ピエル・ルイジ・ネルヴィの形成期における橋梁の建設とその背景

Abstract

In this study, an attempt to shed light on Pier Luigi Nervi's design philosophy(included architectural and structural field) is made, which was formed before he left SACC(the company of Attilio Muggia who was his menter), and its formation process by focusing on a class of S. Canevazzi which Nervi took in School of Engineering and Architecture of Bologna and bridge construction he was actually in charge of in SACC. In chapter 2, the collapse of Risorgimento Bridge in Rome which S. Canevazzi illustrated in his class in 1913 was explained in detail. In Nervi's book published in 1955 (“Costruire Correttamente”), he referred to a German theorist who pointed out that the bridge had points where it exceeds the limit of collapse and the limit of safety according to a result of architectural analysis using elastic equation. By considering this criticism, issues of the bridge construction at that time emerge: the difference between using rigid connection like Hennebique's bridge and using pin joint like three hinges of Robert Maillart(1872-1940)'s bridge. Also, it confirmed the possibility that construction of this bridge of Rome and its discussion invited the development of architectural analysis and construction method of statically indeterminate structure and moreover, the new study of plastic capacity of reinforced concrete parts. In chapter 3, owing to observe his design philosophy and its formation process, the construction of Pelota Arena's roof, Cecina and Pescie Bridges are looked into and magazine articles he wrote at that time are analyzed. For Cecina Bridge, he conclusively adopted a design of Truss bridge with parabolic girders instead of an arch bridge with rigid connection. In contrast, he adopted a bridge of Vierendeel type with rigid connection in joint for Pescie Bridge. In his magazine article, he emphasized the advantages of rigid connection which included strengthening the bridge resistance, thinning parts and reducing materials. Also, this article demonstrated his tendency of putting emphasis on substantive side to prove the safety not only by mathematical analysis but also by measuring actual deformation on site, and his interest in plastic deformation. As a conclusion, it is brought into light that Nervi directed to the construction of statically indeterminate structure after learning about Risorgimento Bridge from S. Canevazzi and also experiencing construction of the Pescia bridge of rigid joint with A. Muggia and L. Poggi in SACC. Nervi, however, did not simply agree with the thinking about safety of F. Hennébique and A. Muggia for bridges based on their empiricism. Nervi's thinking was not only based on his experience in construction but also his calculation about safety of a structure in a scientific way, such as an experiment and numerical calculations with formulas. Furthermore he tried to find a new way to check a safety for construction. Lastly a further issue is to discuss about an idea of “costruttore progettista” proposed by Nervi through consideration of his construction works and his documents after his independence from SACC.