scholarly journals WAVE ANALYSIS OF A L-BEAM STRUCTURE WITH A BLOCKING MASS

Author(s):  
Johnny Tiu ◽  
Richard Bachoo

The wave vibration approach regards the vibrations present within a structure as waves, whereby each wave flows along a structural member and upon meeting a discontinuity; portions of the incident wave are reflected and transmitted across the discontinuity. The reflected, transmitted and propagating wave transformations are represented mathematically by matrices, which are used to develop a set of wave relation equations at each discontinuity that can be used to describe the frequency response of the system holistically. This method creates a systematic approach of analysing structures by utilizing common cases as building blocks for a specific structure. The L-joint, described as two beams meeting at right angles; is a ubiquitous case for spatial portal and structural frames, which may become geometrically complex. Such structures are well suited to a wave vibration approach due to the large number of geometric changes and the prevalence as well as recurrence of specific cases. In this paper, the L-joint expanded to include a blocking mass, typically employed in structural systems and allows for the isolation and reflection of vibration away from contiguous structural elements. Included are; variance of transmission and reflection matrix components as the size of the blocking mass increases, numerical examples and comparison to a Finite Element Model developed in ANSYS.

2020 ◽  
Vol 11 (1) ◽  
pp. 278
Author(s):  
Ivan Hafner ◽  
Anđelko Vlašić ◽  
Tomislav Kišiček ◽  
Tvrtko Renić

Horizontal loads such as earthquake and wind are considered dominant loads for the design of tall buildings. One of the most efficient structural systems in this regard is the tube structural system. Even though such systems have a high resistance when it comes to horizontal loads, the shear lag effect that is characterized by an incomplete and uneven activation of vertical elements may cause a series of problems such as the deformation of internal panels and secondary structural elements, which cumulatively grow with the height of the building. In this paper, the shear lag effect in a typical tube structure will be observed and analyzed on a series of different numerical models. A parametric analysis will be conducted with a great number of variations in the structural elements and building layout, for the purpose of giving recommendations for an optimal design of a tube structural system.


Author(s):  
Gilles Van Staen ◽  
Hans De Backer ◽  
Philippe Van Bogaert

A bridge is nowadays more than a structure that connects people over an obstacle. When a bridge has to be built in an urban area, either it has to be a landmark or it should blend away in the environment. The use of curved steel panels is one option to obtain these requirements. However, due to a lack of knowledge, engineers end up with a conservative design to implement these structural elements. For that reason, a Finite Element Model is made of a railway bridge, where the outer webs of the main girders have a varying web curvature. Six different models are made and compared. The most important parameters that are compared are the deformations and the stresses in the webs. The study finds that curved webs have an equal or even better behavior than flat webs, even with smaller web thickness. This makes that designers can use curved webs in their design, without needing extra steel to make their design safe.


Author(s):  
Valeriy Sutyrin

This paper gives modal analysis results for mid-body of a refrigerator carrier ship by means of combined three-dimensional finite-element model with 1.5 million DOF. The study estimates the error of modal analysis for the ship structure if its boundary conditions are specified in advance, i.e. approximately, as well as analyses the gain in time offered by structuring the analytical model as per reduction (condensation) method. Analytical approaches thus transformed can be successfully applied in filtering lower frequencies and modes of natural vibrations for structural elements and joints of hull in the direct vicinity of exciting force application points.


Author(s):  
Andreas U. Schmidt ◽  
Nicolai Kuntze

Security in the value creation chain hinges on many single components and their interrelations. Trusted Platforms open ways to fulfil the pertinent requirements. This chapter gives a systematic approach to the utilisation of trusted computing platforms over the whole lifecycle of multimedia products. This spans production, aggregation, (re)distribution, consumption, and charging. Trusted Computing technology as specified by the Trusted Computing Group provides modular building blocks which can be utilized at many points in the multimedia lifecycle. We propose an according research roadmap beyond the conventional Digital Rights Management use case. Selected technical concepts illustrate the principles of Trusted Computing applications in the multimedia context.


2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Hui Long ◽  
Yilun Liu ◽  
Changzheng Huang ◽  
Weihui Wu ◽  
Zhaojun Li

A new model is presented for studying the effects of crack parameters on the dynamics of a cracked beam structure. The model is established by the finite element displacement method. In particular, the stiffness matrix of the cracked beam element is firstly derived by the displacement method, which does not need the flexibility matrix inversion calculation compared with the previous local flexibility approaches based on the force method. Starting with a finite element model of cracked beam element, the equation of strain energy of a cracked beam element is formed by the displacement method combined with the linear fracture mechanics. Then, based on the finite element method, the dynamic model of the cracked beam structure is obtained. The results show that the dynamic model discovers the internal relation between the dynamic characteristics of cracked beam structure and structural parameters, material parameters, and crack parameters. Finally, an example is presented to validate the proposed dynamic model.


Author(s):  
Sudarsanam Chellappa ◽  
Alejandro R. Diaz

A method is presented to reduce the size of models used in analysis of elastic systems. The reduction is accomplished using a multiresolution analysis applied to elasticity operators to average fine scale properties and behavior while limiting loss of information. In discretized form, the method results in smaller matrices that can be used as building blocks to construct larger systems. The principal application envisioned is in design problems involving complex structural systems, such as crash-worthiness design, where very intensive computations demand computational efficiency.


2019 ◽  
Vol 72 (10) ◽  
pp. 731 ◽  
Author(s):  
Feng Li ◽  
Leonard F. Lindoy

The use of metalloligands as building blocks for the assembly of metallo-organic cages has received increasing attention over the past two decades or so. In part, the popularity of this approach reflects its stepwise nature that lends itself to the predesigned construction of metallocages and especially heteronuclear metallocages. The focus of the present discussion is on the use of metalloligands for the construction of discrete polyhedral cages, very often incorporating heterometal ions as structural elements. The metalloligand approach uses metal-bound multifunctional ligand building blocks that display predesigned structural properties for coordination to a second metal ion such that the rational design and construction of both homo- and heteronuclear metal–organic cages are facilitated. The present review covers published literature in the area from early 2015 to early 2019.


2015 ◽  
Vol 76 (1) ◽  
Author(s):  
H. M. C. C. Somarathna ◽  
S. N. Raman ◽  
A. A. Mutalib ◽  
K. H. Badri

In many parts of the world, terrorism has become a major threat to nations, and terrorist activities and accidental explosions have been directed towards the destruction of buildings and critical infrastructures. As a result, almost every new development requires the consideration of safety and security aspects such that even a new building incorporates protective engineering features in its design. In this aspect, researchers have been investigating the use of elastomeric polymers (such as polyurethane and polyurea) for structural retrofitting applications due to attractive characteristics and morphology exhibited by these materials. This paper provides a review on this novel approach of strengthening structural elements and systems to enhance their capacity against blast and ballistic threats. The discussions in this review have been focussed on the application of this technique on the most widely used structural systems of masonry, concrete, metallic and composite structural systems. This technique offers an alternative to existing strengthening techniques in protecting structures against the risks of blast, ballistic and impact loads.  


2013 ◽  
Vol 300-301 ◽  
pp. 1263-1266 ◽  
Author(s):  
Zhi Min Yan ◽  
Yong Fei Du ◽  
Jun Guo Huang ◽  
Yu Shun Li

Modern bamboo structural system is a new type of green sustainable building technology, conform with our country’s requirements of developing environment-protecting and energy-saving buildings. This paper presents a new lightweight, high-strength , earthquake-resistant and energy-saving system-steel-bamboo composite structural systems , and given the various structural elements of the composite structural systems of steel-bamboo production methods . This paper also gives the production methods of steel-bamboo composite elements. Steel-bamboo-structural system can per-fectly combine steel and bamboo to bear load together, and it have excellent mechanical properties and broad application prospects.


Author(s):  
David Tsiteladze

The paper analyzes the systematic approach of project management. The description of the structural elements of a systematic approach is given — the project management methodology, game theory and system thinking theory. Due to the qualitative differences between the projects, the levels of project structuring and the needs of interested parties, the work describes a seriesparallel nature of the development stages of the project management. The paper proposes an algorithm for the basic project management processes that is fair for each functional area of the project. Using this algorithm will allow the project manager to increase the quality of management decisions and significantly reduce efforts and time for organizing the project management process.


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