Base isolation of slide-rocking non-symmetric rigid blocks under impulsive and seismic excitations

Egidio, Angelo Di; Contento, Alessandro

doi:10.1016/j.engstruct.2009.06.021

Cited by 64 publications

(24 citation statements)

References 10 publications

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“…They first investigated the motion mechanism of a non-symmetric rigid block placed on both base-fixed and isolated system [21]. In addition, comprehensive parametric studies have been conducted to understand the influence due to the friction coefficient, the eccentricity of the rigid body and the presence of the security stops [21,22]. More recently, they evaluated the use of base isolation system for the protection of art object in a multi-storey frame.…”

Section: Introductionmentioning

confidence: 99%

“…status), a series of studies have been done by Di Egidio and Contento to understand the seismic performance of a non-symmetric rigid block. They first investigated the motion mechanism of a non-symmetric rigid block placed on both base-fixed and isolated system [21]. In addition, comprehensive parametric studies have been conducted to understand the influence due to the friction coefficient, the eccentricity of the rigid body and the presence of the security stops [21,22].…”

Section: Introductionmentioning

confidence: 99%

“…These include investigations into block sliding response to earthquake motions [13][14][15][16][17][18][19][20][21][22][23][24], derivation of formulations and criteria for rigid bodies sliding due to base excitation [21,[25][26][27], and in-field analyses of sliding rock blocks [28][29][30][31][32]. Also, many observations of contents sliding and falling off shelves have been obtained from the 1976 San Fernando, the 1989 Loma Prieta, the 1994 Northridge, and the recent Canterbury earthquakes [33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Building contents sliding demands in elastically responding structures

Lin

MacRae

Dhakal

et al. 2015

Engineering Structures

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Building contents sliding demands in elastically responding structures

Lin

MacRae

Dhakal

et al. 2015

Engineering Structures

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“…In the design of earthquake-resistant structures based on a performance-based design approach in seismic regions [18][19][20], the earthquake resistance can be improved by different methods: (1) Installation of dampers [21][22][23]; (2) Installation of isolators [24][25][26]; (3) Careful design and detailing of the longitudinal and transverse reinforcement [27][28][29], wrapping with external FRP composites [30][31][32] or confining the concrete by hollow steel tube [33][34][35] within the predicted locations of plastic hinge [36][37][38]. Amongst these methods, the third method is the most common in the design of earthquake resistant RC buildings, particularly for low and medium rise buildings.…”

Section: Introductionmentioning

confidence: 99%

Strain gradient effects on flexural strength design of normal-strength concrete columns

Ho¹,

Peng²

2011

Engineering Structures

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a b s t r a c tThe equivalent rectangular concrete stress block has commonly been adopted for the flexural strength design of reinforced concrete (RC) members for decades. In this stress block, the equivalent concrete stress is expressed as αf ′ c (f ′ c is the uni-axial concrete cylinder strength). Currently, the value of α adopted in various RC design codes is only concrete-strength dependent and equal to 0.85 for NSC. However, in an experimental study conducted previously by the authors on NSC columns subjected to concentric and eccentric axial loads, it was found that α increases significantly as the strain gradient increases. Therefore, the effect of the strain gradient should not be neglected. In this paper, a review on the previous test results on NSC columns is presented and a strain-gradient dependent equivalent rectangular concrete stress block is developed. Based on this proposed stress block, a new flexural strength design method for NSC columns that incorporates the effects of the strain gradient is proposed. A series of column interaction diagrams with various concrete strengths and steel ratios are derived for design purposes. Lastly, these interaction diagrams are compared with the existing column design charts provided in various RC design codes to verify their applicability.

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“…Taniguchi [17] updated the diagrams by introducing change in transition boundaries to accommodate the effect of vertical base excitation. Di Egidio and Contento [18] analyzed the influence of base isolation on the behavior of non-symmetric rigid blocks representing works of art. They also modified the diagrams to introduce effects of base isolation.…”

mentioning

confidence: 99%

Effects of base excitation frequency on the stability of a freestanding rigid block

et al. 2015

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The behavior of a freestanding block subjected to base excitation is a nonlinear problem. In the past, many researchers have analyzed freestanding blocks subjected to base excitation and reported their findings. However, still more understanding is required to understand excitation frequency effects on the stability of a freestanding block. Detailed experiments and numerical analysis were performed on a parallelepiped block having an aspect ratio of four, for different values of coefficient of friction and base amplitudes. It was observed that base excitation frequency has a predominant role on the motion and hence the stability of a freestanding block. Contrary to the present understanding of the subject, it was observed that initiation of any mode of motion (like sliding, rocking) from rest depends not only on the parameters like amplitude of base excitation, coefficient of friction and aspect ratio, but also on the base excitation frequency. A freestanding system initially at rest shall remain in rest until excited by a base excitation frequency below a particular value. We numerically determined the value of this frequency (termed as cutoff frequency) for different values of coefficient of friction (0.1-1) and base amplitude (0.1-1 g) for a constant aspect ratio of four of a parallelepiped block with square base. Using data generated from numerical analysis, a three-dimensional diagram named as initiation criteria diagram was developed that identifies various regions corresponding to sliding, rocking, slide-rock and rest (no motion) phase for a freestanding block subjected to base excitation. A novel finding was the presence of a region of no motion above a frequency value for any given combination of parameters. The ratio of the amplitude of acceleration obtained at the top of the block to the amplitude of applied base acceleration (amplification factor) was calculated for different experimental cases. The dependence of the amplification factor on the base excitation frequency was also studied. Hence, it was concluded that the base excitation frequency plays an important role in determining the stability of a freestanding rigid block.

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Base isolation of slide-rocking non-symmetric rigid blocks under impulsive and seismic excitations

Cited by 64 publications

References 10 publications

Building contents sliding demands in elastically responding structures

Building contents sliding demands in elastically responding structures

Strain gradient effects on flexural strength design of normal-strength concrete columns

Effects of base excitation frequency on the stability of a freestanding rigid block

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