• Structural Engineering and Mechanics
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• v.36 no.4
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• pp.401-419
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• 2010

This paper focuses on the development, verification and application of a three-dimensional nite element code for coupled thermal and structural analysis of roller compacted concrete arch dams. The Ostour Arch dam located on Ghezel-Ozan River, Iran, which was originally designed as conventional concrete arch dam, has been taken for the purpose of verication of the nite element code. In this project, RCC technology has been ascertained as an alternative method to reduce the cost of the project and make it competitive. The thermal analysis has been carried out taking into account the simulation of the sequence of construction, environmental temperature changes, and the wind speed. In addition, the variation of elastic modulus with time has been considered in this investigation using Concard's model. An attempt was made to compare the stresses developed in the dam body five years after the completion of the dam with those of end of the construction. It was seen that there is an increase in the tensile stresses after five years over stresses obtained immediately at the end of construction by 61.3%.

• International journal of steel structures
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• v.18 no.5
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• pp.1754-1760
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• 2018

The present article showcases a temperature dependent cohesive zone model (CZM)-based fi nite element simulation of drop weight tear test (DWTT), to analyse fracture behavior of pipeline steel (PS) at different temperatures. By co-relating the key CZM parameters with known mechanical properties of PS at varying temperature, a temperature dependent CZM for PS is proposed. A modified form of Johnson and Cook model has been used for the true stress-strain behavior of PS. The numerical model, using Abaqus/CAE 6.13, has been validated by comparing the predicted results with load-displacement curves obtained from test data. During steady-state crack propagation, toughness parameters (such as CTOA and CTOD) were found to remain fairly constant at a given temperature. These toughness parameters, however, show an exponential increase with increase in temperature. The present paper offers a plausible approach to numerically analyze fracture behavior of PS at varying temperature using a temperature dependent CZM.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.49-49
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• 2010

The most commonly used numerical modelling techniques for acoustics and vibration are based on element based techniques, such as the nite element and boundary element method. Due to the huge computational eorts involved, the use of these deterministic techniques is practically restricted to low-frequency applications. For high-frequency modelling, probabilistic techniques such as SEA are well established. However, there is still a wide mid-frequency range, for which no adequate and mature prediction techniques are available. In this frequency range, the computational eorts of conventional element based techniques become prohibitively large, while the basic assumptions of the probabilistic techniques are not yet valid. In recent years, a vast amount of research has been initiated in a quest for an adequate solution for the current midfrequency problem. One family of research methods focuses on novel deterministic approaches with an enhanced convergence rate and computational eciency compared to the conventional element based methods in order to shift the practical frequency limitation towards the mid-frequency range. Amongst those techniques, a wave based prediction technique using an indirect Tretz approach is being developed at the K.U.Leuven - Noise and Vibration Research group. This paper starts with an outline of the major features of the mid-frequency modelling challenge and provides a short overview of the current research activities in response to this challenge. Next, the basic concepts of the wave based technique and its hybrid coupling with nite element schemes are described. Various validations on two- and threedimensional acoustic, elastic, poro-elastic and vibro-acoustic examples are given to illustrate the potential of the method and its benecial performance as compared to conventional element based methods. A closing part shares some views on the open issues and future research directions.

• Wind and Structures
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• v.39 no.4
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• pp.259-269
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• 2024

The current research on the wind resistance of standing seam metal roofs primarily focuses on the failure modes of the entire roof panel and the contact areas between the seams and supports, with little consideration given to the synergy between the roof seam reinforcements, the web, and the supports. As a result, the failure mechanisms of roof systems cannot be accurately represented. This paper, based on wind uplift tests and ABAQUS simulation modeling, provides a detailed analysis of the wind resistance and failure mechanisms of reinforced standing seam metal roof systems. The study reveals that the deformation and failure of the roof system under wind load can be divided into three stages: elastic deformation, plastic deformation, and failure. In the elastic deformation stage, the areas with higher stress are mainly distributed in the mid-span of the roof panels and along the ribs, where the roof stress remains below the material's yield strength, and the displacement at the roof panel seams is minimal. During the plastic deformation stage, as the load increases, significant vertical deformations appear in the roof panels, the lateral displacement at the seams gradually increases, and the stress growth is pronounced. Without reinforcement, the roof panel withstands a maximum wind pressure of 3.2 kPa, with a central vertical displacement of 109 mm, while the ultimate lateral displacement at the seams reaches 2.3 mm, resulting in unseating failure, marking the structural failure. With reinforcement, the roof panel can withstand a maximum wind pressure of 4.3 kPa, corresponding to a central vertical displacement of 122 mm. The growth of lateral displacement at the seams slows down, and the reinforcement significantly suppresses seam displacement. As the load continues to increase, the reinforcements and the web work synergistically, exhibiting reciprocating counterclockwise and clockwise rotations, with the maximum lateral displacement at the seams increasing to 3.05 mm. Ultimately, unseating occurs at the roof panel seams or tearing at the web. Therefore, the reinforcement system significantly enhances the wind resistance of the roof system, providing theoretical guidance for wind-resistant design in roofing engineering.