6. Frame

A structure in which two or more members are connected by a fixed joint or rigid joint is called a frame, ‘rahmen’ or rigid frame structure.
In other words, a frame is a structure consisting of columns and beams rigidly connected to each other, allowing for the transmission of three forces :bending moment, shear force, and axial force from one member connected to a joint to another.

Structures can be classified mechanically into various categories, including rigid frame structures, composite frame structures, rectangular frame structures, irregular frame structures, and wall frame structures.
Rectangular frame structures are commonly used in regular structures such as offices, schools, hospitals, and other similar buildings.
On the other hand, irregular frame structures are often used in non-regular structures such as sports stadiums, gymnasiums, sculptures, and other similar structures.
Wall frame structures are commonly found in structures such as reinforced concrete bridges, apartments, and other similar buildings, which consist of rigid walls and slabs.

Moreover, an indeterminate frame assumes that the angles formed at each joint remain the same even if the structure undergoes deformation due to external forces.
In other words, even after deformation, the angles at the fixed joint locations remain at a right angle.

The concept of a frame is not different from that of a simple beam, a cantilever beam, or a continuous beam.
A frame is also a linear element like simple beam and continuous beam, but it forms a structure that is connected in two or three dimensions.

If a load in the 𝑧 direction of the element coordinate system is applied to the frame member, deformation ( 𝜔 ) occurs in a direction perpendicular to the 𝑥 axis.
And since the bending moment is in the direction of rotation around the y-axis, the axis of the cross-section also has the direction shown in Figure (b).

The frame can resist vertical and lateral forces in the manner shown in figure below.