On the use of a pendulum as mass damper to control the rocking motion of a rigid block with fixed characteristics

Allowing flexible structures to uplift and rock during earthquakes can significantly reduce the force demands and residual displacements. However, such structures are still susceptible to large deformations and accelerations that can compromise their functionality. In this paper, we examine the dynamic response of elastic rocking oscillators and suggest that their lateral drifts and accelerations can be limited effectively by using inerter devices. To this end, we offer a detailed examination of the effects of structural flexibility on the efficiency of the proposed system. The analytical expressions governing the motion of deformable structures with base uplift are revisited to incorporate the effects of the supplemental rotational inertia. The proposed model is then used to study the structural demands of flexible rocking structures under coherent pulses as well as noncoherent real pulse-like ground motions. Our results show that combining rocking with inerters can be an efficient strategy to control the deformation and acceleration demands in uplifting flexible systems.

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“…Therefore, replacing equations (13) to (15) into equation 16, the equations that describe the motion of the system are obtained as follows:…”

Section: Rocking Phasementioning

confidence: 99%

Seismic control of flexible rocking structures using inerters

Thiers-Moggia

Mariotti

2020

Earthq Engng Struct Dyn

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“…For example, in Corbi, 24 the motion of a rigid block was controlled by a sloshing water damper. More recently, other studies [25][26][27][28] presented studies on the use of a pendulum as dynamic mass absorber. Such studies showed that the use of the dynamic mass absorber leads to a general improvement of the response of the system because the overturning of the block occurs for values of the amplitude of the base excitation higher than those observed without the dynamic mass absorber.…”

Section: Introductionmentioning

confidence: 99%

Protection from overturning of rigid block‐like objects with linear quadratic regulator active control

Egidio

Contento

Olivieri

et al. 2020

Struct Control Health Monit

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Summary In recent years, several studies proposed new techniques aimed at improving the performances of rigid block‐like objects under base excitation. The majority of these studies considered passive control methods, such as base isolation or other techniques based on the tuned mass damper principle. Only few studies considered active and semi‐active control methods applied to the dynamics of rigid blocks. This paper proposes an active control method for symmetric rigid blocks that is based on the LQR approach. The optimal control law is obtained starting from the linearized equation of motion. The effectiveness of the proposed control method is investigated comparing the behaviour of rigid blocks with and without active control under harmonic and seismic excitation. The results are summarized in overturning spectra, in the case of harmonic excitation, and rocking maps, in the case of seismic excitation. Although the proposed active control method is expected to work well for slender blocks, specific analyses show that the method also improves the dynamics of no‐slender blocks and is effective for blocks with different geometrical characteristics. Moreover, the results show that the control law has a good robustness with respect to the sampling time and the time delay.

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“…Similarly, a number of researchers have studied the use of appendages and devices attached to the rocking body to modify its seismic response. For example, De Leo et al 17 analysed the behaviour of a rocking structure with a pendulum attached to it acting as a vibration absorber. They observed important improvements in the overturning capacity of blocks with pendulums in comparison with uncontrolled structures.…”

Section: Introductionmentioning

confidence: 99%

Seismic control of rocking structures via external resonators

Pan

Mariotti

2020

Earthq Engng Struct Dyn

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Summary Tall rigid blocks are prevalent in ancient historical constructions. Such structures are prone to rocking behaviour under strong ground motion, which is recognizably challenging to predict and mitigate. Our study is motivated by the need to provide innovative nonintrusive solutions to attenuate the rocking response of historical buildings and monuments. In this paper, we examine a novel scheme that employs external resonators buried next to the rocking structure as a means to control its seismic response. The strategy capitalizes on the vibration absorbing potential of the structure‐soil‐resonator interaction. Furthermore, the benefits of combining the resonators with inerters in order to reduce their gravitational mass without hampering their motion‐control capabilities are also explored. Advanced numerical analyses of discrete models under coherent acceleration pulses with rocking bodies of different slenderness ratios under various ground motion intensities highlight the significant vibration absorbing qualities of the external resonating system. The influence of key system parameters such as the mass, stiffness, and damping of the resonator and those of the soil‐structure‐resonator arrangement are studied. Finally, a case study on the evaluation of the response of rocking structures with external resonators under real pulse‐like ground‐motion records confirms the important reductions in peak seismic rotational demands obtained with the proposed arrangement.

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On the use of a pendulum as mass damper to control the rocking motion of a rigid block with fixed characteristics

Cited by 29 publications

References 30 publications

Seismic control of flexible rocking structures using inerters

Seismic control of flexible rocking structures using inerters

Protection from overturning of rigid block‐like objects with linear quadratic regulator active control

Seismic control of rocking structures via external resonators

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