the bunker’s volume, dimensions, reinforcement for cylindrical walls and hopper bottoms, and the necessary load and safety factors. The script demonstrates how to calculate the weight of coal, determine reinforcement details for various parts of the bunker, and apply the design formulas. Additionally, the video emphasizes the importance of using correct unit conversions and assumptions for concrete and steel strengths, ensuring accuracy throughout the design process.

Takeaways

• 😀 The cylindrical bunker is designed to store 20 tons of coal with a density of 9 kN/m³ and an angle of repose of 30°.
• 😀 The characteristic strength of concrete is 15 N/mm², and the steel strength is 415 N/mm².
• 😀 The total weight of the coal is 200 kN, and the volume of the bunker is calculated to be 22.2 m³.
• 😀 The assumed dimensions of the bunker include a diameter of 2.8 m and a hopper depth of 1.2 m.
• 😀 The total volume of the bunker (23 m³) is greater than the calculated coal volume (22.2 m³), making it feasible to proceed with the design.
• 😀 The hoop tension for the cylindrical walls is calculated using a formula involving internal pressure, diameter, and height.
• 😀 After applying a safety factor of 1.5, the ultimate hoop tension is found to be 28.3 kN, and reinforcement is calculated accordingly.
• 😀 The minimum reinforcement for the cylindrical walls is 0.2% of the cross-sectional area, and reinforcement is provided with 8 mm bars at 250 mm spacing.
• 😀 For the hopper bottom, a thickness of 180 mm is assumed, and the total load includes both the coal weight and the self-weight of the hopper.
• 😀 The normal pressure from the coal and hopper bottom is calculated, and reinforcement for the sloping slab is provided with 8 mm bars at 200 mm spacing.

Q & A

What is the density of coal used in the design of the cylindrical bunker?

The density of coal used in the design is 9 kN per cubic meter.

What is the angle of repose given in the problem?

The angle of repose is given as 30 degrees.

What is the characteristic strength of concrete used in this design?

The characteristic strength of concrete is 15 N/mm² (Newtons per square millimeter).

What is the characteristic strength of steel used in the design of the bunker?

The characteristic strength of steel is 415 N/mm².

What is the first step in designing the cylindrical bunker?

The first step is to calculate the volume of the bunker using the weight of the coal and its density.

How is the volume of coal related to the bunker design?

The volume of coal is calculated by dividing the weight of the coal by its density. In this case, the volume is 22.2 cubic meters.

What formula is used to calculate the volume of the surcharge in the bunker?

The formula used is 1/3 * π * A² * H, where A is the area and H is the height of the surcharge.

How do you calculate the reinforcement for the cylindrical wall of the bunker?

The reinforcement for the cylindrical wall is calculated using the formula: AST = ultimate hoop tension / (0.87 * FY), where FY is the yield strength of steel.

What is the assumed thickness of the sloping slab in the design?

The assumed thickness of the sloping slab is 180 mm, though it can range between 200 mm and 350 mm.

What is the formula used to calculate the normal component of coal pressure on the sloping side of the bunker?

The formula for the normal component due to the coal pressure is WD * cos(θ), where WD is the total load and θ is the angle of repose.