# Assumptions

We proceed from the assumption that the cross-section is intact and without spalling.

This is the ordering of sides:

• T: Top
• B: Bottom
• L: Left
• R: Right
 The following assumptions are made for rectangular cross-sections:The sides that are exposed to fire may be chosen freely. (L, R, T, B). The following assumptions are made for T-type cross-sections:We may freely choose the sides that are exposed to fire (L, R, T, B). The left and right sides of the body and the bottom of the flange are considered exposed to fire in the same manner as the bottom of the body.During calculation, the cross-section is divided into a body of width b (body width) and height h (original cross-section height) and a flange with width bf and height hf.The body is exposed to fire on the following sides: (L,R,T,B) = (B,B,T,B)The flange is exposed to fire on the following sides: (L,R,T,B) = (L,R,T,B)The flange must be exposed to fire in the same way on the right and left side of the flange (L= R). The following assumptions are made for F-type cross-section:We may freely choose the sides that are exposed to fire (L, R, T, B). The body's left and right sides and the top of the flange are considered to be exposed to fire in the same manner as the top of the body.During calculation, the cross-section is divided into a body of width b (body width) and height h (original cross-section height) and a flange with width bf and height hf.The body is exposed to fire on the following sides: (L,R,T,B) = (T,T,T,B)The flange is exposed to fire on the following sides: (L,R,T,B) = (L,R,T,B)The flange must be exposed to fire in the same way on the right and left side of the flange (L= R). The following assumptions are made for I-type cross-sections:We may freely choose the sides that are exposed to fire (L, R, T, B). The top of the bottom flange and the bottom of the top flange are considered fire exposed in the same manner as the left and right side of the body.During calculation, the cross-section is divided into a body of width b (body width) and height h (original cross-section height) and flanges with width bf and height hf.The body is exposed to fire on the following sides: (L,R,T,B) = (L,R,T,B)The top flange is exposed to fire on the following sides: (L,R,T,B) = (L,R,T,L/R)The bottom flange is exposed to fire on the following sides: (L,R,T,B) = (L,R,L/R,B)Right and left side must be ones exposed to fire (L = R). The following assumptions are made for L-type cross-sections:We may freely choose the sides that are exposed to fire (L, R, T, B). The right side of the body and the top of the flange are considered exposed to fire in the same manner as the top of the body.During calculation, the cross-section is divided into a body of width b (body width) and height h (original cross-section height) and a flange with width bf and height hf.The body is exposed to fire on the following sides: (L,R,T,B) = (L,T,T,B)The bottom flange is exposed to fire on the following sides: (L,R,T,B) = (L,R,T,B) The following assumptions are made for Plate/Wall and Hollow Core Cross-Section:We may freely choose the sides that are exposed to fire (T, B). The end of the plate/wall (left and right) sides are not exposed to fire. The following assumptions are made for circular cross-section:Circular cross-sections are exposed to fire on all sides. 