Reliability-based code calibration applied to thin elements made of UHPFRC

2017 ◽  
Vol 50 (3) ◽  
Author(s):  
Svatopluk Dobruský
2021 ◽  
Vol 11 (12) ◽  
pp. 5474
Author(s):  
Tuomo Poutanen

This article addresses the process to optimally select safety factors and characteristic values for the Eurocodes. Five amendments to the present codes are proposed: (1) The load factors are fixed, γG = γQ, by making the characteristic load of the variable load changeable, it simplifies the codes and lessens the calculation work. (2) Currently, the characteristic load of the variable load is the same for all variable loads. It creates excess safety and material waste for the variable loads with low variation. This deficiency can be avoided by applying the same amendment as above. (3) Various materials fit with different accuracy in the reliability model. This article explains two options to reduce this difficulty. (4) A method to avoid rounding errors in the safety factors is explained. (5) The current safety factors are usually set by minimizing the reliability indexes regarding the target when the obtained codes include considerable safe and unsafe design cases with the variability ratio (high reliability/low) of about 1.4. The proposed three code models match the target β50 = 3.2 with high accuracy, no unsafe design cases and insignificant safe design cases with the variability ratio 1.07, 1.03 and 1.04.


2021 ◽  
pp. 135406612110442
Author(s):  
Tobias Heinrich ◽  
Yoshiharu Kobayashi ◽  
Edward Lawson

Pundits, development practitioners, and scholars worry that rising populism and international disengagement in developed countries have negative consequences on foreign aid. However, how populism and foreign aid go together is not well understood. This paper provides the first systematic examination of this relationship. We adopt the popular ideational definition of populism, unpack populism into its core “thin” elements, and examine them within a delegation model of aid policy—a prominent framework in the aid literature. In so doing, we identify specific domestic political processes through which the core components of populism may affect aid spending. We argue that increases in one component of populism—anti-elitism—and in nativist sentiments, an associated concept, in a donor country lead to a reduction in aid spending through a public opinion channel. We supply both micro- and macro-evidence for our arguments by fielding surveys in the United States and United Kingdom as well as by analyzing aid spending by a large number of OECD donors. Our findings show that nativism and anti-elitism, rather than populism per se, influence not only individual attitudes toward aid but also actual aid policy and generate important insights into how to address populist challenges to foreign aid. Beyond these, our study contributes to the broader International Relations literature by demonstrating one useful analytical approach to studying populism, nativism, and foreign policy.


2016 ◽  
Vol 19 (2) ◽  
pp. 52
Author(s):  
Milan Maksimović

High-contrast gratings (HCG) are ultra-thin elements operating in sub-wavelength regime with the period of the grating smaller than the wavelength and with the high-index grating material fully surrounded by low-index material. Design of MEMS mirrors made from HCG with specific reflectivity response is of great practical interest in integrated optoelectronics. We theoretically investigate design of the spectral response for HCGs with the complex unit cells. We show that the spectral response can be tailored via the unit cell perturbations and with the asymmetric unit cell perturbations may introduce completely new spectral response. Our results can serve as guidance for the design of the complex HCGs and help with the choice of the efficient initial grating topology prior to global optimization procedure.


2018 ◽  
Vol 29 (16) ◽  
pp. 3266-3283 ◽  
Author(s):  
Astrid S Pechstein ◽  
Martin Meindlhumer ◽  
Alexander Humer

We propose a new three-dimensional formulation based on the mixed tangential-displacement normal-normal-stress method for elasticity. In elastic tangential-displacement normal-normal-stress elements, the tangential component of the displacement field and the normal component of the stress vector are degrees of freedom and continuous across inter-element interfaces. Tangential-displacement normal-normal-stress finite elements have been shown to be locking-free with respect to shear locking in thin elements, which makes them suitable for the discretization of laminates or macro-fiber composites. In the current paper, we extend the formulation to piezoelectric materials by adding the electric potential as degree of freedom.


2017 ◽  
Author(s):  
Torfinn Hørte ◽  
Siril Okkenhaug ◽  
Øivind Paulshus
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