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research of the VAT of spherical two-zone envelopments

Settlement schemes, schemes zagruzheny and results of calculation of domes are given on fig. 3, 3. The accepted sectional views are resulted in in work [4].

Calculation on durability of elements of the two-zone dome subject vnetsentrennomu to compression by force N, we carry out as for a beam head with rigidly restrained basic parts.

Settlement lengths of elements of the top belt of trusses also it is accepted as for not cutting rod of constant sectional view with various compressing or stretching stresses, the moment and shear forces (fig. 3.34, 3.39) on lots (number of lots of equal length 2) in the assumption sharnirnogo matings of elements of a lattice and communications and it is defined them as in a plane of a belt of a truss or a basic inclined brace, and from a plane of a belt of a truss.

Fig. 3.34. A mosaic of axial forces for a settlement combination 1+2+4+5 for an one-zone dome with the set rigidness of elements.

For the considered domes-covers at use for opiranija all possible knots axial forces, the moments and shear forces in rods are distributed non-uniformly with increase to vertex.

Fig. 3.35. A mosaic longitudinal, transverse forces and the moments for a settlement combination 1+2+5 for elements at a longitudinal section of an one-zone dome.

At depression of bearers through one there is an alignment of efforts and the moments that reduces number of standard sizes on sectional views of elements. Also from the analysis of making fasts it is visible, that reduction of number of bearers in comparison with greatest possible in two-three times, only levels distribution of efforts in rods, further at the further reduction their concentration is observed.

Fig. 3.36. Mosaics longitudinal, transverse forces and the moments for a settlement combination

1+2+5 for elements of the bottom contour of an one-zone dome with the set rigidness.

However here it is impossible to increase smoothly depression of bearers because of application of panel assemblage of a dome, depression through 2-3 knots as further increase priopornye efforts (fig. 3.34, 3.36, 3.39) therefore will be optimum.

Distribution of efforts in the basic basic trusses of panels of domes -
Envelopments as it has already been told, it is possible to regulate mixture of bearers inside or outside from an axis. A variant of displacement of bearers outside and alignment of efforts in a basic truss are shown for a two-zone dome in drawing 3.38.

Fig. 3.37. The scheme of distribution of efforts for priopornyh trusses of two-zone domes: and - transition from efforts of an one-zone dome to duhpojasnomu; - a mosaic of axial forces at displacement of a bearer of a two-zone dome.

For sharnirnogo opiranija vsparushennogo domes the important means of regulation of efforts there is an application of an optimum eccentricity opiranija.

Its variation allows to level efforts in belts basic trusses and to lower mass of a design to 6-12 %.

Fig. 3.38. Epjury axial forces and the moments for a basic truss of a dome of sport centre: and - epjury axial forces; - moment lines.

Features of an estimation of stability of separate elements and general stability of a panel two-zone dome-cover

At designing of two-zone domes-covers of the big spans also check of local and general stability of designs is obligatory. In such domes static indefinability of settlement schemes sharply increases and the form of loss of stability become complicated. In two-zone domes with sectors from precast hexagonal panels it is necessary to consider influence on general stability set most razrezkoj a maximum of six and a minimum of three symmetry axes. Integration in the form of panels mirror collected in conductors it is possible to level asymmetric forms of loss of stability and to lower probability sheathe stability losses.

For definition of critical central loading at loss of local stability the design value of parametre of an initial deflexion under the formula (3.1) also is preliminary calculated:

- The tolerance on manufacturing of separate rods on bolts, is accepted δ =3 mm.

Dimensionless parametre of a deflection of knot - a turn corner

Rod in a radial plane in the course of a warping). Settlement length l it is defined. As an average value of lengths of the most weighted trusses on a joint of assembly panels. Further also under formulas 3.2 and 3.3 it is defined critical efforts in trusses and loading on knot. We will check up a condition on the Condition of stability for central loading (prevention proshchelkivanija knot) can be defined under the changed formula (3.3) taking into account two belts and the inclined braces getting to sectional view.

proshchelkivanie it is possible at considerable deformations from a plane of the trusses making the panels and at loading on knot exceeding critical. On fig. 3.39. Influence of displacement of a bottom of bearers for a spherical dome is shown at standard distributions of loadings to dome knots at comparison of settlement data of the deformed and not deformed schemes of calculation.

Fig. 3.39. Movings of knots and elements of a model taking into account geometrical nonlinearity from action of total symmetric loading (calculation data, 1-/*maks. - 4,085 mm, without displacement of bearers outside on 100 mm), 2-/*maks. - 5,120 mm).

Optimisation of a dome design at varied parametres of span, a boom of ascending gradient of height of a design and zhestkostej a basic ring

For set span and a boom of ascending gradient of a two-zone precast envelopment optimisation by numerical methods of height of a dome design by criterion of mass of a design is used. The further numerical researches we will result with reference to a dome span 56.0м with the height 600 mm close to the optimum. Results of calculations and optimisation are resulted on schedules fig. 3. At the decision of a problem of numerical optimisation the automated means in systems AutoCAD and LIRA - SAPR 2013, with program elements (the appendix 2, listing 2.1) are used.

Optimisation was spent for different degree of typification of panels and the trusses making the panels.

Fig. 3.40. A mosaic of axial forces for a settlement combination for a two-zone dome with the set rigidness of rods and bearers.

Taking into account restrictions which give razrezki on the basis of sectors 60о, we select optimum by criterion of a minimum of mass two-zone razrezku on sphere for the set parametres of a dome from 3 numbers of repeating circles (fig. 3.25 see, 3.40 - 3.46).

Fig. 3.41. Dependence of mass of a dome for polytypic rods from an ascending gradient boom to span and from rigidness of bearers.

In the minimum mass the bearing part of a coating of a dome span of 56 m with the relation of a boom of ascending gradient to span 1/4,63 with three bearers on sector and rigid connection with a basic ring of the greatest possible rigidness with the minimum typification of sectional views possesses.

Fig. 3.42. Dependence of mass of a dome from two types of rods from an ascending gradient boom to span and from rigidness of bearers

Depending on degree of typification the minimum is sharply expressed in the absence of typification of sectional views.

Fig. 3.43. Dependence of mass of a dome from one type of rods from an ascending gradient boom to span and from rigidness of bearers.

For restriction in the form of two standard sizes of sectional views of belts and, accordingly, one standard size of sectional view of belts, a mass minimum all less depends on the relation of a boom of ascending gradient to span and rigidness of a basic ring.

Fig. 3.44. Dependence of mass of a dome for polytypic rods from an ascending gradient boom to span both from rigidness of a bearer and with rigid opiraniem on a basic ring.

For rigidness of a basic ring influence on mass is expressed on schedules fig. 3.30 - 3.35 poorly, and with almost linear dependence. The variant of influence of an eccentricity or sdvizhki bearers in a ring was considered also.

3.45. Dependence of mass of a dome from two types of rods from an ascending gradient boom to span and from

Rigidness of bearers with rigid opiraniem on a basic ring.


Thus there is an alignment of basic axial forces in trusses and it essentially reduces a lump of especially typified designs. The received results have allowed obosnovanno to offer a variant of the is constructive-technological decision.

Fig. 3.46. Dependence of mass of a dome for one type of rods from an ascending gradient boom to span and from rigidness with rigid opiraniem on a basic ring.

Considering the carried out analysis, a dome-cover of 56,0 m have been accepted by span two-zone in the form of panels from trusses from two types of steel sections in height of 600 mm and a boom of ascending gradient of 12,2 m, with rigid joining to a basic ring.

3.3.4.

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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

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