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In this article we will be calculating different quantities related to rectangular column design.
This is to specify that this Excel sheet does not contain the design of column rather it is the calculation of different quantities related to the safe design of rectangular column.
First we will discuss the design procedure of rectangular or square column.
In the first step you have to determine what are the design requirements such as loading, specifications and the codes you are going to work with e.g. ACI, Euro-code etc.
Also you need to establish the dimensions of the column which will be desirable.
In the next step we move toward calculating axial loads on column to get required compressive strength.
In the third step we have to select the material for concrete and reinforcement bars. Choose the specified concrete mixed design according to its compressive strength which is in MPA or PSI. Also select the grade and type of reinforcement bars used in the design.
Now we have to calculate the required steel area. For this we need to determine the required steel area based on axial load and allowable stresses.
The formula used will be As = (P / (fy * φ))
Where P is the axial load on the column
fy is the yield strength of the reinforcement bars and
φ is the strength reduction factor mostly used as 0.85 or 0.7.
After this step we need to calculate the number of bars according to their size.
Spacing will be calculated in the next step between the reinforcement bars after which we will apply the checks for maximum and minimum spacing.
After designing the main reinforcement longitudinal bars we will design stirrup or ties.
Similarly the spacing between steering will also be calculated.
Once you have determine the size quantity and spacing of both longitudinal and transverse reinforcement it's time to finalize the design of column.
After all this design process you can move on to calculate the different values of axial and moments strength to check the safety and stability of the structure.
In the given spreadsheet be upper portion contains the design quantities where you can alter these quantities according to your requirement.
Ultimate load, ultimate moment, yield strength of steel, compressive strength of concrete, steel ratio reinforcement size and number and column dimensions can be easily changed.
The second portion contains the detailed calculations of factors depending upon different loading conditions where we will calculate nominal moments strength and nominal axial strength by using different strength reduction factors for different loading conditions. A graph will also be provided for different loading cases which represent the interaction diagram between φMn and φPn.
Click the Download link below to get an XLS copy of the file.
