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3D MODELLING
Design of a Super-Light dome structure for a market over the Elsinore freeway
This project is the design of a concrete building to host a market square or other facility in a new urban area. The aim of the design was to make this construction visually appealing, functional, sustainable and integrated into its surroundings.
The project includes every stage of design:
Concept and sketches
The initial requirements stated that the market is to become a landmark of the district. For this, the geometry is based on curved shapes, in contrast with the rectangular building blocks.
The structure is designed to provide shelter for hosting leisure activities whilst opening up the space as much as possible, with plenty of light inlets.
It needed to be integrated into the surroundings and therefore, height was restricted to the height of the neighboring buildings and a green roof has been provided as cover, matching the green park area that will predominate in the new area.
Geometry
The chosen form was two twin domes, increasing the covered area. The final design also includes a lantern at the top of each dome and a gap between the domes for light to get through.
The spherical shape was chosen because it is easier to divide the dome into elementary precast units. These divisions were made taking into account the maximum size that is possible to transport by road.
Choice of materials and technology
Another important aim was to make the construction as light and sustainable as possible. For this, new technologies like Super-light and Pearl-Chain have been implemented.
Super-Light technology allows to lighten the design by providing regular concrete in the areas of the structural elements where it is required while the rest of the structure is composed by a light aggregate concrete.
Pearl-chain technology permits a sustainable construction as it is based on the reduction of temporary supports in construction. In this technology, pre-cast concrete elements are connected together in a larger structural unit by means of prestress tendons.
Static system and design approach
The static system is described with the load path for dead load:
- Light concrete panels work in shear
- Meridional arches in compression and bending – side edge beams of trapezoidal elements
- Additional resistance from rings in tension/compression – top and bottom beams in trapezoidal elements. Deflections in radial arches activate the rings. Bottom cupula ring designed to absorb all tension from above.
- Edge arches receive point loads from meridional arches and resist in bending. Tilting favours stability.
Structural verifications and optimization
All structural elements have been designed to withstand the permanent and variable loads acting on the dome. Material consumption has been reduced by the optimization of the geometry in the cross-sections, as well as the optimization of the cable shape of the pre-stress tendons.
Construction process
1) Foundation – steel pole as temporary supports for PC radial portions
2) Post-tensioning and erection of the edge arches – Temporary supports
3) Post-tensioning and erection of the Pearl-Chain radial portions of the dome – reaction needed when prestressing the longer portions to pre-compress the elements that will be positioned between edge arches.
4) Post-tensioning of the bottom cupula ring
5) Joint casting
6) Temporary supports removal
7) Finishings
Sustainability assessment
The sustainability of the dome design is evaluated by calculating the CO2 emissions derived from its construction and establishing a comparison between the emissions of an analogous in-situ casted concrete shell with the most common construction process used for this kind of structure: wooden formworks.
The calculation analyzes both the production and building phases of both dome designs, focusing mainly on material supply.
