scholarly journals Fragility Assessment of Geotechnical Seismic Isolated (GSI) Configurations

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5088
Author(s):  
Davide Forcellini
Keyword(s):  
Developing Countries ◽  
Finite Element ◽  
Seismic Isolation ◽  
Fragility Curves ◽  
Low Cost ◽  
Soil Layer ◽  
Seismic Energy ◽  
Finite Element Models ◽  
Numerical Finite Element ◽  
Mitigation Technique

Geotechnical seismic isolation (GSI) consists of an innovative technique to mitigate the effects of earthquakes based on interposing a superficial soil layer to filter the seismic energy from the soil to the structure. This approach is particularly applied in developing countries due to low-cost applications. In order to account the uncertainties, the presented paper aimed to develop fragility curves of 3D configurations performed by numerical finite element models. The mail goal is to assess and discuss the potentialities of GSI as a mitigation technique for several configurations. Opensees PL has been applied to perform the numerical analyses and to realistically reproduce the behaviour of GSI.

scholarly journals Assessment of Geotechnical Seismic Isolation (GSI) as a Mitigation Technique for Seismic Hazard Events

Geosciences ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 222 ◽  
Author(s):  
Davide Forcellini
Keyword(s):  
Seismic Isolation ◽  
Low Cost ◽  
Soil Layer ◽  
Seismic Energy ◽  
Historical Earthquakes ◽  
Structural Configurations ◽  
Numerical Finite Element ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Mitigation Technique

Geotechnical seismic isolation (GSI) has emerged as a potential technique to mitigate the effects of earthquakes, with many applications to structural configurations, such as bridges and buildings. It consists of absorbing the seismic energy from the soil to the superstructure by interposing a superficial soil layer in order to reduce the accelerations that filter from the soil to the structure. This mitigation technique is particularly suitable in developing countries since GSIs are low-cost seismic isolation systems that through relatively simple manufacturing processes allow to safe costs and stimulate many applications. The presented study aimed to perform 3D numerical finite element models that overcome the previous contributions by performing several structural configurations. Several historical earthquakes are considered in this paper, and the results may be applied to drive general assessments of the technique in case of future seismic hazards.

scholarly journals Large-scale experimental investigation of a low-cost PVC ‘sand-wich’ (PVC-s) seismic isolation for developing countries

2020 ◽  
Vol 36 (4) ◽  
pp. 1886-1911 ◽  
Author(s):  
Anastasios Tsiavos ◽  
Anastasios Sextos ◽  
Andreas Stavridis ◽  
Matt Dietz ◽  
Luiza Dihoru ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Developing Countries ◽  
Ground Motion ◽  
Seismic Isolation ◽  
Large Scale ◽  
Low Cost ◽  
Seismic Energy ◽  
Earthquake Ground Motion ◽  
Isolation System ◽  
Seismically Isolated

This study presents a large-scale experimental investigation on the seismic performance of an innovative, low-cost seismic isolation system for developing countries. It is based on the beneficial effect of the encapsulation of sand grains between two PVC surfaces on the initiation of sliding and the dissipation of seismic energy between the surfaces. A three-times scaled-down, idealized, seismically isolated model of a prototype single-story structure located in Nepal is subjected to an ensemble of recorded earthquake ground motion excitations. The experimentally derived response of the seismically isolated structure is compared with the response of the corresponding fixed-base structure. This system is part of a wider hybrid design approach where the structure is designed to resist the seismic forces at the design acceleration level. The seismic isolation system sets an upper bound to the response of the structure for ground motion excitations exceeding the design level.

scholarly journals Comparative analysis of conventional and new seismically isolated structure

2021 ◽  
Vol 64 (3) ◽  
pp. 185-193
Author(s):  
Jelena Ristić ◽  
Miloš Vučinić ◽  
Danilo Ristić ◽  
Milutin Vučinić
Keyword(s):  
Seismic Isolation ◽  
Low Cost ◽  
Seismic Energy ◽  
Seismic Excitation ◽  
Isolation System ◽  
Vibration Period ◽  
International Projects ◽  
Dominant Period ◽  
Efficient Protection ◽  
Seismically Isolated

Extensive analytical and experimental research has been done by the authors directed to mitigation of the effects of earthquakes on structures. The research results mainly represent parts of the realized several related international projects. A selected part of the analytical studies directed to comparison between conventional and seismically isolated frame structures is presented in this paper. The responses of the applied newely developed advanced seismic isolation system HC-RMS-GOSEB to the simulated input excitation of three representative earthquakes of intensity 0.50g, have shown that it is very effective for construction of vibro-isolated and seismically resistant buildings, providing activated multistage seismic response and globally optimized seismic energy balance. Its application achieves an increase in the vibration period of the structure, far enough from the dominant period of seismic excitation. The results of the research confirm that this system is a potential solution for achieving low-cost and highly efficient protection of buildings.

Cemented Wellbore Experiments Reveals That Cement Interface Debonding Modeling Overestimate Potential Leakage Rates

2020 ◽  
Author(s):  
Zachary Speer ◽  
Jarrett Wise ◽  
Runar Nygaard ◽  
Geir Hareland ◽  
Eric Ford ◽  
...  
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Models ◽  
Interface Debonding ◽  
Finite Element Models ◽  
Wellbore Integrity ◽  
Cement Interface ◽  
Abandoned Wells ◽  
Numerical Finite Element ◽  
Physical And Chemical

Abstract Leakage pathways may develop in wellbores during construction, production, or during and after plug and abandonment (P&A). These pathways are created due to events and conditions during cementing operations, or because of physical and chemical changes after cementing such as changes in temperature and wellbore pressures, and deterioration of the cement. Common leakage pathways develop inside the cement sheath, or as microannuli along the cement-tubing interface. Numerous evidence exists showing that wellbores leak, but there is no verified method to determine if a well will leak or not. To ensure long term wellbore integrity, leakage risks need to be evaluated for plugged and abandoned wells. To evaluate leakage risks from plugged and abandoned wells, numerical finite element models have been developed and used to investigate leakage scenarios during the life of the well. Currently, little work has been done to verify finite element numerical models with experimental data regarding flowpath size in cement sheaths. The aim of this paper is to model previously published experimental data to determine if the finite element models can accurately predict leakage potentials. Two lengths of cemented annuli were modeled, each with conventional and expanding cement to replicate the Aas et. al. [1] experiments. The numerical results show that the simulated microannuli overestimate flow rate compared to experimental data, indicating that flow path dimensions and/or fluid friction factor does not accurately represent the fluid flow in the experiments.

Seismic Isolation Systems for Developing Countries

2002 ◽  
Vol 18 (3) ◽  
pp. 385-406 ◽  
Author(s):  
James M. Kelly
Keyword(s):  
Developing Countries ◽  
Theoretical Analysis ◽  
Earthquake Engineering ◽  
Seismic Isolation ◽  
Low Cost ◽  
Fiber Reinforcement ◽  
Fiber Reinforced ◽  
Public Buildings ◽  
Shape Factors ◽  
Engineering Research

This paper describes an experimental and theoretical study of the feasibility of using fiber reinforcement to produce lightweight low-cost elastomeric isolators for application to housing, schools and other public buildings in highly seismic areas of the developing world. The theoretical analysis covers the mechanical characteristics of multi-layer elastomeric isolation bearings where the reinforcing elements, normally steel plates, are replaced by a fiber reinforcement. The fiber in the fiber-reinforced isolator, in contrast to the steel in the conventional isolator (which is assumed to be rigid both in extension and flexure), is assumed to be flexible in extension, but completely without flexure rigidity. This leads to an extension of the theoretical analysis on which the design of steel-reinforced isolators is which accommodates the stretching of the fiber-reinforcement. Several examples of isolators in the form of long strips were tested at the Earthquake Engineering Research Center Laboratory. The tested isolators had significantly large shape factors, large enough that for conventional isolators the effects of material compressibility would need to be included. The theoretical analysis is extended to include compressibility and the competing influences of reinforcement flexibility and compressibility are studied. The theoretical analysis suggests and the test results confirm that it is possible to produce a fiber-reinforced strip isolator that matches the behavior of a steel-reinforced isolator. The fiber-reinforced isolator is significantly lighter and can be made by a much less labor-intensive manufacturing process. The advantage of the strip isolator is that it can be easily used in buildings with masonry walls. The intention of this research is to provide a low-cost lightweight isolation system for housing and public buildings in developing countries.

scholarly journals The use of extruded finite-element models as a novel alternative to tomography-based models: a case study using early mammal jaws

2019 ◽  
Vol 16 (161) ◽  
pp. 20190674 ◽  
Author(s):  
Nuria Melisa Morales-García ◽  
Thomas D. Burgess ◽  
Jennifer J. Hill ◽  
Pamela G. Gill ◽  
Emily J. Rayfield
Keyword(s):  
Finite Element ◽  
Mechanical Performance ◽  
Low Cost ◽  
Three Dimensional ◽  
3D Models ◽  
Stress And Strain ◽  
Finite Element Models ◽  
Average Width ◽  
Performance Results

Finite-element (FE) analysis has been used in palaeobiology to assess the mechanical performance of the jaw. It uses two types of models: tomography-based three-dimensional (3D) models (very accurate, not always accessible) and two-dimensional (2D) models (quick and easy to build, good for broad-scale studies, cannot obtain absolute stress and strain values). Here, we introduce extruded FE models, which provide fairly accurate mechanical performance results, while remaining low-cost, quick and easy to build. These are simplified 3D models built from lateral outlines of a relatively flat jaw and extruded to its average width. There are two types: extruded (flat mediolaterally) and enhanced extruded (accounts for width differences in the ascending ramus). Here, we compare mechanical performance values resulting from four types of FE models (i.e. tomography-based 3D, extruded, enhanced extruded and 2D) in Morganucodon and Kuehneotherium . In terms of absolute values, both types of extruded model perform well in comparison to the tomography-based 3D models, but enhanced extruded models perform better. In terms of overall patterns, all models produce similar results. Extruded FE models constitute a viable alternative to the use of tomography-based 3D models, particularly in relatively flat bones.

Tapering Effects on the Installation of Suction Caissons in Clay

2008 ◽  
Author(s):  
Mostafa Zeinoddini ◽  
Woorya H. Shariati ◽  
Mahmood Nabipour
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Finite Element Approach ◽  
Pull Out ◽  
Full Penetration ◽  
Element Approach ◽  
Numerical Finite Element ◽  
Wall Slope ◽  
Suction Caissons ◽  
Considerable Enhancement

This paper reports results from an investigation on the tapering effects on the installation and pull-out performance of suction caissons. A numerical finite element approach has been used for the study. The finite element models have first been calibrated/verified against several available experimental data for the installation of the upright suction caissons in clay. The verified models have then been used to examine the behaviour of the tapered suction caissons during the pull-out and installation phases. Numerical results indicate that tapered caissons present considerable enhancement in their pull-out capacity comparing to those from corresponding upright caissons. Also it has been noticed that in general tapered caissons of positive wall slopes need extra forces, in comparison to their equivalent upright caissons, to achieve a full penetration. However, at least with those models studied, these extra forces have found to be less than twenty five percent when the wall slope varies from zero (upright) to 15%. This is while the additional pull-out capacities that might be achieved from these tapered suction caissons could reach to several hundred percents. An almost linear relationship has been observed between the total installation force and the caisson’s wall slope.

Improvement of the polyurethane spring isolation device for HV post insulators and its evaluation by fragility curves

2021 ◽  
pp. 875529302098196
Author(s):  
Tansu Gökçe ◽  
Engin Orakdöğen ◽  
Ercan Yüksel
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Numerical Models ◽  
Fragility Curves ◽  
Low Cost ◽  
Steel Plates ◽  
Isolation System ◽  
Base Isolation System ◽  
Isolation Device ◽  
Seismic Base Isolation

A novel seismic base isolation system has been developed for high-voltage (HV) porcelain post insulators. The seismic isolation device consists of two steel plates, four polyurethane springs, and a steel rod, which are low-cost components compared to the post insulators. Two alternative designs of the device are experimentally and numerically assessed in this article. A simple and robust numerical model consisting of linear line elements and nonlinear springs was generated, and subsequently validated using the experimental results. Incremental dynamic analyses (IDAs) were then performed to obtain fragility curves. Ten historical earthquake profiles, scaled to intensities between 0.1 and 2.0 g, were then applied to the numerical models. The fragility curves, generated according to the latest version of IEEE-693, demonstrate that the seismic isolation devices are highly effective in diminishing the base moment of the porcelain insulator. It should be noted that relatively large displacements at the top of the pole must be accounted for by ensuring adequate slackness in the flexible conductors.

scholarly journals Finite Element Study on Continuous Rotating versus Reciprocating Nickel-Titanium Instruments

2016 ◽  
Vol 27 (4) ◽  
pp. 436-441 ◽  
Author(s):  
Mohamed I. El-Anwar ◽  
Salah A. Yousief ◽  
Engy M. Kataia ◽  
Tarek M. Abd El-Wahab
Keyword(s):  
Finite Element ◽  
Low Cost ◽  
Nickel Titanium ◽  
Finite Element Models ◽  
Element Analysis ◽  
Cross Sectional ◽  
Design And Manufacturing ◽  
Cad Cam ◽  
Strain Stress ◽  
Sectional Shape

Abstract In the present study, GTX and ProTaper as continuous rotating endodontic files were numerically compared with WaveOne reciprocating file using finite element analysis, aiming at having a low cost, accurate/trustworthy comparison as well as finding out the effect of instrument design and manufacturing material on its lifespan. Two 3D finite element models were especially prepared for this comparison. Commercial engineering CAD/CAM package was used to model full detailed flute geometries of the instruments. Multi-linear materials were defined in analysis by using real strain-stress data of NiTi and M-Wire. Non-linear static analysis was performed to simulate the instrument inside root canal at a 45° angle in the apical portion and subjected to 0.3 N.cm torsion. The three simulations in this study showed that M-Wire is slightly more resistant to failure than conventional NiTi. On the other hand, both materials are fairly similar in case of severe locking conditions. For the same instrument geometry, M-Wire instruments may have longer lifespan than the conventional NiTi ones. In case of severe locking conditions both materials will fail similarly. Larger cross sectional area (function of instrument taper) resisted better to failure than the smaller ones, while the cross sectional shape and its cutting angles could affect instrument cutting efficiency.

Reliability Analysis of Seismic Isolation in Retrofitting of Simply Supported Bridges

2016 ◽  
Vol 847 ◽  
pp. 391-400
Author(s):  
Luigi Petti ◽  
Alessio Lodato ◽  
Angelo Mammone
Keyword(s):  
Seismic Isolation ◽  
Fragility Curves ◽  
Seismic Intensity ◽  
Finite Element Models ◽  
Design Strategies ◽  
Limit States ◽  
Damage Level ◽  
Simply Supported ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses

The paper investigates the reliability of simply supported bridges, retrofitted or less with seismic isolation, by means of fragility curves, which represent the probability of reaching a certain damage level for an assigned seismic intensity. Taking advantage of the Multi Stripes methodology, several nonlinear dynamic analyses of a multi-span bridge representing the existing ones in Italy built in the 60 ' characterized by means of non linear finite element models in different design configurations of seismic retrofit have been carried out, in order to obtain the fragility functions.The obtained results allow to assess the isolation retrofit strategies effectiveness to mitigate the seismic risk of simply supported bridges, highlighting the influence of different design strategies on the probability of exceeding the limit states considered.

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