Stairs are divided into two types: staircases and beams. Slab stairs are composed of platform beams, platform slabs, and ramp slabs. Beam staircases have increased ramp sloping beams compared to slab stairs.
The stair steps and plates have similar stress conditions and are inclined plate-type bending members
Considering the influence of the diagonal support of the reinforced concrete cast-in-situ staircase on the overall structure, effective measures should be adopted in the design to reduce its impact, the calculation result of the overall structure should be adjusted or its impact should be included in the overall structure calculation, and the stairwell components Do strengthening treatment.
(1) When designing the structure, first consider the scheme design. The plane position of the stairs will have an influence on the stiffness center, torsion and period of the structure. To determine the plane position of the stairwell, the balance of the overall structure stiffness should be considered. For example, an anti-seismic wall should be installed in the stairwell, but it should not cause a large torsional effect.
(2) In the design of the frame structure, for example, when the stair members and the main structure are poured, the stair slab acts as inclined support, which has a greater impact on the stiffness, bearing capacity and regularity of the structure and should be included in the overall calculation. When effective measures are taken, such as the sliding support of the platform on the platform, the structure of the stairs has a small impact on the overall structure, so it is not necessary to participate in the calculation of the overall structure.
(3) In the design of the frame-shear wall structure, because the staircase has a small impact on the overall structure, especially when the stairwell is arranged in the cylinder, the stiffness effect of the stairwell is negligible, and it may not be included in the overall structure calculation. When arranging in the shear tube, the influence of the stairwell should be considered, and its structural change law is similar to that of the frame structure. Through conceptual design, effective measures are taken to adjust the calculation results of the overall structure and to strengthen the treatment of the components of the stairwell.
(4) In the structure of shear wall, because of its large stiffness, the influence of stairs on its stiffness can be ignored.