Una Casa
Breganza, Italy

Mario Botta, architect

Location

History

Bricks and masonry have been a significant construction element for thousands of years. Mario Botta is a modern architect exploring the use of these materials in contemporary architecture. though we are not attracted to the overall form of this residenc e, we are intrigued by Botta's use of masonry block for a number of different applications. Bricks and masonry blocks are used as decoration, flat and curving wall, column, as crenelated wall, as staircase and floor.

Physical Description

Building Function: single family residence
Building Size: 930 square meters
Construction Materials: masonry block, glass and steel

This structure consists of clearly defined solid and void. The entrance is marked by a vertical planar element about which the building is symmetrically oriented. From this vertical element comes a horizontal element- a bridge- which leads one through t he two central columns and into the center of the house. The center of this house is void. The overall shape suggests a traditional box form split open at the corner with this bridge taking us right into the middle of it. The flat walls that define the sides morph into symmetrical curvilinear walls at the upper level. They turn towards each other but stop short of meeting. They appear to be floating in the photos.

The plan is based on a square with two central columns placed about one third of the way towards the center from the corner along a line connecting two opposite corners. These two columns form the end points (and end supports) for the rectangular shaped bridge which defines the entrance. This rectangle is therefore at forty five degrees to the natrual axis of the square.

The exterior facade of brick and masonry block is probably not the load-bearing structure whereas the concrete floors are the surfaces of the floor system. The exterior facade consists of horizontal strips which consist of a double layer of gray masonry and a single later of white brick.

The curved wall portion which cantilevers over the upper deck is clearly a use of masonry in a way that denies its inherent structure. It is used as wall surface while the underlying structure is concrete and steel. While we may not agree with his use o f masonry as decoration, this curved element is an evocative piece of this building.

Building Process

The majority of the vertical loads in this buildign are easily resisted by load bearing masonry walls. Loads are distributed to the walls which support the reinforced concrete floors. No structural details were available of the floor or wall constructio n or the floor to wall connection, but we will conjecture that the structure of the wall is masonry block with rebar placed in it, which ties to the rebar in the floor system, and then concrete poured within the masonry blocks. The slab floor probably ha s steel beams which span between the load bearing walls and the two central load bearing brick-clad columns. If there are steel beams in the floor system, they rest on the masonry blocks in the bearing walls.

The connection where the floor meets the wall may be described as a pin connection (assuming the construction details are as I have described). The steel of the floor is tied into the steel of the wall, but most likely, it is not a welded connection. Th e floor may have I-beams which rest on the masonry blocks. The concrete within the wall and the concrete floor are poured at different times and are therefore, exxentially, separate systems. Therefore, I do not think that this is a moment connection. T his system will allow for some lateral movement to occur without breaking.

Structural Descripton/Aspects

Vertical Loads
If one were standing on the roof of this building, loads would be carried out to a load bearing wall by the rigid horizontal frame created by the steel members in conjunction with the concrete slab. The force is then carried down through the wall to the foundation. It is a very simple structural system with the exception of the two cantilevered curved sections which protrude on the third floor above the entrance. If one were standing on the roof of this portion of the building, a load would be placed o n the cantilevered end of a rinforced concrete floor system. These forces are transferred to the two central bearing columns and the exterior bearing walls. The moment created within the cantilver is counteracted by the wall and its connection to the fo undation.

Lateral Loads
This building resists lateral loads by the combination of diaphrams on the two perpendicular back walls in conjunction with diaphrams inherent in the floor slabs. Thenecessary triangulation seen in timber frame structures, for example, is not necessary h ere because tringulation is complete within the slabs. This structure achieves the strength of a concrete slab cube with almost no structure on the two entrance walls. In addition to acting as diaphrams, the floors also resist buckling in the columns by decreasing the effective buckling length.

Conclusions

Bibliography

Mario Botta: Una Casa. Electa, Milano, Elemond Editori Associati, 1989.

Associated Buildings

Ambrose Poh and Michael Zaretsky
ARCH 461/561 Spring 1995

Do you have questions about adding a case? or a building to suggest??????? send a message to me....... chrisl@aaa.uoregon.edu

Una Casa Breganza, Italy