SU1296698A1 - Method of producing ferroconcrete slab for ceilings - Google Patents

Abstract

The invention relates to construction. The aim of the invention is to increase sound insulation while reducing the reduced thickness. Interfloor overlap panels are manufactured with a preliminary compression stress, which prevents the appearance of treshin. This provides the required insulation from airborne noise without increasing the thickness of the slab. The prestressing force is determined from the dependence N (B – Cj):: Cr, where B, C and C; - values depending on the geometrical dimensions of the plate, the properties of the material and the standard moment, on the short-term effect of the external load. & (Lü from 05 05 to 00

Description

The invention relates to the construction of residential, public and industrial buildings.

The aim of the invention is to increase the sound insulation while reducing the reduced thickness.

Interfloor overlap panels are made with a preload of such a magnitude of compression, which will resist the action of an external regulatory load, preventing the occurrence of cracks in the stretched zone of the slab, thereby accepting the rigidity of the entire concrete section, the panel will work resiliently and will be able to provide adequate insulation. from airborne noise without increasing the thickness of the product.

In this case, the rigidity of the section without cracks should be determined by the expression

In KiK2K3Bo5

where B is the actual stiffness of the section with regard to the change of the neutral axis;

B e is the stiffness of the cross section about the neutral axis passing through the center of gravity;

KI - coefficient taking into account the increase in the stiffness of the cross section due to the modulus of elasticity of the concrete using the superplasticizer 1 K, 2;

Kg, - coefficient taking into account the increase in the stiffness of the cross section due to a change in the position of the neutral axis during tension of the reinforcement K

Cs is the coefficient taking into account the increase in the stiffness of the cross section due to the increase in the stiffness of the reinforcement when the position of the neutral axis is changed during tension of the reinforcement (1 + -).

In this case, the limiting frequency fz should be within 56 ftp70 Hz at () 0 kg / m, and the rigidity of the full cross section of the slab and the modulus of elasticity should be higher than normal concrete when using a superplasticizer.

The prestressing should be carried out in all floor panels, operating not only on a large span, but also on a small span, as well as in contour support.

The tension of the reinforcement should provide crack resistance under normal load.

Dependence of tension value in reinforcement on slab stiffness:

, Bgv

where is - (1-С) +

g, 6f5

1o (KS-1) + KSG

N is the total pre-tension of all reinforcement with allowance for losses (from relaxation

With

five

0

about

five

0

five

reinforcement, deformation of the form and stops, in which the construction, shrinkage and creep of concrete are made); B - the rigidity of the slab is the product of the modulus of elasticity and the moment of inertia of the cross section of the structure; - normative moment from short-term external load;

C is a coefficient taking into account the effect of the long-term creep of concrete and depends on the humidity conditions, the environment in which the structure operates; C 2 and 3 (respectively, when the ambient humidity is greater than 40% and lower than 40 / o);

The coefficient taking into account the plastic properties of the material, depending on the shape of the section, ranges from 1.5 to 1.75;

h is the plate thickness;

RP is the standard tensile strength of concrete;

f - plate deflection;

to is the distance from the center of gravity of the tensioned reinforcement to the center of the body of the cross section;

K is the coefficient of accuracy of the tension of the reinforcement (taken to be 0.9);

 - radius of inertia, distance from the center of sheet metal to the wood point.

Consequently, the creation of a prestress allows one to take the moment of inertia of the total cross section in the floor slabs and to obtain a crack-resistant structure under operational load, which, with increasing insulation from both airborne and shock noise, will limit the thickness of the floor slab and, as a result, its mass.

According to the invention, the high crack resistance of pre-stressed reinforced concrete increases the resistance to dynamic loads, corrosion resistance, durability, which ultimately will ensure the stability of sound insulation properties during operation.

Claims (1)

Invention Formula A method of manufacturing a reinforced concrete slab of interfloor overlap, including the installation of reinforcement, its prestressing and pouring with concrete, characterized in that, in order to increase sound insulation while reducing the reduced thickness, the prestressing stress is determined from the dependence G o (KS-1) + KSG 2 9; w N is the total pre-tension of all the reinforcement, taking into account losses (from relaxation of the reinforcement, deformation of the form and stops, in which the construction, shrinkage and creep of the concrete is made); In ESIg, the rigidity of a slab is the product of the modulus of elasticity and the moment of inertia of the cross section of the structure; М „, - the normative moment from the short-term action of an external load; C is a coefficient taking into account the effect of long-term creep of concrete and depends on from humid conditions, the environment in which the structure operates; C 2 and 3 (respectively, when the humidity of the environment is more than 40 ° / o and less than 40%); Y - coefficient taking into account the plastic properties of the material, depending on the shape of the cross section, ranges from 1.5 to 1.75; h is the plate thickness; RP is the standard tensile strength of concrete; f - plate deflection; The distance is from the center of the body of the stiffened reinforcement to the center of the body of the body of the section; K is the coefficient of accuracy of the tension of the reinforcement (taken to be 0.9); g is the radius of inertia, the distance from the center of gravity of the section to the wood point.