# Winder

The structural frame
The construction
The reinforcement I
The reinforcement II
Quantity/Cost estimation
Detailing drawings
Introduction >

Wind and Seismic Forces >
Structural model and Analysis
Slabs
Seismic behavour of frames
Appendix A
Appendix B
Appendix C
Appendix D
Introduction >
Modelling slabs

Materials
To be continued >
Introduction

## Plan view of a winder staircase

For space economy, in small buildings the staircase is constructed with winder steps and therefore its flights are not plane but crooked.
These flights to facilitate reinforcement forming and positioning, are considered to be plane and are reinforced by following rules similar to those regarding straight staircases.

## Section 1-1 of a winder staircase

The support of the staircase on the shear wall can be achieved by various ways based on the designer’s simulation model and the prevailing practices.

## Section 3-3 of a winder staircase

The hidden slab beam along the secondary direction of the staircase’s support, could be ommitted, however -as a slab’s free edge- the area would require hairpin reinforcement. The use of a hidden slab beam disposing of a top and bottom reinforcement enhances the ductile behavior of the staircase.

## Section 4-4 of a winder staircase

In winder staircases, extra attention must be paid to the open well area between the flights both during the design and the planking of the staircase so as to ensure that the staircase’s thickness (vertically measured from the planking) is equal to the thickness of its outer flight.

## Section 5-5 of a winder staircase

Regardless whether starter bars were placed in the formwork or they were fixed in place afterwards using resins, the bars of the hidden slab beam should be single pieces.

## Extending the staircase under the floors’ beams

Extending the staircase under the floors’ beams is not mandatory however, when it is done is ensures a more effective staircase reinforcement and a better brick fitting. The above figures show 4 cases where the stair is extended under the beams:

(a) Masonry stretcher bond without thermal insulation

(b) Double stretcher bond with thermal insulation

(c) The same as (b), with an additional bond beam at the free wall

(d) Extension of the staircase to the entire wall thickness and a thermal insulation strip placed to the staircase’s end