<<
>>

research of the is intense-deformed condition of geodetic domes-covers.

Considered above a design of geodetic domes can have various variants of bracing of panels and opiranija on racks. For the analysis of these variants numerical researches with use of a program complex «ЛИРА-САПР-2013» (schemes of static calculation and the deformed schemes, fig.

3) have been carried out.

Axial forces, the moments and shear forces in rods and movings to knots are defined from the most unprofitable combinations of loadings. Data are resulted for two variants of bracings of panels and for two ways opiranija: And - to sharnirno-mobile bearers with string pieces; - with string pieces at level of the second floor and to sharnirno-mobile bearers (to basic plates with string pieces). Comparison of settlement schemes and loadings, and also distribution of efforts in schemes And - rigid joints of a dome without string pieces, - with string pieces (fig. 3.10 and) shows rigid joints, that settlement efforts and the maximum pressure with string pieces differ no more, than on 15 %, from efforts without string pieces, but complicate knots and make heavier a dome (fig. 3). For the further analysis we will select the basic variant of the settlement scheme with rigid joints and with opiraniem at one level without intermediate string pieces.

Fig. 3.10. The scheme of making fasts for identical zagruzheny in two variants of a dome from pyramidal panels: and - without intermediate string pieces; - with string pieces at floor level.

The limiting condition on the first group comes as a result of plastic hinge occurrence in knots of a dome with the same rods and knots on equator. Further there is an increase of movings at this level of a dome and taking into account plastic work of knots of steel rods there comes a limiting condition of the second group with horizontal movings more than 10 mm. Redistribution of efforts gives a stock of a load-carrying capacity to 20-30 %.

Fig. 3.11. Mosaics of axial forces (and,) for settlement zagruzhenija on everyone

Knot of a dome with string pieces at level of bearers

Influence of assemblage with sorting, then mirror assemblage it is realised for check on a test-bed of a similar dome (fig. 4.19) and in settlement models (fig. 3).

Fig. 3.12. Mosaics of the moments for settlement zagruzhenija domes: and - with apertures and string pieces on a contour; - with string pieces at ground floor level.

Round five axes of similar geodetic domes pair hexagonal pyramidal panels which it is collected by the mirror image, one on ready another are located on schemes. As has shown experiment, even such operations lead to decrease in critical loadings on the central knots of panels of a dome.

Check of stability of separate elements and general stability of panel geodetic domes-covers.

At designing of domes of all types check of degree of geometrical nonlinearity of a load-carrying structure which is estimated by [154,156,164] parity of a total design load and critical loading Fcr is obligatory.

At rigid connections between panels of an one-zone geodetic dome the parity zhestkostej connections on joints of these panels and zhestkostej connections in panels influences size of general critical loading. In a variant with sharnirnymi joints mezhu panels show also influence of integration of elements of a coating.

As has shown experiment, this influence is shown even at application
Site joint of a rod dome with identical knots of connection both in pyramidal panels, and on joints between them, only at the expense of levelling of geometrical deflexions at assemblage with preliminary sorting of elements according to length, and at the expense of creation of the integrated fragments of a surface with the verified accuracy.

Fig. 3.13. Movings of knots and elements of a dome with apertures from a design load

For definition of critical central loading the angle of slope of panels to a plane tangent line β, parametre of an initial deflexion ξ0и parametre of a deflection of knot ξ is preliminary calculated.

Angle of slope of panels to a plane tangent line in knot -

The minimum length of the panel of a dome. Skewness R-radius.

Design value of parametre of an initial deflexion:

Where δ - the tolerance on manufacturing of rods on length and the panel of a dome, we accept δ =1,0 mm.

Dimensionless parametre of a deflection uzlabezrazmernyj parametre

Initial deflection of knot - a corner of turn of a rod in

Radial plane in the course of a warping, - an initial corner

Rod turn in relation to nominal position.

- Factor of decrease in critical loading;

Parametre of non-uniformity of a weighting of the next knots; F1 - loading on the considered knot, F2 - loading on the next knot (for constant and wind loadings m=1, for snow m=0,5).

However above resulted existing technique is that, that formulas do not consider variants of operational loadings with a parity mдля the loaded and not loaded knots less than 0,5. Therefore we offer effort in the most weighted rod of the panel taking into account its increase in the course of a warping of a panel dome to define under the formula [113] taking into account small values m for rigid panels and sharnirnyh assembly joints

Where the k1-factor of increase of longitudinal force, is defined under the formula:

It also is limited to value 1,65 for a snow load.

On effort Nefподбираем sectional view of a rod from a stability condition as central-compressed element. It is recommended to accept flexibility of rods no more than 80-90, otherwise it is necessary to consider influence of decrease in their longitudinal rigidness on size of critical loading.

Where E - an elastic modulus of a material of a rod, R cr - critical loading on knot, A - an area of cut of a rod of a mesh dome, p - the parametre accepted under schedule [115]).

The maximum central loading on knot

As a matter of fact, calculation on local stability estimates work of a mesh or geodetic dome at symmetric forms of a warping of its rods in relation to action of the basic external forces and stability loss occurs in the most weighted elements. As the estimation of asymmetric forms of loss of stability is insufficiently worked, it is better to prevent formation of these forms structurally -

Technological methods which are easily realised in constructive systems offered in given work.

3.1.1.

<< | >>
A source: Antoshkin Vasily Dmitrievich. is constructive-TECHNOLOGICAL DECISIONS of PRECAST SPHERICAL SHELLS. The dissertation on competition of a scientific degree of a Dr.Sci.Tech. Saransk - 2017. 2017

More on topic research of the is intense-deformed condition of geodetic domes-covers.:

  1. RESEARCH OF IS CONSTRUCTIVE-TECHNOLOGICAL DECISIONS OF GEODETIC DOMES-COVERS.
  2. features of settlement models of precast geodetic domes-covers.
  3. research of the is intense-deformed condition of a settlement model of a dome.
  4. Algorithms of definition of the is intense-deformed condition ferro-concrete sing integral ploskonaprjazhennoj designs with corrosion damages
  5. research of is constructive-technological decisions of geodetic domes
  6. 5.1.2 Choice of variants of the is constructive-technological decision of geodetic domes
  7. offers on increase of reliability of supporters of geodetic domes.
  8. offers for choice the optimum scheme razrezki and to geometrical calculation of geodetic domes
  9. THE CHOICE OF IS CONSTRUCTIVE-TECHNOLOGICAL DECISIONS OF PRECAST GEODETIC DOMES
  10. features of installation of a precast geodetic dome
  11. THEORETICAL PRECONDITIONS OF FORMATION OF OPTIMUM TRIANGULAR NETWORKS OF GEODETIC ENVELOPMENTS