Reuse of Steel Structural Elements with Bolted Connections

2018 ◽  
Author(s):  
Janis Kreilis ◽  
◽  
Edgars Zeltins
Keyword(s):  
Structural Elements ◽  
Bolted Connections

A Preliminary Study of Self-Loosening in Bolted Connections

1993 ◽  
Author(s):  
Rick I. Zadoks ◽  
Xiong Yu
Keyword(s):  
Sliding Friction ◽  
Transverse Force ◽  
Transverse Motion ◽  
Structural Elements ◽  
Bolted Connections ◽  
Bolted Connection ◽  
Cause Of Failure ◽  
The Relationship ◽  
Minimum Force ◽  
Insight Into

Abstract Bolted connections are the most common method used to fasten together two or more structural elements. After fatigue, self-loosening is the most frequent cause of failure of dynamically loaded bolted connections. Bolted connections experience self-loosening due to relative motion between the thread flanks and between other contact surfaces of the clamped or clamping elements. If the relative motions are eliminated, then no dynamic self-loosening can occur. It is found that the relative transverse motion d at a bolted connection is directly related to the preload Q and the transverse force F applied to the bolt. As a basis for the study of bolt self-loosening, a model of thread slipping is established, and relationships between Q, F and d are theoretically derived. It is found that the stiffness of the bolt threads is approximately parabolic. Due to this nonlinear relationship between Q and d, it is found that the relationship between F and d is also nonlinear. For a given set of geometrical and material parameters, the critical transverse force Fcr (i.e., the minimum force needed to make the threads slip) can be predicted. Experiments are run and though the results are obscured by the presence of other effects including sliding friction between the clamped parts and bending of the bolt body, it seems that qualitative agreement exists between the theoretical model and a physical system. The results presented in this work serve as the preliminaries to the development of a model of the dynamic self-loosening of bolted connections and, as such, offer an insight into the mechanisms that lead to self-loosening. Additionally, these results offer clues regarding methods that could be used to prevent bolted connection failures.

NON-DESTRUCTIVE APPROACH TO THE BOLT JOINTS QUALITY CONTROL

2020 ◽  
pp. 37-42
Author(s):  
N. V. Mikhalevich ◽  
O. S. Plotnikova
Keyword(s):  
Quality Control ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Experimental Research ◽  
Bolted Joints ◽  
Reinforced Concrete Structures ◽  
Structural Elements ◽  
Bolted Connections ◽  
Non Destructive ◽  
Destructive Methods

Bolted connections are often used to connect structural elements in steel, wood and reinforced concrete structures. In structural inspecting, there is often no marking on bolted joints. So, it is necessary to determine the bolt strength to assess the bolt joint bearing capacity. The bolt strength can be determined by destructive and non-destructive methods. The article presents the experimental research to determine the bolt strength using the scratch method and compares the results with the destructive method (bolt breaking).

Structural phenomena in the growth of carbon nanotubes

1993 ◽  
Vol 51 ◽  
pp. 750-751
Author(s):  
Jun Jiao
Keyword(s):  
Carbon Nanotubes ◽  
Growth Mechanism ◽  
Carbonaceous Material ◽  
Cluster Growth ◽  
Structural Elements ◽  
Rich Variety ◽  
Different Shapes ◽  
Point To Point

HREM studies of the carbonaceous material deposited on the cathode of a Huffman-Krätschmer arc reactor have shown a rich variety of multiple-walled nano-clusters of different shapes and forms. The preparation of the samples, as well as the variety of cluster shapes, including triangular, rhombohedral and pentagonal projections, are described elsewhere.The close registry imposed on the nanotubes, focuses attention on the cluster growth mechanism. The strict parallelism in the graphitic separation of the tube walls is maintained through changes of form and size, often leading to 180° turns, and accommodating neighboring clusters and defects. Iijima et. al. have proposed a growth scheme in terms of pentagonal and heptagonal defects and their combinations in a hexagonal graphitic matrix, the first bending the surface inward, and the second outward. We report here HREM observations that support Iijima’s suggestions, and add some new features that refine the interpretation of the growth mechanism. The structural elements of our observations are briefly summarized in the following four micrographs, taken in a Hitachi H-8100 TEM operating at an accelerating voltage of 200 kV and with a point-to-point resolution of 0.20 nm.

Designing TIMP (tissue inhibitor of metalloproteinases) variants that are selective metalloproteinase inhibitors

2003 ◽  
Vol 70 ◽  
pp. 201-212 ◽  
Author(s):  
Hideaki Nagase ◽  
Keith Brew
Keyword(s):  
Three Dimensional ◽  
Therapeutic Interventions ◽  
Tissue Inhibitors Of Metalloproteinases ◽  
Structural Basis ◽  
Structural Elements ◽  
Ridge Structure ◽  
Extracellular Matrix Components ◽  
Metalloproteinase Inhibitors ◽  
The Matrix ◽  
A Disintegrin And Metalloproteinase

The tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of the matrix metalloproteinases (MMPs), enzymes that play central roles in the degradation of extracellular matrix components. The balance between MMPs and TIMPs is important in the maintenance of tissues, and its disruption affects tissue homoeostasis. Four related TIMPs (TIMP-1 to TIMP-4) can each form a complex with MMPs in a 1:1 stoichiometry with high affinity, but their inhibitory activities towards different MMPs are not particularly selective. The three-dimensional structures of TIMP-MMP complexes reveal that TIMPs have an extended ridge structure that slots into the active site of MMPs. Mutation of three separate residues in the ridge, at positions 2, 4 and 68 in the amino acid sequence of the N-terminal inhibitory domain of TIMP-1 (N-TIMP-1), separately and in combination has produced N-TIMP-1 variants with higher binding affinity and specificity for individual MMPs. TIMP-3 is unique in that it inhibits not only MMPs, but also several ADAM (a disintegrin and metalloproteinase) and ADAMTS (ADAM with thrombospondin motifs) metalloproteinases. Inhibition of the latter groups of metalloproteinases, as exemplified with ADAMTS-4 (aggrecanase 1), requires additional structural elements in TIMP-3 that have not yet been identified. Knowledge of the structural basis of the inhibitory action of TIMPs will facilitate the design of selective TIMP variants for investigating the biological roles of specific MMPs and for developing therapeutic interventions for MMP-associated diseases.

Formation Of An Estimate For A State Contract With A Firm Price In The Construction Sector

2020 ◽  
pp. 47-57
Keyword(s):  
Construction Projects ◽  
Cost Of Capital ◽  
Federal Budget ◽  
The State ◽  
Structural Elements ◽  
Construction Sector ◽  
Construction Process ◽  
Practical Application ◽  
Stage Of Development ◽  
Capital Construction

The issues of determining the estimated cost of capital construction projects with the involvement of Federal budget funds at the stage of development of project documentation, during verification of the accuracy of determining the estimated cost and the initial (maximum) contract price are considered. On the basis of the assessment of amendments to urban planning legislation for the purpose of implementing a state contract by the contractor ( based on the results of competitive procedures or without competitive procedures by decision of state authorities), the procedure for forming the estimate as part of a state (municipal) contract, the price of which is firm, is presented. For the purpose of mutual settlements between the customer and the contractor for the work performed, the formation of primary accounting documentation, as well as for checking the work performed by regulatory authorities, an example of drawing up an estimate of the state (municipal) contract on the basis of grouping costs according to structural elements and complexes of work is given. The result of the research conducted was the development of regulations and the formation of criteria for their practical application by state bodies, institutions, organizations and other participants in the investment-construction process, as well as recipients of budget funds, who perform the functions of the state (municipal) customer, developer and technical customer.

Duality, Opposition and Typology in the Qur'an: The Apocalyptic Substrate

2008 ◽  
Vol 10 (2) ◽  
pp. 23-49 ◽  
Author(s):  
Todd Lawson
Keyword(s):  
Structural Elements ◽  
Prominent Feature ◽  
Apocalyptic Literature ◽  
Cultural Traditions ◽  
Bona Fide

This article highlights two features of Qur'anic style and content: duality/opposition and typological figuration, which can be seen as providing a continuous and consistent ‘narrative stream’ through the Qur'an. It is of some interest that both of these features have been singled out as distinctive of apocalypse as a genre in the study of numerous religious and cultural traditions. As debate on whether or not the Qur'an is a bona fide example of apocalyptic literature quietly continues, the interplay of conceptual and substantive oppositions and dualities is discussed in order to highlight the importance of this prominent feature to both the form and contents of the Book. It is suggested that its function is profoundly related to the typological figuration indispensable to the Qur'anic depiction of, for example, the character of the prophets and therefore prophethood. Whether or not this represents a genuine instance of apocalyptic literature, it nonetheless remains that the prominence of the motif renders the Qur'an susceptible of a reading expressive of something called an apocalyptic imagination. It is hoped that this article succeeds in demonstrating that in fact these apparently familiar subjects are stimulated to new life by considering them as defining, interlocking, structural elements of a distinctive Islamic apocalypse.

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