The Large Scale Test Control Systems Designed and Built by the Boeing Company to Support the 757 and 767 Major Fatigue Tests

1991 ◽  
Author(s):  
Steven A. Onustack
Author(s):  
Peter Schaumann ◽  
Alexander Raba ◽  
Anne Bechtel

Grouted connections represent a common joining technique between substructure and foundation piles of offshore oil & gas platforms as well as of offshore wind turbines. Due to cyclic loads arising from wind and wave actions the fatigue performance of the connection has to be considered. In lattice substructures like jackets the grouted connections are located at seabed level being fully submerged during their entire lifetime. Today’s fatigue design regulations are based on investigations neglecting any influence of the surrounding water since they were conducted in dry ambient conditions. So far, only Germanischer Lloyd gives additional recommendations for submerged grouted connections. At the Institute for Steel Construction, Leibniz Universität Hannover, Germany investigations of the joint research project ‘GROWup’ focus on the fatigue performance of axially loaded grouted connections. The project is funded by the Federal Ministry for Economic Affairs and Energy (BMWi, funding sign: 0325290) and is the third project in a row dealing with grouted connections. As part of this research project, cyclic loading tests on small-scale and large-scale grouted connections with shear keys are conducted. Small-scale fatigue tests showed a reduced number of endurable load cycles for connections when tested in wet ambient conditions. However, the transferability of these findings to a larger scale was still doubtful due to unknown scale effects. Therefore, the impact of water on the fatigue performance was tested recently at large-scale grouted connections. Previous to the submerged large-scale grouted connection fatigue tests, similar test specimens were exposed to alternating loads at dry ambient conditions. Comparison of both large-scale test results under wet and dry conditions enable to estimate the influence of water on the fatigue performance of grouted connections. Reflection of the small-scale test results gives hints on the scale effect. Test preparation, test results and design recommendations are presented in the paper.


2020 ◽  
Author(s):  
Rui Sun ◽  
Disa Sauter

Getting old is generally seen as unappealing, yet aging confers considerable advantages in several psychological domains (North & Fiske, 2015). In particular, older adults are better off emotionally than younger adults, with aging associated with the so-called “age advantages,” that is, more positive and less negative emotional experiences (Carstensen et al., 2011). Although the age advantages are well established, it is less clear whether they occur under conditions of prolonged stress. In a recent study, Carstensen et al (2020) demonstrated that the age advantages persist during the COVID-19 pandemic, suggesting that older adults are able to utilise cognitive and behavioural strategies to ameliorate even sustained stress. Here, we build on Carstensen and colleagues’ work with two studies. In Study 1, we provide a large-scale test of the robustness of Carstensen and colleagues’ finding that older individuals experience more positive and less negative emotions during the COVID-19 pandemic. We measured positive and negative emotions along with age information in 23,629 participants in 63 countries in April-May 2020. In Study 2, we provide a comparison of the age advantages using representative samples collected before and during the COVID-19 pandemic. We demonstrate that older people experience less negative emotion than younger people during the prolonged stress of the COVID-19 pandemic. However, the advantage of older adults was diminished during the pandemic, pointing to a likely role of older adults use of situation selection strategies (Charles, 2010).


2021 ◽  
Vol 13 (4) ◽  
pp. 544
Author(s):  
Guohao Zhang ◽  
Bing Xu ◽  
Hoi-Fung Ng ◽  
Li-Ta Hsu

Accurate localization of road agents (GNSS receivers) is the basis of intelligent transportation systems, which is still difficult to achieve for GNSS positioning in urban areas due to the signal interferences from buildings. Various collaborative positioning techniques were recently developed to improve the positioning performance by the aid from neighboring agents. However, it is still challenging to study their performances comprehensively. The GNSS measurement error behavior is complicated in urban areas and unable to be represented by naive models. On the other hand, real experiments requiring numbers of devices are difficult to conduct, especially for a large-scale test. Therefore, a GNSS realistic urban measurement simulator is developed to provide measurements for collaborative positioning studies. The proposed simulator employs a ray-tracing technique searching for all possible interferences in the urban area. Then, it categorizes them into direct, reflected, diffracted, and multipath signal to simulate the pseudorange, C/N0, and Doppler shift measurements correspondingly. The performance of the proposed simulator is validated through real experimental comparisons with different scenarios based on commercial-grade receivers. The proposed simulator is also applied with different positioning algorithms, which verifies it is sophisticated enough for the collaborative positioning studies in the urban area.


2020 ◽  
Vol 53 (2) ◽  
pp. 2634-2641
Author(s):  
Vinicius Lima ◽  
Mark Eisen ◽  
Konstatinos Gatsis ◽  
Alejandro Ribeiro

2011 ◽  
Vol 415-417 ◽  
pp. 1531-1536
Author(s):  
Fu Ming Liu ◽  
Duan Yi Wang

This paper presents the results of laboratory and performance tests for an asphalt treated base (ATB) and mixes developed in this study for perpetual asphalt pavements. Laboratory tests for the mixes included moisture susceptibility, wheel tracking and fatigue tests. The results of performance test indicated that the resistances of the high content binder ATB against moisture and fatigue damage were better than those of the lower one. It was also found from the full scale test sections that the tensile strain values at the bottom of the asphalt layer for the ATB sections were low when the asphalt layer thicknesses of the ATB sections were not thicker than those of the conventional sections. All the tensile strain values measured from the ATB sections were within the fatigue endurance limit of 70 microstrain which is the fatigue criterion of a perpetual asphalt pavement.


1987 ◽  
Vol 20 (12) ◽  
pp. 395-400
Author(s):  
G.M. Dimirovski ◽  
M.M. Carevski ◽  
D.J. Mamucevski

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