Experimental behavior and design of a new kinematic isolator

Besa, Jaime; Llera, Juan Carlos de la; Jünemann, Rosita

doi:10.1016/j.engstruct.2009.10.012

Cited by 3 publications

(1 citation statement)

References 2 publications

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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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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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Seismic Performance of Segmental Rocking Columns Connected with NiTi Martensitic SMA Bars

Moon

Roh

Cimellaro

2015

Advances in Structural Engineering

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As well known, the damping or energy dissipation capacity of bridge columns is very important because it is directly related to the design spectrum and affects the seismic performance of whole bridge systems. For this reason, several investigations evaluating the energy dissipation capacity of segmental columns, which has a small energy dissipation capacity itself, have been conducted by adopting various material types of energy dissipating (ED) bars. This paper investigates the damping capacity of post-tensioned (PT) segmental rocking columns connected with large diameter (36.5 mm) martensitic SMA bars at their base as ED bars. Two aspect ratios for the columns are considered: 7.5 for slender and 5.0 for medium size. Moment-curvature relationships and complementary computational tools are adopted to model the behavior of the columns. A bilinear model for the PT tendon and a modified four-spring model for the martensitic SMA bar are used. From the quasi-static cyclic analysis, the martensitic SMA bars leads to an equivalent damping ratio between 10.5% and 12.5% for the different aspect ratios and PT tendon forces. For the sake of comparison, another material type of the SMA bar, which is 25.4 mm diameter superelastic bar, is considered. The damping ratio of the columns with the martensitic SMA bars is much higher than the use of the superelastic SMA bars showing between 5% and 7% damping ratio.

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Experimental evaluation of geomembrane/geotextile interface as base isolating system

Kalpakci

Bonab

Özkan

et al. 2018

Geosynthetics International

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The objective of this study is to evaluate the effect of the geomembrane/geotextile interface on the seismic response of small-to-moderate height structures. Three building models with first-mode natural frequencies changing between 2–4 Hz (representing two, three and four storey structures) were tested with and without the addition of geomembrane/geotextile interface using the shaking table test setup by employing harmonic and modified/scaled ground motions. Experimental results showed that the geomembrane/geotextile interface significantly reduced the floor accelerations, especially at moderate-to-high ground shaking levels. The interaction between the first-mode natural frequency of the model and the predominant frequency of the input motion is significant, and the interface is most effective when these two frequencies are close to each other. This effect is more clearly seen when the harmonic motions are employed during the tests compared to the modified/scaled ground motions. The results of the tests with modified/scaled ground motions were used to evaluate the efficiency of the composite liner system in reducing the spectral accelerations in the frequency domain. The results presented here document that the geomembrane/geotextile interface reduces the floor accelerations in a certain frequency range and underline the potential of this interface to be used as a base isolation material.

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Experimental behavior and design of a new kinematic isolator

Cited by 3 publications

References 2 publications

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

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

Seismic Performance of Segmental Rocking Columns Connected with NiTi Martensitic SMA Bars

Experimental evaluation of geomembrane/geotextile interface as base isolating system

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