# Load bearing capacity of a tall column

• Barnsaver
In summary, the load bearing capacity of an 8" x 8" x 10 foot tall white oak column is dependent on the material's elasticity, the length of the column, and the height of the column. If the column is not supported evenly, it may collapse under the weight of the object being supported. A structural engineer is needed to provide more accurate information.
Barnsaver
Could someone please tell me the load bearing capacity of an 8" x 8" x 10 foot tall white oak column. The oak is fully cured and would be placed on an appropriately sized concrete footing. It would be mechanically fastened to a beam that it would be supporting.
Any assistance or explanation with the calculation would be sincerely appreciated. Thank you.

If we consider the base as "fixed", and the opposite end as "free" end condition. Then the critical load from Euler's Formula:

$$P_{cr} = \frac{ \pi^2 E I}{L_e^2}$$

Where

## P_{cr} ## is the critical load for the onset of buckling
## E ## is the Modulus of Elasticity for your material ( oak - white oak - if you can find it )
## I ## is the moment of inertial about the centroid of your 8 in square column ##= \frac{1}{12} b^4 ##
## L_e ## is the effective length of the column for the given end condition ## = 2 L ##
## L ## is the height of the column

Make sure you convert all your units so they are consistent.

This model assumes the load is not eccentric ( i.e it can be effectively applied at the centroid of the column cross section )

Also, in practice there is most likely a Design Factor of Safety applied (depending on the application and material type)

You're probably ok if the actual load is less than half of the critical load, but I wouldn't say for sure.

You should consult a Structural Engineer for more accurate information on column design and applicable code, or if this thing collapses (because the actual loading situation was not accounted for) people could be seriously injured.

Last edited:
russ_watters and Lnewqban
Before using the Euler formula, it is necessary to calculate the slenderness ratio to find if the Euler column buckling formula is applicable. The end support conditions are critical - uneven support can cause big problems.

If the Euler formula does not apply, it is a simple compressive stress problem. But even a simple compressive stress problem is critically dependent on a correct value for allowable stress. Allowable stress for wood varies widely depending on grain direction, defects, knots, moisture content, and other variables.

A complete and correct answer would require more information and a deeper engineering analysis, and is beyond what PF does. Therefore, and for liability reasons, this thread is closed.

russ_watters and erobz

## 1. What is load bearing capacity?

Load bearing capacity refers to the maximum amount of weight or force that a structure or component can withstand without collapsing or failing.

## 2. How is load bearing capacity determined?

The load bearing capacity of a tall column is determined by factors such as the material it is made of, its dimensions, and the type of load it will be subjected to. Engineers use mathematical calculations and simulations to determine the load bearing capacity of a column.

## 3. What factors affect the load bearing capacity of a tall column?

The load bearing capacity of a tall column can be affected by factors such as the material properties, column height, cross-sectional area, and the type of load it will be subjected to. Other factors such as temperature, humidity, and environmental conditions can also play a role in determining the load bearing capacity.

## 4. How does the shape of a column affect its load bearing capacity?

The shape of a column can greatly impact its load bearing capacity. For example, a circular column is able to distribute weight more evenly compared to a square column, making it stronger and able to withstand higher loads.

## 5. Can the load bearing capacity of a tall column be increased?

Yes, the load bearing capacity of a tall column can be increased by using stronger materials, increasing its dimensions, or adding reinforcement such as steel bars. However, it is important to carefully consider and calculate the changes to ensure the structural integrity of the column is not compromised.

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