S. Stupak

SENSITIVITY OF DYNAMIC BEHAVIOUR OF THE FE MODEL: CASE STUDY FOR THE IGNALINA NPP REACTOR BUILDING

Abstract The 3D thin‐walled finite element model of Ignalina NPP Unit 2 reactor building was developed aimed at the evaluation of the global dynamic behaviour with a focus on the seismic response. The model comprises description of the monolithic structures, while prefabricated frame structures are ignored and replaced by external masses. Sensitivity study of the selected dynamic characteristics of the model with respect to data uncertainties is considered. Uncertainty of the model is considered in terms of masses of removed structures and wall stiffness. Seismic input is represented by the site specific free‐field ground response acceleration spectra. The sensitivity study concerns variations of frequencies and acceleration of in‐structure horizontal response spectra at specified points. Maximal bending moments are also considered. It was obtained that the reactor level is not sensitive to the uncertainties considered, while discernable sensitivity was detected at the top level of the structure.

Critical factors of the application of nanotechnology in construction industry by using ANP technique under fuzzy intuitionistic environment

AbstractNanotechnology plays a significant role in construction industry. The construction industry has been employed nanomaterials to improve the performance of construction components and the safety of the structure and to reduce the energy consuming and the cost of maintenance. In other words, nanotechnology has a substantial impact on the construction industry. Therefore, it is necessary to identify and evaluate the critical factors of the application of nanotechnology in construction in order to concentrate on the most critical factors. However, several techniques have been developed to prioritize the evaluation criteria. Analytical network process (ANP) technique, a branch of multi criteria decision making (MCDM) methods, is a powerful tool to rank a limited number of criteria. This technique takes into account both tangible and intangible criteria in the process of formulation of a decision making problem. This method is capable of handling all types of independence and dependence relationships. On...

PECULIARITIES OF CALCULATING THE CYCLIC STRENGTH OF IMPORTANT THREADED JOINTS

Abstract The calculation of the strength of important threaded joints is started by defining the minimum size of the cross-section of bolts (studs). Then the static and cyclic strength is tested. The studs of the demountable joints of nuclear power equipment are calculated in accordance with the norms of the Russian Federation and the ASME Code. The calculation methods coincide in essence, they are based on similar limit states; however, there also some differences exist. The authors investigate and compare both methods in their work. There is a brief analysis of calculation methods in the article. For closer definition of standards and their substantiation the authors used experimental and theoretical investigations performed at Laboratory of Strength Mechanics of Vilnius Gediminas Technical University. In order to develop a uniform cyclic strength and shakedown calculation procedure for critical threaded joints, a completely new calculation of a progressive profile change is recommended to be performed ...

ANALYSIS OF EXPERIMENT AND CALCULATION OF THE THREADED JOINTS UNDER TENSION AND CYCLIC BENDING

Summary The effect of individual elements of the system “bolt-nut” under tension and bending on the cyclic strength is a complicated and insufficiently clear subject. The data presented in the works of the laboratories of strength mechanics and those of the present authors have been obtained when the ratio of bending and tension stress caused by eccentrically applied tension force was from 0 to 1.5. If stresses caused by bending account for 0.25 σ y of tension stresses, the strength to low-cycle fatigue somewhat increases. When σ m = 1.5σ n , the decrease in longevity is observed. The results obtained, however, differ insignificantly from the longevity of threaded joints under cyclic tension as long as bending stresses do not exceed 0.5. σ y . A comprehensive experimental study of these problems and the analysis are presented in the works of the present authors. One of the main factors determining the cyclic strength of the system “bolt-nut” is the distribution of internal resultants. The distribution of ...