# You are to design a tension member

• General_Sax
In summary, the design stress for the tension member (square rod) to carry a mass of 575 000 kg with a safety factor of 2 against yield and a safety factor of 3 against static fracture is 429 MPa. To determine the appropriate bar dimensions, the equation [sigma] = F/l*w is used, where F is the force of 5.641 MN and l and w are the length and width of the bar. After calculating the area using this equation, it is important to check the units to ensure a sensible answer is obtained.
General_Sax
You are to design a tension member...

You are to design a tension member (square rod) with a cross section to carry a mass of 575 000 kg with a safety factor of 2 against yield and a safety factor of 3 against static fracture (overload).

a) What is the design stree that you will use for the application? Why?

b) What are the appropriate bar dimensions for use?

=============================================================

FS = UTS / R

[sigma] = F / Ao

Ao = L * w

======================================================

FS = 1279MPa / 3 = 426.33333... MPa ~ 426 MPa
that's the design stress considering static fracture

FS = 862 / 2 = 431 MPa
that's the design stress consider yield stress/strength

So, I'm considering using a design stress that is the average of these two values, which would be: 429 MPa

I'm just confused, because we haven't done anything like this in class.

Now for part b)

[sigma] = F / l*w

F = 575 * 103(kg) * 9.81(m/s2)
F = 5.641 MN (mega Newtons)

429 = 5.641 MN / Ao

Ao = 13148.6014 MM (mega meters? I'm not sure about the units on this one)

l = w = 6574 MM

Of the three stresses (426, 429 & 431) you have calculated only one gives a safety factor of 3 against fracture.

Which one is it?

This is the only one which satisfies both the safety factors of at least 2 and at least 3.

I'm sure if you check the units of (426, 429 & 431) in part (b) you will be able to calculate a more sensible area.

## What is a tension member?

A tension member is a structural element that is designed to resist tensile forces, or forces that pull on the member rather than push on it. It is typically used in situations where a structure needs to support weight or withstand external forces.

## What factors should be considered when designing a tension member?

When designing a tension member, it is important to consider the material properties, such as strength and ductility, as well as the loading conditions, such as the magnitude and direction of the applied forces. The geometry of the member, including its cross-sectional shape and length, also plays a crucial role in the design process.

## What are the common types of tension members?

The most common types of tension members include rods, cables, and wires. These members are typically made of materials such as steel, aluminum, or titanium, and are used in a variety of applications, including bridges, buildings, and industrial equipment.

## How do you determine the required cross-sectional area for a tension member?

The required cross-sectional area of a tension member can be determined by calculating the maximum tensile stress in the member and dividing it by the allowable stress of the material. The cross-sectional area should be large enough to safely carry the applied load without exceeding the material's yield strength.

## What are the different types of connections used for tension members?

The most commonly used connections for tension members are threaded connections, welded connections, and bolted connections. The type of connection chosen will depend on the specific design requirements and the properties of the materials being used.

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