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This article discusses in the design of staircase and provide the design sheet as well.
Stairs can be of various shapes and sizes but in this part design will be talking about rectangular stair and its design.
While designing the staircase we must consider various prescribed requirements and specifications.
In this regard we need to decide the height and width of Riser and thread.
Also the number of steps and width of landing is predetermined. Compressive and yield strength of concrete and steel must be decided before hand.
In this spreadsheet each step is provided and solved with details and can be changed accordingly.
The first step is to collect data of the required staircase that needed to be designed. For that we have total number of steps in the flight to be 12, the dimensions of tread and riser will be 400 mm and 200 mm respectively. Width of landing beam will be 500 mm. Also staircase width is 1000 mm.
After providing the pre decided data we need to calculate the effective span which is equal to the sum of width of landing beam and product of tread and number of steps. Effective span in our case will be 5300 mm or 5.3m.
Thickness of waist slab will be 1 in 20 of this effective span.
In the next step, we need to calculate different type of loads acting on the staircase. Dead load on slab in sloppy portion will be 6.625 KN/m while on horizontal span it will be 7.41 KN/m.
Dead load on one step is one KN/m.
So total dead load will be 11.4 KN/m.
Service live load is 5 KN/m which makes total load as 16.44 KN/m.
Hence, total factored load is 24.66 KN/m.
Now we will calculate bending moments due to this factored load which comes out to be 86.57 KN.m.
Now check is applied for the safety of depth of waist slab. From the given formula, the depth must be smaller than the effective depth as calculated earlier.
To design the main reinforcements, we need to calculate area of steel required for main reinforcement bars. From that we can decide the diameter and number of bars used.
In our case we need to provide 16 mm diameter bars at 200 mm spacing.
Distribution bars considered to be 0.12 % of the cross section and hence we use 4 bars of 10 mm diameter at 200 mm centre to centre spacing.
Hope that the above article and the given Excel spreadsheet will help you in designing staircase of your choice. If you have any issue please comment down in the section below.
Click the download button to get a copy of Excel spreadsheet of design of staircase.
