Engineering analysis of earthquake measures in the construction of Amir Tora Madrasah

Engineering analysis of the earthquake measures in the construction of Amir Tora Madrasah
B.S.Raxmonov, PhD of pedagogical sciences, associate professor (UrSU)

A.A.Aytbaeva trainee teacher,

A.M.Dauletbaeva trainee teacher (KSU)
Annotation. This article presents the seismic strength of the construction of architectural and historical monuments, which, based on the laws of proportion and symmetry, has a positive role in the seismic resistance of buildings and structures.

Keywords: brick wall, dome, shells, bouquet, stern.

Аннотация. В данной статье представлена ​​сейсмостойкость строительства памятников архитектуры и истории, которые, исходя из законов пропорции и симметрии, играют положительную роль в сейсмостойкости зданий и сооружений.

Ключевые слова: кирпичная стена, купол, ракушки, букет, корма.

The land of Khorezm with its highly developed civilization has a unique place in the history of mankind.

The comprehensive study of the scientific heritage of our ancestors, the methods used by architects and masters in the past, the analysis of architectural and tectonic systems show, that the science of architectural design was fully formed in our country in the Middle Ages.

It is known from history that in our country the mathematical thinking of our ancestors was very high. Many laws of mathematics were created or developed here. There was a gradual transition from mathematical thinking to architecture, construction culture, applied art, and in the process of mathematization of knowledge there was a transition from the rules of mathematics to art and then to the art of construction. The high level of development of mathematical science at that time opened up great opportunities for the application of architects' ideas in construction.

In the hands of architects appeared complex spatial systems, such as ellipsoidal and geodetic domes, consisting of a parabaloid circle on the surface, which was, of course, the application of the achievements of mathematical science to the practice of construction. [1,3,4,5].

The introduction of spatially thin-walled domes, domes, shells, lattice structures into the construction process was a testament not only to the product of scientific and technological progress, but also to the aesthetic taste of the time.

These conditions are conclusions drawn on the basis of the achievements of the science of seismicity of buildings and structures, which have successfully passed the "test" of the impact of many earthquakes that occurred in these buildings. Now we analyze all the processes associated with the construction of architectural monuments, from design to construction, on the basis of the laws and regulations of the science of earthquake resistance of modern buildings and structures.

The analysis of Khiva's architectural monuments - building projects shows that in the past, architects first constructed buildings square or close to the plan. In particular, the dimensions of the building of Amir Tora Madrasah were tried to be closer to the square, and in terms of functional necessity, its dimensions were 52.6 * 36.7m, the size of the yard was 30.7 * 19.35m, and the size of classrooms was 5 * 5m. in size. The portal part of the façade of the building is made symmetrically in an oriental compositional solution with a balcony, and the balcony is made of wooden beams with a small specific weight as the main load-bearing and secondary load-bearing structure.

The upper lintel constructions of the doors are also made of wood material, the part of which is embossed to the exterior facade in the form of an arch, which was a very correct and reasonable solution by the builders. This is because the use of arch structures allows maximum use of the load-bearing capacity of the brick material, which was traditional for that period. It is known that the brick material in the arch construction system undergoes compression deformation in this case. The ability of a brick material to resist compression is dramatically greater than that of elongation.

The same situation is observed in the project of the building of Amir Tora madrasah. In the construction of this building, the height in the corners of the building is 8.66 m. 4 architectural elements - "bouquet" were used (Fig. 1). Their height is significantly different from the main height of the building, which is also noticeable on the facade of the building. The use of such an architectural element - "bouquets" - in fact has a negative impact on the seismic stability of the building. First, the presence of such massive aggregates in the corners leads to the emergence of additional dynamic stresses in the corners of the building during an earthquake. Second, dynamic pressure unevenness occurs during an earthquake in contact of the foundation tag surface with the foundation soil, which negatively affects the seismic priority of the building.

However, they were able to minimize its negative impact on the seismic stability of the building by reducing the size of the “bouquet” with increasing height, i.e. by making it into an equally resistive body shape.

Today, the methods of calculating the strength of our ancestors and the peaks of their theoretical knowledge are not clear to us. But their highly intelligent construction culture is a sign of their high level of theoretical knowledge. In the past, during the construction process, special attention was paid to the interaction of the foundation and the foundation (in the event of an earthquake, the seismic effect on the building is determined by this situation). Before laying the foundation for the Amir Tora Madrasa building, the builders repeatedly moistened the pit to strengthen the foundation, thereby maximizing the compaction and compaction of the foundation soil. In this way, they tried to prevent uneven subsidence of the foundations of buildings and structures and to achieve a uniform distribution of seismic forces along the length of the foundation during the earthquake.

At the top of the building, at a height of about 0.5 m, the wall is covered with a layer of wood for seismic insulation, stone blocks collected in a special mixture (clay), and in most cases a layer made of reeds or reeds. These bedding is an extremely sensible measure from a scientific point of view and has been successfully tested by nature for centuries. Used as an anti-seismic measure, these special layers have the ability to extinguish vertical waves propagating along the wall during an earthquake, as well as to sharply reduce the horizontal seismic forces acting on the wall through the foundation. (Figures 2, a and b)

Figure 1 Plan view of Amir Tora Madrasa building.

Figure 2 Placed on the part of the building, plinth reed layer scheme (a), an example of placing a layer of timber under the wall.

As the height of the towers increases, the cross-sectional area decreases. With this, the architect and builders gained predominance in the case of static loading in the first place. In addition, the normal stress in the towers caused by external and internal forces does not increase sharply, that is, the tower resists the forces as a beam with equal resistance. It is known from the course of material resistance that the most sensible way to prevent a sudden increase in the normal stress in the body of the body (tower) is to build a tower structure with a variable surface, i.e. to bring its resistance to forces equal to the resistance of the beam. We think that in the past, architects and builders chose this method based on theoretical knowledge. Towers can be thought of as ground-mounted (cantilever) rods. During an earthquake, such structures may bend due to horizontal seismic forces or shear deformations, depending on its height. Reducing the cross-sectional area depending on the height of the tower ensures that the value of these deformations does not increase sharply, and that these structures have a sufficient priority. A similar rational solution of architects and builders can be seen in the construction of buildings such as Islam Khoja, Kalta Minor [2].

In some cases, architects have used tower structures as parts of buildings or to decorate them. One of them is the building of Amir Tora Madrasah, in the construction of which the architects effectively used the same building element. Figure 3 below shows the architectural element in a “bouquet” schematically.

Figure 3 Schematic view of the architectural element "bouquet".

In the past, builders have been able to accurately assess the role of elastic and ductile properties of building mixes in ensuring the seismic strength of brick structures. Given the increase in the vertical force due to the specific gravity of the brick wall from top to bottom and the seismic force during the earthquake is proportional to the weight of the structure, the thickness of the joint in the horizontal joints is not uniformly determined by the height of the wall. At the bottom of the wall of the building of the Amir Tora Madrasah, the thickness of the mixture was determined to be greater (about 3 cm thick), and as the height of the wall increased, the thickness of the mixture decreased. Thus, they managed to increase the elastic properties of the brick-mixing system. Therefore, in this case, the share of gypsum mixture in the total brick wall volume is about 20-30%.

Thus, the main goal of architects and builders of the past was to provide adequate stability and priority to buildings and structures. The methods of construction created by them are based on the achievements of science and have been applied in practice at the level of aesthetic requirements of the time.

The unique architectural work of each architect is a reflection of his unique style, architectural and artistic culture, aesthetic outlook and deep knowledge.

In short, each architectural element has some shortcomings, in addition to the architectural effect. The strength of any building or structure is more important than its architectural beauty. When these two factors are combined, a building of the required level is built.

Thus, without increasing the values ​​of spatial dimensions of buildings and structures, their construction on the basis of the laws of proportion and symmetry has a positive effect on the seismic resistance of buildings and structures. When buildings or structures are large in size, regardless of their symmetrical and simple construction, they cannot withstand the effects of seismic waves as a whole body. In the past, architects followed the laws of symmetry not only in the plan but also in the facades of buildings. Of course, the effectiveness of the law of symmetry in the construction of architectural monuments in our country is clearly seen in a number of monuments, which are among the masterpieces of all human culture. On the other hand, the application of the laws of symmetry in the plan view of these buildings and structures and in the volumetric form in general makes it possible to achieve an even distribution of mass and virginity. This is one of the key factors in ensuring the earthquake resistance of buildings. The fact that the architectural monuments that have survived to the present day have passed the "tests" of nature is a clear proof of this idea.