SPIRAL STAIRCASE DESIGNER FREE

The stair would be designed as cantilever. Stair own weight = area x unit weight of concrete = 0.027 x 24 = 0.648 kN

SPIRAL STAIRCASE DESIGNER FREE

For domestic buildings, the common span is 900 mm with thickness ranging from 100 mm or 125 mm at the column end and tapering to 75 mm at the free end.ĭesign a spiral stair case for a domestic dwelling with the following dimensionsĭiameter of central column = 300 mm (See Figures 2 and 3)Ĭharacteristic strength of concrete, f ck = 25N/mm 2Ĭharacteristic strength of steel, f yk = 460 N/mm 2Īrea of section around column = /4 = /4 = 0.011 m 3Īrea of the cantilever section = 0.5 (0.1 + 0.075) x 0.725 x 0.25 = 0.016 m 3 There is no need to check for deflection. Depending on the span, depth ranges between 100 and 175 mm. In most cases, the steps are narrower at the column end and increase in width towards the tip. The steps are cantilever slabs and are designed as such. The column can be designed axially with some little eccentricities allowed. They are usually pre-cast members and are arranged around the periphery of the central column or post.

They can go as far as four stories in height. Using an ideal riser of 170 mm, number of steps = 3770/170 = 22.18 = 23 stepsĪccording to Oyenuga (2011), spiral stair case is the most commonly used stair case in dwelling places. Using the useful line principle, (2/3) x 5655 = 3770 mm would be where people would step on the stair. If it is assumed that the stair case will stop (insertion) at the point where it would start (origin), the angle of rotation would be 360 0.

If a spiral stair case would be built in 900 mm radius and 3200 mm height determine the other dimensions of the stair case. This principle is normally applied to the length of the steps. The useful line principle assumes that the person climbing the stairs walks at usually 2/3 from the centre. The Useful line principle is normally used. The irregularity of the shape of the staircase as it approach the central post affects the point of application of the calculation of the steps. Where, R = radius of stair α = angle of rotation. The length of the staircase can be determined by the formula, (π x R x α)/180 The number of steps: To determine the number of steps, it is important to know the length of the staircase and the diameter. The angle of rotation: This depends on the origin and insertion of the stairs.Ĥ. The distance between floors of the stair case: This may normally depend on the headroom of the structure. It states thus 2R + T = 620…640 mm, where R = riser height and T = thread length.Ģ. The formula provided by Francis Blondel have been most popular. The determination of ideal stair case dimensions considers four important factors vizġ. Figure 1 Circular spiral stair configuration

Spiral staircase designer