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Opis: While the effects of axial compression on beams have long been known, the effect of tensile axial loads on one-sided transversely cracked beams is less known. The crack namely shifts the position of the resultant of the axial normal stresses deeper into the uncracked part of the cross-section, and the crack tends to open, causing a transverse displacement. Therefore, this paper focuses on empirical modeling of the considered phenomenon for slender prismatic beams in order to establish a suitable 1D computational model based on detailed 3D FE mesh results. This goal can be achieved through the already established simplified model, where the crack is represented by an internal hinge endowed with a rotational spring. Several analyses of various beams differing in geometry, crack locations, and boundary conditions were executed by implementing 3D FE meshes to establish the appropriate model’s bending governing differential equation. After that, the corresponding parameter definitions were calibrated from the database of 3D FE models. By redefining the model’s input parameters, a suitable solution is achieved, offering a good balance between the results’ accuracy and the required computational effort. The functionality of the newly obtained solutions was verified through some comparative case studies that supplement the derivations.
Ključne besede: transverse cracks, axial tensile forces, simplified model of crack, transverse displacements
Objavljeno v DKUM: 13.03.2025; Ogledov: 0; Prenosov: 2
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Opis: The aim of this paper is to analyse the quality assessment of single-pass corner steel welded joints. The testing revealed the most burdened welded joints, which were cut out of the workpiece and prepared for metallographic macroscopic and microscopic analysis. Thus, for all examinations of single-pass corner steel welded joints, the standard test procedures were used to determine the weldability and quality assessment of base materials and welded joints. Additionally, the effects of various welded defects of single-pass weld material on the bearing strength of corner welded joints will be analysed.
Ključne besede: welded joints, microstructure, cracks, undercut, main frame
Objavljeno v DKUM: 13.11.2023; Ogledov: 399; Prenosov: 46
Celotno besedilo (3,61 MB)
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Opis: Retaining walls are proposed in many projects, such as bridges, coastal structures, road constructions and wherever lateral support is required for the vertical surface of an excavation. The active lateral pressure coefficient of soil, Ka , is an important parameter for studying the static and dynamic behaviors of these retaining walls. Many studies have evaluated this coefficient in static situations, but in most previous dynamic studies, researchers have worked on the behavior of cohesionless backfill soil or made simplifying assumptions (e.g., pseudo-static status) for cohesive soils as backfill soil. In this study, the size of the active lateral earth pressure coefficient (Ka) was studied in a full dynamic situation (Kae). A retaining wall with cohesive backfill soil is evaluated using the finite-difference method (FDM) and the effects of important soil and loading properties are assessed. The model is based on Mohr-Coulomb failure criteria under seismic loading. The results show that the value of Kae at the top of the wall, where it is highly sensitive to any variation in the soil and loading properties, is greater than one due to the high pressure value induced by the horizontal dynamic acceleration and the presence of tension cracks.
Ključne besede: dynamic active lateral earth pressure coefficient (Kae), cohesive backfill soil, finite difference method (FDM), tension cracks, retaining wall, seismic loading
Objavljeno v DKUM: 18.06.2018; Ogledov: 1549; Prenosov: 122
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Opis: The effect of strength mismatch for welded joints performed with different geometries on the yielding constraint has been investigated in the context of single-edged fracture-toughness specimens subjected to bending SE(B) using the finite-element method. The crack was located in the centre of the weld. Two geometri cal parameters have been identified as being the most important: the crack-Iength ratio a/W and the sIenderness of the welded joint (W-a)/H. They were systematically varied as follows: a/W = 0.1; 0.2; 0.3; 0.4; 0.5 and W = 2H, 4H, 8H, 16H, 24H. Basic equations and plane-strain finite-element solutions for the overmatched SE(B) specimen with all configuration combinations are given. The results are in good agreement with those in literature. This paper aims to establish yield-Ioad solutions for the same weldment configurations, but with materials dissimilarity present within the weld. This situation is usually encountered during repair welding. For this purpose, a practical combination of filler materials, with the same portion of overmatched part with M = 1.19 and undermatched part with M = 0.86, has been selected. Plane-strain solutions for the heterogeneous weld with the cracklocated in the overmatched half were obtained. The influence of the yielding-constraint key parameters has al so been evaluated. Yield-Ioad results for the specimens performed with different weld widths have the greatest scattering for the a/W = 0.5. The transition from the overmatched to the undermatched solution with increasing H is evident. On the other hand, the behaviour of the specimen with a shallow crack is dictated by the overmatch region ahead of the crack tip and depends very little on the weld slenderness. An approximated 3-D area of the yield-Ioad solutions depending ona/W and (W-a)lH has been proposed. Furthermore, the stress triaxility parameter h has been calculated using 2-D and 3-D finite-element analysis, and given as a field in the spec imen to get an insight into yielding-constraint regions. It was found that the 3-D yield-Ioad solutions are very close to the plane-strain solutions. Also, the effect of a/W on the yielding constraint is more significant than the effect of Mand (W-a)/H.
Ključne besede: welded structures, welded joints, fracture mechanics, cracks, SE(B) specimens, yielding load, yielding constraint parameters
Objavljeno v DKUM: 06.04.2017; Ogledov: 1488; Prenosov: 133
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Opis: The paper describes the reasons for the derivation of a new definition of a rotational spring that can be utilised in the simplified computational model for the computation of transverse displacements of cracked beam structures dueto transverse load. This definition plays an extremely important role in the inverse identification of cracks.
Ključne besede: linear springs, rotational spring, displacement analysis, transverse displacements, cracked beam structures, transverse load, inverse problems, transverse displacements, inverse identification of cracks
Objavljeno v DKUM: 01.06.2012; Ogledov: 2244; Prenosov: 100
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