The Design of Timber Trusses in Italy: From Empiricism to Structural Analysis

Until the mid-nineteenth century timber trusses were empirically designed thanks to centuries-old experience. Since the early nineteenth century the theory of statically-determinate trusses had been elaborated for the analysis of metal trusses, but this could not be used for timber trusses, because loads were not applied in joints, a hypothesis required to ignore static indeterminacy. In the late 1850s a specific analysis method was developed for timber trusses: it considered rafters as continuous beams on rigid supports, thus it did not satisfy constitutive and strain-displacement equations. However, theoretical developments of the 1870s allowed the exact calculation of statically-indeterminate structures, thus engineers often continued to resort to empiricism, or simplified methods.