The spiral stairs with curved glass railings in the foyer of the KfW Bank in Frankfurt combine design and aesthetic demands with technical and functional requirements. With an underside soffit of varnished steel sheet matched to the stairs flight run, this staircase possesses all the characteristics necessary to qualify it as modern architecture. The glass railings and the high-grade wooden handrails are a perfect combination.
Spiral stairs with glass railings in the foyer of the KfW Bank in Frankfurt
The stairs structure consists of box-type stringers with folded stair flights welded in between them. The outer stringers have holes to provide indirect lighting for the steps. The evenly rounded stairs flight with a width of up to 1,400 mm integrates harmoniously with the architecture of the lobby.
The box-type stringers are welded from rectangular/H-sections and fixed with steel base plates to the unfinished floor. They hold the panes of the glass railings. In accordance with trends in modern architecture, the curved soffit lining was constructed with 5 mm-thick steel sheet.
Stairs tread construction:
- Folding stairs of 5 mm-thick steel sheet, bent at the front.
- Suitable for a wooden or stone covering
Glass railings with wooden handrails
In order to comply with legal building regulations for glass railings, the requirements concerning the rail load and the glass thickness specified by the TRAV (Technical Rules for the Use of Fall Protection Glazing) and the stairs code DIN 18065 are taken into account.
The glass panes for the glass railings are fixed with a casting method especially developed for this purpose and approved by the supervising construction authorities. A great benefit of this method compared to other typical fastening techniques practiced on the marked is that it dispenses with laborious wedging of the glass panes.
- Balusters of flat steel, baluster supports welded in the stringer grooves.
- Balustrade filling of 16 mm-thick laminated safety glass panes made of two-layer float glass (white glass) with low ferrite content and polished exposed edges.
- Handrail for the glass railings made of walnut wood, ground and lacquer-finished, with a groove at the bottom to insert the glass panes.
In addition to the delivery and the professional assembly of the spiral stairs and the glass railings in the building of the KfW Bank in Frankfurt, the following work and services were performed
- Verifiable structural analysis
- Vibration resistance verification
- Failure tests
- CAD construction and detail drawings