CONNETTORI METALLICI INCLINATI PER IL CONSOLIDAMENTO DI SOLAI

Andrea Antonio Bassoli1, Daniele Rampoldi2, Lorenzo Jurina3

1 Ingegnere e Architetto libero professionista, Milano, andrea.bassoli@gmail.com

2 Ingegnere libero professionista, Milano, d_rampo@inwind.it

3 Politecnico di Milano - dip. ABC, lorenzo.jurina@polimi.it

ABSTRACT

The consolidation of wooden floors and roofs is a frequent topic in the recovery of existing buildings. Adaptation to new functions usually means adaptation to new loads, which are often higher than the ones originally adopted. As a consequence, the residual capacity of the structures could be unsufficient.

A widely adopted consolidation technique consists in the realization of mixed sections (wood-concrete, wood-steel, wood-wood), in which the type and distribution of the connectors defines the degree of collaboration between the two materials. A variety of patented systems, materials, geometry and anchoring techniques are available, even if the use of simple steel grouted bars, mainly arranged vertically, remains the most used.

In some recent consolidation projects a change in the use of traditional metal connectors was proposed, adopting metal bars inclined at 45° instead of vertical.

The new timber structure, such consolidated, behaves as a sort of reticular truss beam. The upper current (in the specific case a r.c. thin slab) is subject to compression, while the lower current (the wooden beam) is subjected to traction. The inclined connectors are alternately either in tension or in compression, as in a normal truss. The solution is particularly useful when one has to bypass empty spaces between the upper floor and the main beam, such as the space occupied by the secondary beams.

In the present paper the results of some experiments, based on the comparison between FE models and real load tests, are shown. The proposed cases are Villa della Porta Bozzolo in Casalzuigno (VA) and Scotti’s Palace in Laino d’Intelvi (CO), where the consolidation of inclined timber roofs was performed, and the Tower of Cassina de' Pecchi (MI) and Brivio-Crosti-Colombo’s Palace in Nova Milanese (MI) where the consolidation of horizontal timber slabs was needed.

All these applications have demonstrated the effectiveness of the inclined bars system and have allowed to reach the standard requirements in terms of resistance and sag, obtaining interesting formal results, at the same time.

Parole chiave/Key-words:

Consolidation, Timber slabs, Truss beam, Inclined connectors