I have modelled a steel structure using beam elements in Abaqus and attached to this structure reinforced concrete slab. The analysis that I am making is heat transfer of the structure. The materials of steel and concrete have all defined the thermal conductivity, specific heat and expansion all according to Eurocodes. The element that I used for slab is shell element with rebar layers but when I run the analysis it shows that I cannot use rebar layers for heat transfer and I don't know how to fix this. Also when I run the analysis it shows that all the element of my structure don't have section assigned even though I assigned every section of each element. Beam element have been used for steel beams and columns and they connected by fix joints. The errors can also be shown at the figures below