40 روش ﺳﺎل ﻣﻬﻨﺪﺳﯽ، در ﻋﺪدي ﻫﺎي 40 ﺷﻤﺎر ، ه 2 ، زﻣﺴﺘﺎن 1400
optimization. Since steel structures generally have more slender members compared to concrete structures, buckling analysis of steel members is of more importance. Determining the critical load of functionally varying cross-section columns using the analytical solution is a time-consuming process. In this paper, buckling analysis of non-prismatic steel columns is conducted using the meshless local Petrov-Galerkin (MLPG) method. In meshless methods, the scattered nodes are used rather than the elements to model the problem domain and its boundaries. The change of the inertia moment within the length of a column is characterized by introducing a power function with variable taper ratio and exponent. The radial basis function is used to discretize the differential equation governing the buckling. The penalty method is used for the imposition of the boundary conditions. Numerical examples of the critical buckling load for prismatic and non-prismatic columns using the proposed methodare compared with the analytical solution, and the effectiveness of the MLPG method for buckling analysis of non-prismatic columns is validated. Also, buckling analysis of muscle column members subjected to non-uniform axial load is carried out to show the efficiency of the proposed method. The effect of several parameters such as non-uniformity of the load and variation of the cross-section on the buckling load of the column is discussed in details.
Liquefaction is a phenomenon in which soil loses its bearing capacity, large settlements occur, and it may cause lateral spreading and failures. Numerous studies and cases in the world have shown that liquefaction occurs in the alluvium foundations of earth dams. The occurrence of widespread liquefaction can cause the entire dam to fail. In this paper, methods of assessment and numerical analysis have been used to assess the Shourijeh reservoir dam liquefaction. According to the latest criteria, it was observed that by considering the acceleration of the maximum credible earthquake level (MCE), the alluvial foundation of Shourijeh Dam is liquefiable in some areas. The dynamic analysis and liquefaction modelling based on linear equivalent analyses have been used. By analysing the sliding block and sliding circles based on the limit equilibrium method and the Newmark sliding block analysis, the stability safety factors of slopes for Shourijeh Dam after the earthquake have been investigated for three different earthquakes and various states of reservoir water level. Stress redistribution analysis has been used to estimate the permanent deformation of the structure due to seismic loading. The results of this research, in addition to providing helpful information regarding the performance of earth dams against liquefaction and its effects, have shown that the settlements caused by liquefaction in the studied dam are not so large that they would cause extensive damage and collapse of the dam at the MCE level.
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