| Statically determinate: | (english) A statically determinate structure is one where there is only one distribution of internal forces and reactions which satisfies equilibrium. In a statically determinate structure, internal forces and reactions can be determined by considering nothing more than equations of equilibrium. |
| Statically indeterminate: | (english) A statically indeterminate structure is one where there is more than one distribution of internal forces and/or reactions which satisfies equilibrium. |
| Stiffness: | (english) This is a general term which may be applied to materials or structures. When a force is applied to a structure, there is a displacement in the direction of the force; stiffness is the ratio of the force divided by the displacement. High stiffness means that a large force produces a small displacement. When discussing the stiffness of a material, the concept is the same, except that stress substitutes for force, and strain substitutes for displacement; see modulus of elasticity. |
| Strength: | (english) A very general term that may be applied to a material or a structure. In a material, strength refers to a level of stress at which there is a significant change in the state of the material, e.g., yielding or rupture. In a structure, strength refers to a level of level of loading which produces a significant change in the state of the structure, e.g., inelastic deformations, buckling, or collapse. |
| Support: | (english) A support contributes to keeping a structure in place by restraining one or more degrees of freedom. In a structural model, supports represent boundary entities which are not included in the model itself, e.g., foundations, abutments, or the earth itself. For each restrained translation degree of freedom at a support, there is a corresponding reaction force; for each restrained rotation degree of freedom, there is a reaction moment. |
| System of Forces: | (english) One or more forces and/or moments acting simultaneously. |
| Translation: | (english) Motion of an object where the path of every point is a straight line. |
| Transmissibility: | (english) The principle stating that a force has the same external effect on an object regardless of where it acts along its line of action. |
| Yield stress: | (english) A material loaded beyond its yield stress, no longer exhibits linear elastic behavior. Metals, particularly mild steel, generally have a very well defined yield stress compared to other materials. Yield stress is sometimes called yield strength. |
| Yield strain: | (english) A material deformed beyond its yield strain, no longer exhibits linear elastic behavior. See yield stress. |