scholarly journals VERIFICATION OF A SIMPLIFIED GEOTECHNICAL RELIABILITY ANALYSIS SCHEME OF SPATIAL VARIABILITY BASED ON LOCAL AVERAGE OF GEOTECHNICAL PARAMETERS

Author(s):  
Yu OTAKE ◽  
Yusuke HONJO
2019 ◽  
Vol 91 (4) ◽  
pp. 549-557
Author(s):  
Yuhui Wang ◽  
Peng Shao ◽  
Qingxian Wu ◽  
Mou Chen

Purpose This paper aims to present a novel structural reliability analysis scheme with considering the structural strength degradation for the wing spar of a generic hypersonic aircraft to guarantee flight safety and structural reliability. Design/methodology/approach A logarithmic model with strength degradation for the wing spar is constructed, and a reliability model of the wing spar is established based on stress-strength interference theory and total probability theorem. Findings It is demonstrated that the proposed reliability analysis scheme can obtain more accurate structural reliability and failure results for the wing spar, and the strength degradation cannot be neglected. Furthermore, the obtained results will provide an important reference for the structural safety of hypersonic aircraft. Research limitations/implications The proposed reliability analysis scheme has not implemented in actual flight, as all the simulations are conducted according to the actual experiment data. Practical implications The proposed reliability analysis scheme can solve the structural life problem of the wing spar for hypersonic aircraft and meet engineering practice requirements, and it also provides an important reference to guarantee the flight safety and structural reliability for hypersonic aircraft. Originality/value To describe the damage evolution more accurately, with consideration of strength degradation, flight dynamics and material characteristics of the hypersonic aircraft, the stress-strength interference method is first applied to analyze the structural reliability of the wing spar for the hypersonic aircraft. The proposed analysis scheme is implemented on the dynamic model of the hypersonic aircraft, and the simulation demonstrates that a more reasonable reliability result can be achieved.


2020 ◽  
Vol 57 (4) ◽  
pp. 518-536
Author(s):  
Guicai Shi ◽  
Yutao Pan ◽  
Zhaohua Sun ◽  
Yong Liu ◽  
Fook-Hou Lee

In Eurocode EC7, a “characteristic” strength is used as a cautious estimate of the local average strength that governs the bearing capacity of the foundation. The objective of this paper is to examine the correlation between the local average strength and the bearing capacity of a stiff caisson foundation resting on spatially variable ground using random finite element analyses. The results show that using the local average strength over some assumed or postulated failure zones tends to overestimate the mean bearing capacity of the ground. This can be attributed to two possible reasons. Firstly, the postulated failure zone is unlikely to be fully reflective of the real failure zone in spatially variable ground. Secondly, the bearing capacity is more affected by the strength of the weak zones than that of the strong zones. Both of these factors lead to a lowering of the bearing capacity. A more indicative way of determining a characteristic strength that will give a better indication of the bearing capacity is also recommended, together with a strength reduction factor that accounts for the effect of spatial variability.


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