Vertical architecture versus spatial context. Multi-story development design.

Poznań University of Technology (Politechnika Poznańska), Faculty of Architecture, Poznań

Project idea

The aim of the concept was to create high-rise architecture. An important aspect before undertaking the design work was to carry out a thorough spatial analysis. The design of the complex with two skyscrapers was based on a research study, which made it possible to select the city in Poland with the greatest potential for the development of high-rise architecture. The selected city is Gdynia in the Śródmieście district in the area of Molo Rybackie. The city of Gdynia, in accordance with the provisions of the Study of Conditions and Directions for Spatial Development and the local spatial development plan, has laid out plots of land where high-rise development is allowed. Some of the plots have a height restriction, but not all. This is due to the intention to introduce a seamlessly transitioning city silhouette, gradually descending from the Sea Towers, currently the tallest building in the city, measuring 142 m in height. Once the design plot was selected, analyses were undertaken that influenced the formation of the building's massing. It was important to analyse the composition of the surroundings in order to properly create the more and less representative elements of the building. It was decided to erect two high-rise buildings that are symmetrical with the two skyscrapers of the Sea Towers complex. The towers of the designed architectural complex are attached to two mid-rise buildings with office and retail functions. The entire building complex is connected by a glazed overhang, in which a recreational zone is located. The local zoning plan called for the location of a viewing point, so it was arranged on the top floor of the 90-metre tower.
We called the planned development complex Sailor's House. The name was given due to the location of the development by Gdynia's harbours.

Project description

The proposed development can be divided into 6 distinct parts in terms of their function and development.

Shopping centre building
The 13.5 m high building is designed as a shopping centre. Its ground floor has been divided into a communication area, 5 shops, two fire staircases, one customer toilet area and social areas including toilets and changing rooms for employees. The storage areas are located in the south-western part of the 60 m high tower, which is connected to the shopping centre building. The warehouses have a goods lift and a similar layout also runs through the 2nd and 3rd floors. The upper floors (2 and 3) also have circulation corridors of the same width (up to 6.4 m), shops, staircases, customer toilets and staff toilets. They have the added benefit of viewing terraces in the northern part of the building facing the Baltic Sea.

The hotel building
The 60-metre-high tower has been designed as a three-star hotel with meeting rooms and a restaurant on the top floor. On the ground floor there is an entrance hall with a reception and a small restaurant for hotel guests, which occupy 102 m². Behind the reception is the hotel security room, cloakrooms, toilets and a staff welfare room. The hotel's vertical communication consists of two separate staircases and three large lifts, measuring 2.5 x 1.6 m. The vertical communication is the same for all floors of this building. The 2nd floor houses two meeting rooms for 32 people each, with the possibility of combining them. On this floor there is also a restaurant, a cloakroom and toilets for the guests of the conference rooms. The next floor has 3 large meeting rooms, two smaller rooms and guest toilets. Floor 4 is connected to the recreation area. Cloakrooms for users of this zone have been distributed in part of the tower. Floor 5 has been allocated to the administrative area for the management of the hotel, which includes: the boss's room, the manager's room, administration (including the secretariat) and accounting. On this floor there is also a laundry room with drying room and a utility room for those in charge of cleaning the facility. The upper floors (from 6 to 16) have been allocated to hotel rooms, of which there are a total of 9 on each floor, for a total of 99 rooms in the entire building. The layout of the units is the same on each floor.
Each floor provides rooms:
- triple rooms with separate double and single beds (2 such units per floor)
- single rooms
- double rooms with separate beds
- double with double bed
- three-room flat (one room with a double bed, one room with a single bed, living room with kitchenette)
- handicapped accessible double room with double bed
- double-bedded room adapted to people with disabilities with single beds
- triple room adapted to people with disabilities with one double bed and one single bed
Each hotel unit has a private bathroom. The rooms are of a higher standard. Accommodation can be used by up to 231 guests at a time. There is a restaurant on the top floor of the building with views of the city and the sea. The hotel has been designed in accordance with the standards and requirements, in terms of equipment and scope of services provided, promulgated by the Minister of Sport and Tourism in the Journal of Laws of the Republic of Poland of 24 November 2017 on hotel facilities and other facilities where hotel services are provided. The last floor (17) has a restaurant for hotel guests and external visitors.

Residential building
The 90 m high tower is located to the left of the lower skyscraper. It connects on the first 3 floors to the office building and on the 4th floor to the wellness&spa. The remaining floors (from 6 to 24) have been allocated to flats and flats. The highest floor of the building is a public viewing point from which the city and the sea can be observed. The ground floor of the tower on the courtyard side has the entrance to the residential building, along with a reception area, security room, utility room, cloakrooms, toilets and staff welfare room. The western part of the tower on this floor has been dedicated to office functions. The next two floors, due to the connection between the high-rise and the office building, have been entirely dedicated to offices for rent. The 4th floor has changing rooms and bathrooms for those using the leisure area. Floor 5, as in the hotel building, has administrative rooms and a private laundry for residents. From floors 6 to 14 there are one-, two- and three-bedroom flats and studios. There are two studios per floor and they each have 36 m². The 2-room flats are five per floor and range in size from 44 to 64 m². There is one 3-room flat on the first floor with a floor area of 62 m². Floors 7 to 24 have 4 flats per floor, two are 3-room flats occupying 88 m² each and a further two are 4-room flats of 117 m² and 118 m² each. In total, there are 132 flats in all. The area of the top floor (25) with a viewpoint is 473 m² (not including the communication riser). The space of this level is not landscaped in detail, with only benches for visitors viewing the views.

Office building
The building that houses the office building is 21 m high, with the first three floors reaching up to 18 m for office space and the last set-back floor being the wellness&spa area. The ground floor has a large entrance hall with reception area, social room (canteen), staff toilets, two staircases with lifts and 10 offices for rent. Floor 2 and 3 have the same floor plan layout, containing social rooms, staff toilets, two staircases with lifts, wide corridors, a waiting area for visitors/clients and 11 offices each. The staircases have been designed in accordance with fire regulations and the emergency access to the staircases does not exceed 20m. The lifts are 2.1 x 1.1 m in size and only have an overhead shaft so as not to interfere with the underground car park (to whose level they do not descend).

Wellness&spa building
The wellness&spa area is not only a recreational function, but is also an important part of the building in terms of its use. It was designed to be a suspended link between the two towers. It occupies the 4th and 5th floors and houses swimming pools, jacuzzis, saunas, a gym with training rooms, a bowling alley and billiards with other gaming tables. The aquatic zone (pools, jacuzzi and saunas) is spread over 798 m², the entertainment zone (bowling, billiards and others) accounts for 1054 m², while the gym in the lower part has 655 m² and the mezzanine with training rooms 303 m². A highlight of the wellness&spa is that the entire part of the building is glazed, allowing views of the sea and the surrounding area while relaxing and training.

Underground garage
The underground section provides space for all the technical infrastructure necessary for the functioning of the building, solid waste collection areas - separate for the residential, service and catering areas, a delivery zone with storage facilities and a parking space divided into 6 sectors, none of which exceeds an area of 5,000 m². According to the provision of the local plan, 1-1.4 parking spaces per residential unit, 1-3 spaces per 100 m² of service area and 1-2 spaces per 100 m² of office area should have been planned, and furthermore 20% of these spaces should have been public spaces. This means that 132 to 185 parking spaces must be provided for the 132 designed dwellings in the project, 67 to 134 for the 6684 m² designed office space and 59 to 176 for the 5864 m² designed service space, for a total of 258 to 495 parking spaces and 310 to 594 including public spaces. In accordance with the Hotel Facilities Ordinance, only an arrival/departure parking space is sufficient for the hotel part in the case in question. Taking these criteria into account, 438 parking spaces located on two underground floors were designed. As the wording of the local plan indicated the possibility of developing the basement of the neighbouring plot , it was therefore used for parking purposes. The underground exits of this plot were backfilled with earth material excavated during construction and coherently integrated into the park to improve the aesthetic quality.

Conditions for use by persons with disabilities:
The entire complex is designed in accordance with the idea of barrier-free architecture, that is, all zones and rooms are accessible to people with different levels of mobility. The floor level of the first floor is at the level of the sidewalk in front of the entrance, and door thresholds do not exceed 0.02 m in height. For each public hygiene and sanitation facility, a place is provided for people with limited mobility to take care of their needs. In the event of a difference in floor height in the Wallness&SPA area, a stair platform is used. At least one type of residential and hotel unit each is adapted for use by wheelchair users (free space with a diameter of 150 cm).

Technical information

Construction layout and implementation technology :
The complex, excluding the towers and the wallnes&SPA area, is designed in columnar construction. The largest span between the columns is 18.7 m. The stability of such a structure required the use of prestressed structures. Due to the complexity of the shape of the building, it was decided to use load-bearing elements in a post-tensioned concrete structure made on site.
The two towers were designed with a column and stem construction. The shaft is the communication riser located in the central parts of the buildings and is entirely cast in situ in concrete (wall thickness assumed to be 40 cm). At the extension of the axis of each wall of the shaft is an 80 cm diameter column. An expansion joint is used at the junction of the towers with the rest of the complex. The vertical structural arrangement remains unchanged on all storeys - the displacement of each successive storey relative to the previous one is only achieved by rotating the horizontal partition relative to its central point. The difference in the angle of rotation between the first and last storey for each of the towers is 15°.
Wallnes&SPA provides a link between the towers with no direct connection to the foundation. The force reactions are transmitted to the ground through the load-bearing elements of the office and retail building. The load-bearing capacity of the connector is provided by steel profiles installed in the façade and connected to the floors, which form a box-like structural system.

Foundations:
The structure of the subsoil is unknown and would require a detailed study by relevant professionals, but due to its proximity to the sea, it can be concluded that the soils under the proposed plot are weak-bearing. The building was set on a monolithic foundation slab 200 cm thick. Loads are transferred to the load-bearing soil layer from the slab via 120 cm diameter piles to a minimum depth of 18 m.