In addition to voltage

In technical mechanics, secondary stresses are understood to mean stresses within a truss, which additionally include, for example, through the elastic bending deformation of the trusses to the tensions of the ideal truss according to the theory of the subject. Under certain conditions, the secondary voltages can assume considerable values. The stresses due to loads perpendicular to the fuselage plane, for example, from wind loads, also belong to the secondary stresses. Secondary stresses are particularly important if the trusses have a low slenderness. Edit NullStateQual

Zero bars are rods in the framework that do not experience tensile or compressive forces under a given load effect according to the theory of the first order, ie they are de-energized according to the theory of the subject. However, they can nevertheless have secondary voltages. A rod which is a zero rod in the case of a load case can be a pressure or tension rod in another load case. There are three rules for detecting zero bars: (However, there may be additional zero bars in the system.)

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