RU2188916C2 - Reinforced concrete structural unit - Google Patents

Abstract

FIELD: construction industry, reinforced concrete bent structures ( collar beams ) of type of beam or girder which are embedded with metal reinforcement to respond to tensile stress. SUBSTANCE: bent sheet perforated reinforcement of closed box-shaped section with sheet perforated insert placed along diagonal along path of major tensile stress is positioned in section of collar beam near supports. Closed form of sheet reinforcement produces effect of casing for concrete, raising its strength. Sheet insert both responds to tensile stress and secures resistance of side surfaces of sheet reinforcement to bulging from plane and enhances torsional rigidity of sections near supports. EFFECT: raised strength of sections of collar beam near supports. 2 dwg

Description

 The invention relates to construction, namely to reinforced concrete bending structures (girders) such as trusses or beams, into which metal reinforcement is introduced to absorb tensile forces.

 Reinforced concrete crossbars are known, in the supporting sections of which transverse and inclined rod reinforcing bars are introduced to absorb tensile forces [1].

 The disadvantages of these solutions are the high metal consumption and the complexity of manufacturing at a low bearing capacity of supporting sections.

 The closest technical solution is a reinforced concrete crossbar, which includes in each zone, instead of transverse and inclined rods, additional reinforcement in the form of a pair of metal plates with notches on the side surfaces, interconnected at the top and bottom by connecting rods [2].

The disadvantages of this technical solution are as follows:
the complexity of manufacturing plates with notches of strict inclination to the crossbar axis, in which the strips between the notches must have alternating protrusions and depressions for adhesion to concrete; notches have the shape of a rectangle with a high concentration of stresses in the corners, reducing the strength of the plates; the combination of plates on the top and bottom of the connecting rods does not ensure the stability of the plate to buckle from the plane of the crossbar.

 These drawbacks are eliminated by the fact that in a reinforced concrete crossbar, including a concrete body and longitudinal rod working reinforcement for the entire length of the crossbar, in the middle zone there are transverse rod reinforcement and connecting rods, and in supporting sections, bent sheet perforated reinforcement of a closed box section with lengths l from h to 2h (h is the height of the crossbar in the support zone), inside of which a perforated sheet insert is located diagonally along the path of the main tensile stress.

 Figure 1 shows the support zone of the crossbar, side view; figure 2 - bent sheet perforated reinforcement closed box section with a sheet of perforated insert, General view.

 The reinforced concrete crossbar includes a concrete body 1, a longitudinal bar working reinforcement 2, a transverse bar reinforcement 3, connecting rods 4, a bent sheet perforated reinforcement of a closed box section 5 and a perforated sheet insert 6. A longitudinal bar working reinforcement extends along the entire length of the crossbar and is welded to a bent sheet perforated reinforcement located in supporting sections; transverse bar reinforcement and connecting rods are located in the middle zone of the crossbar.

 The box-shaped section of sheet reinforcement in the supporting sections is formed by cold bending steel perforated sheets, then a perforated sheet insert is welded into the box reinforcement. A longitudinal rod working reinforcement is introduced into the holes of the perforated insert and welded to the sheet perforated reinforcement in the supporting sections and combined by the transverse rod reinforcement and connecting rods in the middle zone of the crossbar.

 The finished metal frame is placed in the formwork and concreted. The holes (perforation) in the sheet reinforcement and insert can be of any shape, but without sharp corners (round, ellipsoidal, rectangular with rounded corners). Sizes c and d are assigned from the condition of ensuring strength along inclined sections of supporting sections and workability of the concrete mixture. The length l of the bent sheet perforated reinforcement is in the range from h to 2h.

 The proposed solution of the support section of the reinforced concrete crossbar has the following advantages.

 The lateral planes of the sheet reinforcement in the best way perceive and distribute the main stresses in the plane stress state. The trajectories of the main stresses pass smoothly, without concentration, between the holes. Anchoring of sheet reinforcement in a concrete body is carried out by holes (perforations) and sheet inserts. The closed form of sheet reinforcement creates a cage effect for concrete, increasing its strength. In the ultimate state, the concrete pressure on the side surfaces of the sheet reinforcement is perceived by the sheet insert, ensuring the stability of the side surfaces to buckle from the plane of the crossbar. In addition, the sheet insert perceives tensile stresses in the longitudinal direction, increases the torsional stiffness of the supporting sections and the crossbar as a whole.

 A flat perforated sheet is significantly less labor intensive to manufacture compared to sheets with notches and alternating protrusions and depressions in adjacent strips between the notches.

Sources of information
1. Baykov V. N., Sigalov E.E. Reinforced concrete structures: General course: Textbook. for universities. - 5th ed. reslave. and add. - M .: Stroyizdat, 1991 .-- 36-53 p., 150-161 p., 413-423 p., 409-413 p.

 2. A.S. 1779726, cl. E 04 C 5/06, 3/20. S.N. Bulgakov, V.A. Ivakhnyuk, Yu. N. Kardovsky. Central Research and Design and Experimental Institute of Industrial Buildings and Structures.

Claims (1)

 Reinforced concrete crossbar, including a concrete body, a longitudinal rod working and transverse rod reinforcement and connecting rods, characterized in that in each support section there is a bent sheet perforated reinforcement of a closed box section with a length of 1 from h to 2h, where h is the height of the crossbar in the support zone, with a sheet of perforated insert located diagonally along the path of the main tensile stress.

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