Flexural members support the load by controlled bending which generates bending stresses and strains. They generally are horizontal members that are used to support gravity loads like the self-weight of the structure, people in buildings or vehicles on a bridge. Beams are commonly used to support the floor or deck of a structure. A girder is used to support a series of beams and carry the load to the columns. They are sometimes thicker because they must support the extra mass of the curtain wall.
Slabs generally have a thickness that is much less than both their length and width.
Slabs are supported by beams and girders. Often when beams and slabs are poured as one integral unit they are designed and analyzed as T beams where the slab is the compression flange and the beam provides the tensile capacity. They function by resisting normal stresses and transferring the loads to the structure foundation. The flexural members transfer the gravity loads to the columns in a structure and the columns transfer this load into the foundation. Although columns are primarily axial compression members, it is important to recognize that most columns also experience flexure loadings as well.