Construction of large modern facilities of industrial, warehouse, commercial or any other purpose cannot be done without using steel pillars and bearing structures in the form of frames undergoing compression with lateral deflection. The main purpose of the frames is distribution and bearing of the roofing loads and their transfer to the building foundation through supports in the form of pillars.
The main elements of a pillar are the shaft, which actually bears the loads, the anvil used for connection to the frameworks and the base the purpose of which is connection, and load distribution over the area of the foundation. As a rule, the pillars are calculated jointly with the frames.
The frame is a dimensional system of rods rigidly connected at the nodes creating a structure with constant geometry, where the length is up to 20 times more than the width. Though the frames are more labor-intensive in manufacturing, they are capable of bearing larger loads than the all-metal beams having at the same time lesser proper weight.
Components of flat frames are the constituent contours of the band and the rods (posts and bracing) forming a grid inside the band connected at the nodes. The bands bear longitudinal stresses, and the grids bear the transversal ones like the beam walls.
All frames are divided into the groups of flat frames, with all elements located in one plane, and dimensional frames, consisting so to speak of several (3 to 4) flat frames each of which is their edge. Naturally, the flat frames are stable only in the plane of location of the elements, whereas the dimensional ones are stable in all directions. Angles, tubes and other rolled articles are used for rods. The number of rods (k) and nodes (n) in a flat frame are related as follows:
The flat frames are divided into the following kinds: triangular frames, frames with parallel bands, trapezoid frames and polygonal frames (with broken arrangement of bands). Though the frames with parallel bands are the most raw material intensive ones, they are at the same time the easiest to manufacture due to simplicity of their structure. The triangular frames are the most rational ones for manufacturing beam systems, with the load concentrated at the center. The trapezoid ones enable to make a frame nod of sufficient stability, and the polygonal frames, due to the band break at each node, enable to make its form close to a parabolic one, which is closest to the frame diagram.