scholarly journals Overview of the modified magnetoelastic method applicability

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 167
Author(s):  
Tomáš Klier ◽  
Tomáš Mícka ◽  
Michal Polák ◽  
Milan Hedbávný
Keyword(s):  
Prestressed Concrete ◽  
Concrete Structures ◽  
Engineering Practice ◽  
Structural Elements ◽  
Engineering Structures ◽  
Advantages And Disadvantages ◽  
Axial Forces ◽  
Technical Practice ◽  
Tensile Forces

<p class="Abstract">A requirement of axial force determination in important structural elements of a building or engineering structure during its construction or operational state is very frequent in technical practice. In civil engineering practice, five experimental techniques are usually used for evaluation of axial tensile forces in these elements. Each of them has its advantages and disadvantages. One of these methods is the magnetoelastic method, that can be used, for example, on engineering structures for experimental determination of the axial forces in prestressed structural elements made of ferromagnetic materials, e.g., prestressed bars, wires and strands. The article presents general principles of the magnetoelastic method, the magnetoelastic sensor layout and actual information and knowledge about practical application of the new approach based on the magnetoelastic principle on prestressed concrete structures. Subsequently, recent results of the experimental verification and the in-situ application of the method are described in the text. The described experimental approach is usable not only for newly built structures but in particular for existing ones. Furthermore, this approach is the only one effectively usable experimental method for determination of the prestressed force on existing prestressed concrete structures in many cases in the technical practice.</p>

scholarly journals New information about practical application of the modified magnetoelastic method

2020 ◽  
Vol 310 ◽  
pp. 00026
Author(s):  
Tomáš Klier ◽  
Tomáš Míčka ◽  
Michal Polák ◽  
Tomáš Plachý ◽  
Milan Hedbávný ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Experimental Evaluation ◽  
Engineering Practice ◽  
Structural Elements ◽  
Practical Application ◽  
New Approach ◽  
Axial Forces ◽  
Technical Practice ◽  
New Information ◽  
Prestressed Reinforcement

In the technical practice there is very often a need of axial force determination in the important structural elements of a building during its construction or operational state with adequate precision. The magnetoelastic method is one of the five experimental techniques usually used for that purpose in civil engineering practice. The modified magnetoelastic method is especially aimed on experimental evaluation of the axial forces in the prestressed steel reinforcements on prestressed concrete structures and it is usable not only for newly built structures but in particular for existing ones. New information and knowledge about practical application of the new approach based on the magnetoelastic principle is introduced in the paper. The results of three experiments are summarized, which were realized on the full locked cable PV 150 standardly used as a cable stay strand, on the MUKUSOL threadbar 15FS 0000 generally applied as a temporary prestressed reinforcement and on some prestressed tendons of an existing concrete road bridge, which is about thirty years old.

scholarly journals Bending–torsional-coupled vibrations and buckling characteristics of single and double composite Timoshenko beams

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983445
Author(s):  
Ma’en S Sari ◽  
Wael G Al-Kouz ◽  
Rafat Al-Waked
Keyword(s):  
Slenderness Ratio ◽  
Equations Of Motion ◽  
Mode Shapes ◽  
Timoshenko Beams ◽  
Engineering Structures ◽  
Axial Forces ◽  
Double Beam ◽  
Tensile Forces ◽  
Torsional Coupling ◽  
The Stability

The stability and free vibration analyses of single and double composite Timoshenko beams have been investigated. The closed-section beams are subjected to constant axially compressive or tensile forces. The double beams are assumed to be connected by a layer of elastic translational and rotational springs. The coupled governing partial differential equations of motion are discretized, and the resulted eigenvalue problem is solved numerically by applying the Chebyshev spectral collocation method. The effects of the elastic layer parameters, the axial forces, the slenderness ratio, the bending–torsional coupling, and the boundary conditions on the critical buckling loads, mode shapes, and natural transverse frequencies have been studied. A parametric study was performed, and the obtained results revealed different features, which hopefully can be useful for single- and double-beam-like engineering structures.

scholarly journals SHAPE DETERMINING OF A LOADED CABLE VIA TOTAL DISPLACEMENTS

2005 ◽  
Vol 11 (4) ◽  
pp. 283-291 ◽  
Author(s):  
Algirdas Juozapaitis ◽  
Arnoldas Norkus
Keyword(s):  
Flexural Rigidity ◽  
Engineering Practice ◽  
Suspension Bridges ◽  
Large Displacements ◽  
Structural Elements ◽  
Principle Of Superposition ◽  
Structural Element ◽  
Engineering Structures ◽  
Cable Structure ◽  
Total Displacement

Cable structures are very efficient (in economic aspect) when applied to cover large spans. The cable structure consists of a single cable or a network of cables. The cable attractive feature is the highest ratio of strength to weight amongst other carrying structural elements, usually applied in engineering practice. But a cable is a specific structural element able to response only one type of deforming ‐ tension (flexural rigidity actually vanishes). Therefore, when loaded a cable shapes the form to resist tension only. This adaptation is followed by large nonlinear displacements. Thus, the nature of geometrical nonlinear cable behavior is quitie a different from that of rigid structural elements. Both elements response via small deformations when loaded, but large displacements of a cable are conditioned by its adaptation to loading, and those of rigid structural elements ‐ by actual deformations. One can also note that deformations of a cable are significantly less than those of rigid structural elements, but at the same time actual cable displacements are significantly larger. Thus, the main disadvantage of a cable structure is its response to loading by large displacements caused by asymmetric loading component (usually met in engineering practice, e.g. the design of suspension bridges, coverings of stadium, etc). Therefore stiffness conditions predominate in the actual codified cable design. Having identified governing factors conditioning displacement magnitudes one can introduce the constructional means/solutions assigned to reduce them if required. Therefore the evaluation of cable displacements by a reliable and sufficiently exact method compatible with the calculation of actual engineering structures is under current necessity. When analyzing total displacements the principle of superposition is employed in a special sequence. Total displacement is split into two components: kinematic and elastic. The first component represents cable form shaping the loading, the second one is conditioned by elastic deformations. Any point displacement of an asymmetrically loaded cable can be expressed via its middle span. The developed analytical expressions to evaluate middle span displacements are presented. They enable to identify maximal displacements and their locations. The developed analytical method for total displacements evaluation is tested numerically. The comparative analysis in respect of the influence of various parameters conditioning displacement magnitudes is performed. The displacement evaluation errors, their causality conditioned by the application of approximate‐ widely applied engineering methods, are discussed.

scholarly journals Application of Laminated Plate Construction Technology in Prefabricated Building Structure

CONVERTER ◽  
2021 ◽  
pp. 30-36
Author(s):  
Li Jianghua, Weng Mei
Keyword(s):  
Prestressed Concrete ◽  
Engineering Practice ◽  
Construction Technology ◽  
Building Structure ◽  
Laminated Plate ◽  
Composite Slab ◽  
Advantages And Disadvantages ◽  
Budget Analysis ◽  
Material Budget ◽  
Prefabricated Building

With the development of China's construction field, prefabricated building structure has gradually become a very common building structure in the current construction engineering by virtue of its many advantages in the actual construction field. Combined with the engineering practice, this paper summarizes the hoisting technology of precast composite slab and precast staircase in prefabricated building structure. This paper focuses on the optimization design of laminated plate support under the conditions of wood formwork and aluminum formwork system and the key and difficult points in the construction process, and puts forward a set of practical and feasible construction methods for prefabricated components. This paper focuses on the analysis of the design concept, materials, structural form, manufacturing technology, hoisting and installation, and construction technology of M-type light steel concrete composite slab. This paper discusses and summarizes the advantages and disadvantages of M-type light steel reinforced concrete composite slab at present, and analyzes its development and application prospects. At the same time, in order to determine the reasonable type of laminated plate, the material budget analysis of assembled laminated plates with different structural forms is carried out. The conclusions are as follows: PK prestressed concrete composite slab has great advantages in the whole material budget cost, which is suitable for all kinds of span buildings. One way steel truss slab and YH prestressed concrete composite slab are suitable for small span buildings.

Torsion of Reinforced Concrete Structural Members

2018 ◽  
Vol 272 ◽  
pp. 178-184
Author(s):  
Vladimír Křístek ◽  
Jaroslav Průša ◽  
Jan L. Vítek
Keyword(s):  
Bending Moments ◽  
Structural Elements ◽  
Structural Members ◽  
Structural System ◽  
Shear Forces ◽  
Axial Forces ◽  
Methods Of Calculation ◽  
Tensile Forces ◽  
Torque Capacity ◽  
The Common

According to the common design methods of calculation of the stress state induced by torsion of massive prismatic concrete structural elements, the structural system is reduced to a simple cage consisting of ties and struts. This model has, however, a number of principal shortcomings, the major of them is the fact that all of simultaneously acting effects like axial forces, bending moments and shear forces are not taken into account – the compressive axial forces increase very significantly the torque capacity of structural members, while due to action of tensile forces, bending moments and shear forces the torque capacity is reduced. These phenomena, applying non-linear approaches, are analysed and assessed.

PERFORMANCE OF PRESTRESSED CONCRETE BEAM INCORPORATING AN AXIAL YIELD DAMPER USING UNBONDED REBAR

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Yuki Shirai ◽  
Kazushi Shimazaki
Keyword(s):  
Energy Absorption ◽  
Prestressed Concrete ◽  
Absorption Capacity ◽  
Structural Elements ◽  
Structural Members ◽  
Equivalent Damping ◽  
Sufficient Energy ◽  
Tensile Forces ◽  
Continuous Use ◽  
Hysteresis Characteristics

Unbonded prestressed concrete (UBPC) has shown considerable promise for structural elements in continuous-use applications. However, little research has evaluated the performance of UBPC structural elements or their low energy absorption ability, and such elements are therefore not commonly used as main structural members. In this study, a small axially yielding hysteresis damper was developed, which can be replaced in the event of earthquake damage to a UBPC beam in high continuous use. The damper was designed to use the axial yielding of deformed rebars so that it has the same performance under compressive and tensile forces. It was mounted in a knee brace shape and had a mass of about 10 kg. The damper exhibited positive and negative hysteresis characteristics even after the deformed rebars had yielded axially and it had sufficient energy absorption capacity. In a structural experiment, installing the damper, the shear force that can be borne by the beam and the equivalent damping constant increased, which means that the damper is useful.

Control of the leveling network when laying benchmarks on strongly hectic soils

2017 ◽  
Vol 926 (8) ◽  
pp. 20-24
Author(s):  
D.A. Afonin ◽  
N.V. Kanashin ◽  
A.A. Nikitchin
Keyword(s):  
High Altitude ◽  
High Speed ◽  
Control Methods ◽  
Structural Elements ◽  
Engineering Structures ◽  
Structure Comparison ◽  
Subsequent Determination ◽  
Comparison And Analysis

The article describes the experience of controlling a high-altitude geodesic alignment network in the case of the displacement of most of its points by the example of a network for the construction of a bridge across the river. Vere-bushka in the high-speed toll highway Moscow - St. Petersburg. For the case under consideration, the biases of the high-altitude network points were determined based on the use of A. Kostechel’s method and leveling with respect to the subplane areas of the structure. Comparison and analysis of the results are performed, on the basis of which it was concluded that the data obtained by the A. Kostekhel method under the conditions of deformations of most points of the network are inaccurate. To control the high-altitude network in the construction of engineering structures in such conditions, it is proposed to fix additional benchmarks on stable structural elements with the subsequent determination of their marks relative to existing points. In order to ensure the continuity of the altitude system during the construction of the facility, it was suggested, when monitoring a high-altitude network, to use the heights of such frames as initial ones, when known control methods do not give unambiguous results.

Concrete Structures Restoration from the Fire Safety Point of View

2013 ◽  
Vol 688 ◽  
pp. 113-119 ◽  
Author(s):  
Isabela Bradáčová ◽  
Petr Kučera
Keyword(s):  
Critical Temperature ◽  
Temperature Distribution ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Point Of View ◽  
Engineering Practice ◽  
Cover Layer ◽  
Subsequent Determination ◽  
Bearing Structure

The need of concrete structures restoration in order to ensure their fire resistance can, in engineering practice, occur for reasons of damage to the structure by fire (spalling of concrete cover layer) or by the failure to cover the load-bearing structure during construction. The paper is devoted to the evaluation of the structure cover of the evaluated structure, the determination of temperature distribution in the structure with consideration to the choice of probable fire scenario, subsequent determination of critical temperature of the structure and the optimization of possible methods of the restoration of damaged or wrongly made constructions.

scholarly journals APPLICATION OF THE MODIFIED MAGNETOELASTIC METHOD AND AN ANALYSIS OF THE MAGNETIC FIELD

2018 ◽  
Vol 15 ◽  
pp. 46-50 ◽  
Author(s):  
Tomáš Klier ◽  
Tomáš Míčka ◽  
Michal Polák ◽  
Tomáš Plachý ◽  
Milan Hedvábný ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beam ◽  
Structural Elements ◽  
Practical Application ◽  
New Approach ◽  
Knowledge Based ◽  
Axial Forces ◽  
Magnetoelastic Properties ◽  
Prestressed Reinforcement ◽  
The Magnetic Field

In the technical praxis there is very often a need of axial force determination in the important structural elements of a building during its construction or operational state. The paper presents practical application of the new approach based on the magnetoelastic principle, especially aimed on experimental evaluation of the axial forces in the prestressed reinforcement on prestressed concrete structures. Described approach is usable not only for newly built structures but in particular for existing ones. The experiment was realized on a prestressed concrete beam dismantled from a bridge that was put out of operation. The influence of a simulated defect of the reinforcement on its magnetoelastic properties has also been investigated. During result evaluation, the knowledge based on the theoretical analysis of the electromagnetic field was used.

LONG-TERM CORROSION BEHAVIOR OF CONCRETE STRUCTURES IN CHLORIDE-BASED INDUSTRIAL ENVIRONMENTS: CASE STUDIES

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Ioan Pepenar
Keyword(s):  
Corrosion Protection ◽  
Prestressed Concrete ◽  
Concrete Structures ◽  
Corrosion Damage ◽  
Structural Elements ◽  
Damage State ◽  
Intervention Measures ◽  
Industrial Environments ◽  
Resistance Stability

The paper presents two cases of reinforced and prestressed concrete structures damaged by corrosion in chloride-based industrial environments having as main aggressive agents: chlorine, hydrochloric acid and chlorides. To evaluate the corrosion damage of the concrete structures, in-situ and laboratory tests using specific investigation techniques were performed. Investigation of the damage state of structures revealed that many of the examined structural elements showed severe damage due to corrosion. This damage was in various stages of development and had a different influence on the resistance, stability and durability of structures. The corrosion-damage of the structural elements was favoured and accentuated by the absence of efficient intervention measures (repair, corrosion protection) for these elements. In order to ensure normal service conditions of the reinforced and prestressed concrete structures there were proposed intervention measures to remedy existing damages, regarding repair, strengthening, replacing, and corrosion protection of the damaged elements.

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