scholarly journals Cyclic and post-cycling anchor response in geocell-reinforced sand

2019 ◽  
Vol 56 (11) ◽  
pp. 1700-1718 ◽  
Author(s):  
S.N. Moghaddas Tafreshi ◽  
M. Rahimi ◽  
A.R. Dawson ◽  
B. Leshchinsky

Plate anchors are commonly used to resist static, cyclic, and monotonic post-cyclic uplift loads. Under cyclic loading, progressive sudden failure may occur, characterized by accumulated displacement — even under loads significantly less than the static capacity. Despite extensive usage of geocell materials for increasing cyclic resilience, the influence of geocell reinforcements on cyclic uplift capacity is not well understood. In this study, a series of near-full-scale experimental tests, with and without geocell, are presented. Results show that the unreinforced system fails cyclically under a load that is almost 70% of its ultimate uplift capacity (Pu), but use of geocell enables stable cyclic resistance of over 100% Pu. For the given soil and configurations, a cyclic displacement rate that reaches less than 0.05 mm/cycle tends to highlight a likely stable response. Evaluation of the soil’s response to cyclic loading demonstrates that, with increasing loading cycles, the loading is increasingly transmitted through the soil close to the anchor in the unreinforced case, but that the reinforced case is less prone to this phenomenon. The monotonic post-cycling capacity of both reinforced and unreinforced anchors decreases after application of cyclic loading; however, the unreinforced scenario demonstrates larger decreases in capacity, particularly in the residual capacity.

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 104
Author(s):  
Dong-Hyeop Kim ◽  
Young-Cheol Kim ◽  
Sang-Woo Kim

Airworthiness standards of Korea recommend verifying structural safety by experimental tests and analytical methods, owing to the development of analysis technology. In this study, we propose a methodology to verify the structural safety of aircraft components based on airworthiness requirements using an analytical method. The structural safety and fatigue integrity of a linear actuator for flap control of aircraft was evaluated through numerical analysis. The static and fatigue analyses for the given loads obtained from the multibody dynamics analysis were performed using the finite element method. Subsequently, the margin of safety and vulnerable area were acquired and the feasibility of the structural safety evaluation using the analytical method was confirmed. The proposed numerical analysis method in this study can be adopted as an analytical verification methodology for the airworthiness standards of civilian aircraft in Korea.


Author(s):  
M. Mongiardini ◽  
J. D. Reid

Numerical simulations allow engineers in roadside safety to investigate the safety of retrofit designs minimizing or, in some cases, avoiding the high costs related to the execution of full-scale experimental tests. This paper describes the numerical investigation made to assess the performance of a roadside safety barrier when relocated behind the break point of a 3H:1V slope, found on a Mechanically Stabilized Earth (MSE) system. A safe barrier relocation in the slope would allow reducing the installation width of the MSE system by an equivalent amount, thus decreasing the overall construction costs. The dynamics of a pick-up truck impacting the relocated barrier and the system deformation were simulated in detail using the explicit non-linear dynamic finite element code LS-DYNA. The model was initially calibrated and subsequently validated against results from a previous full-scale crash test with the barrier placed at the slope break point. After a sensitivity analysis regarding the role of suspension failure and tire deflation on the vehicle stability, the system performance was assessed when it was relocated into the slope. Two different configurations were considered, differing for the height of the rail respect to the road surface and the corresponding post embedment into the soil. Conclusions and recommendations were drawn based on the results obtained from the numerical analysis.


2015 ◽  
Vol 36 ◽  
pp. 98-105 ◽  
Author(s):  
Laura Biganzoli ◽  
Gaia Racanella ◽  
Lucia Rigamonti ◽  
Roberto Marras ◽  
Mario Grosso

Author(s):  
Athanasios Vratsikidis ◽  
Dimitris Pitilakis ◽  
Anastasios Anastasiadis ◽  
Anastasios Kapouniaris

Author(s):  
Liviu Crudu ◽  
Radu Bosoancă ◽  
Dan Obreja

The evaluation of ship resistance is of paramount importance having a decisive impact on the economic performances and efficiency depending on mission. If new IMO requirements through the Energy Efficiency Design Index (EEDI) are taken into account the necessity to have more and more accurate tools capable to consider the influences of different parameters became mandatory. The availability of towing tank facilities and the full scale trials are the practical means in order to be able to confirm the accuracy of theoretical formulations and to define the limits of CFD applications. Based on the results of the towing tank tests, a direct comparison with the results provided by classical methods and CFD computations can be systematically can be performed. On the other hand, the influences of the modifications operated on the fore part of the ship aretheoretically evaluated and compared with the towing tank results. Consequently, the paper is focused on the comparison of the results evaluated using different tools which have been carried out for a Chemical Tanker built by Constanta Shipyard Romania.


2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Rasool Ahmadi ◽  
Omid Rashidian ◽  
Reza Abbasnia ◽  
Foad Mohajeri Nav ◽  
Nima Usefi

An experimental test was carried out on a 3/10 scale subassemblage in order to investigate the progressive collapse behavior of reinforced concrete (RC) structures. Investigation of alternative load paths and resistance mechanisms in scaled subassemblage and differences between the results of full-scale and scaled specimens are the main goals of this research. Main characteristics of specimen response including load-displacement curve, mechanism of formation and development of cracks, and failure mode of the scaled specimen had good agreement with the full-scale specimen. In order to provide a reliable numerical model for progressive collapse analysis of RC beam-column subassemblages, a macromodel was also developed. First, numerical model was validated with experimental tests in the literature. Then, experimental results in this study were compared with validated numerical results. It is shown that the proposed macromodel can provide a precise estimation of collapse behavior of RC subassemblages under the middle column removal scenario. In addition, for further evaluation, using the validated numerical model, parametric study of new subassemblages with different details, geometric and boundary conditions, was also done.


2019 ◽  
Vol 281 ◽  
pp. 02001 ◽  
Author(s):  
Layal Jradi ◽  
Bassel Seif El Dine ◽  
Jean-Claude Dupla ◽  
Jean Canou

This paper presents an experimental study that investigates the influence of the non-plastic fines on the initiation of instability of sands under cyclic loading. The materials used for this study and the experimental device are first presented, then the results of typical liquefaction tests for both loose and medium dense specimens are presented with emphasis on the exhibited behaviour. The results of a series of cyclic undrained tests that were done with the aid of a triaxial apparatus for different percentages of fines are also presented and analysed. The results reveal that the increase in the non-plastic fines content lead to an increase in the liquefaction resistance of sands.


2020 ◽  
Vol 10 (16) ◽  
pp. 5560 ◽  
Author(s):  
Matthias Hillebrand ◽  
Josef Hegger

In the recent years, bridges, as an important part of the national and international infrastructure, had to comply with stricter requirements due to increased heavy load traffic. Many of these bridge structures built in the 1960s and 1970s often contain less web reinforcement than the modern required minimum web reinforcement. In this context, the shear resistance under cyclic loading is of special interest. For this reason, experimental tests were conducted on prestressed concrete beams with and without shear reinforcement at the Institute of Structural Concrete of RWTH Aachen University to investigate the shear fatigue strength. This paper describes the recent tests on ten Tshaped prestressed beams with web reinforcement. The specimens were able to resist more load cycles than predicted by the approaches implemented in the Eurocodes for bridges. Based on the test results, design models for shear under cyclic loading should be reviewed and improved, especially regarding the assessment of existing structures.


Author(s):  
Jean Macedo ◽  
Stéphane Chapuliot ◽  
Jean-Michel Bergheau ◽  
Eric Feulvarch ◽  
Olivier Ancelet ◽  
...  

Abstract In order to investigate the ratcheting behavior and to determine new design rules, some experimental tests were conducted in many countries in the last decades. In France, some tests were carried out under mechanical or thermal cyclic loading to examine this risk. The first section of the current article is addressed to the state of the art concerning the ratcheting effects. The difference between Local and Global Ratcheting is clarified. The second section is dedicated to the experimental observations of ratcheting. The following section describes the constitutive models which are able to simulate material/structural ratcheting responses. The models presented are Linear Kinematic, Armstrong-Frederick, Chaboche, Ohno-Wang and Chen-Jiao-Kim. Finally, the ratcheting rules in design codes are exposed. Both simple and complex rules are presented.


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