CHAPTER 1 www.uthm.edu.my
STRAICASE DESIGN (Based on EC) By Tuan Norha Norhaya yati ti binti binti Tuan Chik Chik JKSB, FKAAS, UTHM
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Introduction www.uthm.edu.my
Stairs are an essential part of every building since they lead from one floor to another and connect different levels. •
It consists of a flight of steps, usually with one or more intermediate landings provided between the floor levels. •
Figure below shows and explains the basic terminology of stairs •
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Introduction www.uthm.edu.my
Stairs are an essential part of every building since they lead from one floor to another and connect different levels. •
It consists of a flight of steps, usually with one or more intermediate landings provided between the floor levels. •
Figure below shows and explains the basic terminology of stairs •
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Introduction www.uthm.edu.my
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Introduction www.uthm.edu.my
The dimension of stair should be such as to give the maximum comfort to the users, which depends on the use of the building. •
For example, in public buildings the riser (R) is not more than 180 mm, whereas in private buildings is not more than 200 mm. •
The going (G) shall not be less than 255 mm in public buildings and varies between 250 mm to 400 mm in private buildings. •
For comfort, the riser (R) and going (G) dimensions can be proportioned according to the following formula; (2 x R) + G = 600 mm [ See UBBL, BS 5395, Handbook ] •
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Types of Staircase www.uthm.edu.my
There are different types of stairs, which depend mainly on the type and function of the building and on architectural requirements. •
•
The most common types are shown as follows.
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Types of Staircase www.uthm.edu.my
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Types of Staircase www.uthm.edu.my
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Types of Staircase www.uthm.edu.my
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General Design Considerations www.uthm.edu.my
The reinforced concrete stairs should be designed generally similar to reinforced concrete slabs, except as indicated otherwise in this section. •
1. ACTIONS When considering the permanent load for the flights of stair, care should be taken to ensure that a sufficient allowance is made to cater the weight of the steps and finishes as well as the increase loading on plan occasioned by the inclination of the waist. Where stair with open wells have two intersecting landings at rightangles to each other, the actions on the areas common to both spans may be divided equally between the spans. 29/08/2012
General Design Considerations www.uthm.edu.my
2. BENDING MOMENTS AND SHEAR FORCES Stair slabs and landings should be designed to support the most unfavorable arrangements of design loads. For example, where a span is adjacent to a cantilever of length exceeding one third of the span of the slab, the case should be considered of maximum load on the cantilever and minimum load on the adjacent span. Stairs which are continuous and constructed monolithically with their supporting slabs or beams can be designed for a bending moment of say FL/10, where F is the total ultimate load. 29/08/2012
General Design Considerations www.uthm.edu.my
3. EFFECTIVE SPANS The effective span of stairs spanning between beams or walls is the distance between centre-line of supporting beams or walls. The effective span of stairs spanning between landing slabs is the distance between centre-line of supporting landing slabs, or the distance between the edges of the supporting slabs plus 1.8 m, whichever is the smaller.
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Example 1.1 www.uthm.edu.my
(Stair spanning longitudinally continuous over supports)
A longitudinal straight reinforced concrete stairs supported by reinforced concrete beams at both ends is shown in the figure (unit mm). Landing slabs at both ends of the stairs are monolithically connected to the stairs. Using grade 25 concrete and grade 500 steel, design the stair for a variable action of 4.0 kN/m2 and permanent action from finishes, baluster and railing of 1.0 kN/m2 . Assume nominal concrete cover 25 mm and bar size 10 mm. 29/08/2012
Solution Example 1.1
Example 1.2 www.uthm.edu.my
(Stair spanning longitudinally with landing and continuous at one end)
A longitudinal straight reinforced concrete stairs supported by reinforced concrete beams at both ends is shown in the figure (unit mm). Landing slabs at both ends of the stairs are monolithically connected to the stairs. Using grade 25 concrete and grade 500 steel, design the stair for a variable action of 4.0 kN/m2 and permanent action from finishes, baluster and railing of 1.0 kN/m2 . Assume nominal concrete cover 25 mm and bar size 10 mm. 29/08/2012
Solution Example 1.2
Example 1.3 www.uthm.edu.my
(Stair supported by landing spanning perpendicular to stair flight)
variable actions
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Example 1.3 www.uthm.edu.my
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Solution Example 1.3
Example 1.4 www.uthm.edu.my
(Two stairs spanning perpendicular to each other sharing a landing)
Design and detail a typical two flight shown in figure below. The flights are spanning perpendicularly to each other sharing one common landing. The overall depth of landing and waist of both flights is 150 mm, while the width of going and height of riser are 255 mm and 170 mm respectively. Assume a variable action of 3.0 kN/m 2 and permanent action from finishes, baluster and railing of 1.0 kN/m 2. Use grade 25 concrete, grade 500 steel and nominal concrete cover of 25 mm.
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1500
Example 1.4 0 0 5 1
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Solution Example 1.4
