| Bright Drawing | (english) The process of drawing hot rolled steel through a die to impart close dimensional tolerances, a bright scale free surface and improved mechanical properties. The product is termed bright steel. |
| BTC | (english) Buttress threaded and coupled |
| Center of Gravity (CG): | (english) The location of the resultant of gravity forces on an object or objects: sometimes called center of mass. |
| Elastic energy: | (english) The energy stored in deformed elastic material (e.g., a watch spring). Elastic energy equals where k is the stiffness, and is the associated deflection. Elastic energy is sometimes called elastic potential energy because it can be recovered when the object returns to its original shape; see potential energy. |
| External force: | (english) A surface force or body force acting on an object. External forces are sometimes called applied forces. |
| Fixed connection: | (english) In two dimensions, a fixed connection between two members restrains all three degrees of freedom of the connected member with respect to one another. A fixed connection is sometimes called a rigid connection or moment-resisting connection. |
| Gravity: | (english) An attractive force between two objects; each object accelerates at a rate equal to the attractive force divided by the object's mass. Objects near the surface of the earth tend to accelerate toward the earth's center at a rate of ; this value is often called the gravitational constant and denoted as g. |
| Internal force: | (english) Forces which hold an object together when external forces or other loads are applied. Internal forces are sometimes called resisting forces since they resist the effects of external forces. |
| Normal strain: | (english) Strain measuring the intensity of deformation along an axis. Normal strain is usually denoted by . Average normal strain between two points is calculated as (Delta L / L), where L is the original distance between the points, and L is the change in that distance. Normal strain is often simply called strain. |
| Normal stress: | (english) Stress acting perpendicular to an imaginary plane cutting through an object. Normal stress has two senses: compression and tension. Normal stress is often simply called stress. |