Hall B

Hall B was inaugurated on 15 September 1948. Conceived like a cathedral, the hall consists of a nave covered by an undulated thin vault, and of an apse with a ribbed hemispherical dome. Figure 2 shows a plan of the complex, with the Hall B coloured in red (on the left), and a detail of the ribbed apse (on the right). In its first configuration, Hall B measured 96 metres in width and 110 metres in length. Between 1952-1954, Hall B was enlarged by five spans in order to move the façade on the street. Hall B reached the length of 155 metres. For the vault, the architect studied special wave-like elements in prefabricated ferrocement. The centre line of the arched vault of Hall B, approaches the funicular of permanent loads, and is formed by the union for each arch of the 13 prefabricated thin ferrocement undulated elements of approximately 4.5 m weighing 1500 kg each. Their ends are stiffened by diaphragms that leave an empty space of 4 cm to be filled with cement mortar. These waved elements were patented in August 1948 just before the inauguration of Hall B (Patent n. 445781). The idea was to shape the prefab elements using a geometry that would guarantee a high moment of inertia with a minimum amount of material. The problem of obtaining a true static collaboration of the precast elements was resolved by casting in place a concrete rib on both the top and the bottom of the undulations. These ribs were large enough to resist the principal stresses, while the sides of the precast elements assured the static tie between the ribs and re-established the monolithic nature of the whole (Nervi, 1948) (Nervi, 1965). 

As it has emerged from the preliminary knowledge phase, Hall B is a very complex building (see 3-D representation). The building is composed by a large number of elements, 390 pre-casted ferrocement pans in seven different depths, slanted pillars and innovative solutions like the fanned elements, that Nervi designed to condense loads from lightweight, folded plate roofs into the piers. 

The underground Pavilion by Riccardo Morandi

The underground Pavilion (also known as Pavilion V), designed by Morandi in 1958 as an expansion of the Exhibition Center dedicated to hosting the industrial vehicle section of the Turin Automobile Show, is one of his most artistic buildings. At the same time it is one of his most complex structural artifacts. The Pavilion, largely inspired by the underground Lourdes Cathedral designed in those years by Pierre Vago and Eugène Freyssinet, consists of a single wide space, 69 m in width and 151 m in length, located 8 m below ground level. The general static scheme corresponds to the schemes frequently used by Morandi in bridges and overpasses, consisting in post‒tensioned beams on two inclined supports, with two cantilevering side spans subsequently anchored by post‒tensioned tendons at their ends, exerting a balancing effect on the bending moments in the main span. Differently from these usual schemes, in the Pavilion of the Turin Exhibition Center the main post‒tensioned ribs are not parallel beams, but are diagonally directed and reciprocally interconnected in order to obtain a spatial structure offering a high overall rigidity and lateral stability, and to contrast the instability of the very thin webs (16 cm) of the main ribs. In addition, the post‒tensioned ties at the ends of the side spans are not inclined tendons anchored on the foundations of the main inclined supports, as in the usual schemes for bridges and overpasses by Morandi, but are short ties embedded in prestressed concrete prismatic elements, whose tension forces are balanced by the lateral retaining walls and by the load of the soil acting on their foundations.