Columns

Precast concrete columns can be manufactured of rectangular or circular cross-section in various lengths. Concrete surface is smooth, edges are rounded. Minimum cross-section of the columns, required to install the parts of column-beam connection shall be 300x300 mm. The fire resistance of such dimensions columns is 2 hours. Precast concrete has a great advantage to compare with other type structures, because a good fire resistance performance enables using precast concrete columns in various purpose buildings.

Table 1 Standard dimensions of columns

Width

Height

Diameter

Length

K – rectangular columns

300 - 1200

300 - 600

to 18000

KO – circular columns

300 - 800

to 1800

Column length depends on a project idea. On customer‘s wish, also a 20 - 24 m length solid column can be manufactured without joining, still, it is more economical to use one-storey high columns. Precast concrete columns can be manufactured with one or several short cantilevers, against which floor slabs, roof beams, crane girders etc. are propped.

Table 2 Rectangular column characteristics

Rectangular columns	h mm	b mm	Weight kN/m
300 / 300	300	300	2.20
300 / 400	300	400	2.94
400 / 400	400	400	3.92
400 / 500	400	500	4.90
500 / 500	500	500	6.12
500 / 600	500	600	7.35
600 / 600	600	600	8.82

Table 3 Circular column characteristics

Circular columns	Diameter mm	Weight kN/m
300	300	1.73
400	400	3.08
500	500	4.81
600	600	6.92

The curves of column operating performance, depending on axial loading and bending moment values, are provided in the graphic representation. Calculations have been made for modular cross-sections of rectangular columns from 3Mx3M (300 x 300 mm) to 6Mx6M, for circular columns from Ø3M to Ø6M. Nd and Md – estimated limiting values of axial force and momentum during destruction, which means that sizes of constant and variable impacts are multiplied by respective safety coefficients.

Stačiakampio skerspjūvio kolonų darbinių charakteristikų kreivės

Fig. 1. Operating performance curves of rectangular columns

Apvalaus skerspjūvio kolonų darbinių charakteristikų kreivės

Fig. 2. Operating performance curves of circular columns

The columns are secured in the bowl of the foundation and joined by means of released reinforcement rods or fastened by means of anchor bolts. The first method frequently is used for shallow foundations, the second and the third methods are applied to pilework foundations. The columns are joined to each other by means of bolted mechanical joints, anchored in the parts of prefabricated elements, or using continuous reinforcing in the assembly of the joint.