The Riding School in the Royal Palace of Naples: Transformations ...

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The possibility of evaluating the structural reliability of the design realized by Niccolini is interesting as the riding school was demolished only 20 years after the building of the new covering system: its preservation for a long period cannot thus testify of its efficiency. The calculation scheme has been modelled in the hypothesis of a plane problem, with one- dimensional finite elements, in the range of linear elasticity. The presence of the Jupiter’s dart like joints, fixed with pins, between the timber elements constituting the tie-beam and the principal rafters has allowed the schematization of those structural parts as single beams, as the locked indentations obstacle mutual sliding. The timber corbel and the lower timber corbel under the tie-beam cannot be assumed integral with it, and so in the scheme can’t be inserted a variable cross-section tie-beam, because of the lack of special devices introduced to prevent completely mutual sliding, as the insertion of hard timber wedges. In any case, the introduction in the calculation scheme of elements modelling all the metallic strips and connections described in the document allows the schematization of the effective transmission and distribution of stresses between the structural elements. An analogous situation can be envisaged referring to principal rafters, jack-rafters and lower rafters (fig.9). Figure 9. Calculation scheme of the truss As concerns the constraints between the timber structure and the perimeter masonry walls, the possibility of sliding and rotation has been left for the truss headpieces, while for the lateral trestles the absence of lower ends translations have been assumed, as those extremities are housed in slots expressly cut in the masonry. 612
As just described, the structure is made of timbers of different species, oak, chestnut, fir, and also poplar for the centrings, used as illustrated in the following drawing (fig.10). For those different timber elements, the characteristic values have been taken from the Italian norm UNI 11035-2 and are quoted in (table 1). Figure 10. Distribution of the different timber used in the truss Table 1. Characteristic values assumed for the different timber employed FIR CHESTNUT OAK POPLAR f c,0,k (MPa) 23 22 27 22 f m,k (MPa) 29 28 42 26 f t,0,k (MPa) 17 17 25 16 E 0,mean (MPa) 12 000 11 000 12 000 8 000 G mean (MPa) 750 950 750 500 mean (kg/m 3 ) 415 550 825 460 The calculation scheme has been completed introducing loading as can be inferred from Niccolini’s detailed description; particularly, action of the dormer-windows on the principal rafters as well as that of the centrings on the tie-beams have been schematized as single forces transferred at the 613
Page 1 and 2: The Riding School in the Royal Pala
Page 3 and 4: equired staff: pageboys, coachmen,
Page 5 and 6: Figure 2. Model of Naples Royal Pal
Page 7 and 8: Figure 4. Front page of the documen
Page 9 and 10: Measures of weight, also used to qu
Page 11 and 12: The clear span is the same of that
Page 13: An evident element thought to stren
Page 17 and 18: Figure 12. Bending moments diagram
Page 19 and 20: Both the calculation schemes analyz

The Riding School in the Royal Palace of Naples: Transformations ...

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