reinforced concrete structures included in this system have been carried out,
specifications for their manufacture have been developed, and a method for calculating
the bearing capacity by the kinematic method of limit equilibrium has been developed
[1].
The combined operation of the system elements is carried out at the expense of
their joints progressive solutions. Overcolumned slabs are attached to the column
reinforcement by welding the casing embedded in them. The spaces between the
column and the slab casing, as well as between the slabs are filled with high-strength
fine-grained concrete. In this case, keys are formed in the concreted spaces, the
concrete of which is additionally strengthened due to the all-round compression. When
calculating the slab keyed connection of KUB-2.5 column system, a single-keyed
compressed joint of a trapezoidal profile is considered with a height of h
k
= 160 mm, a
key depth of l
k
= 170 mm, an aspect ratio of l
k
/h
k
= 1.06, and an angle of inclination of
the key supporting surfaces ψ = 26
о
; class of monolithing concrete С32/40 is accepted.
When assessing the strength of a joint for the effect of a shear force, both strength
characteristics of concrete f
cd
and f
ctd
, the ratio of the geometric parameters of the key
l
k
/h
k
, the angle of inclination ψ and the value of compression σ are taken into account.
Suggestions for improving the design of the specified joint by changing the key
geometry were developed. It is proposed to reduce its depth to l
k
= 80 mm, which will
lead to l
k
/h
k
= 0.5 (Fig. 8), an increase in the strength of the keyed joint and an
improvement in the transmission conditions of the vertical load.
Figure 8. The connection design of the improved joint between the overcolumned
slab and the column: 1 ‒ column; 2 ‒ overlapping slab; 3 ‒ key;
4 ‒ metal casing; 5 ‒ embedded item; 6 ‒ metal sheet; 7 ‒ fixation rod
CONCLUSION
The problem of providing the population with affordable housing can be solved
by introducing effective frame precast-cast-in-place structural systems of reinforced
concrete, characterized by a minimum set of prefabricated elements and a significant
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