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In the design of engineering structures, concrete is assumed to have homogeneously mechanical properties. However, in reality, the concrete material is usually not uniform with respect to the height of structures because segregation mostly occurs during construction. The higher density is presented at, the lower part of the structure due to a higher proportion of aggregate and vice versa. Moreover, the disparity of creep, shrinkage, hydration heat, and curing method also leads to the difference in the quality of concrete. Therefore, it is necessary to study the responses of a concrete element with various mechanical properties. In this study, the functional elastic modulus of concrete material (FGC) is investigated numerically for its effects on the static responses of the element under axial compression. Conventional Finite Element Method (FEM) and Meshless method are used to model the structure. The reliability of the numerical model is validated by comparing the obtained results with experimental data.

In the paper, a method of determining the structural damage using the Particle Swarm Optimization (PSO) algorithm is presented. PSO is a famous algorithm to search optimization. Damaged structural system members are detected by the PSO through the frequency change before and after the damage.

Ground improvement with the prefabricated vertical drain (PVD) has become widely employed for soft ground treatment because of its economical and efficient method. While numerous numerical and analytical methods have been derived for PVD however, it is still an extensively high demand for a simpler and more accurate method for design steps. This paper proposes a method for solving the problem of one-dimensional (1D) consolidation with prefabricated vertical drains. The current approach introduces a 1D equivalent permeability, increasing linearly with depth to perform the consolidation of soft ground improved with PVD. The analytical solutions have been carried out and verified by analyses for two cases of one-way drainage and two-way drainage for uniform soil layer. The results show that the error of excess pore pressure determined by the proposed method is less than that obtained by the simpler method of Chai and smaller than 10% compared to the theoretical solution. The paper also compares the analytical solution with the FEM by ABAQUS software. It is found that the excess pore pressures and consolidation degrees obtained by these methods are similar and close to the theory. These confirm that the introduced 1D equivalent permeability can be employed to perform the consolidation of PVD improvement by analytical and FEM methods.

The aim of this work is to investigate the free vibration and buckling characteristics of sigmoid functionally graded (FG) nanoplate with the influence of porosity. The modified rule of the mixture is utilized to calculate the effective material properties of porous sigmoid functionally graded (P-SFGM) nanoplate. Three schemes of porosity distribution, including uniform, symmetric and nonsymmetric are investigated. The first-order shear deformation theory is utilized to simulate the displacement fields of P-SFGM nanoplate. Eringen's nonlocal elastic theory and isogeometric analysis (IGA) are used to establish the governing equations for free vibration and buckling analysis of nanoplate structure with small size effect. By using NURBS as a basic function, IGA can fulfill the higher-order derivative requirement of governing equations. The accuracy of the presented solution is verified. By taking the nonlocal parameter into account, the stiffness of the plate is softened. Also, the effects of porosity distribution across the plate's thickness, porosity parameter, material power index, boundary conditions (BCs) and aspect ratio on the frequency response of P-SFGM nanoplate are presented. [ABSTRACT FROM AUTHOR]

For reflecting the actual working of the tower transmission, requirements about analysis model and review during processes used in the design must be determined and clearly assessed.The non-elastic analysis will directly overcome the disadvantages of methods that were based on linear elastic analysis above-mentioned. Main advantage of this method which based on direct analysis of nonlinear geometric effects and nonlinear materials is: (i) without using coefficientof computed length because nonlinear geometric effects are integrated directly; (ii) the interaction due to plastic flow and gradual instability as per increasing load is taken into account; (iii) to provide results of internal forces of the entire structure with consideration over the internal force redistribution as true status of the system; (iv) to predict the stiffness of the structures transmission tower with a more accuracy; (v) to figure out the nonlinear behavior of the system, order and modes of failure of structures and structural systems, as well as ultimate bearing capacity of the system; (vi)to apply suitably and reasonably all kind of frame structures including unbracing frame, bracing frame and mixed frames.In this paper, following problems have been solved: Beam-column method using stability function with plastic hinged in both ends in order to describe the nonlinear behavior of structural steel transmission tower, then a nonlinear algorithm for analyzing the system subjected to static load was created. A practicable Fortran program for analyzing nonlinear system rigid frame, bracing frames, steel frames and power supply towers was established. After then, the reliability of the developed program has been evaluated and compared to that ofSAP2000 results. Finally, developed programs was used to design electricity transmission towers.

Nonlineargeometricismentionof geometric errorof structureatthe pointincreasing forceandthe nonlinearmaterialismentionof a change material. Nonlineargeometricanalysis byusingbeam-column method andnonlinearmaterialsthat includingplastichinge oftheendingelementsfor simulationtheworkingoftheelementsas wellastheentirethe trusses systemunderthe effect ofexternal forces. Beam-column includingthe effects ofcompressionandbendingthat describesthecombininganalysis of thedeviationof the beamgeometryandstability issuesoftheload-bearingcolumn. The articleusesadvanced analyticalmethods to analyzethe relationship betweenforceanddisplacementofthe trusses systemthroughquadratic curvewhich includingthecombination of effects, Analysisthe relationship between theforce-displacement ateachincreasingforcepoint andthe point reaching structure’slimit. Using thestabilityof beam-column methodenablesto reduce the declarationofelement,reduceanalysis timeand reduce the problem of computer memorycache

This paper studies dynamic reduction of combining damper consisting of Viscous Fluid Damper, VFD, which set inside individual structure and Magneto Rheological Damper, MRD, which set between two structures under ground motion. The MRD is simulated by springs, dashpot with damping force depending on displacement, velocity and voltage of equipment. The VFD is also expressed by the relation of damping force and velocity. The governing equation of motion of a structure is derived and solved by step by step procedures of Newmark method. A program is also established base on MATLAB language to analyse dynamic response of the structures. The result obtained from the numerical study is drawn effective of combining damper.