Being the historical residence of Bonanni Family, an well-known noble family of Tuscanian origin, the palace was built in the sixteenth century and then modified and integrated, also after the damages occurred after the 1703 earthquake.
Close to Regina Margherita square, the building presents an renaissance architecture characterized by heavy angular buttress with clear evidences to fifteenth century patterns. The family coat of arms is placed in a corner of high visibility.
The present design includes an architectural ensemble consisting of four structures built in different times around a central courtyard. Originally, therefore, the Palace consisted of one main building (block 1) close to which additional buildings were erected during the centuries, up to the current planimetric configuration
The building which has been subject to consolidation and seismic retrofitting is shown as Porzione 1 (Blocco 1, Blocco 2, Blocco 3, Blocco 4) and consists of four blocks, as shown in the figure n.1 below.
A brief description of the vertical and horizontal structures of Portion 1 of the relevant built-up area is shown below:
- Foundations: The foundations of Portion 1 of the built-up area make the natural continuation of the masonry in elevation, with a slightly greater thickness.
- Masonry: All levels of the building have vertical structures made of unconnected stone courses, similar to rubble masonry.
- Ceilings Floors: Brick vaults characterize the ceilings of the basement levels of the whole building and of the first and second planking of block 1 (blocco 1). The remaining horizontal structures are made of steel beams and bricks and, to a small extent, of concrete and masonry floors.
- Roof: The bearing structure of the roof is mainly made of wooden main beams, wooden counterframe and top planking and tiles. Small portions of the roof feature a concrete and masonry bearing structure.
DAMAGE FROM THE EARTHQUAKE
The earthquake occurred on 6th April 2009 and the following days caused severe and widespread damage of various types and grades to both vertical and horizontal structures, especially in blocks 1 and 2 (corpo 1 and corpo 2). In particular, the front wall facing Piazza R. Margherita (block 1) shows remarkable detachment and start of tipover.
Less widespread and smaller blemishes affect the walls and floors of block 3.
No blemishes were found in floors or reinforced concrete structures of block 4, which was built later with a reinforced concrete framework joined to the relevant portion of the built-up area.
DECRIPTION OF INTERVENTIONS
The project of repairs and seismic retrofit included a number of interventions that did not alter the size in plan and elevation of the pre-earthquake conditions, also considering the valuable architectural characteristics as stated by the Ministry of Architectural Heritage. The interventions were carried out in compliance with general principles of coherence, compatibility and reversibility of materials and techniques, according to the guidelines of Ministry.
To guarantee minimum safety levels, according to the Italian seismic protection standards, some reinforcements to the vertical and horizontal structures are planned.
For block 1 and 2, the structural works are as follows:
> MASONRY WORKS
Consolidation with injections of fluid non-shrinking hydraulic grout fluid in the whole bearing rubble masonry. The method consisted in injecting a binder mix, either pressed or poured, into the gaps of the wall to be consolidated, so as to restore continuity in case of widespread blemishes. Moreover, to improve strength to the minimum limit required to reach minimum improvement, the masonry has been reinforced with fiberglass mesh and mortar. Because of the mechanical resistance, durability, reversibility and compatibility with mortars and original building materials, a reinforcing system, consisting of G.F.R.P. (Glass Fiber Reinforced Polymer) mesh, connectors and angle elements made of AR (alcalyne Resistant) glassfiber with thermosetting resin, has been used. All masonry reinforcing elements were produced and supplied by Fibre Net srl. The mesh, size 66x66 mm, has been applied on both sides of masonry and has been connected through connectors, all made of G.F.R.P., in order to guarantee the most suitable and effective cooperation between reinforcement and masonry structure. An acceptable improvement of mechanical performances (shear resistance) of the structure has been achieved.
Such technique does not present the typical corrosion problems shown by traditional materials and is suitable to be applied with any type of mortar (i.e. lime mortar), fully in compliance with recommendations and guidelines for historical-artistic buildings.
The application of G.F.R.P. reinforcements together with lime mortars grants a non rigid, transpiring plaster very different from the traditional cement mortar and steel mesh systems.
The reinforcement has been applied on all the masonry surface, resulting in an homogeneous and diffused seismic improvement.
Moreover, the following works have been carried out:
- filling the niches with solid bricks fastened to the masonry with the indenting (cuci-scuci) method;
- rebuilding an internally damaged wall with antiseismic bricks.
> PLANKING WORKS
All obsolete or worn-out floors have been dismantled and rebuilt with new steel bearing elements and brick flooring blocks.
The iron and brick floors not rebuilt have been consolidated.
The rebuilding and consolidation of iron floors and flooring blocks have been carried out with a special care devoted to:
• Anchoring the steel beams to the masonry with stumps welded to the beams and fastened with bolt anchors to the perimeter masonry;
• Filling the steel beams with lightweight materials up to their top edge;
• Preparing a thin concrete screed (maximum 4 cm), reinforced and anchored to the perimeter masonry by means of metallic tie-rods with bolt anchoring.
The brick vaults were reinforced by emptying and re-filling them with lightweight materials.
The wooden roof is bound to be rebuilt. Minor works.
[by Cecilia Zampa e Allen Dudine]