Architects:

Jose M. Bassalo and Flavio C. Nascimento

Structural Engineer:

Paulo A. B. Barroso, Technica Consultoria & Projetos Industriais Ltda., http://www.technica.com.br

Ananindeua is a small town in near the suburbs of Belem, capital of the state of Para. One of the most important sources of income for this community is its abundant commerce of fish and fruit, produced by the local fishermen and farmers. As a result of the ever expanding market, the existing site and its surroundings had turned into one of the busiest places in town. The infrastructure had become unsuitable and insufficient, and the search for a better place was urgent.

The new market place was inaugurated by November 2006. It covers 3250sqm of an old and unused public land. This particular location was chosen mostly because it could provide better and more convenient transit and transportation facilities. The new market site could also benefit from other important advantages already present, like a sewer system, and the supply of electricity and drinking water.

The membrane roof was conceived as a combination of three main structural elements: 42 hexagonal chalices (inverted umbrellas) with a diameter of 9.6m, 4 hexagonal umbrellas with a diameter of 16m, and 2 main conical tents – hexagonal shaped, with a 16m diameter as well.

The membrane roof elements were designed to be supported by a very rigid tubular steel space frame, fixed on bases by anchor bolts, and their edges clamped by circular steel rings. This entire structural system behaves as a whole, thus providing exceptional stiffness to withstand pre-tension stresses and all service loads.

The corners of the chalices, umbrellas, and cone tents were designed with tensioning devices, in order to be able to provide all respective membranes with the appropriate tension. Membrane edges are sustained by threaded rods, protected by pockets, and fixed at the ends by nuts. This would allow for additional tension regulation, and for stretching membrane borders as well.

Rain water is collected by special steel plated funnels at the centre of each chalice. Funnel and  its inferior steel ring also served for additional tension regulation . Thus, each membrane structure element had 6 peripheral sets of restraints, and one internal point at the bottom.

For better internal ventilation and dynamical air and heat exchange, each inner connecting ring was provided with an air exhauster.

To seal gaps between the hexagonal edges of the chalices, an additional skylight covering was necessary, in the shape of semi-elliptical eyes. By choosing an opaque white textile membrane, a special effect could be achieved especially under artificial lighting.

Because of the aggressive hot and damp north Brazilian tropical weather, with heavy rains almost every day, all metalwork had to be protected against corrosion by hot dip galvanization. This will improve the weather resistance capacity of all steel parts to match the membrane's life cycle.

Market on the run