3.3 Wood trusses

Figure 7.

Figure 8.

36

Málaga (1721) [MPD, 64, 022].

Tortosa (1721) [MPD, 64, 019].

Military Engineering

These are gunpowder magazines having a pitched roof and a timber framing. In some instances a joggle-truss is used, i.e., in the projects for Cádiz (1718) [MPD, 64, 020] and Gerona (1755) [MPD, 10, 073]. In other instances a collar-beam truss is used, i.e., in Barcelona (1731) [MPD, 18, 100 and MPD, 18, 101]. But mainly these magazines are built using the Spanish double-framed roof. This is the case of the gunpowder magazines in Zaragoza (1729) [MPD, 28, 009], Zamora (1734) [MPD, 65, 042], El Ferrol (1772) [MPD, 04, 089], or Cartagena (1795) [MPD, 46, 051 and MPD, 46, 052]. Sometimes they are Spanish double roofs with small variations affecting the inclined tie beams, i.e., in Pamplona (1723) [MPD, 64, 023]

Figure 9. San Sebastián (1722) [MPD, 28, 034].

and El Ferrol (1738) [MPD, 47, 094]. Other projects feature scissors trusses, i.e., in Monzón (1740) [MPD, 54, 049], Palma (1748) [MPD, 65, 047], and Valencia (1754) [MPD, 06, 170]. The project for Barcelona (1796) [MPD, 46, 035] features a double-framed roof but with two horizontal rafters as tie beams. In other cases, such as the project for Málaga (1721) [MPD, 64, 022] (Figure 8), there is a mansard truss with two horizontal rafters (this structure is more similar to the models used in the upper body of military barracks).

brick masonry with a lime and pebble covering, as in the case of San Sebastián

Scientific Knowledge of Spanish Military Engineers in the Seventeenth Century

As for the projects which use ceramic bricks, a distinction must be made between four different types: firstly, those which feature a single-layer ceramic vault, like the ones for Zamora (1738) [MPD, 13, 113] or Ciudad Rodrigo (1739) [MPD, 12, 154]; secondly, those which feature a bottom layer of ceramic bricks, an intermediate layer of stone, and a top layer of lime and pebble, like the gunpowder magazine in Cardona (1718) [MPD, 18, 028]; thirdly, vaults designed with a double layer of ceramic bricks and a top fill of lime and pebble, like in the projects for Pamplona (1718) [MPD, 31, 032; MPD, 31, 033; MPD, 31, 034; MPD, 31, 035; MPD, 31, 036]; and lastly, projects which feature three layers of ceramic bricks, for instance, in Longone, Italy (1728) [MPD, 12, 221], or even four layers, like in

Pointed vault structures were described by Bélidor (1729), and Müller (1769) said they are less resistant to bomb impacts than barrel vaults. They belong to the Gothic building tradition, and they need a smaller abutment than barrel vaults, even though magazine walls in military treatises are dimensioned depending on the impact of pyroballistic weapons (those employing gunpowder) and not on the basis of masonry mechanic criteria. This is the case of the gunpowder magazines in Zaragoza (1729) [MPD, 39, 041] and San Fernando de Cádiz (1749) [MPD, 56, 029], which have only one enclosure. It is the same construction type as the projects for Gerona (1738) [MPD, 01, 018] and San Sebastián (1749) [MPD, 27, 094], but these two magazines are protected by an encircling wall, and therefore they have two enclosures. The gunpowder magazine projects for Gibralfaro Castle in Málaga (1724) [MPD, 59, 046 and MPD, 59, 047] (Figure 10) and Ceuta (1737)

[MPD, 07, 180] feature two parallel vaulted vans which are separated by square pillars supporting round arches, thus forming the central valley of the roof.

In the construction of gunpowder warehouses, barrel and pointed vaults are generally used, although there are some examples with elliptical vaults, such as that one built in 1694 by Hércules Torelli in Pamplona. This construction was remodelled by Francisco Larrando de Mauleón (1718) [MPD, 31,031] (Figure 11) [43]. Mauleón was professor at the Mathematics School of Barcelona and Zaragoza and authored the Estoque de la Guerra y Arte Militar, published in Barcelona (1699). The viceroy had ordered the repair of the fortifications and the gunpowder warehouses to make them bombproof. The elliptical vault was replaced by a barrel vault to make it less visible and vulnerable to enemy artillery. It was reinforced and reduced in height according to the concept introduced in the military treatises by General Ambroise

The simple vault of the warehouse of Montjuïc mountain in Barcelona (1731) [MPD, 07, 057], a project attributed to Miguel Marín (Figure 12), is not generated through an arch of circumference. The geometric study reveals that the vault has a length of 16 feet in toise, a rise of 11.5 feet, a width of 3 feet, and a buttress of 7 feet. A geometric element having the shape of a catenary can be drawn running through

4. The curve of equilibrium and the Spanish military engineers

(d. 1587) in Le Timon du Capitaine (1587) [44].

39

(1722) [MPD, 28, 034] (Figure 9).

DOI: http://dx.doi.org/10.5772/intechopen.87060

Badajoz (1749) [MPD, 65, 045].

3.5 Pointed vaults
