Low-cost hybrid design of masonry structures for developing countries: Shaking table tests

Tsiavos, Anastasios; Sextos, Anastasios; Stavridis, Andreas; Dietz, Martin; Dihoru, Luiza; Michele, Francesco Di; Alexander, Nicholas A

doi:10.1016/j.soildyn.2021.106675

Cited by 42 publications

(26 citation statements)

References 38 publications

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“…Tsiavos et al [36][37][38][39] (and references therein) have suggested the use of a sand/rubber mixture as an isolation layer underneath the superstructure and have tested the properties of the mixture. Preliminary results show that the friction coefficient of this layer is on the order of 0.25-0.30.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of a spherical rubber isolator for use in low income countries

Katsamakas

Belser²,

Vassiliou³

et al. 2022

Engineering Structures

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This paper presents an experimental study of a low-cost seismic isolator that can be used for the protection of low-rise houses in low-income countries. The isolator is based on rolling of a rubber sphere on flat or spherical concrete surfaces. Using a closely spaced grid of such spheres may allow for avoiding of the diaphragm slab at the isolation level, or of reducing its thickness. Avoiding the cost of this extra slab is crucial for building seismically isolated low-rise dwellings economically feasible in low-income regions of the globe.The effects of the geometry of the rolling surface (i.e., flat or concave), of the diameter of the rolling sphere (i. e., 25, 50 or 100 mm), and of the applied compressive load on the seismic behavior of such isolation bearings were investigated. Initially, the rubber isolators were subjected to monotonic uniaxial compression to examine their behavior under vertical loading. Subsequently, cyclic tests were performed to obtain the lateral force--displacement diagram of the isolation system. Finally, a slab supported by 4 isolators was subjected to a group of 61 ground motions. Eight different configurations were tested, leading to a total of 488 dynamic tests.It was found that the restoring force of such systems can originate not only from the curvature of the concrete surface, but also from the vertical motion induced by the drastic change of the shape of the rubber spheres, as well. In fact, for the configurations tested, the vertical motion sourcing from shape of the deformed sphere was much larger than the vertical motion sourcing from the curvature of the concrete surfaces.Moreover, equations offering the coefficient of friction as a function of the vertical load, the size and the deformation of the sphere were derived. This is crucial for design, as the governing parameter for the design of the rubber spheres is not material failure, but excessive compressive deformation that leads to undesirably high rolling friction. Dynamic tests proved that the proposed low-cost rolling rubber isolators can substantially reduce the accelerations transmitted to the superstructure The cost of the tested 25 mm, 50 mm and 100 mm diameter natural rubber spheres is 0.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of a spherical rubber isolator for use in low income countries

Katsamakas

Belser²,

Vassiliou³

et al. 2022

Engineering Structures

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“…In light of these challenges, Tsiavos et al (2020Tsiavos et al ( , 2021a have experimentally confirmed the efficiency of a novel low-cost and sustainable seismic isolation strategy based on the encapsulation of a thin layer of sand between two PVC surfaces, defined as PVC sandwich (PVC-s) seismic isolation through the conduction of large-scale shaking table tests. Evidently, the earthquake excitation of structures founded on this PVC-s seismic isolation above a critical amplitude of 0.2 g triggers a rolling-sliding response of the upper PVC surface relative to the bottom PVC surface.…”

Section: Introductionmentioning

confidence: 99%

“…However, the investigation of the PVC-s seismic isolation by Tsiavos et al (2020Tsiavos et al ( , 2021a did not include any design recommendation for the recentering of the structure at its original position after the end of the seismic excitation. Moreover, this study was limited to the use of only one material (PVC) as the sliding layer and did not investigate the use of timber as a means of sustainable seismic protection of structures (Yenidogan et al 2020(Yenidogan et al , 2022.…”

Section: Introductionmentioning

confidence: 99%

“…The aim of this study is to overcome the limitations of the feasibility study of the PVC-s seismic isolation proposed by Tsiavos et al (2020Tsiavos et al ( , 2021a) through a large-scale experimental investigation. This large-scale investigation entails the conduction of shaking table tests that demonstrate the efficiency of a novel energy dissipation device with recentering ability.…”

Section: Introductionmentioning

confidence: 99%

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Shaking table investigation of a low-cost and sustainable timber-based energy dissipation system with recentering ability

Tsiavos

Kolyfetis

Panzarasa

et al. 2022

Bull Earthquake Eng

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SummaryThe aim of this paper is to demonstrate the efficiency of a low-cost and sustainable timber-based energy dissipation system with recentering ability, which can be used as a seismic isolation system or a tuned mass damper for the seismic protection of structures in developing or developed countries. The system, defined as Dovetail with SPrings (Dove-SP), utilizes the attractive properties of timber to store CO2, thus reducing the carbon footprint of the existing energy dissipation systems: It comprises two timber slabs that are designed to slide against each other in a motion that is restrained by a dovetail sliding joint. Two sliding interfaces that allow this sliding motion at an attractively low friction coefficient are experimentally investigated: A PVC sand-wich (PVC-s) sliding interface, comprising a thin layer of sand that is sand-wiched between two PVC layers and a timber sand-wich sliding interface consisting of a thin layer of sand encapsulated between two beech timber surfaces. A set of low-cost steel springs is designed and installed on both sides of the dovetail joint to recenter the structure back to its original position after the end of an earthquake ground motion excitation. A novel, low-cost and deformable wood material fabricated from delignified balsa wood is used to reduce the pounding effects before the activation of the steel springs. The seismic behavior and the recentering ability of the novel timber-based energy dissipation system subjected to an ensemble of recorded earthquake ground motion excitations was experimentally investigated through a large-scale shaking table investigation at ETH Zurich.

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“…However, communication with engineers from Peru and Cuba has revealed that in many low-income countries, neither galvanized steel nor polyethylene is available at a low cost. Other studies suggested the creation of a sliding mechanism below the isolation slab using special sand layers (Tsiavos et al, 2019;Tsiavos et al, 2020a;Tsiavos et al, 2020b;Tsiavos et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Feasibility Study on Re-Using Tennis Balls as Seismic Isolation Bearings

Katsamakas

Chollet

Eyyi

et al. 2021

Front. Built Environ.

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This paper presents an experimental study of a low-cost seismic isolator that can be used for the protection of residential structures in low-income countries. The isolator is based on mortar-filled, used tennis spheres, rolling on flat or spherical concrete surfaces. The tennis spheres serve as permanent, spherical molds to cast mortar, and they are not removed after casting. The thin rubber shell of the tennis sphere offers increased damping and reduces stress concentrations at the contact areas. At the same time, this procedure creates a promising solution for the re-use of tennis spheres. Using a closely-spaced grid of such spheres may allow for avoiding the diaphragm slab at the isolation level, or reducing its thickness. Avoiding the cost of this additional, heavily reinforced isolation slab is crucial for making seismically isolated low-rise dwellings economically feasible in low-income regions of the globe. Initially, the tennis isolators were subjected to monotonic uniaxial compression to examine their behavior under vertical loading. Different mixes and low-cost reinforcement approaches to increase their strength were tested. Subsequently, cyclic tests were performed to obtain the lateral force-displacement diagram of the isolation system. The effects of the geometry of the rolling surface (i.e., flat or concave) and of the applied compressive load (i.e., 2.08, 3.23, 4.74, or 8 kN/sphere) on the cyclic behavior were investigated. It was found that the restoring force of such systems mainly originates from the curvature of the concrete surface. However, the vertical motion induced by the compressed sphere and its local casting imperfections is not negligible. When surface imperfections become significant, the force-displacement loops deviate from the bilinear curves that a rigid-body model suggests. When the spheres are properly cast, they experience zero damage even under 8 kN of compressive force, and their loops have a bilinear form. For the tested configurations, the rolling friction (defined as the ratio of lateral to vertical force at zero displacement) was in the range of 4.7–7.2%, thus suitable for seismic isolation applications. The cost of the tested tennis ball isolators was 0.05 $ per sphere.

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Low-cost hybrid design of masonry structures for developing countries: Shaking table tests

Cited by 42 publications

References 38 publications

Experimental investigation of a spherical rubber isolator for use in low income countries

Experimental investigation of a spherical rubber isolator for use in low income countries

Shaking table investigation of a low-cost and sustainable timber-based energy dissipation system with recentering ability

Feasibility Study on Re-Using Tennis Balls as Seismic Isolation Bearings

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