Response of multistory steel structure subjected to differential settlements of its foundation

PurposeThis article aims to address an outstanding problem dealing with the structure and its foundation.Design/methodology/approachDifferential settlement between foundation units of a multistory structure has been responsible for serious damage to buildings and often catastrophic failure and loss of life. The dynamic changes in the loading conditions of the structure, and the variability of the underlying ground due to environmental changes, are causing the undesirable differential settlement, which is manifested in the form of additional stresses in beams, columns and distortion of the structure elements. The structural response to the differential settlements depends on the type of the structure (concrete or steel), type of beam-to-column connections (rigid or semi-rigid), number of floors and the spans of the beams in the building. This paper presents the results of a numerical model, which was developed using the finite element technique and the software “ABAQUS” to analyze a nine-floor steel structure. The model was capable to capture the stresses and the strains developed in beams and columns and the relationships of moment–settlement and rotation–settlement for the structural during the differential settlement of its foundation. After validating of the model, data were produced for a wide range of governing parameters for rigid and semi-rigid connections and accordingly the mode of failure. The results can be used as a guideline for the design of steel structures.FindingsResults are useful for those design steel structures.Research limitations/implicationsThis study is based on the experimental and numerical data of the authors.Practical implicationsThis study provides a guideline for the design of steel structures.Originality/valueThis is the original research developed by the authors.

Finite Element Modeling for Static Bending Behaviors of Rotating FGM Porous Beams with Geometrical Imperfections Resting on Elastic Foundation and Subjected to Axial Compression

The static bending analysis of the FG porous beam resting on the two-parameter elastic foundation is initially carried out using a combination of Reddy’s high-order shear deformation theory and the finite element technique, where the initial geometrical imperfection and rotation movement in one fixed axis are calculated. Through the power-law distribution function with porosities, material characteristics vary constantly from one surface to the next in the direction of thickness, and the beam is concurrently impacted by an acting force perpendicular to the beam axis and an axial compressive force. The stiffness matrix of the beam element changes as a result, and the static bending response of this beam is significantly different from that of ordinary beams. Comparison cases with published findings are used to verify the computational theory. The calculations clearly reveal many innovations for rotating beams that are influenced by many different kinds of loads, which may be used to the designing, manufacturing, and usage of these structures in reality.

Investigation of vibratory bed effect on abrasive drag finishing: a DEM study

Purpose The purpose of this paper is to investigate the effect of a vibratory bed, as an assistant agent, on the improvement of the drag finishing process. The dynamics and kinematic of the process were surveyed in microscale for different frequencies and amplitudes and the results were compared to the basic process. Design/methodology/approach The discrete element tool was used to find out the effect of the vibratory bed on the drag finishing process. To this end, the Hertz-Mindlin model was used to investigate the contact of abrasive particles and workpiece. At the first stage, the numerical model was validated with the experimental results, and then the effect of different parameters on the finishing process was evaluated and compared with the basic case. Findings The chosen numerical model was in good agreement with the results measured in the previous literature. Moreover, the results show that not only vibrated bed enhances the contacts of abrasive particles to the workpiece, but it also increases the uniformity of the finished surface. Originality/value In comparison to the experiments, the discrete element technique consumes lower cost and time to estimate the optimum conditions of the finishing process, as well as it provides a good understanding of this phenomenon on the micro-scale.

Analytical and Numerical Solutions for the Thermal Problem in a Friction Clutch System

The dry friction clutch is an important part in vehicles, which has more than one function, but the most important function is to connect and disconnect the engine (driving part) with driven parts. This work presents a developed numerical solution applying a finite element technique in order to obtain results with high precision. A new three-dimensional model of a single-disc clutch operating in dry conditions was built from scratch. As the new model represents the real friction clutch including all details, the complexity in the geometry of the clutch is considered one of the difficulties that the researchers faced using the numerical solution. The thermal behaviour of the friction clutch during the slip phase was studied. Meanwhile, in the second part of this work, the transient thermal equations were derived from scratch to find the analytical solution for the thermal problem of a clutch disc in order to verify the numerical results. It was found, after comparison of the numerical results with analytical results, that the results of the numerical model are very accurate and the difference between them does not exceed 1%.

Development and evaluation of novel modules for deployable tension-strut structures

There is a growing need for new alternatives of long-span roof structures with high level of transformability and structural robustness. This led to the development of deployable cable-strut structures, which are composed of a continuous net of struts and another continuous net of cables. Subsequently, a special type of these systems was pioneered and given the term deployable tension-strut structures (DTSSs). The motivation beyond this new concept was the lack of structural efficiency and form flexibility of conventional space trusses that are usually employed for covering large spaces. Typically, DTSSs are roof structures consisting of multiple modules put together to form the roof system. This paper is mainly concerned with developing new robust modules for DTSSs. The technique that was adopted for this purpose is a form-creation methodology previously introduced in the literature. A few modules were already developed based on this shape grammar. However, its potential to develop multiple efficient modules has not been sufficiently investigated. In this current work, the afore-mentioned algorithm was utilized to form 16 new modules. A comparative study based on a nonlinear finite element technique was conducted to investigate the efficiency of the novel modules as compared to that of the previously proposed in the literature. The results show that some of the new proposed modules are far more efficient than those presented in previous researches. Based on this comparative study, the most two efficient modules among the novel ones were picked for further study. Parametric studies were conducted on these two systems under gravity loads and wind loads considering the following parameters: no. of modules, span/depth ratio, and cables’ pre-stress level. For each parameter, the optimal range of values were determined to be used as a guide for the design of such systems.

Finite Element Analysis of Thermal-Diffusions Problem for Unbounded Elastic Medium Containing Spherical Cavity under DPL Model

In this work, the thermo-diffusions interaction in an unbounded material with spherical cavities in the context dual phase lag model is investigated. The finite element technique has been used to solve the problem. The bounding surface of the inner hole is loaded thermally by external heat flux and is traction-free. The delay times caused in the microstructural interactions, the requirement for thermal physics to take account of hyperbolic effects within the medium, and the phase lags of chemical potential and diffusing mass flux vector are interpreted. A comparison is made in the case of the presence and the absence of mass diffusions between coupled, Lord-Shulman and dual phase lag theories. The numerical results for the displacement, concentration, temperature, chemical potential and stress are presented numerically and graphically.

Photostrictive effect in 1-3 composites of photovoltaic and piezoelectric phases: A numerical study

Coalesce of photovoltaic effect with converse piezoelectric effect will turn into a photostrictive phenomenon. The current study conceptualizes a 1-3 photostrictive composite consists of a photovoltaic polymer as matrix and fibers of piezoelectric material. The proposed artificial photostrictive composite is capable of replacing lead-based naturally occurring photostrictive material, not only opening a potential for new applications but also caters to tailor the desired properties. Present study employs poly{4,8-bis[5-(2-ethyl-hexyl)thiophen-2-yl]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno[3,4-b] thiophene-4,6-diyl} (PTB7-Th) as organic photovoltaic polymer and Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-35PT) as the fibers. A representative volume element technique (RVE) is employed to embrace the local variation of multi-physics properties. The actuation response of cantilever and simply supported beam bonded to photostrictive composite patch is accurately predicted by finite element method, while discretizing the structure with degenerated shell element. Photostrictive composite with 60% volume fraction of fibers, arranged in square pattern have deflected the cantilever tip to 1.95 mm. Therefore, we provide 1-3 photostrictive composite as a solution for future wireless and lightweight vibration control applications.

Electromagnetic Simulation of New Tunable Guide Polarizers with Diaphragms and Pins

In this article we present the results of mathematical simulation, development and optimization of a waveguide polarizer with a diaphragm and pins. A mathematical model was developed using the proposed approach on the example of a waveguide polarizer with one diaphragm and two pins. The diaphragm and pins were modeled as inductive or capacitive elements for two types of linear polarization of the fundamental modes. The applied model uses a wave scattering matrix. The total matrix of a polarizer was obtained using wave matrices of transmission of individual elements of the device structure. Using the elements of the common S-parameters the electromagnetic characteristics of the device, which is considered, were obtained. To check the performance of the developed mathematical model, it was simulated in a software using the finite element technique in the frequency domain. The designed structure of the polarizer is adjustable due to mechanical change in the length of the pins. The developed waveguide polarizer with one diaphragm and two pins provides a reflection coefficient of less than 0.36 and a transmission coefficient of more than 0.93 for two types of polarizations. Therefore, a new theoretical method was developed in the article for analysis of scattering matrix elements of a waveguide polarizer with diaphragms and pins. It can also be used for the development of new tunable waveguide polarizers, filters and other components with diaphragms and pins.

Efficiency Improvement of Permanent Magnet BLDC Motors for Electric Vehicles

A permanent magnet Brushless DC (BLDC) motor has been designed with different rotor configurations based on the arrangement of the permanent magnets. Rotor configurations strongly affect the torque and efficiency performance of permanent magnet electric motors. In this paper, different rotor configurations of the permanent magnet BLDC motor with parallel the Halbach array permanent magnet were compared and evaluated. Many applications of electric drives or air-crafts have recently preferred the surface-mounted permanent magnet design due to its ease of construction and maintenance. The finite element technique has been used for the analysis and comparison of different geometry parameters and rotor magnet configurations to improve efficiency and torque performance. A comprehensive design of a three-phase permanent magnet BLDC 35kW motor is presented and simulations were conducted to evaluate its design. The skewing rotor and Halbach magnet array are applied to the permanent surface-mounted magnet on the BLDC motor for eliminating torque ripples. In order to observe the skewing rotor effect, the rotor lamination layers were skewed with different angles and Halbach sinusoidal arrays. The determined skewing angle, the eliminated theoretically cogging torque, and the back electromotive force harmonics were also analyzed.