scholarly journals Pullout behaviour of geosynthetics in a recycled construction and demolition material – Effects of cyclic loading

2020 ◽  
Vol 23 ◽  
pp. 100346 ◽  
Author(s):  
Castorina S. Vieira ◽  
Fernanda B. Ferreira ◽  
Paulo M. Pereira ◽  
Maria de Lurdes Lopes
1994 ◽  
Vol 31 (1) ◽  
pp. 110-119 ◽  
Author(s):  
Y.V.S.N. Prasad ◽  
S. Narasimha Rao

This paper presents the effect of lateral cyclic loading on the pullout capacity of model and helical piles in clayey soil. The tests were conducted on short rigid model piles in the laboratory in three phases, namely lateral static load tests, lateral cyclic load tests, and vertical pullout tests. From the test results it was found that the lateral cyclic loading affects the pullout capacity of piles substantially. Reduction in pullout capacity mainly depends upon the lateral deflection of the pile during cyclic loading and the embedment ratio of the pile. This reduction in the pullout capacity of model piles is presented in terms of nondimensional parameters, viz., degradation factor, lateral deflection ratio, and embedment ratio of pile. However, in the case of helical piles under similar conditions, it was found that the lateral cyclic loading has very little influence on the pullout capacity. The reasons for the better performance of helical piles over ordinary piles are explained. Key words : clay, degradation factor, helical pile, lateral cyclic loading, lateral deflection, Joading level, pile, pullout capacity.


Bauingenieur ◽  
2021 ◽  
Vol 96 (01-02) ◽  
pp. 1-10
Author(s):  
V. Oettel ◽  
J.-P. Lanwer ◽  
M. Empelmann

Zusammenfassung Zur Erfassung des Trag- und Verformungsverhaltens von ultrahochfestem Stahlfaserbeton (UHPFRC) unter zyklischer Zugbeanspruchung wurde das Ermüdungsverhalten der einzelnen Komponenten („nackte“ Stahlfaser, faserfreier UHPC, einbetonierte Stahlfasern) untersucht. Dazu wurden zyklische Zugversuche an der „nackten“ Mikrostahldrahtfaser sowie am faserfreien UHPC mit variierenden Schwingbreiten durchgeführt und Wöhlerdiagramme aufgestellt. Durch verschiedenartige Pullout-Versuche mit unterschiedlichen Anordnungen von Mikrostahldrahtfasern im UHPC konnten wesentliche Erkenntnisse zum Auszugverhalten unter monoton steigender und zyklischer Belastung gewonnen werden.


2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.


Author(s):  
R. Z. Aminov ◽  
A. N. Bayramov ◽  
M. V. Garievskii

The paper gives the analysis of the problem of the primary current frequency regulation in the power system, as well as the basic requirements for NPP power units under the conditions of involvement in the primary regulation. According to these requirements, the operation of NPPs is associated with unloading and a corresponding decrease in efficiency. In this regard, the combination of nuclear power plants with a hydrogen complex is shown to eliminate the inefficient discharge mode which allows the steam turbine equipment and equipment of the reactor facility to operate in the basic mode at the nominal power level. In addition, conditions are created for the generation and accumulation of hydrogen and oxygen during the day, as well as additionally during the nighttime failure of the electrical load which allows them to be used to generate peak power.  The purpose of the article is to assess the systemic economic effect as a result of the participation of nuclear power plants in combination with the hydrogen complex in the primary control of the current frequency in the power sys-tem, taking into account the resource costs of the main equipment. In this regard, the paper gives the justification of cyclic loading of the main equipment of the hydrogen complex: metal storage tanks of hydrogen and oxygen, compressor units, hydrogen-oxygen combustion chamber of vapor-hydrogen overheating of the working fluid in the steam turbine cycle of a nuclear power plant. The methodological foundations for evaluating the working life of equipment under cyclic loading with the participation in the primary frequency control by the criterion of the growth rate of a fatigue crack are described. For the equipment of the hydrogen complex, the highest intensity of loading is shown to occur in the hydrogen-oxygen combustion chamber due to high thermal stresses.  The system economic effect is estimated and the effect of wear of the main equipment under cyclic loading is shown. Under the conditions of combining NPP power units with a hydrogen complex, the efficiency of primary reg-ulation is shown to depend significantly on: the cost of equipment subjected to cyclic loading; frequency and intensity of cyclic loading; the ratio of the tariff for peak electricity, and the cost of electricity of nuclear power plants.  Based on the developed methodology for assessing the effectiveness of the participation of nuclear power plants with a hydrogen complex in the primary frequency control, taking into account the damage to the equipment, the use of the hydrogen complex is shown to provide a tangible economic effect compared with the option of unloading nuclear power plants with direct participation in frequency control.


PCI Journal ◽  
1998 ◽  
Vol 43 (6) ◽  
pp. 58-71 ◽  
Author(s):  
Rosa M. Vasconez ◽  
Antoine E. Naaman ◽  
James K. Wight

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