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Energy Today
Published in Anco S. Blazev, Global Energy Market Trends, 2021
Gravitational force, or gravity, is a natural phenomenon, where physical bodies attract each other with a force proportional to their masses. It is the invisible force that keeps our solar system together, where the sun’s large mass attracts all celestial bodies, making them rotate around it. Gravity is also responsible for the moon’s rotation around the Earth, which in turn create tides, natural convection, and a number of other phenomena.
Finite Element Analysis: Background Concepts
Published in Steven M. Lepi, Practical Guide to Finite Elements, 2020
The concept of minimum total potential energy, as applied to the finite element method, is considered in Zienkiewicz [5]. Essential boundary conditions, playing a fundamental role in engineering analysis, will be introduced in the next section. For now, consider how TPE can be used to determine the equilibrium displacement in the spring-mass system depicted in Figure 1.11. As shown, a mass is connected to ground by a linear spring, and supported at X!; gravity acts upon the mass to provide potential energy. When the support is removed the mass begins to travel and, assuming that its kinetic energy is dissipated, comes to rest at its static equilibrium position, X2. In this example, displacement is defined as the distance between the initial location of the mass and its final position, while the force on the mass is generated by gravitational acceleration, g:
Design
Published in Ajaya Kumar Gupta, Peter James Moss, Guidelines for Design of Low-Rise Buildings Subjected to Lateral Forces, 2020
Edwin G. Zacher, Coley Altman, Douglas A. Foutch, Louis F. Geschwinder, Melvyn Green, Mark Schaefer, Mete A. Sozen, John R. Tissel
Low-rise buildings have been generally characterized as buildings in which gravity load strength requirements dominate the design of the system as well as the individual members. Historically the typical approach to design for lateral forces was linked to the ratio of height to width of the building. Where this ratio was less than 0.5 it was assumed that wind stresses would be so small they could be ignored in design [McDonald, 1975]. The lateral forces due to earthquake in regions of low seismicity have typically also been ignored. There has been an assumption that internal walls and partitions and unaccounted for redundancies were available to provide resistance to lateral forces and limit lateral displacement, drift. For many buildings this is a false assumption, especially with open warehousing, commercial and manufacturing uses and new construction techniques in office and residential uses. The structural systems must, of course, be adequate to support the gravity loads to which they will be subjected during the useful life of the structure. The structural systems must be integrated with all other systems in the building. Interference between systems has resulted in sacrificing the integrity of the structural system.
Seismic Retrofit of Existing Masonry Buildings through Inter-story Isolation System: A Case Study and General Design Criteria
Published in Journal of Earthquake Engineering, 2022
Diana Faiella, Bruno Calderoni, Elena Mele
To the authors’ knowledge, no similar application has been yet proposed for masonry buildings; however, two peculiar additional advantages can be obtained by means of this retrofit strategy for masonry structures, which are characterised by almost no tension resistance and relatively large compression capacity. First, the increase of compression due to gravity loads gives rise to a global improvement of the building capacity, i.e. to a stabilizing effect which reduces, or even counteracts, the local demand (tensile stresses) that arise in the walls due to lateral load bending and shear effects. Second, exploiting the mass damper effect, the global demand in terms of bending and shear effects on the existing building can be also reduced. Therefore, massive interventions in the lower structure can be avoided and the retrofit works can be carried out with almost no disruption of the activity hosted in the existing building. Of course, an essential requirement, to be preliminary assessed, is the availability of compression over-strength in the lower structure for bearing the extra gravity loads due to the upper structure; however, well-designed masonry structure in terms of gravity load usually has compression strength demand to capacity ratio quite low, between one-fifth and one-tenth (DM 20 November 1987; Heyman 1966).
Modeling and control of a 3-DOF articulated robotic manipulator using self-tuning fuzzy sliding mode controller
Published in Cogent Engineering, 2021
Aderajew Ashagrie, Ayodeji Olalekan Salau, Tilahun Weldcherkos
Therefore, kinetic and potential energy analysis of each link of the manipulator must be carried as shown in Figure 2. The kinetic energy can be both rotational and translational; it is a function of both position and velocity, . The potential energy is due to conservative forces exerted by gravity. The Euler-Lagrange equations for the n-DOF system are defined as: