On an urban scale, Koszykowa Street, which forms part of the wider Stanisławowska Axis, determines the shape of the built environment through its deviation from the orthogonal street grid, resulting from the radial layout of the development’s main compositional axes. The block within which the building in question was constructed resembles an elongated right-angled triangle, bounded by Emilii Plater, Wilcza and Koszykowa Streets. The wedge-shaped plot, tapering towards the west, determined the basic functional decisions and also influenced the configuration of the structural grid. The character of the spatial composition was determined by strictly design-related decisions, namely the shaping of the building’s storeys as successive ‘slices’ shifted horizontally relative to one another. As a result, the monumental corner structure gained a sense of lightness, whilst the rounded corner block was fitted with balconies which, when planted with greenery, will form a vertical garden in the heart of the urbanised city.
However, this did not come without affecting the structural design, introducing additional challenges related to the lack of continuity in certain load-bearing elements. The building, which has two underground storeys, comprises seven above-ground storeys, topped by a recessed and roofless technical ‘storey’, raised approximately 30 metres above pavement level. Characteristic bay windows, projecting approximately 1.5 metres, form arcades over Wilcza and Koszykowa Streets. The composition of the façade of the first two storeys, almost entirely glazed, contrasts slightly with the storeys from the third upwards, where anthracite concrete predominates. This has a functional rationale – the hotel rooms begin on the third storey, whilst the two lower storeys are occupied by a multifunctional, event space and a restaurant.
Structurally, the new building comprises three interconnected structural systems, corresponding to the functional layout: the basement, intended for technical functions and hotel back-of-house facilities; the first two above-ground storeys, designated for public functions; and the remaining storeys above, housing hotel rooms and circulation spaces.
The two-storey underground section is founded on an 80 cm thick reinforced concrete base slab. The floors, supported by slotted walls and a reinforced concrete wall core serving as vertical circulation, have a span of up to 12 metres. To achieve the serviceability states of the structure specified in the Eurocodes (EC2), installation elevations of 15–25 mm were used at the mid-span points.
The first two above-ground storeys were designed using a column-and-slab system, best suited to their intended functions and allowing for the installation of large horizontal glazing.
The upper storeys feature a system of reinforced concrete walls separating hotel rooms with a module of B = 381 cm. All walls on these storeys are designed as 24 cm thick reinforced concrete structures extending to roof level and are founded on a thickened floor slab. These design decisions were also influenced by acoustic considerations, which are particularly important in this type of building.
The whole structure is topped by a flat roof on a 25 cm thick reinforced concrete slab. A steel grating is installed on the flat roof, serving as a substructure for technical equipment. Positioning the equipment approximately 1 metre above the surface of the flat roof provided additional acoustic insulation and allowed for the routing of service ducts to individual units and service risers.
