Investigation of Moisture Condensation on the Surface of the Bottom Chord of a Steel Truss of a Historical Building

This paper investigates the conditions under which moisture condensation occurs on the surface of the bottom chord of a steel truss at the ceiling level of the attic hall of a historical building in Poltava, Ukraine. Moisture condensation on steel structural elements leads to steel corrosion and a decrease in the thickness of structural elements. As a result, the load-bearing capacity of both individual elements and the entire structure can be reduced. This paper describes how different parameters affect the process of condensate formation on the surface of steel bottom chord angles of the truss. Three parameters are investigated: the filling of the gap between the angles and precast reinforced concrete elements resting on the lower flange of the angles with thermal insulation; the filling of the gap between the two angles of the bottom chord of the truss with thermal insulation; and the possibility of detachment of the different sizes of finishing layer from the bottom flange surface of the angles. Verification calculations of the possibility of condensation forming on the metal surfaces of the bottom chord of trusses were also performed for the developed design solutions for restoration.