Beams

“Betonika” provides prestressed reinforced beams in a variety of shapes, sizes and lengths suitable for the building frame structures. The cross-section of the beams is standardized. The prestressing force and the beam length is adapted to each specific proje

	R beams: rectangular roof or floor beams for moderate spans.
	RF beams: rectangular floor beams for composite action with floor slabs.
	RT beams: inverted T-beams for floors of middle to large spans.
	RL beams: L-beams for edge floors.
	I beams: for roofs and large floor-beam spans.
	SI beams: roof beams with sloped pans for large spans.

Precast beams can be subdivided into roof beams and floor beams. Roof beams are generally characterized by an I-shaped cross-section with a straight or variable length profile. The span length can go up to 30 m. Floor beams are usually rectangular or inverted T-beams. The latter enable a reduction in the construction depth of the floor structure.

SI beams

SI-beams with variable height are particularly suited for roofs with large column free spans - for example, in industrial halls. The I-shaped cross section is typical for prestressed beams. The slope of the top face is 1:16. According to Eurocodes, the SI-beam types have a fire resistance up to 120 minutes. Standard cross-sections are shown in the table below.

Profile	h	b	c	d	e	f	b_w	L_min	L_max
SI 900/500	900	500	150	190	95	150	120	6000	12000
SI 1050/500	1050	500	150	190	95	150	120	6000	12000
SI 1200/500	1200	500	150	190	95	150	120	8000	16000
SI 1350/500	1350	500	150	190	95	150	120	10000	20000
SI 1500/500	1500	500	150	190	95	150	120	12000	25000
SI 1650/500	1650	500	150	190	95	150	120	14000	28000
SI 1800/500	1800	500	150	190	95	150	120	15000	30000
SI 1950/500	1950	500	150	190	95	150	120	16000	32000

I-beams

I-beams are used for flat and sloped roof structures and for floor beams with heavy loading and large spans. The beams are in prestressed concrete and the fire resistance is, according to Eurocodes, up to 120 minutes.

The technical characteristics are placed in the table below.

Profile	h	b	c	d	e	f	b_w
I 900/500	900	500	150	190	95	150	120
I 1200/500	1200	500	150	190	95	150	120
I 1500/500	1500	500	150	190	95	150	120
I 1800/500	1800	500	150	190	95	150	120

L-beams & Inverted T-beams

L-beams and inverted T-beams are typical floor beams because of the reduced overall structural depth. The beams are in prestressed or reinforced concrete.

Standard cross-sections are shown in the table below.

Changes in floor level may be accommodated by either an L-beam or by building up one side of an inverted T-beam.

The width of L-beams and inverted T-beams may be confined within the width of the column or may project forward to the column. The latter solution allows the floor units to remain plain edged. In this case, the floor modulation becomes independent of the column spacing and is thus simplified. When beams are not wider than the column width, it will be necessary to form notches in the floor units.

Rectangular beams

Rectangular beams are mainly used for roof structures, and also for floors with composite action. They are usually in prestressed concrete, although classical reinforced concrete is possible. Standard sections are shown in the table below.

Standard profiles and weight per m length

b mm	300	400	500	600
h mm	kN/m	kN/m	kN/M	kN/m
400	2.94
500	3.67	4.90
550	4.04	5.39	6.74
600	4.41	5.88	1055
650	4.78	6.37	7.96	9.56
700	5.14	6.86	8.58	10.29
800	5.88	7.84	9.80	11.76
900		8.82	11.03	13.23
1000			12.25	14.70

Composite floor beams

R - beams may be designed composite with the floor to enhance the flexural and shear capacity, fire resistance and stiffness. The main advantage of a composite beam structure is that it permits less structural depth for a given load-bearing capacity. The breadth of the compression flange can be increased to the maximum permitted value, as in monolithic construction. For composite action with hollow core floors, the collaborating section is through the unfilled hollow core. This comprises only the top and bottom flanges of the slab. Detailed information about the load-bearing capacity is available from the technical department.