Álvaro Siza, Viana do Castelo, Portugal, 2000
The building of the Municipal Library of Viana do Castelo has two stories divided structurally into two distinct zones. One (zone 1) continuously supported at floor 0 level in the foundation, and another (Zone 2) which is supported on two L-shaped columns and in the zone 1, freeing the lower space as was intended by the architecture.
The soil type is characterized by the existence of heterogeneous landfills, with mixed stone blocks, above Rock with a depth ranging 10.0m and 20.0 meters north to south. For this reason was chosen an indirect foundation consisting of jet grouting columns, involving micro-stakes (Type IV) sealed in the rock.
The building zone supported on the ground is constituted of slabs and walls forming an orthogonal grid; this zone is supported in these columns along the walls. The L-Shaped pillars of the elevated zone are supported in an reinforced concrete solid tied to columns in groups of jet and Micros. SUPERSTRUCTURE
We can consider two different situations:
In Zone 1: Solid or composite steel slabs supported by concrete bearing walls of reinforced concrete.
In Zone 2: The structure of this this zone having the existing spans and apparent concrete finishing apparent consists of a steel skeleton coated with concrete.
The structural scheme adopted consists of a beam lattice grid at the coverage level supported zone 1 of the building and in two crossed metal which under the 1 floor becomes two L´s that for architectural reasons have one of the flaps placed in the less inconvenient, yielding tractions on the outer side of this flap. This metal grid suspends by struts the floor of the library that consists of a mixed structure of steel beams with reinforced concrete blades on the upper and lower face (apparent concrete).
Given that this whole area should have the minimum possible deformations, we decided to prestress with Dywidag rods the traction area of the cross shape support and with post-tension the mixed slabs of the hanging deck.
It should be noted that the apparent concrete is white and that the special characteristics of the work, drawing stereotomy, presence of metal structure, proximity to the sea, thick concrete sometimes thin sometimes thick (0.12 , 0.30 , 0.42 , 0.54) demanded great accuracy in the study of its composition, and the study of the formwork. The collaboration of the contractor including the direction and site preparation, enable the successful completion, with the necessary quality, designed the building.