destruction at ρ
w
= 1.03 reached the yield strength; therefore, reinforcement up to
1
%
w
=
can be considered effective.
With an increase of the reinforcement percentage in the range from 0.34 to 1.03,
the strength of the samples increased up to two times.
Analysis of experimental studies confirmed the kinematically possible failure
schemes by shearing, adopted in theoretical solutions, and indicates the reliability of
the joints calculating proposed method.
The calculation of the contact-platform six-keyed joint with the dimensions of the
slab bearing areas taken beyond the wall plane 1.2×8.1 m and a thickness of
220 mm (the slab has 6 voids with a diameter of 159 mm). The ratio of the adopted key
sizes (its depth to height)
0.5
kk
lh=
, class of the monolithic concrete C20/25, the keys
are reinforced with transverse reinforcement 4Ø6 A240С. The resulting calculated
shear resistance f
sh
is 3.11 MPa. A possible stress reduction for a round cross section
of keys is taken into account by introducing a reduction factor of 0.9. The joint bearing
capacity of the slab with wall panels in the reinforcement of all the keys is provided
with a large margin and it is possible to reinforce only two, the rest keys can be
provided for concrete.) with the cross-sectional dimensions of 150×600 mm allows one
key to perceive
The shear strength calculation of the longitudinal keyway between the slabs
according to the proposed method takes into account the possibility of failure along an
inclined plane within the joint thickness, and the shear strength is 72.5 N/m. The key
joints calculation of the slabs on horizontal loads shows that the keyed seam (Fig. 3the
force V
Rd,k
=325.4 kN. The number of keys along the length of the slab depends on the
value of the horizontal force acting in the floor slab disk. For the further development
of large-panel housing construction, a promising direction is the integrated use of
reinforced ceramsite concrete to create lightweight structures.
Improving the joints of precast-cast-in-place structural systems. ARKOS is
one of the common structural systems of multi-storey frame buildings [11], in which:
precast-cast-in-place overlapping disks with the use of hollow-core slabs are made flat,
without protruding parts into the volume of the premises (Fig. 4); with a given
thickness of 12 – 14 cm to the continuous floor slab, width of spans up to 7.2 m are
ensured; in the design of floor slab discs, accounting for reactive thrust forces arising
under load, which made it possible to reduce the consumption of steel for their
reinforcement by 30–40%, was implemented.
The slabs are supported on monolithic bearing girders with the help of concrete
keys formed in the voids of the slabs at their ends surface when girders concreting.
The combined work of the slabs among themselves and the bracing girders is also
ensured by the work of the keys.
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