P-70 system of reinforced concrete hall construction
System P-70. In the FF system, halls with only one span were built 18,0 m; while in the P-70 system, single-bay and multi-bay halls with spans from 6,0 do 24,0 m, with a change in span co 3,0 m. For halls with spans 12,0; 15,0 i 18,0 m the spacing of the poles was assumed in the longitudinal direction 6,0 i 12,0 m.
Similar to the FF system, one hall structure- and multi-bay consists of:
a) one poles- and two-branch,
b) prestressed concrete girders,
c) post-tensioned concrete girders,
d) reinforced concrete roof panels,
e) prestressed roof panels,
f) reinforced concrete craneway beams, from prestressed concrete and steel,
g) wall elements.
The columns in the realized system buildings are solved individually. The foundation footing cup should be deeper by at least 20% from the greater transverse dimension of the column.
Prestressed concrete girders: a) girder with parallel strips, SB-l-80/12, b) girder with parallel strips with concrete sloping SBn-I-65/15, c) girder SBSFF-90/18, d) girder SBL-24, e) cross sections with details of the support of the roof panels;
1 - stirrups protruding from the girders, 2 - ribbed plate, 3 - concrete overlay between the slabs, B15, 4 - B35 slope concrete overlay.
The figure shows the prestressed concrete girders used for covering the halls. The prestressed concrete girders are manufactured of constant and variable height with spans 9,0; 12,0; 15,0; 18,0 i 24,0 m, Whereas post-tensioned concrete girders with an arc-shaped upper flange are manufactured with a span 18,0; 21,0 i 24,0 m. The P-70 system provides for the use of reinforced concrete and prestressed roof panels. There are several varieties of reinforced concrete roof panels, namely; with transverse ribs along the length of the slab, no ribs, with openings for skylights, as well as eaves and lighting fixtures. The length of the reinforced concrete slabs is 587 cm, width 119 i 149 cm, and the height 30 cm.
Pre-stressed flat plates from the FF system and a Pt-12p shell plate are used for the coverings of the halls.
The crane beams of the P-70 system include: reinforced concrete beams with a span 6 m and height 40, 60 i 80 cm, from prestressed concrete and spans 6 m and height 60 i 90 cm and the span 12 m and height 90 i 120 cm, as well as steel with a height from 83 cm do 130 cm.
The P-70 system distinguishes between wall panels without insulation and with thermal insulation. The boards were produced in many varieties and shapes. The cross-sections of the hall's longitudinal walls in the P-70 system are shown in the figure.
Longitudinal wall sections: a) section of the hall without overhead cranes, b) with an overhead crane; 1 - pole, 2 - prestressed concrete girder, 3 - post-tensioned concrete girder, 4 - roof panels, 5 - wall plate, 6 - spread footing, 7 - crane beam, 8 - ground beam.
