PSI - Issue 28

M.L. Puppio et al. / Procedia Structural Integrity 28 (2020) 330–343 Puppio M.L. et al/ Structural Integrity Procedia 00 (2020) 000–000

332

3

Table 1. Causes of collapse and repairing costs.

n° Date

Location

Collapsed portion Observed cause

Repair costs

1 2 3 4 5 6 7

Sept. 2011 Pistoia

50 m

Poor masonry quality and low maintenance 1.500.000 €

Nov. 2012 Magliano in Toscana 30 m

Poor masonry quality and intense rainfall

980.000 € 170.000 € 1.500.000 €

Oct. 2013 Jan. 2014

Cana di Roccalbegna 13 m

Intense rainfall and low maintenance

Volterra

35 m 20 m

Intense rainfall and poor drainage system

Mar. 2014 Volterra

Intense rainfall and low maintenance

500.000 €

Dec. 2014 Apr. 2018

Magliano in Toscana 15 m

Poor masonry quality and low maintenance 300.000 €

San Gimignano

20 m

Intense rainfall

500.000 €

In Section 2 a set of case failures for urban walls are briefly described. In Section 3 the survey methodology is illustrated. In Section 4 a specific form is presented to activate a quick and applicable procedure. Discussion and conclusions are reported on Section 5. 2. Collapses of urban walls in Tuscany in the last decade (2011-2020) Seven cases of failure that involved the urban walls of five historical villages in Tuscany Region in the last ten years are here briefly described (Fig. 1) (Table 1) [5]. 2.1. Pistoia On September 2011, about 50 meters of medieval walls partially collapsed in Pistoia after an intense rainfall. The evidences of the collapse (related to the internal face) showed the low material quality of the walls, essentially polished stones from the Brana river (h=11.0 m; h’=7.0 m; b=1.6m) with a earth filling of about 4,0m. A visual examination displayed some rearrangements of the masonry texture, testifying of previous collapses and reconstructions occurred in the past [6]. Fig. 2 highlights a weak core of the walls and the presence of vegetation which is an evident sign of moisture. A reconstruction based on a series of steel diatons has been carried out.

Fig. 2. Collapse of façade of Pistoia walls (September 2011).