This page explains the commonly used shortcuts and conventions graphically for planar and linear elements, offering clarity on how these elements are defined, interact, and behave within the software environment.
Discover below more about the linear and planar elements conventions:
Local axes:


Fx: Normal force Attention! Fx is positive in case of tension and negative in case of compression, regardless of the orientation of local x. 

Fz: shear force due to a load applied along the local z axis 

Fy: shear force due to a load applied along the local y axis 

My: bending moment about the local y axis. ( = the moment generates a load applied along local z) Note: My > 0 => the upper fibre (z+) is tensioned (generally, on the supports) My < 0 => the lower fibre (z) is tensioned (generally, on the span) 

Mz: bending moment about the local z axis. (= the moment generates a load applied along local y) Note: Mz > 0 => the upper fibre (y+) is tensioned Mz < 0 => the lower fibre (y) is tensioned 
Az: reinforcement provided by moment My Az is provided with a “  ” sign when in lower fibre and with a “ + ” sign when in upper fibre My positive provides Az reinforcement in upper fibre (because the upper fibre is tensioned). (generally, on the supports) My negative provides Az reinforcement in lower fibre (because the lower fibre is tensioned). (generally, on the span) 

Ay: reinforcement provided by moment Mz 

Atz: shear reinforcement provided by the shear force Fz 

Aty: shear reinforcement provided by the shear force Fy 
Normal stress (normal force and moments) Shear stresses σxz: stress in the plan of the x normal, in the direction parallel to z σxy: stress in the plan of the x normal, in the direction parallel to y Von Mises stresses (normal and shear stress) 
Local axes:


Fxx: Normal force along the local x axis Fyy: Normal force along the local y axis
Attention! Fxx is positive in case of tension and negative in case of compression, regardless of the orientation of local x (Idem for Fyy) 

Fxz: shear force in the plan of the x normal, in the direction parallel to z 

Fyz: shear force in the plan of the y normal, in the direction parallel to z 

Mxx: bending moment about the local x axis Note: Mxx > 0 => the upper fibre (z+) is tensioned (generally, on the supports) Mxx < 0 => the lower fibre (z) is tensioned (generally, on the span) 

Myy: bending moment about the local y axis Note: Myy > 0 => the upper fibre (z+) is tensioned (generally, on the supports) Myy < 0 => the lower fibre (z) is tensioned (generally, on the span) 
Axi and Axs: reinforcement bars parallel to the local x axis (provided by the moment Myy) Myy positive provides Axs reinforcement (in upper fibre) (because the upper fibre is tensioned). Myy negative provides Axi reinforcement (in lower fibre) (because the lower fibre is tensioned). 

Ayi and Ays: reinforcement bars parallel to the local y axis (provided by the moment Mxx) Mxx positive provides Ays reinforcement (in upper fibre) (because the upper fibre is tensioned). Mxx negative provides Ayi reinforcement (in lower fibre) (because the lower fibre is tensioned). 
Normal stress (normal force and moments) Along x Along y Shear stresses σxz : stress in the plan of the x normal, in the direction parallel to z σyz : stress in the plan of the y normal, in the direction parallel to z Von Mises stresses (normal and shear stress) 