Reduction Of Dynamic Response Research Articles

Enhancing seismic resilience of nonlinear structures through optimally designed additional mass dampers

Reducing dynamic responses in structures subjected to external excitations like earthquakes and strong winds is crucial for ensuring safety and serviceability. Conventional tuned mass dampers (CTMDs) have limitations in mitigating nonlinear vibrations efficiently. This research proposes the use of additional mass dissipation (AMD) devices to control nonlinear dynamic responses more effectively than CTMDs. The AMD concept involves installing an auxiliary mass–damper system atop the primary structure. An analytical approach is developed to determine the optimal design parameters of AMDs for linear and nonlinear single-degree-of-freedom systems using H2 and H∞ optimization techniques. Transfer function and harmonic balance methods are employed to evaluate the dynamic response reduction capabilities. Compared to optimally designed CTMDs, the proposed H2 and H∞ optimized AMDs demonstrate remarkably superior vibration mitigation achieving up to 77 % and 73.71 % greater reductions in dynamic responses, respectively. The Newmark-beta numerical validation confirms AMDs outperforming CTMDs by 16.06 % in minimizing structural vibrations. The novel AMD concept, coupled with the derived optimal design formulations, offers a highly effective vibration control strategy for both linear and nonlinear structural systems under harmonic and random excitations. This analytical solution paves the way for implementing AMDs in practice to enhance structural safety and longevity against external dynamic loads.

The nonlinear negative stiffness inertial amplifier base isolators for dynamic systems

The nonlinear negative stiffness inertial amplifier base isolators (NNSIABI) for vibration reduction of dynamic systems are introduced in this paper. H 2 and H ∞ optimization methods are applied to derive the exact closed-form expressions for the optimal design parameters of novel isolators. For SDOF system, the dynamic response reduction capacity of H 2 and H ∞ optimized linear NSIABI are significantly 64.78% and 77.14% superior to the optimum traditional base isolators. In contrast, the dynamic response reduction capacities of H 2 and H ∞-optimized nonlinear NNSIABI are significantly 64.66% and 66.56% superior to the optimum traditional base isolators. For MDOF systems, the optimum linear NSIABI’s dynamic response reduction capacities are significantly 95.06% and 97.80%, superior to the optimum traditional base isolators. In addition, the optimum nonlinear NNSIABI are significantly 94.88% and 97.68%, superior to the traditional base isolators. All the results are mathematically corrected and applicable for practical applications.

Vibration reduction performance for the novel grounded inerter-based dynamic vibration absorber controlling a primary structure under random excitation

This paper investigates the control performance of a novel grounded inerter-based dynamic vibration absorber (GI-DVA) for random vibration reduction. First, the dynamics equations of the coupled system are written and the transfer function is obtained based on the Laplace transform. Then, assuming that the primary structure is under random white noise excitation, the displacement variance of the primary structure is calculated based on the exact definition of the H2 norm, by solving the Lyapunov equation. By imposing that the partial derivatives of the response variance of the primary structure with respect to the system parameters are simultaneously equal to zero, the optimum design values of the H2 optimized GI-DVA were derived numerically for given different mass ratio. It can be found that the optimal design parameters as the inerter-to-mass ratio, the stiffness ratio and the damping ratio increase, while the frequency ratio decreases with the increase in the mass ratio. Under the optimal conditions, the response analysis showed that the primary structure response controlled by the H2 optimized GI-DVA can decrease with the increase in the mass ratio, but is less sensitive to large mass ratios, and can be robust to the mistuning on the optimum design parameters. Then, the control performance evaluation is first performed in the frequency domain, which reveal that the dynamic response reduction capacity of the H2 optimized GI-DVA are significantly 62% and 48% superior to the H2 optimized classic DVA (CDVA) and high-performance passive nontraditional inerter-based DVA (NIDVA-C4), respectively. Furthermore, for the root mean square response evaluation ( H2 performance), the H2 optimized GI-DVA can provide significantly H2 performance 58% and 50% than the H2 optimized CDVA and NIDVA-C4, respectively. To obtain more realistic results, the time domain simulation is performed, which showed that the GI-DVA can provide significantly performance for random vibration reduction.

Active Vibration Control of Flexible Structures with Super-Coiled Actuators

Flexible structures show low natural frequencies and light damping and often suffer from various dynamic loads, leading to low-frequency vibrations. Active vibration control is necessary for precision operation and long-term service of such structures, and a flexible actuator with a large actuation force and stroke is a key limitation. In this paper, super-coiled (SC) actuators, fabricated from fibers by twisting and inserting, were introduced to actively suppress the low-frequency vibration of flexible structures. Two SC actuators were symmetrically mounted on both surfaces of a cantilever beam to generate actuation forces. The force model of thermally driven SC actuators was developed, and a dynamic model of a cantilever beam with SC actuators was then proposed and validated via experimental actuation. Three types of control strategies, open loop, velocity negative feedback, and linear quadratic regulator (LQR), were adopted for vibration suppression. The results show that the proposed model fits quite well with the experimental data, and the maximum error between the experiment and the prediction is 3.90% among various driven currents. In velocity negative feedback control and LQR control, a 91.83% reduction of dynamic response is achieved, which validates the feasibility of using the actuator for low-frequency vibration control.

The optimal design of negative stiffness inerter passive dampers for structures

The combination of negative stiffness devices and inerters to traditional base isolators (TBI) and tuned mass dampers (TMD) does not exist in any state-of-the-art. Therefore, to pursue the research using the above-mentioned research scope, the negative stiffness inerter passive dampers such as negative stiffness inerter-based base isolators (NSIBI), negative stiffness base isolators (NSBI), negative stiffness inerter-based tuned mass dampers (NSITMD), and negative stiffness tuned mass dampers (NSTMD) are introduced in this paper. H2 and H∞ optimization methods are applied to derive the exact closed-form expressions for the optimal design parameters of these novel passive vibration dampers. Newton’s second law applies to derive the governing equations of motion of the controlled structures. The transfer function formation and Newmark-beta method are applied to determine the dynamic responses of the controlled structures analytically and numerically. Hence, H2 optimized NSIBI and NSBI have 45.98% and 46.71% more dynamic response reduction capacities than optimum TBI. In addition, H∞ optimized NSIBI and NSBI have 58.36% and 57.32% more dynamic response reduction capacities than optimum TBI. Furthermore, the optimum NSITMD and NSTMD have 0.42%, 10.84%, and 4.5%, 13.48% more dynamic response reduction capacities than traditional TMD. All the derivations are mathematically accurate.

The optimum inerter-based additional viscoelastic mass dampers for dynamic response mitigation of structures

The additional inerter-based viscoelastic mass dampers (AIVMD) and additional viscoelastic mass damper inerters (AVMDI) are introduced in this article. H 2 and H ∞ optimization schemes are utilized to derive the optimal closed-form solutions for these novel dampers analytically. A parametric study performs to investigate the sensitivity of the optimal design parameters with other system parameters such as damper mass ratio, inerter mass ratio, and stiffness ratio. Thus, a higher damper mass ratio, a higher inerter mass ratio, and a higher stiffness ratio are recommended to design optimum novel dampers for achieving robust vibration reduction capacities. Therefore, H 2 optimized AIVMD and AVMDI have 53.23 % and 57.73 % dynamic response reduction capacities while H ∞ optimized AIVMD and AVMDI can provide 72.97 % and 75.57 % dynamic response reduction capacities subjected to harmonic excitation, respectively. In addition, random-white noise excitations are also applied instead of harmonic excitation to cross-check the accuracy of the optimal design parameters. The overall result shows that 74.24 % and 82.17 % dynamic response reduction capacities for H 2 optimized AIVMD and AVMDI, furthermore, 92.14 % and 94.36% dynamic response reduction capacities for H ∞ optimized AIVMD and AVMDI. These optimal closed-form solutions are mathematically accurate and relevant for practical applications.

The optimum inertial amplifier viscoelastic base isolators for dynamic response mitigation of structures: an analytical study

ABSTRACT The inertial amplifier viscoelastic base isolators (IAVBI) are introduced in this paper. The viscoelastic materials are implanted inside the core material of the inertial amplifier base isolators. The standard linear solid (SLS) models are applied to formulate the viscoelastic material mathematically. The viscoelastic materials are also implanted inside the traditional base isolators to enhance their dynamic response reduction capacity. The optimal dynamic responses of structures controlled by novel viscoelastic base isolators are derived analytically. The exact closed-form expressions for optimal design parameters of novel viscoelastic base isolators for structures are derived using and optimization methods. The feasibility of these optimal design parameters has been tested by frequency domain analysis. The optimal dynamic response reduction capacity of inertial amplifier viscoelastic base isolators has been determined to investigate the robustness of the and optimized design parameters. The closed-form expressions for optimal design parameters of novel base isolators are mathematically correct and effective for design purposes.

The optimum enhanced viscoelastic tuned mass dampers: Exact closed-form expressions

This paper introduces the inertial amplifier viscoelastic tuned mass dampers (IAVTMD). The viscoelastic materials are implanted inside the core material of the inertial amplifier tuned mass dampers. The standard linear solid models are applied mathematically to formulate the viscoelastic material. H2 and H ∞ optimization mechanisms apply to derive the exact mathematical closed-form formulations for optimal design parameters for novel inertial amplifier viscoelastic tuned mass dampers. The optimum IAVTMD installs at the top of the structures to mitigate the dynamic responses, determining the dynamic responses analytically through transfer function formation. At first, IAVTMD’s dynamic response reduction capacity compares with the conventional tuned mass damper’s (CTMD) dynamic response reduction capacity. As a result, H2 optimized IAVTMD’s dynamic response reduction capacity is significantly 20.87% and 26.47% superior to two well-established H2 optimized conventional tuned mass damper’s dynamic response reduction capacity. In addition, H ∞ optimized IAVTMD has 15.48% more dynamic response reduction capacity than H ∞ conventional tuned mass damper. H2 and H ∞ optimized tuned mass damper inerters with optimal closed-form solutions are introduced in this paper. A higher damper mass ratio and a lower inerter mass ratio are recommended to produce H2 and H ∞ optimized tuned mass damper inerter (TMDI) with a lower frequency and damping ratio in an affordable range. Accordingly, H2 and H ∞ optimized IAVTMD’s dynamic response reduction capacities are significantly 6.94% and 23.29% superior to H2 and H ∞ optimized TMDI’s dynamic response reduction capacity. The closed-form expressions for optimal design parameters of inertial amplifier viscoelastic tuned mass dampers and tuned mass damper inerters are mathematically correct and effective for practical applications.

The optimal configuration of negative stiffness inerter-based base isolators in multi-storey buildings

The negative stiffness inerter-based base isolators (NSIBI) are introduced in this paper. The negative stiffness device and inerters are installed inside the core of the conventional base isolators (CBI) to enhance their dynamic response reduction capacity. The novel isolators have been installed at the multi-storey building’s base to mitigate their dynamic responses during vibration. H2 optimization method applies to derive the exact closed-form expression for negative stiffness inerter-based base isolators’ optimal design parameters, such as frequency and viscous damping ratio for multi-storey buildings. Applying these H2 optimized design parameters, the optimum NSIBI for dynamic response mitigation of multi-storey buildings have been achieved. The dynamic responses of the NSIBI-controlled multi-storey buildings are compared with the dynamic responses of multi-storey buildings isolated by optimum CBI to determine the exact superior dynamic response reduction capacity of optimum NSIBI. The dynamic responses of isolated structures in the frequency domain are evaluated by forming the transfer function. Therefore, for five-storey buildings, the dynamic response reduction capacity of NSIBI is significantly 51.93% and 81.24% superior to the dynamic response reduction capacity of CBI subjected to harmonic and random-white excitations. In contrast, for ten-storey buildings, the optimum NSIBI has 77.73% and 94.02% more dynamic response reduction capacity than the optimum CBI subjected to harmonic and random-white excitations. In addition, using the Newmark beta method, a numerical study further conducts to verify the accuracy of the H2 optimized design parameters by obtaining the time history results for isolated structures subjected to near-field pulse-type earthquake base excitations. Accordingly, the optimum NSIBI have 57.591% and 55.398% more displacement and acceleration capacity than the optimum CBI for five-storey buildings. Besides, for ten-storey buildings, the displacement and acceleration capacities of optimum NSIBI are significantly around 56.42%and 55.80%, superior to the optimum CBI. Thus, the vibration reduction capacity of optimum CBI is significantly decreasing while the storey level of the multi-storey buildings increases, whereas NSIBI is still efficient in reducing the dynamic responses effectively. The paper’s outcomes are mathematically accurate and applicable to practical implementation.

The Optimum Inertial Amplifier Tuned Mass Dampers for Nonlinear Dynamic Systems

The optimum inertial amplifier tuned mass dampers (IATMD) for vibration reduction of linear and nonlinear dynamic systems are introduced in this paper. [Formula: see text] and [Formula: see text] optimization methods are applied to derive the exact closed-form expressions for optimal design parameters such as frequency and viscous damping ratios in simplified form mathematically for IATMD. From the parametric study, using these optimal closed-form solutions, a higher damper mass ratio, a higher amplifier mass ratio, and a lower inertial angle are recommended to design optimum IATMD to achieve robust dynamic response reduction capacity having moderate viscous damping and lower frequency ratios at an affordable range. The optimum IATMD systems are installed on top of linear and nonlinear single-degree-of-freedom systems to mitigate their dynamic responses of them. The linear dynamic responses are determined through transfer matrix formations, and nonlinear dynamic responses are derived using the harmonic balance (HB) method. [Formula: see text] optimized IATMD is significantly [Formula: see text] and [Formula: see text] superior to the [Formula: see text] optimized conventional tuned mass damper one (CTMD1) and conventional tuned mass damper two (CTMD2). Furthermore, [Formula: see text] optimized IATMD is significantly [Formula: see text] superior to the [Formula: see text] optimized conventional tuned mass damper (CTMD). According to the nonlinear dynamic analysis, [Formula: see text] optimized IATMD systems are significantly [Formula: see text], [Formula: see text], and [Formula: see text] superior to the [Formula: see text] optimized CTMD. Furthermore, [Formula: see text] optimized IATMD systems are significantly [Formula: see text], [Formula: see text], and [Formula: see text] superior to the [Formula: see text] optimized CTMD. The results of this study are mathematically accurate and feasible for practical applications.

Dynamic Response Reduction of Reinforced Concrete Structure using Tuned Mass Damper and Tuned Liquid Damper

Damping devices are used to reduce the dynamic response of a structure by energy dissipation. Common types of damping devices are fluid viscous dampers, tuned mass dampers, and tuned liquid dampers. This project aims to study the effectiveness of TMD and TLD in controlling the response of the structure when it is subjected to acceleration records of different earthquakes. A 20-storey reinforced concrete bare frame structure has been subjected to two earthquake acceleration records with and without dampers in SAP 2000. The dampers are modelled using link elements. The structure is attached with TMD and TLD having a mass of 0.5%, 2%, 4%, 6%, 8% and 10% of the modal mass. The analysis procedure used is nonlinear modal time history analysis (FNA). The variation in base shear and top storey displacement has been obtained and plotted.

Machine learning-based predictive models for equivalent damping ratio of RC shear walls

Energy-based seismic design is being rapidly developed and suggests that the seismic demands are met by the energy dissipation capacity of the structural members. Equivalent damping ratio is a measure of energy dissipation in structural members that accounts for the post-elastic behavior of the member and provides insight regarding the dynamic response reduction during a seismic event. The present study implements a machine learning algorithm to estimate the equivalent damping ratio in reinforced concrete shear walls at displacements corresponding to a 1.0% lateral drift ratio. Five different machine learning models, namely, Robust Linear Regression, K-Nearest Neighbor Regression, Kernel Ridge Regression, Support Vector Regression, and Gaussian process regression were evaluated in order to choose the model with the highest accuracy. Among all models, Gaussian process regression, a machine learning method with successful implementation experiences in civil/structural engineering related problems, is selected to identify the equivalent damping ratio. The developed GPR-based algorithm uses a database of 161 rectangular shear walls subjected to quasi-static reversed cyclic loading with geometry and mechanical properties commonly found in building stocks of many earthquake-prone countries. The proposed algorithm estimates the equivalent damping ratio for each specimen by predicting the cyclic dissipated energy and lateral force values as two dependent variables. The model validation results show a mean coefficient of determination (R2) of about 0.89; a relative root mean square error of about 0.14 and a mean absolute percentage error of 10.44%, which is considered a substantially accurate prediction for such a complex problem. An open-source model and the entire database are provided which can be used by researchers and also design engineers. The proposed predictive model enables comparing the damping capacity of shear walls and the outcomes of this study are believed to contribute to the energy-based design or performance evaluation procedures in terms of predicting the energy capacity of shear walls.

The optimal design of dynamic systems with negative stiffness inertial amplifier tuned mass dampers

The negative stiffness inertial amplifier tuned mass dampers (NSIA-TMD) are introduced in this paper. Another two novel tuned mass dampers such as negative stiffness tuned mass damper (NS-TMD) and inertial amplifier tuned mass damper (IA-TMD) are mathematically developed from the negative stiffness inertial amplifier tuned mass dampers (NSIA-TMD) and the static masses of these three novel dampers are retained constant. The exact closed-form expressions for optimized system parameters for these novel dampers are obtained using H2 and H∞ optimization techniques. The dynamic responses of the SDOF systems controlled by H2 and H∞ optimized novel tuned mass dampers subjected to base excitations are obtained analytically. The dynamic response reduction capacities of the novel tuned mass dampers are compared with the dynamic response reduction capacities of traditional tuned mass dampers (TMD). Therefore, the dynamic response reduction capacities of H2 optimized NS-TMD, NSIA-TMD, and IA-TMD are significantly 45.51%, 43.47%, 41.08% superior to the H2 optimized traditional tuned mass dampers. Furthermore, the dynamic response reduction capacities of H∞ optimized NS-TMD, NSIA-TMD, and IA-TMD are significantly 3.31%, 8.98%, 13.79% superior to the H∞ optimized traditional tuned mass dampers. The nonlinear negative stiffness inertial amplifier tuned mass dampers (NNSIA-TMD) are also introduced in this paper. As a result, the dynamic response reduction capacities of H2 optimized nonlinear negative stiffness tuned mass damper (NNS-TMD), NNSIA-TMD, and nonlinear inertial amplifier tuned mass damper (NIA-TMD) are significantly 24.54%, 21.92%, 19.12% superior to the H2 optimized traditional tuned mass dampers. Furthermore, the dynamic response reduction capacities of H∞ optimized NNS-TMD, NNSIA-TMD, and NIA-TMD are significantly 3.01%, 9.04%, 15.08% superior to the H∞ optimized traditional tuned mass dampers. The outcomes of this research are mathematically accurate and relevant to practical design applications.

Control of vortex-induced vibrations of the cylinder by using split-ter plates immersed in the cylinder wake at low Reynolds number

The vortex-induced vibrations of a cylinder with two plates symmetrically distributed along the centerline of the wake are studied by using the fluid-structure interaction simulations on the Arbitrary Lagrangian-Eulerian method. In this study, the different geo-metrical distribution parameters of the splitter plates and inflow velocities are taken into account. The physical mechanisms of vortex-induced vibration of the cylinder with symmetrical plates are revealed from the cylinder amplitude, hydrodynamic force characteristics, vortex shedding frequency, and flow pattern modification. The results show that the dynamic interaction between the vortex shed from the oscillation cylinder and plates is responsible for the wake stabilization mechanism, and the stable wake and the dynamic response reduction of the main cylinder can be achieved at a wide range of reduced velocities by placing sym-metrical sheets at suitable locations.

Applying a modified model predictive current control method to improve surface‐mounted permanent magnet synchronous motor drives performance in transient and steady‐state operations

The performance of the conventional model predictive current control (MPCC) method is not without steady-state ripples in electrical drives. Although some recently proposed MPCC methods have succeeded to mitigate this drawback, they have led to reductions in the dynamic speed response inherent to the conventional MPCC method. An improved MPCC is proposed here which would enhance the conventional MPCC method without any side effect on its merits. In this proposed method, three control strategies are presented for transient- and steady-state operations. The first two strategies are applied to improve motor performance in the steady state, through calculating the voltage vector (VV) and its optimal duration to minimise ripples in both d–q -axis currents. The third strategy is applied in the transient-state operation, where, instead of two VVs, an allowable non-zero VV is applied throughout the control cycle to prevent dynamic response reduction caused by zero VV. The experimental results confirm the effectiveness of this proposed method in reducing torque ripples, flux ripples, and the stator current total harmonic distortion in relation to those obtained by the previous MPCC methods.

Building mass damper design based on optimum dynamic response control approach

The building mass damper (BMD) design features the use of partial structural mass, instead of additional tuned mass, as an energy absorber. Therefore, it becomes more effective in dynamic response reduction compared to the conventional tuned mass damper (TMD) design with very limited added tuned mass. In this study, an optimum building mass damper (OBMD) design approach, namely optimum dynamic response control approach, based on a simplified 3-lumped-mass structure model is proposed to enhance the seismic performances of both the superstructure (or tuned mass) and substructure (or primary structure) respectively above and below the control layer. A series of shaking table tests on one bare and two OBMD specimens were conducted to experimentally verify the efficacy of the proposed OBMD design approach. To further demonstrate the advantage of the OBMD design conditionally over other passive control approaches, the seismic responses of the same structure model but respectively designed with a mid-story seismic isolation (MSI) system and additional energy dissipation devices are also numerically analyzed and compared. It is found that the OBMD design can reveal a better seismic performance than the energy dissipation design. More importantly, it can have a comparable and even superior seismic performance to the MSI design especially when the structure model has a medium or long period of vibration.

Reduction of dynamic response of a bar using constrained layer damping composite structure

The bar structure has been widely used in products and equipment. The tool holders of cutting machines and the support bars in processing are prone to vibration under the unstable excitation. Firstly, a universal and general-purpose constrained layer damping composite bar is proposed to reduce dynamic response for the bar structure. The composite bar can reduce vibration through adding the damping ratio and compensates stiffness. The constrained layer damping structure of the composite bar are consisted of constrained layer, damping layer and substrate. Secondly, the modal characteristics of the composite bar are analysed. According to the modal characteristics calculation and the optimization principles of reduction vibration, the geometric parameters of the composite bar are determined. And 42CrMo steel, four viscoelastic materials and the hard metal are chosen as the materials of substrate, damping layer and constrained layer, respectively. Finally, the modal tests for the composite bars with various materials are performed. The constrained layer damping composite structure is optimized by the test result. The optimal constrained layer damping composite bar can increase the damping ratio by 400% and can reduce the vibration obviously.

Structural Control for an Offshore Wind Turbine with a Tuned Mass Damper in Floating Platform

In recent years, offshore wind energy has become an attractive option due to the increased demand for the renewable energy. A method incorporating a tuned mass damper (TMD) in offshore wind turbine platform is proposed to demonstrate the improvement on structural dynamic performance in this investigation. The Lagrange's equations are applied to establish a limited degree-of-freedom (DOF) mathematical model for the barge-type offshore wind turbine. Genetic algorithm (GA) is then employed to find the globally optimum TMD design parameters. Numerical simulations based on FAST have been carried out to evaluate the effect of the passive control system. A changeable mass for the floating wind turbine will be brought for installing a heavy tuned mass damper in the platform. In this case, partial ballast is substituted for the equal mass of the tuned mass damper, and the vibration mitigation is simulated in five typical load cases. Results show that the passive control approaches can improve the dynamic responses of the barge-type wind turbine by placing a tuned mass damper in floating platform. Through replacing partial ballast with the equal mass of the tuned mass damper, a significant reduction of dynamic responses is also observed in simulation results for the barge-type floating structure.

Numerical and experimental nonlinear dynamic response reduction of smart composite curved structure using collocation and non-collocation configuration

In this work, a generic geometrical nonlinear mathematical model of smart composite curved shell panels has been developed for the evaluation of the linear and nonlinear dynamic responses. Further, the dynamic deflections are reduced by employing the piezoelectric material with the parent composite using two different arrangements (sensor and actuator). The current layered structure model is developed based on the higher-order mid-plane kinematics including the stretching effect. The electric potential due to the piezoelectric material included via a quadratic function of thickness for the current combined electro-elastic modeling. The geometrical distortion of the smart shell panel structure accounted via Green-Lagrange strain field including all of the nonlinear higher-order terms. The desired responses are evaluated computationally using an original computer code (MATLAB environment) with the help of the current higher-order model and finite element steps. The nonlinear dynamic deflection values are obtained through the direct iterative method in conjunction with Newmark’s integration. Additionally, the accuracy of the proposed model is demonstrated via comparison study with the available published literature with and without electric field potential. The reduction of response frequencies is also compared with the in-house experimental data. Lastly, few more numerical examples are computed for the various geometrical parameter including the shell configuration and the comprehensive behaviour of the currently developed nonlinear numerical model for the analysis of smart layered structure discussed in details.

NUMERICAL SIMULATION OF YIELDING SUPPORTS IN THE SHAPE OF ANNULAR TUBES UNDER STATIC AND SHORT-TERM DYNAMIC LOADING

Occurrence of extreme man-made impacts on buildings and structures has become frequent lately as a consequence of condensed explosives or explosive combustion of gas- vapor or air-fuel mixtures. Such accidents involve large human and economic losses, and their prevention methods are not always effective and reasonable. The given research aims at studying the way of enhancing explosion safety of building structures by means of yielding supports. The paper presents results of numerical studies (finite element, 3D nonlinear) of strength and deformability of yielding supports in the shape of annular tubes under static and short-term dynamic loading. The degree of influence of yielding supports was assessed taking into account three peculiar stages of deformation: elastic; elasto-plastic; elasto-plastic with hardening. The methodology for numerical studies performance was described. It was established that rigidity of yielding supports influences significantly their stress-strain state. The research determined that with increase of deformable elements rigidity dependency between load and deformation of yielding supports in elastic and plastic stages have linear character. Significant reduction of dynamic response and increase of deformation time of yielding supports was observed by increasing the plastic component. Therefore it allows assuming on possibility of their application as supporting units in reinforced concrete constructions