T.I. Baranova, Dr., prof., member of Russian Academy of Architecture and Construction sciences,

J.S. Pulpinsky, Dr., prof.,

O.V. Boldyreva

Penza State University of Architecture and Construction, Penza, Russia.

SHAPING FROM CONTOUR HEAT ISOLATING WALL PANELS

 

With the development of  monolithic framing in the construction the external walls of a building have ceased to carry out bearing function, and are, basically, heat and sound insulation. With the relation to this various kinds of heat insulating panels  have been developed at the Penza state university of architecture and construction.

During the development of variants of panels the following factors were taken into account:

1). Adaptability to manufacture and a possibility of manufacturing of pre-production models on already available equipment;

2). Simplicity of installation (weight of the separate panel and convenience of installation of system of panels);

3). Good heat-insulating characteristics.

In one of the offered versions (pic. 1) external walls are set from light vertical elements of channel sections in height of one floor same as groove walls: elements are settled down in two lines with thickness of a wall, mutually blocking formed joints. After assembly the wall represents a light three-layer construction 500mm thick.

The constructive version (pic. 1) is developed for buildings with 9-13 floors with  3m height of one floor and intended for III climatic area. Bearing skeleton of a building is monolithic framed spatial skeleton with an arbitrary grid of columns. Erection of a skeleton is stipulated with the use of  fixed warmed timbering of factory manufacturing. Elements of a fixed timbering of a skeleton and wall fillings have the same design as expanded-clay concrete shells of a gutter structure with a heater from foampolystyrene. Variants of replacement of foampolysterene with other kinds of  heater are possible: polystyrene-concrete, foamglass etc.

Pic.1

The purpose is to develop wall element of such form that will meet the following  requirements: necessity of heat-shielding, isolation of a heater, elimination of penetration of cold air  in places of connections, small weight, absence of a finishing layer, simplicity of manufacturing etc.

First of all, there was an attempt to get rid of necessity of putting connections between external layers which in many cases became the reason of technological complications and premature damage of walls. The chosen decision provides independent stability of external and internal layers of a wall owing this to channel-shaped section of facing shells of wall elements and theirs floorwise unchuck with crossbars of bearing skeleton.

The aim to provide a freedom of placing of apertures and  various configurations of walls in the plan have dictated their vertical cutting on modular elements of small width.

For the achievement of necessary lagging qualities of a barrier the expanded-clay concrete shells of walls elements are supplied with warming loose leaves made from foampolysterene (thermal resistance of various sites of walls  is in a range from 3 up to ) which simultaneously allow to fix mutual design position of modular elements, to remove thinnesses in places of a contiguity and to arrange dry joints between elements, without closing up by a solution.

Decrease of thickness of an external layer which sustain more than half of cost and energy loss, allows considerably improve parameters of a multilayered wall and to reduce its thickness. For the observance of fire safety the 30 mm thickness of an external layer is accepted. The shell carries out a part of a timbering for a heater and provides its nonseparation. By means of facets the form of a shell provides formation of the optimum joints excluding penetration of moisture.

By applying the chosen lagging foampolysterene it’s necessary to observe an obligatory condition: full isolation of foampolysterene surface from direct solar rays.

Pic.2

All these requirements have dictated the choice of channel forms of section of elements of a wall (pic. 2). They are common for all constructive elements of the warmed frame buildings.

Some prvisions were laid into the basis of designing of wall elements:

1. A possibility of using of already available equipment.

2. Parities(ratio) of gold section and generalized Fibonacci numbers.

Proportions of gold section are used in architecture for a very long time - these proportions are found and in the Egyptian pyramids, and in Parthenon, and in the constructions of ancient Rome [1], [2]. However, as the ideology of designing of architecturals constructions  and machine-building constructions is used seldom. [3], [4].

Since the output of heat goes from a surface, and if one of the measurement is constant - from perimeter, ratios of perimeters were accepted as the criterias of an optimality.

Heat keeps a layer of foampolysterene, therefore the ratio of the common area of an element to the area of bearing(carrying) layer should be as greate as possible. At the same time the element should remain strong enough.

Having analysed the geometrical sizes of section Рabcdeflk=501,6mm; Рazpnmk=546,2mm; Рzpnm=306,2mm, authors have drawn some conclusions confirming an optimality of the chosen form.

1. The perimeter of a zone of contact of foampolysterene and expanded-clay concrete is equal to perimeter of expanded-clay concrete .

2. The ratio of perimeter of expanded-clay concrete, adjoining with foam to perimeter of an external surface expanded-clay concrete  (it is close to Fibonacci number φ = 1,618).

3. The ratio of the area of section of the whole element to the area of section of expanded - clay concrete is close to φ3 =4,2358 : , , .

The bearing(carrying) ability of vertical element of wall (pic. 3) is checked up in the laboratory conditions.

Pic.3

 

The geometrical measurements of tested model of an element correspond to the life sized measurements 2420×298мм. As a material for elements of a wall was used expanded - clay concrete of 5-15 mm fractions of bulk density . The structure of concrete was selected from 28 days of normal solidification.

The amount of the applied load was supervised by the use of Tokarev's dynamometer. Load was applied by steps: at 10% per calculated limit. The amount of an expected maximum load was defined on СНиП 2.02.01-83 and is equal 36000 N. A step – 3600 N.

Pic.4

Deformations of concrete of a wall element were measured with the help of resistive-strain sensors 2ПКБ-10-200В with  the base of 50 mm, which were pasted on it’s obverse and lateral surfaces on edges and in middle of an element.

The wall element is lead up to destruction which occured in the following sequence (pic. 4). At the load which is close to calculated limiting durability (36000N), in zones of assumed support of wall crossbars  have appeared  inclined hair cracks. At the further increase of load up to 40000N had happened an opening up to 2 mm . At loading of 54000N  took place the crumbling of concrete from basic "wiper ". Opening of cracks reached up to 3-4mm. Calculated operational load on vertical wall element for the period of concreting of a crossbar and installation of panels of overlapping . The ultimate load is . The wall element is capable to perceive load at installation of panels of overlapping(blocking) and for the period of concreting of bearing crossbar of a skeleton. Safety factor is .

 

References

 

[1] Шевелев И. Ш., Марутаев И. А., Шмелев И. П. Золотое сечение: Три взгляда на природу гармонии. - М.: Стройиздат, 1990. - 343 с.

[2] Шевелев И.Ш. Геометрическая гармония.– Кострома, 1963.

[3] Акуленко С.В., Груданов В.Я. Золотое сечение в конструировании глушителей шума двигателей внутреннего сгорания. / Циклы // Материалы III Международной конф. – Ставрополь. Изд.-во СевКавГТУ, 2001.

[4] Крутов А.В. Некоторые прикладные задачи: Геометрико-кинематические модели. URSS/ 2001. 252 с