What are the structural forms of cast-in-place reinforced concrete stairs? What are their characteristics?

Cast-in-place reinforced concrete stairs usually have four structural forms: 1. Beam stairs; 2. Flat stairs; 3. Scissors stairs; 4. Spiral staircase. As shown in the figure below:

1. Crossbeam staircase

Figure 3- 1 (a) is an example of a typical double-beam staircase. Its advantage is that when the stair steps are long, it is more economical and lighter than slab stairs, so it is widely used in office buildings, teaching buildings and other buildings. The disadvantage is that the formwork is complicated and the construction is inconvenient. In addition, when the size of the inclined beam is large, its appearance is very heavy.

2. Flat stairs

Figure 3- 1 (b) is a typical example of double running stairs. This kind of stairs consists of pedals, platform plates and platform beams. The load acting on the pedal is directly transferred to the platform beam. The pedal is supported on the rest board and the platform beam of the floor. The rest board is supported on the rest board platform beam.

The lower surface of slab stairs is flat, the formwork is simple and the construction is convenient. The disadvantage is that the inclined slab is thick (span 1/30 ~ 1/25), which leads to a large amount of concrete and steel and a heavy structure weight, so it is generally used when the span of the tread slab is less than 3 m. Because of its lightness and beauty, this kind of staircase has been widely used in some public buildings in recent years.

3. Scissors stairs

? Figure 3- 1 (c) is a typical example of scissor stairs. This kind of stairs consists of pedals and pedals. Characterized by elegant and beautiful appearance. Suitable for public buildings. Formwork construction is simple and convenient, but its disadvantages are complex stress and thick plate, which leads to a large amount of concrete and steel and a large weight of the structure. Widely used in hotels, shopping malls and other large public buildings.

4. spiral stairs?

Figure 3- 1 (d) is an example of a spiral staircase. Characterized by elegant and beautiful appearance. Suitable for public buildings. Save space. However, the formwork is complex, the construction is difficult, the stress is complex, the amount of concrete and steel is large, and the structure is self-important.