Master thesis at the Chair of Construction History and Structural preservation, written by Konrad Frommelt in the summer semester 2018.

England and France are commonly referred to as the early centres of iron usage in building. Besides that, significant development on the design and construction of full iron structures also took place in 18th century Russia. These structures are a sign of a flourishing metallurgical industry and they document the search for longlasting and fireproof building materials.

An impressive example of the beginning use of iron as primary construction material is the roof structure of the Marble Palace in St. Petersburg, erected in the 1770s and covering an area of more than 4000 m². It consists of multiple girders with spans up to 13 m, adapted to many different situations and roof geometries of the palace’s attic. 

Based on extensive in-situ investigation, this thesis documents the geometry and the conservation state of this structure, systems used and typical connections. A statical analysis of a part of the structure is carried out to investigate structural behaviour and load bearing capacities. This is supplemented by material analysis of samples obtained in situ; helping to gain a better understanding of the properties and capacities of the used materials.

Although the main and stiffening structures can still be considered capable of taking all loads, apparent structural flaws are identified where the structure is not optimized for occurring bending stresses. The investigation shows, that systems and connections relate closely to common solutions in timber construction, which are combined with innovative developments. The load bearing behaviour is based on a layering of several bearing systems. Analysis of varying solutions in different parts of the structure suggests that the whole roof structure served as a kind of laboratory being developed iteratively.