The task is to determine the dynamic characteristics of a 35-storey monolithic building in the city of Almaty. Dynamic tests were performed using a V-3 inertial vibration machine installed on the building floor. Oscillations were recorded using a digital instrumentation system. The results of dynamic tests of a 35-storey building of a frame-wall structure (monolithic) were obtained. For the first time, vibration periods were obtained for the first three vibration forms of a high-rise building, respectively, 1.38 s; 0.38 s; 0.195 s. Values of accelerations are determined by 3 forms of oscillation of buildings, respectively, 0.016 g, 0.199 g, 0.240 g. Dissipative properties of a high-rise building were estimated (logarithmic decrement of oscillation by oscillation forms 0.08 – 0.22). Somewhat unexpected here was the relatively small magnitude of the logarithmic decrement of the first form – 0.08. The features of the building behavior under dynamic impacts and the assessment of the ability of floor disks to distribute horizontal seismic loads between vertical elements were studied. The RMS acceleration of the first three forms is 0.312 g. After vibration tests, no damage or cracks were noted in the bearing structures of the building. In some partitions, cracks with a small opening are noted, which are formed, as a rule, at the junction of non-bearing structures with bearing ones. Conclusions are drawn about the need to adjust regulatory documents in construction. The results of the work can be used in the design of high-rise monolithic buildings.

 

In 2017-2018, the total certification of the housing stock of multi-apartment buildings in Almaty was carried out for the first time. According to the results of certification, a total of 8,171 buildings were entered into the database, of which 1,425 are multi-storey monolithic buildings of various storeys and structural types. It was also revealed that 1305 monolithic buildings are earthquake-resistant, 27 – non-earthquake-resistant and 93 are located in the zone of tectonic faults on the territory of the city. Therefore, it is useful to accept the pessimistic hypothesis that buildings located in the zone of tectonic faults will be destroyed. Under these conditions, quantitative estimates of the failure probability and reliability values for monolithic buildings were obtained for the first time. The high earthquake resistance of monolithic buildings has been confirmed. It is established that when taking into account the influence of tectonic faults, the probability of failure of a monolithic building increases by more than 4 times. The frequency of earthquakes is taken into account according to the current "Map of seismic zoning of the Republic of Kazakhstan". Methods of strengthening monolithic buildings should be individual and determined by the results of experimental studies.

In 2017-2018, for the first time in the city of Almaty, a complete certification of the housing stock of apartment buildings was carried out. 1607 multi-storey brick buildings 2-4 floors high were identified. Based on the results of certification, quantitative estimates of the probability of failure and reliability for brick buildings were first obtained. The frequency of earthquakes is taken into account. A priori probabilities of brick buildings failure were calculated by statistical modeling using experimental data obtained during the recording of explosions in MEDEO. The results of reliability and failure estimates will be used for practical recommendations to reduce risk and expected losses in possible earthquakes.

For the first time in Almaty full passport of apartment stock of multiapartment building was carried out. The structure of the housing stock was revealed with the allocation of groups of buildings according to structural solutions and assessment of their seismic resistance. Based on the results of certification, quantitative estimates of failure probability values for different types of buildings were obtained. Formulas for estimation of quantitative value of seismic risk are obtained. The number of deaths in the estimated zem-shakes was estimated. The results of the assessments will be used for practical recommendations to reduce risk and expected losses in possible earthquakes.

To study the seismic insulating properties of buildings in Almaty there is a special polygon. It includes buildings with conventional strip foundations with a system of cross-belts, seismic kinematic and supports with PTFE gaskets. The buildings are equipped with stations of engineering and seismometric service (seismic stations 20,21,22). The results of experimental studies of the house on fluoroplastic gaskets, performed in the late 80s, are analyzed. The results are compared with the instrumental records of the earthquakes of May 31, 2012 and August 16, 2014. The period of maximum spectrum coincides with the resonance in the initial stages of vibration tests-0.44-0.47 seconds. Using a single-mass calculation scheme taking into account the presence of dry friction forces, the dynamic model of the building was calculated for the impact of an unsteady random process. The median acceleration values at the base correspond to the “Seismic Zoning Map of the Republic of Kazakhstan” for earthquakes with a frequency of 475 years and 2475 years. Probabilistic estimates of displacement values at the support level are obtained.

The results of reference building (analogous building) research at the seismic isolation site is presented in the study. A system of cross-strips foundations, seismic insulating kinematic foundations and pillars with fluoroplastic gaskets were utilized in building construction. There are stations of engineering seismological measurement services installed on the buildings. It is analyzed the experimental studies for analogous building performed in the late 80s. The results are compared with the earthquake instrumental records happened on August 16, 2014. According to the seismological measurement services the building oscillation period is 0.40 sec, that fully corresponds to data vibration test with a minimum load of unbalances - 0.39-0.42 sec. It has been established that the floor distortions decrease with building height. Mainly the building is deformed by shear scheme. Taking into account the experimental data, a piecewise linear diagram of the deformation of a single-mass dynamic model of a building is constructed.

To study the seismic insulating properties of buildings in Almaty there is a special polygon. It includes buildings with conventional strip foundations with a system of cross-belts, seismic kinematic and supports with PTFE gaskets. The buildings are equipped with stations of engineering and seismometric service. The results of experimental studies at home on KF, performed in the late 80-ies. The results are compared with the instrumental records of the earthquakes of May 31, 2012 and August 16, 2014. The period of maximum spectrum coincides with the resonance in the initial stages of vibration tests-0.45-0.51 seconds. It is established that floor distortions of floors of the building decrease with height. With the use of a one-mass calculation scheme, taking into account the nonlinear deformation diagram, the dynamic model of the building is calculated for the impact in the form of accelerograms of the specified earthquake at the Foundation level.

Model of earthquake effect in the form of combination of simple functions with random parameters is analyzed. Random process simulating earthquake effect is given by non-canonical representation. Method of generation of artificial accelerograms of local earthquakes is proposed based on presentation of correlation function as a sum of cosine exponential summands. Approximation parameters of correlation function were defined earlier on the basis of least square method by using MATLAB package with the application of methods of nonlinear approximation. Coincidence of initial and generated spectral curves is used as a quality criterion. Selections of random process realizations from 20 to 10000 accelerograms are used. Algorithms are simply implemented in present day systems of computer mathematics MATLAB, SCILAB. Mathematical model of accelerogram of earthquake in El Centro, 1940, has also been considered. Algorithms application area — computations with the use of Eurocode 8 and standards ISO 2394, ISO 8930, including with the application of probabilistic methods, reliability assessment of buildings and constructions based on the method of statistical testing.

Approaches to proportioning of buildings and structures, based on direct numerical integration of dynamic equations, continue to be relevant. For this purpose realistic or artificial accelerograms are used. Probabilistic methods of calculation are based on generation of artificial accelerograms as random-process realizations. There is proposed method of generation of artificial accelerograms, based on representation of correlation function as sum of cosine-exponential summands. Approximation parameters are defined on the basis of least squares method through the use of Curve Fitting Toolbox CKM MATLAB package. Artificial accelerograms are generated by utilizing design formula of autoregression (moving average). Accuracy of generation is illustrated by computation of spectral curves. 

The paper studies the matters of quantitative estimation of seismic risk values for buildings and structures with due consideration of new seismic territorial zoning maps of the Republic of Kazakhstan. On the example of seismic risk value calculation for 2 experimental fragments of skeleton-type industrial buildings, influence of occurrence frequency of earthquakes is assessed. Non-linear deformation of indicated building fragments is taken into consideration. There is also provided an example of risk value calculation for buildings at the local site. Importance of availability of necessary legalized
seismologic information for seismic risk assessment for RK inhabited localities is noted.

Instrumental records of accelerations at the Kapchagay HPP facilities (soil, HPP building and channel dam) at the intensity 5 earthquakes are given for the first time. Spectral curves ? are built. It has been established that under the effects of two earthquakes, the least spectral curves differ for the case of a channel dam, the most – for the recording point on the soil. Recommendations are given for expansion in the number of recording points.

In KazNIISA JSC studies of seismic isolating properties of buildings equipped with special earthquake protection systems are carried out at the special field test site. Displacement, velocity and acceleration measuring sensors were installed on three houses constructed with the same above-foundation part (9-storey large-panel houses of series 158), but with different foundations: conventional strip foundations with the system of crossstrips, seismically isolating kinematic foundations and supports with PTFE gaskets. On these buildings instrumental records of the earthquake were received in the transverse direction on August 16, 2014. The resulting accelerograms were used to construct spectral curves ?. The possible effect of seismic isolation, as well as the influence of foundation constructions on the dynamics of buildings with foundations of conventional type and seismically isolated ones is assessed.

Analysis of instrumental records made by stations of Engineering and Seismometric Service on buildings has been performed to assess changes in dynamic characteristics of the 25-storeyed building of the “Kazakhstan” hotel in Almaty. The building is located near tectonic fault. During two earthquakes, representative instrumental data were obtained at the seismic station No. 16 (“Highrise hotel”) equipped with digital instrumentation system. The building is twenty-five storied with a stiffening core, was built in 1976. Using ADXL accelerometers and RSM-8 recorder, qualitative instrumental records of accelerations were received in the basement, on the floors and on the roof of the building, and spectral curves ? were also built. The features of the dynamics of this building during the earthquake are noted. Under the impact of remote earthquake, building oscillation periods were revealed on the first and second oscillation modes. Dynamic characteristics of the house were compared according to the measurements of 1977 and 2018. Significant increase in the magnitude of oscillation period on the first mode by 25-48% as compared with the measurements of 1976-1977 over the 40-year period of operation was established.

Methodological fundamentals for application of the network of stations of Engineering Seis-mometric Service of KazNIISA JSC are described. Based on the type of problems being solved, all stations are divided into groups (polygons). Buildings located in close proximity to tectonic faults are gathered separately. Buildings equipped with seismic protection and analog house systems are situated at one site. Instrumental records processing means are analyzed – adjustment of zero baseline of the accelerogram according to the type of correlation function, building of accelerations distribution on azimuthal plane. Capabilities to process instrumental records over a long recording interval are analyzed. Recommendations are given for further development of Engineering Seismometric Service of KazNIISA JSC.

The stations of the engineering seismometric service of KazNIISA JSC recorded more than 15 lo-cal earthquakes with the foci in Almaty and Almaty region in 2018. Accelerograms recorded on rigid and flexible buildings during 3 sensible earthquakes were selected from the obtained instru-mental records. These are accelerograms recorded in the basement parts of a four-storeyed frame building and an 11-storeyed steel-framed building. In one instance, the instrumental rec-ords registered in the basement of a 17-storeyed building are used. Flexible buildings are locat-ed near tectonic faults. The spectral curves characterizing the frequency content of the seismic effect are built. It has been established that the frequency response characteristics of the foundation composed of soils of the 2nd category by seismic properties are high-frequency with prevailing periods of 0.1-0.20 sec. Resonance phenomena for flexible buildings under the influence of local earthquakes are not observed. Instrumental records are included into the accelerogram database of KazNIISA JSC.

With budget funding for two years in 2017-2018, the total certification of the housing stock of multi-apartment buildings was carried out for the first time. A total of 8,171 buildings were entered into the database, of which 1,847 are multi-storey frame buildings of various storeys and

design solutions. It is established that 1628 frame buildings are earthquake-resistant, 59-buildings with the first flexible floor are non-earthquake-resistant and 160-are located in the zone of tectonic

faults on the territory of the city. The hypothesis is accepted that buildings located in the zone of tectonic faults will be destroyed. Under these conditions, quantitative estimates of the failure probability and reliability values for frame buildings of various types were obtained for the first time. The frequency of earthquakes is taken into account according to the current "Map of seismic zoning of the Republic of Kazakhstan". The results of the reliability and failure estimates are used for practical recommendations to reduce the risk and expected losses in possible earthquakes. Total reinforcement of frame buildings with the first flexible floors (59 buildings) is proposed. However, the conditional probability of failure for a group of residential frame buildings will remain non-zero. The method of amplification should be determined based on the results of experimental studies.

The construction of monolithic buildings in the city of Almaty is being discussed. The high-rise building has received significant development in the megalopolis area - more than 100 buildings up to 38 floors have been built. Experimental dynamic characteristics of buildings with

dynamic characteristics of a tall building (periods and forms of natural oscillations, decrement of

oscillations) and verification of the correctness of the calculated prerequisites adopted in their construction are relevant. The regulatory framework for the construction of earthquake-resistant buildings in Kazakhstan was analyzed. The data are given to determine the dynamic characteristics of a 22-storey monolithic building. The results are compared with the periods of fluctuations of a 25-storey hotel in Kazakhstan and a 35-storey building along Al-Farabi Street (Nurli Tau district). The results of the work can be used in the design of high monolithic buildings.

The results of studies of the dynamic characteristics of a three-storey fragment of a frame building made according to the SBK-SCF system "Prefabricated frigless frame with seismic-insulating kinematic foundations" are presented. Magnetic dampers are used at the support level.The building fragment was tested by loading the system with a horizontal static load using a stationary winch with subsequent load relief. It is established that the value of the oscillation period varies within 1.8-2.1 seconds depending on the amplitude of the impact.