Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (2024)

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In multi-storey buildings, ramps, elevators, escalators, and stairs are often used to facilitate vertical circulation. Circulation refers to the movement of people and goods between interior spaces in buildings, and to entrances and exits. Stairs are important building elements that are used to provide vertical circulation and access across different floor levels in a building. It is also recommended that when an access height exceeds 600mm, a staircase should be provided. A staircase can be made of reinforced concrete, steel, timber, and other composite construction materials.

In modern architecture, stairs are designed to be aesthetically pleasing, and they contribute immensely to the interior beauty of a building. There are different types of stairs with different configurations. For stairs in a building, the recommended slope for comfort is 27°, but for practical purposes, this can sometimes be extended to 35°.

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (2)

Types of staircase

Generally, stairs are usually of the following types:

  • straight flight staircase
  • circular staircase
  • helical staircase
  • spiral staircase, or
  • a combination of the above-mentioned types.

Straight stairs are stairs along which there is no curvature or change in direction on any flight between two successive floors or levels. There are several possible arrangements of straight stairs. For example, they may be arranged in a straight run with a single flight between floors, or a series of flights without a change in direction.

Also, straight stairs may permit a change in direction at an immediate landing. When the stairs require a complete reversal of direction, they are called parallel stairs or half-landing stairs (turning through 180°). When successive flights are at an angle to each other, (usually 90°), they are called angle stairs or quarter-turn stairs. In addition, straight stairs may be classified as scissors stairs when they comprise a pair of straight runs in opposite directions and are placed on opposite sides of a wall.

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (3)

Circular stairs when viewed from above appear to follow a circle with a single centre of curvature and large radius.

Curved stairs when viewed from above appear to follow a curve with two or more centres of curvature, such as an ellipse.

The picture below shows a helical staircase.

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (4)

Spiral stairs are similar to circular stairs except that the radius of curvature is small and the stairs may be supported by a column.

Terminologies in staircase design

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (5)

Flight: A series of steps extending from floor to floor, or from a floor to an intermediate landing or platform.

Guard: Protective vertical barrier along edges of stairways, balconies, and floor openings.

Landings (platforms): Used where turns are necessary or to break up long climbs. Landings should be level, as wide as the stairs, and at least 1000mm long in the direction of travel.

Step: Combination of a riser and the tread immediately above.

Rise: Distance from floor to floor.

Run: Total length of stairs in a horizontal plane, including landings.

Riser: Vertical face of a step. Its height is generally taken as the vertical distance between treads.

Tread: Horizontal face of a step. Its width is usually taken as the horizontal distance between risers.

Nosing: Projection of a tread beyond the riser below.

Soffit: Underside of a stair.

Railing: Framework or enclosure supporting a handrail and serving as a safety barrier.

Baluster: Vertical member supporting the handrail in a railing.

Balustrade: A railing composed of balusters capped by a handrail.

Handrail: Protective bar placed at a convenient distance above the stairs for a handhold.

Ideas on the selection of staircase dimensions

Ample headroom should be provided not only to prevent tall people from injuring their heads but to give a feeling of spaciousness. A person of average height should be able to extend his hand forward and upward without touching the ceiling above the stairs. The minimum vertical distance from the nosing of a tread to overhead construction should preferably never be less than 2100 mm.

Stairway Width
The width of a stairway depends on its purpose and the number of persons to be accommodated in peak hours or emergencies. Also, there are building codes that regulate the geometric design of stairways. The following can be used as guidelines;

  • For residential flats between two to four storeys, use a minimum width of 900 mm, for flats more than 4 storeys, use a width of 1000 mm.
  • For public buildings of under 200 persons per floor, use a width of 1000 mm, for buildings between 200 – 400 persons per floor, use a width of 1500 mm. For over 400 persons, use a width between 1500 – 3000 mm. However, when the width of a stairway exceeds 1800 mm, it is necessary to divide it using handrails.

Step Sizes
Risers and treads generally are proportioned for comfort and to meet accessibility standards for the handicapped, although sometimes space considerations control or the desire to achieve a monumental effect, particularly for outside stairs of public buildings. Treads should be at least 250 mm, exclusive of nosing.

The most comfortable height of riser is 175 mm. Risers less than 100 mm and more than 200 mm high should not be used. The steeper the slope of the stairs, the greater the ratio of the riser to tread. In the design of stairs, account should be taken of the fact that there is always one less tread than riser per flight of stairs. No flight of stairs should contain less than three risers.

Structural design of a staircase

The theoretical procedures employed in the structural analysis of stairs is the concept of an idealised line structure and when detailing the reinforcement for the resulting stairs, additional bars should be included to limit the formation of cracks at the points of high-stress concentration that inevitably occur. Typical detailing of corners (edge between flight and landing) of a staircase is shown below;

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (6)
Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (7)

The ‘three-dimensional’ nature of the actual structure and the stiffening effect of the triangular tread areas, both of which are usually ignored when analysing the structure, will result in actual stress distributions that differ from those calculated, and this must be remembered when detailing (Reynolds et al, 2008). The typical nature of internal stresses induced in a simply supported straight flight stair and reinforcement pattern is as shown in the picture below.

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (8)

Simple straight flights of stairs can span either transversely (i.e. across the flight) or longitudinally (i.e.along the flight). When spanning transversely, supports must be provided on both sides of the flight by either walls or stringer beams. In this case, the waist or thinnest part of the stair construction need be no more than 60 mm thick say, the effective lever arm for resisting the bending moment being about half of the maximum thickness from the nose to the soffit, measured at right angles to the soffit. When the stair spans longitudinally, deflection considerations can determine the waist thickness.

In principle, the design requirements for beams and slabs apply also to staircases, but designers cannot be expected to determine the deflections likely to occur in the more complex stair types. BS 8110 deals only with simple types and allows a modified span/effective depth ratio to be used. The bending moments should be calculated from the ultimate load due to the total weight of the stairs and imposed load, measured on plan, combined with the horizontal span. Stresses produced by the longitudinal thrust are small and generally neglected in the design of simple systems.

Sample design of reinforced concrete staircase

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (9)

A section of a staircase is shown above. The width of the staircase is 1160mm. We are expected to carry out a full structural analysis and design of the staircase according to EC2 using the following data; Density of concrete = 25 kN/m3; Compressive strength of concrete (fck) = 30 N/mm2; Yield strength of steel (fyk) = 460 N/mm2; Concrete cover = 25mm; Imposed load on staircase (qk) = 4 kN/m2 (category C3).

The structural idealisation of the staircase is shown below;

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (10)

Loading of the staircase

Thickness of waist and landing = 200 mm
Depth of riser = 150mm
Load actions on the stairs
Concrete self weight (waist area) = 0.2 × 25 = 5 kN/m2 (normal to the inclination)
Stepped area = 0.5 × 0.15 × 25 = 1.875 kN/m2 (global vertical direction)
Finishes (say) = 1.2 kN/m2

We intend to apply all gravity loads purely in the global y-direction, therefore we convert the load at the waist of the stair from local to global direction by considering the angle of inclination of the flight area to the horizontal;

𝛼 = tan−1(1.2/1.75) = 34.438989°

Therefore the UDL from waist of the stair in the global direction is given by = (5 × cos 34.438989) = 4.124 kN/m2

Total dead load on flight area (gk) = 4.124 + 1.875 + 1.2 = 7.199 kN/m
Variable load on staircase (qk) = 4 kN/m2
The load on the flight area at ultimate limit state = 1.35gk + 1.5qk
Ed = 1.35(7.199) + 1.5(4) = 15.719 kN/m2

On the landing;
gk = 5 + 1.2 = 6.2 kN/m2; qk = 4 kN/m2

The load on the landing at ultimate limit state = 1.35gk + 1.5qk
n = 1.35(6.2) + 1.5(4) = 14.370 kN/m2

The loading of the structure for dead and live loads at ultimate limit state is shown below;

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (11)

The ultimate bending bending moment diagram due to ultimate loads is shown below;

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (12)

The ultimate shear force diagram is shown below;

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (13)

Flexural design of the staircase span

A little consideration will show that it is best to use the design moment MEd = 41.119 kNm to design the entire stairs.

MEd = 41.119 kNm
d = h – Cc – ϕ/2
Assuming ϕ12mm bars will be used for the construction
d = 200 – 25 – 6 = 169mm; b = 1000mm (designing per unit width)

k = MEd/(fckbd2) = (41.119 × 106)/(30 × 1000 × 1692) = 0.0479

Since k < 0.167 No compression reinforcement required
z = d[0.5+ √((0.25 – 0.882k)] = z = d[0.5+ √(0.25 – 0.882 × 0.0479)] = 0.95d

As1 = MEd/(0.87fykz) = (41.119 × 106)/(0.87 × 460 × 0.95 × 169) = 639.96 mm2/m

Provide Y12mm @ 150mm c/c BOT (As,prov = 753 mm2/m)

To calculate the minimum area of steel required;
fctm = 0.3 × fck(2⁄3) = 0.3 × 302⁄3 = 2.896 N/mm2 (Table 3.1 EC2)

As,min = 0.26 × fctm/fyk × b × d = 0.26 × 2.896/460 ×1000 ×169 = 276.631 mm2/m
Check if As,min < 0.0013 × b × d (219.7 mm2/m)
Since, As,min = 276.631 mm2, the provided reinforcement is adequate.

Check for deflection

k = 1.0 for simply supported beams and slab
ρ = As/bd = 753/(1000 × 169) = 0.004455 < 10-3√30

Since ρ < ρ0
L/d = k [11 + 1.5√(fck) ρ0/ρ + 3.2√(fck) (ρ0/ρ – 1)1.5]

L/d = 1.0 [11 + 1.5√30 × (0.005477/0.004455) + 3.2√30 (0.005477/0.004455 – 1)1.5] = 1.0 (21.1 + 1.9258) = 23.0258

Modification factor βs = 310/σs
σs = (310fykAs,req)/(500As,prov) = (310 × 460 × 639.96)/(500 × 753) = 242.358 N/mm2

βs = 310/242.358 = 1.2789
Taking the distance between supports as the effective span, L = 4.35m
The allowable span/depth ratio = βs × 23.0258 = 1.2789 × 23.0358 = 29.460
Actual deflection L/d = 4350/169 = 25.739
Since 25.739 < 29.460, deflection is ok.

Shear design

Ultimate shear force VEd = 35.358 kN
v = VEd/bd = (35.358 × 1000)/(1000 × 169) = 0.209 N/mm2
VRd,c = [CRd,ck(100ρ1fck)1/3] ≥ (Vmin)

CRd,c = 0.18/γc = 0.18/1.5 = 0.12

k = 1 + √(200/d) = 1 + √(200/169) = 2.087 > 2.0, therefore, k = 2

Vmin = 0.035k1.5fck0.5
Vmin = 0.035 × 21.5 × 300.5 = 0.5422 N/mm2

ρ1 = As/bd = 753/(1000 × 169) = 0.0044556 < 0.02

VRd,c = [0.12 × 2(100 × 0.0044556 × 30)1/3] = 0.569 N.mm2
Since VRd,c > VEd , no shear reinforcement is required. Shear is ok

Staircase reinforcement details

Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (14)
Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (15)

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Design of Reinforced Concrete (R.C.) Staircase | Eurocode 2 - Structville (2024)


What is reinforced concrete staircase? ›

R.C.C Stairs OR Reinforced Concrete Stairs:

RCC stairs may be the most common stairs widely used than any other types of stair. These stairs can be easily moulded to any desired shape and are better wear and fire resistant. The steps of RCC stairs are made by using ordinary cement concrete.

What is the 18 rule for a staircase? ›

Rule one says that rise plus run (r+R) should equal 18 inches. Why? That's what most people find to be a comfortable stride on most stairs. You can cheat a bit up or down, but below 17” and more than 19” will result in steps that require strides either too big or too small for most people.

How do you calculate concrete reinforcement? ›

To do this simply multiply the length of the slab by the width. Now that you have your area calculation, you need to divide the area by 12.5. This will give you the number of steel mesh sheets required to reinforce your concrete slab.

Is code for RCC staircase design? ›

21m dimensions stair design as per IS 456 2000 code standards. As per the dimensions of the stair case the long span is taken as 4.87m and short span is taken as 1.21m.

What is the standard size of staircase? ›

According to the Indian National Building Code, the minimum space for staircase in terms of width in a normal residential building should be 3 feet and 6 inches, minimum width of tread without nosing should be 10 inches and if nosing is required, it should be 10 ¼ inches.

How do you calculate the length of a staircase? ›

Its length is measured from the outer edge of the step, which includes the nosing if it is present, to the vertical portion of the stair called the riser.

What is the thickness of concrete stairs? ›

At minimum, the concrete thickness should be 4 inches between the inside of the step to the ground. In order to determine the number of risers, divide the total height of the steps by the number of risers desired. No individual riser should be greater than 7 to 7½ inches.

What is the standard size for concrete steps? ›

The 7-11 rule is one that's frequently used (maximum riser height of 7 inches and minimum tread depth of 11 inches). Risers should also be at least 4 inches in height.

What is the cost of RCC staircase? ›

RCC Straight Run Precast Concrete Staircase at Rs 18000/piece in Tambaram | ID: 23348652612.

Why are concrete stairs used? ›

Concrete stairs can withstand heavy loads and high impact and do not rust in wet conditions. In addition, concrete is fire-resistant, which is why it is often used for fire exit stairwells. Because concrete can absorb vibrations, it is effective in soundproofing, making it ideal for hospital or school staircases.

Which grade of concrete is used for staircase? ›

normally concrete mix M15 (1:2:4) / 20mm aggregate. minimum “cover” to reinforcement should be 15mm or bar diameter or higher value for 1 hour fire resistance. waist slab thickness – 100 – 250mm (based on stair type) mainly mild steel or tor steel reinforcement is utilized.

What is the maximum angle for stairs? ›

Background: OSHA standard 29 CFR 1910.24(e), states: Fixed stairs shall be installed at angles to the horizontal of between 30 deg. and 50 deg. Any uniform combination of rise/tread dimensions may be used that will result in a stairway at an angle to the horizontal within the permissible range.

What is the minimum size of a stair landing? ›

Every landing shall have a minimum depth, measured parallel to the direction of travel, equal to the width of the stairway or 48 inches (1219 mm), whichever is less. Doors opening onto a landing shall not reduce the landing to less than one-half the required width.

What is the maximum rise for stairs? ›

The OSHA standard for rise and run of stairs is maximum 9.5" rise and minimum 9.5" run (tread depth). The IBC maximum rise of a single stair flight is 12.

What is the formula in reinforcement? ›

= [volume × density.] Reinforcement bar.

Do you show stairs in RCP? ›

Sometimes when you are designing a grand staircase, it is useful to document the underside of the stair. Currently, there is no good way to display an accurate representation of a stair's underside in an RCP view.

Is standard for stair? ›

Stairs standard size:– the stair's width measured from one side to other usually varies depending on the type of building but for a normal residence, stairs size standard tends to be 3 feet 6 inches (100cm, 1m or 1000mm) wide and for other commercial, industrial, educational, institution building even goes up to 5 to 7 ...

How much space is required for staircase and lift? ›

The amount of space needed depends on the staircase, but we can offer an estimate for this stair lift requirement. Light and medium-duty stair lifts need about 24 inches beyond the bottom step, while heavy-duty models require around 30 inches.

What is the spacing for stairs? ›

The International Residential Code states that risers, which are the height of each step, cannot be more than 7.75 inches. Treads, or the run of the staircase, should be at least 10 inches wide to accommodate the average foot size. An example of a standard rise and run is 6-3/4 inches by 10 inches.

What is the best width for stairs? ›

Building regulations state that the width of your individual stairs should be at least 3 feet or wider. As long as the 3 foot width is met, you can expand as much as you like. The entire width of your staircase needs to reach a minimum of 36 inches wide.

What is a normal staircase? ›

The stair's width usually varies depending on the type of building the staircase is in, but for a normal residence, the standard tends to be 3 feet, 6 inches (106.7 cm). The minimum, in most places, is 2 feet 8 inches (81.3 cm). If a staircase exceeds 44 inches (111.8 cm), handrails are required for both sides.

How many square feet is 14 stairs? ›

Multiply 648 by 14, which is the total number of stairs. The answer is 9072 square inches. The square inches equate to 63 square feet of carpet size.

How do you calculate reinforcement ratio? ›

Reinforcement ratio of the column

= Sectional area of steel ÷ Sectional area of column concrete. = Ast ÷ b × d.

How is reinforcement cover calculated? ›

For reinforcement bars the minimum cover for bond is calculated in accordance with EN1992-1-1 Table 4.2N as: cmin,b = 1.0⋅Φ, where Φ is the diameter of the reinforcement bar (or equivalent diameter of bundled bars). Therefore minimum cover for bond is cmin,b = 20.0 mm.

What is the maximum spacing of reinforcement? ›

Normally these spacing will be as mentioned below : For beams, these distances are 300 mm, 180 mm and 150 mm for grades of main reinforcement of Fe 250, Fe 415 and Fe 500, respectively. (ii) The maximum spacing between two secondary parallel bars shall be 5dor 450 mm or whichever is less.

What is the maximum area of reinforcement? ›

The maximum allowed area of reinforcement is 4% for each tension and compression of its cross-sectional area. Depending on the casting method and the lapping of reinforcements, it can be seen different reinforcement ratios (for longitudinal direction) in BS 8110 Part 01 1997.

What is the standard length of reinforcement? ›

Reinforcing Steel Bar Length: The maximum length of any type bar shall be 60 feet. Bar lengths greater than 40 feet will require oversized vehicles for hauling.

What is the minimum reinforcement ratio of RC columns? ›

What is the minimum reinforcement ratio in a column? The minimum reinforcement ratio for column is 0.01.

What is minimum spacing of reinforcement? ›

Minimum spacing between reinforcement bars

The minimum spacing between two reinforcement bars should be at least equal to the maximum coarse aggregate dimension plus a margin of 5 mm. For Greece, the maximum aggregate grains dimension for usual concrete, is 32 mm and for self-compacting concrete is 16 mm.

What is nominal cover in RCC? ›

The nominal cover is the distance between the exposed concrete surface to nearest reinforcement bar ( it may be any bar main bar, longitudinal bar and even links or stirrups). The nominal cover should not be less than the diameter of the bar.

How is reinforcement calculated in RCC slab? ›

how to calculate steel Quantity for RCC slab ? Ok - YouTube

How do you calculate the depth of an RCC beam? ›

Total depth = effective depth + diameter of bar/2 + clear cover size. Width of beam = Depth/1.5 ( width of beam should not be less than 200 mm). Total depth of beam = effective depth + diameter of bar/2 + clear cover size.

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