Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 9
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

The Dez dam was commissioned in 1963 and since sediments accumulated in the reservoir up to an elevation of approximately 15m below the intake of the power tunnel. One of the possible measures to improve operation of the reservoir is by heightening of the existing dam. This paper describes the conducted procedure for static and thermal calibration of this 203m dam in Iran based on micro geodesies measurements. Also the nonlinear response of existing dam is investigated under maximum credible earthquake ground motions considering joint behavior and mass concrete cracking and safety of dam is evaluated for possible heightening. For thermal calibration of provided numerical model, transient thermal analysis was conducted and results were compared with thermometers records installed in central block. In addition, for static calibration; thermal distribution within dam body, dam self weight, hydrostatic pressure and silt load applied on the 3D fi nite element model of dam-reservoir-foundation were considered. Results show that the distribution of stresses will be critical within dam for heightening case under seismic loads in MCL.

Go to article

Authors and Affiliations

M.A. Hariri-Ardebili
H. Mirzabozorg
Download PDF Download RIS Download Bibtex

Abstract

The effect of laser, as a heat source, on a one-dimensional finite body was studied in this paper. The Cattaneo-Vernotte non-Fourier heat conduction model was used for thermal analysis. The thermal conductivity was assumed temperature-dependent which resulted in a non-linear equation. The obtained equations were solved using the approximate-analytical Adomian Decomposition Method (ADM). It was concluded that the non-linear analysis is important in non-Fourier heat conduction problems. Significant differences were observed between the Fourier and non-Fourier solutions which stresses the importance of non-Fourier solutions in the similar problems.

Go to article

Authors and Affiliations

Mohammad Javad Noroozi
Seyfolah Saedodin
Davood Domir Ganji
Download PDF Download RIS Download Bibtex

Abstract

In recent years significant progress has been made in structural application of glass elements in building industry. However, the issues related to computer modelling of glass panes, as well as analytical procedures allowing for taking into account the bonding action of PVB foil are not widely known in the engineering environment. In this paper results of numerical study of laminated glass plates are presented. The scope of the research covers over 40 cases of panes. Narrow (characterized by edge length ���� >2) and square (��/�� = 1) panes made of two or three layer laminated glass have been taken into account. The paper deals mainly with point supported glass. However, selected results for linearly supported plates have been included as well for comparison. For each considered case an advanced computational model have been developed within the environment of Abaqus software. Pointwise supports have been modelled using methods of various complexity. The obtained results have been compared with the results of standard calculations using Wölfel–Bennison and Galuppi– Royer–Carfagni hypotheses. The analytical procedures proposed by CEN have been applied as well. As a result, recommendations for static calculations of laminated glass panes have been formulated. The computational procedure based on the hypothesis presented by L. Galuppi and G. Royer-Carfagni should be considered the most universal. The remaining methods may be applied only in limited scope. In order to estimate maximum principal stress in the support zone an advanced computer model has to be used. The support may be modelled in an exact or simplified manner.
Go to article

Authors and Affiliations

Piotr Woźniczka
1
ORCID: ORCID

  1. Cracow University of Technology, Faculty of Civil Engineering, Warszawska 24, 31-155 Cracow, Poland
Download PDF Download RIS Download Bibtex

Abstract

The article presents detailed guidelines for the nonlinear modelling of wood–CFRP beams with full cross-section using the Finite Element Method (FEM). Reviewing the literature has shown that behaviour of such composites is a current research topic, undertaken by many scientists. Complex numerical models made in the Simulia ABAQUS software are the basis for modelling recommendations. Properties of the materials consider the orthotropy and plasticity of wood and CFRP tapes, and the stiffness of adhesive layers with delamination. Results of laboratory experiments, got for a statistically significant number of specimens, confirm the model assumptions. This research paper provides a rich source of knowledge and experiences for scientists and engineers, who deal with mechanics of wood–CFRP composites. The uniqueness of the presentation lies in the detailed description of the complex numerical model. Specification comprises the steps necessary to do complete and successful calculations. The model is suitable for analysing the behaviour of wood–CFRP composites in different reinforcement configurations.
Go to article

Authors and Affiliations

Bartosz Kawecki
1
ORCID: ORCID

  1. Lublin University of Technology, Faculty of Civil Engineering and Architecture, ul. Nadbystrzycka 40, 20-618 Lublin, Poland
Download PDF Download RIS Download Bibtex

Abstract

Beam-to-column end-plate joints can be classified as rigid (fully restrained), semi-rigid (partiallyrestrained) or pinned, depending on their type, configuration and the connector arrangement. Fullyrestrained joints are needed for rigid frames in which there is assumed that the frame joints havesufficient rigidity to maintain – under the service state – the angles between the intersecting mem-bers, ensuring the full moment transfer. In contrast in semi-continuous frames, partially restrainedjoints are characterized by relative rotations occurring between the intersecting members so thatthe bending moment can only be transferred partially. In recent years, the idea of using partiallyrestrained, unstiffened joints in building structures has gained momentum since this idea appearsto be more practical and economical. Semi-continuous frames can resist actions by the bendingmoment transfer in partially restrained joints, allowing in the same time for a certain degree ofrotation that enhances the overall ductile performance of these structures. One of the effective waysthat affects ductility of end-plate beam-to-column joints is to use thinner end-plates than those usednowadays in practical applications. In the current study, a certain class of steel-concrete compositejoints is examined in which the thickness of end-plates is to be equivalent to approximately 40-60% of the bolt diameter used in all the composite joints investigated in the considered joint class. Thispaper is an extension of the authors’ earlier investigation on numerical modelling of the behaviourof steel frame joints. The aim of current investigations is to develop as simple as possible andyet reliable three-dimensional (3D) FE model of the composite joint behaviour that is capable ofcapturing the important factors controlling the performance of steel-concrete end-plate joints inwhich the end-plate thickness is chosen to be lesser than that used nowadays in conventional jointdetailing. A 3D FE model constructed for composite joints of the considered joint class is reportedin this paper and numerical simulations using the ABAQUS computer code are validated againstexperimental investigations conducted at the Warsaw University of Technology. Comparison betwe-en the nonlinear FE analysis and full scale experimental results of the considered class of compositejoints is presented which conclusively allows for the accuracy assessment of the modelling tech-nique developed. Comparison between the FE results and test data shows a reasonable agreementbetween the numerical FE model developed and physical model of experimentally examined jointspecimens. Finally, practical conclusions for engineering applications are drawn.

Go to article

Authors and Affiliations

M.A. Giżejowski
W. Barcewicz
W. Salah
Download PDF Download RIS Download Bibtex

Abstract

State-of-the-art analyses for the rotordynamic assessment of pumps and specific requirements for the simulation tools are described. Examples are a horizontal multistage pump with two fluid film bearings in atmospheric pressure, a horizontal submerged multistage pump with many bearings, and a submerged vertical single-stage pump with water-lubricated bearings. The rotor of the horizontal pump on two bearings is statically overdetermined by the seals and the static bearing forces depend on the deflection in the seals and the bearings. The nonlinear force-displacement relation in the bearings is considered in this paper. The stability of pumps is assessed by Campbell diagrams considering linear seal and bearing properties. Cylindrical bearings can have a destabilizing effect in the case of low loads as in the examples of the submerged pumps. For the pump with many bearings, the influence of the bearing ambient pressure and the bearing specific load on the stability is analyzed. For the vertical pump, the limit cycle, i.e. the vibration level of stabilization, is determined with a nonlinear analysis. All examples have a practical background from engineering work, although they do not exactly correspond to real cases. Analyses were performed with the rotordynamic software MADYN 2000.
Go to article

Bibliography

  1.  D. Childs, Turbomachinery Rotordynamics, New York, Chichester, Brisbane, Toronto, Singapore: Wiley Inter Science Publication, 1993.
  2.  J. Glienicke, “Feder- und Dämpfungskonstanten von Gleitlagern für Turbomaschinen und deren Einfluss auf das Schwingungsverhalten eines einfachen Rotors,” Dissertation, Technische Hochschule Karlsruhe, 1966.
  3.  J. Lund and K. Thomsen, “A Calculation Method and Data for the Dynamic Coefficients of Oil Lubricated Journal Bearings,” in Topics in Fluid Film Bearing and Rotor Bearing System Design and Optimization. New York: ASME, 1978, pp. 1–28.
  4.  X. Cheng, “Einfluss einer Schmierfilmkavitation auf die dynamischen Eigenschaften von Quetschöldämpfern,” Fortschr.-Ber. VDI Reihe 1 no. 243, Düsseldorf, VDI-Verlag.
  5.  A. Fuchs, J. Schmied, and A. Kosenkov, “Hydrodynamic Bearings – State of the Art Calculations,” in Proceedings of the 11th Conference on Vibrations in Rotating Machines (SIRM), Magdeburg, Germany, 2015.
  6.  R. Nordmann and F.J. Dietzen, “Calculating Rotordynamic Coefficients of Seals by Finite-Difference Techniques,” ASME J. Tribol., vol. 109, pp. 388–394, July 1987.
  7.  J. Schmied, “Application of MADYN 2000 to rotor dynamic problems of industrial machinery,” in Proceedings of the 13th International Conference on Dynamics of Rotating Machines (SIRM), Copenhagen, Denmark, 2019.
  8.  American Petroleum Institute, “Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries – ANSI/API Standard 610,” Eleventh Edition, September 2010.
  9.  J. Schmied and A. Fuchs, “Nonlinear Analyses in Rotordynamic Engineering,” in Proceedings of the 10th International Conference on Rotor Dynamics – IFToMM, 2019, vol. 3, pp. 426‒442.
Go to article

Authors and Affiliations

Frédéric Gaulard
1
Joachim Schmied
1
Andreas Fuchs
1

  1. Delta JS AG, Technoparkstrasse 1, 8005 Zürich, Switzerland
Download PDF Download RIS Download Bibtex

Abstract

In the paper there the laboratory tests of interaction between thin-walled beams of the Z crosssection and the sandwich panels with PIR foam core are presented. The different numbers of connectors (0, 4, and 8) were used to connect the sandwich panels with the thin-walled beams. Furthermore, the parallel and perpendicular to the longitudinal axis of the thin-walled beam load arrangement was analysed. The research provides a qualitative and quantitative comparison of the mentioned experiments using the ultimate capacity, the deformation capacity, and the stiffness. In the second part of the paper, the numerical analysis of the thin-walled beam was also performed. The beam was modelled as a shell element and loaded in two ways, which corresponded to the loading scenario during laboratory tests (uniformly distributed and concentrated loads). The results of the numerical calculations of the beam without lateral stabilization were compared with the laboratory results of the beam stabilized by the sandwich panels.
Go to article

Authors and Affiliations

Katarzyna Ciesielczyk
1
ORCID: ORCID
Robert Studziński
1
ORCID: ORCID

  1. Poznan University of Technology, Faculty of Civil and Transport Engineering, ul. Piotrowo 3, 60-965 Poznan, Poland
Download PDF Download RIS Download Bibtex

Abstract

In recent years, the intensity of the loads caused by mining activity has increased in Poland. This exploitation is often carried out in urbanized areas, so their operation on structures is not only a social problem, but also a challenge for engineers. Many of the surface facilities safe use affects the failure-free operation of the mine. The paper presents the results of representative measurements of surface vibrations from mining areas in Poland and earthquakes and their comparison. Particular attention was paid to the values of PGA/PGV ratios and the most commonly used methods for dynamic calculation of the structure. The last part of the work presents an experimentally verified dynamical model of the selected RC skip tower. The forced vibrations of the model were analysed by taking representative earthquakes and mining origin tremors. Time history non-linear analysis and push over methods were used. The nonlinear concrete model was adopted in the analyses. The results show that pushover analysis is not able to capture the seismic demands imposed by far-field or near-fault ground motions, especially for short-period systems for which it can lead to significant errors in the estimation of the seismic demands. The results confirmed the qualitative results of the linear analysis. The carried out inventory of cracks to the skip tower also allowed their location in bearing elements of the skip tower. The results of non-linear numerical analyses allowed us to assess the safety of the structure.
Go to article

Authors and Affiliations

Filip Pachla
1
ORCID: ORCID
Tadeusz Tatara
1
ORCID: ORCID

  1. Cracow University of Technology, Faculty of Civil Engineering, ul. Warszawska 24, 31-155 Cracow, Poland
Download PDF Download RIS Download Bibtex

Abstract

In the research of long-time operating road bridge superstructures, it should note that when the internal forces in the beam elements reach specific values, the stiffness of the cross-section of these elements should decrease. Besides that, if there are damaged places in the beam-element of the road bridge superstructures, the element could not work normally, and the redistribution of internal forces between elements in the whole system would happen. This phenomenon was not taken into account in the initial design calculation. In practice, it shows that many road bridges are subjected to greater loads than the calculated loads in the design process, but they still normally operate. This article proposes the other limit state criteria in evaluating the load capacity reserve of road-bridge superstructures using nonlinear analysis based on nonlinear deformational models of modern construction codes. The proposed calculation procedure is established to explain the load capacity reserve of long-time operating road bridge superstructures in the case of the lack of experimental evaluation. From the obtained results, the suitable limit state criteria for road bridge superstructures are suggested, and the conclusions about the accuracy of the proposed approach of nonlinear structural analysis are recommended.
Go to article

Authors and Affiliations

Thuy Van Tran Thi
1
ORCID: ORCID
Quyen Vu Thi Bich
1
ORCID: ORCID

  1. Hanoi Architectural University, Faculty of Civil Engineering, Km.10 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam

This page uses 'cookies'. Learn more