CC BY
325
Ibragimov B. T., Ph.D.,
Raypov D. R.,
Mirzayev SH. V.,
Ilyashov Z.,
Turdaliyev B. M., The Institute of Fire Safety of the Ministry of Internal Affairs of the Republic of Uzbekistan E-mail: jasrash@mail.ru
CALCULATION OF SEISMIC PROTECTIVE QUALITIES OF DAMPEFER AND ABSORTER
Abstract. In article the technique of comparative calculation for determination of quality of seismoprotection devices is given. The example of calculation for a damper and quencher is carried out. Calculations show that use of seismoprotection devices reduces K3 coefficient more, than twice. This circumstance allows to draw a conclusion that the offered damping device reduces seismic loading almost with the same efficiency as quenchers (difference by 0,3 times), falling on the protected construction on 1-2 points.
Keywords: Seismoprotection devices, damper, seismoquencher, dissipation coefficient, fluctuation decrement, seismoinfluence.
When calculating the degree of impact of seismic effects, taking into account active seismic protection on the object of study, follow the normative data laid down in KMK 2.01.0396 "Construction in seismic areas". Table 2.7 of clause 2.13 KMC normalizes the coefficient a depending on the seismic-
ity of the construction site (in points). In order to determine the correction value of the coefficient, the coefficient of acceleration reduction K3 is introduced, which is necessary to take into account the cumulative effect of active seismic protection devices on the protected building.
A) view of the facade of the building; B) axonometry of the damper device; C) the location of the 23 -damper devices under the building. 1 - paronite damping device; 2 - metal fastening plates; 3 - reinforced concrete cushion (basement production compartment) Figure 1. Layout of damping devices under the building
The estimated value of K3 - as shown in the work of L. L. Soldatova. This determined from the condition of not exceeding the total shear force above the level of the sliding belt, according to the formula:
k 3 = ftp ËqJ
(i)
where: f - coefficient of sliding friction in the supports when using seismic protective devices;
k=1
f - allowed to specify on the basis of model or field tests. For the case of calculation without seismic protection device for concrete, f = 0.445
Tp
For the damping device, f = 0.2775; For dampers f = 0.1304;
Tp
ZQkd - the sum of vertical loads when using a damper; ZSgk - total shear seismic force when using a damper. ZQg - the sum of vertical loads when using a damper; ZS, - is the total shear seismic force in use.
A number of refinements are also taken from the KVM, the coefficient a was determined according to table 2.7, depending on the seismicity of the construction site, laid down for the determination of Sik.
Sik = KKK KS . (2)
0 n эт p oik v '
where, K0 coefficient of responsibility taken according to table 2.3, depending on the limit state adopted for the building, for structures according to the degree of importance of such power plants is assumed to be 1.5;
A) view of the facade of the building; B) damper circuit; B) the location of the 7 - absorbers under the building. 1 - Extinguisher; 2 - Pneumosupercharger; 3 - reinforced concrete cushion (basement production compartment) 4 - rod with a piston; 5 - Fluid damping Figure 2. Layout of dampers under the building
Kn - factor of taking into account the frequency of earthquakes, taken according to table 2.4 is equal to 1.2;
Km - the coefficient depending on the number of floors of the building, taken in paragraph 2.17 equal to 1.
Kp - coefficient of regularity, determined according to item 2.25 is taken equal to 1.
Soik - the average value of seismic load corresponding to the i-th tone of natural oscillations, determined under the assumption of elastic deformation of the structure using the formula.
Soik= aQW^j (3)
where, Q - loads (permanent and temporary), causing iner-tial force at the point k and are determined by clause 1.3 KMK 2.01.07-96 "Building codes and rules for the load and impact."
njk - coefficient depending on the shape of the building deformation during its free vibrations, is taken according to the KMK p. 2.18 and 2.19. calculated by the following formula.
The design scheme with a dynamic oscillation damper - m (x) is the linear mass of building structures. X(x) is the ordinate of the normalized form of the natural oscillations of the building, according to the basic tone (the ordinate at the point of suspension of the damper is taken
to be unity). mk is the mass of structures for loads, concentrated at the point with coordinate xk h is the total height of the building. n - total number of concentrated masses. F - dry friction force in the C extinguisher - viscous fric-
mp 1 r O
tion coefficient in the Uk extinguisher acceleration of the base during an earthquake.
n = Xk tQjX;/ ±QX (4)
For the parameters of the building shown in Fig. 1. A, the calculated value of j without seismic protection is 1.049, for the case of using a damper device, j =1.213, for the case of using a damper, j = 1.104. KS - coefficient taking into account the dissipative properties of the structure, is taken in accordance with paragraph 2.16. KMK 2.01.03-96 according to the formula: a is the coefficient determined according to table 2.7 depending on the seismicity of the construction site; W, is the spectral coefficient determined by item 2.14 depending on the period of natural oscillations of the building, in our case it is assumed to be equal to 0.83 [10]. At the same time, the period of free oscillations found experimentally was used as a period, i.e. T = 0.5 sec.; Estimated value
A B Q
Q - load per floor. Comparative schemes of the building: A - without damping device; Bx- with damping device
Figure 3. Design schemes for the damper and damper
A form i. form 2.
Figure 4. Design scheme (A) 1st and 2nd forms (B) of free vibrations of a building when using active seismic protection: where: 5 is the decrement of active seismic protection oscillation; f - coefficient of sliding friction when using active seismic protection
k= 13.59 KPa. (0.548 - yfô )(0.1 + 0.7/y[T~i )K = e (5) where, S is the decrement of oscillation, taken from the results of full-scale tests in the elastic stage of buildings (structures) similar to the designed one. According to the results of experimental data for a building without a damper, S = 0.10. For the case of the use of the damping device, S = 0.15; For the case of damper S = 0.18;
T - the period of natural oscillations of the building, taking into account the use of active seismic protective systems, is assumed to be 0.5 seconds, for a building without damping systems 0.3 seconds Consequently,
(o.548-V018 )(O.1+OJ)/T/05 . — ¿>\ ' —
,, ,= 0.296 x 14.61/1.107 = 3.906
¿(extinguisher)
,= 0.32 x 14.61/1.15 = 4.065
3 (damper)
K3 ,h t eH , = 0.13x14.61/1.557 = 1.219
3 (without protection)
After determining K3, the values of horizontal seismic loads Sik reduced by the use of a damping system, taking into account which it is necessary to calculate the above-ground structures of the building, are found using formulas (1) and (3) with the replacement of a values by aK3 values.
Sik(extinguisher) Sik(extinguisher) ^3 (extinguisher) 1.107 3.9°6 4.32
) *= Sk(d , x K(d . = 1.15 x 4.065 = 4.67
ik(damper) ik(damper) 3 (damper)
*= S.,
S
- S x K
!.k(withoutprotection) ik(without protection) 3 (without protection) - 1
— 1.557 x 1.219
O _
(extinguisher ) e
KS,
(damper)
KS,,
= 1.23,
fO.548-,/0715 )( 0.1+0.7)/VÖ5 = è ! ' = 1.28,
Í0.548-V07 )( 10.1+0.7 )/VÔ3
= e ' = 1.73
(without damper)
Substituting the obtained values in (3), we determine that Soik with 8 points without a damping device is 5.68 kN, when using a damping device 6.01 kN, based on a damper 6.2 kN. Calculation Sik.
S.,, „ ., , = 1 x 0.9 x 1.23 = 1.107 kh
ik(extinguisher)
S.UJ , = 1 x 0.9 x 1.28 = 1.15 kH
ik(aampcr)
S
, - 1 x 0.9 x 1.73 - 1.557 kH
ik (without p rotection)
The data obtained make it possible to calculate the coef-
The reduction of Sk for the case of using a damping device as compared to the variant without using a seismic protection device a seismic device is 4.67/1.899 = 2.46 times. Comparing with the quencher for the variant, the 4.32/1.899 = 2.276 times.
Thus, the calculations show that the use of seismic protection devices reduces the coefficient K3 more than twice. This circumstance allows us to conclude that the proposed damping device reduces the seismic load with almost the same efficiency as absorbers (difference by 8%) falling on the protected structure by 1-2 points. However, it must be borne in mind that the cost of damping devices much cheaper compared to dampers. In addition, damping devices have a high degree of interchangeability.
ficient K, :
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