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Limam, Marouene
Publications (8 of 8) Show all publications
Heistermann, C., Heistermann, T., Limam, M. & Veljkovic, M. (2012). Finite element analysis of a single lap joint (ed.). In: (Ed.), Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings. Paper presented at Nordic Steel Construction Conference : 05/09/2012 - 07/09/2012 (pp. 673-682). Oslo: Norwegian Steel Association
Open this publication in new window or tab >>Finite element analysis of a single lap joint
2012 (English)In: Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings, Oslo: Norwegian Steel Association , 2012, p. 673-682Conference paper, Published paper (Refereed)
Abstract [en]

A single shear lap joint of steel grade S355 is modelled with finite elements to investigate the influence of externally applied tensile loading on the loss of pretension in the engaged bolts. Additionally, a parameter study is performed to understand the effect of various steel grades on the loss of pretension. It is found that the slip resistance of the specimen depends on the steel grade of the clamped plates. Besides, the final resistance of the single shear lap joint has been found to increase after a slip of 0,15 mm has occurred due to a secondary bending moment. However, the final resistance of the specimen has been found to depend on the size of assembling tolerances; the bigger the distance between the clamped plates, the lower the resistance.

Place, publisher, year, edition, pages
Oslo: Norwegian Steel Association, 2012
National Category
Building Technologies
Research subject
Steel Structures; Centre - Centre for High Performance Steel (CHS)
Identifiers
urn:nbn:se:ltu:diva-31856 (URN)62975fba-e835-4908-9131-60fd87333747 (Local ID)978-82-91466-12-5 (ISBN)62975fba-e835-4908-9131-60fd87333747 (Archive number)62975fba-e835-4908-9131-60fd87333747 (OAI)
Conference
Nordic Steel Construction Conference : 05/09/2012 - 07/09/2012
Note

Godkänd; 2012; 20120920 (chrott)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-03-29Bibliographically approved
Limam, M., Heistermann, C. & Veljkovic, M. (2012). Finite element analysis of a single shear lap joint connection (ed.). In: (Ed.), Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings. Paper presented at Nordic Steel Construction Conference : 05/09/2012 - 07/09/2012. Oslo: Norwegian Steel Association
Open this publication in new window or tab >>Finite element analysis of a single shear lap joint connection
2012 (English)In: Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings, Oslo: Norwegian Steel Association , 2012Conference paper, Published paper (Refereed)
Abstract [en]

In steel tubular towers flange connections are used to assemble two segments of the tower. As an alternative for the economical and technological barriers, a new type of friction connection is investigated.This connection consists of the upper tower segment, where normal clearance holes are made and where bolts are preinstalled and the lower tower segment where open slotted holes are prepared.This paper describes a method based on a three-dimensional finite element model of a single shear lap joint connection. A finite element (FE) model is developed using the non-linear code ABAQUS and a number of FE simulations are made by varying the most significant parameters which can affect the accuracy and efficiency of the model; boundary conditions, mesh density, fabrication tolerances etc.. The ability of the models to give a satisfactory representation of the assembling connection in a tower for wind turbines is evaluated. Secondary bending, which occurs because of geometric eccentricities when the element is loaded in tension, is studied by simplified analytical model and by ABAQUS.Results of FEA and resistance according to European codes, series EN1993-1-8 are considered.

Place, publisher, year, edition, pages
Oslo: Norwegian Steel Association, 2012
Keywords
Finite Element Model, ABAQUS, Gap, High Strength Friction Grip Connection, Tubular Steel Tower, Secondary Bending., Engineering mechanics - Construction engineering, Teknisk mekanik - Konstruktionsteknik
National Category
Building Technologies
Research subject
Steel Structures; Centre - Centre for High Performance Steel (CHS)
Identifiers
urn:nbn:se:ltu:diva-35892 (URN)a9e7d46d-f409-4051-a6a8-3b84a1a3f713 (Local ID)978-82-91466-12-5 (ISBN)a9e7d46d-f409-4051-a6a8-3b84a1a3f713 (Archive number)a9e7d46d-f409-4051-a6a8-3b84a1a3f713 (OAI)
Conference
Nordic Steel Construction Conference : 05/09/2012 - 07/09/2012
Note

Godkänd; 2012; 20121101 (andbra)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-03-29Bibliographically approved
Veljkovic, M., Heistermann, C., Husson, W., Limam, M., Feldmann, M., Naumes, J., . . . Kinnunen, H. (2012). High-strength tower in steel for wind turbines (Histwin): Final report (ed.). Paper presented at . Brussells: European Commission Joint Research Centre
Open this publication in new window or tab >>High-strength tower in steel for wind turbines (Histwin): Final report
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2012 (English)Report (Refereed)
Abstract [en]

Innovative solutions for assembling joints of a tubular tower for wind turbines were studied and the project provides a background for design. This solution is simpler to produce and 80 % less expensive than traditional flange connection. Our feasibility study at the production plant indicates that the towers would be easy to assemble in situ. In addition to the direct cost savings due to the technical simplicity of the solution, the higher fatigue endurance than that of the flange connection is experimentally established. Further reduction of costs due to optimal use of higher-strength steel grades, especially in the bottom segments of the tower where the stiffening of the door opening is costly, is shown in the report. The total reduction of the costs for tower is estimated at about 10–15 % compared to the traditional tower. The project objectives are achieved in following sequences. • Experimental activities of the friction connection: small-scale tests to establish resistance of the friction connection for a variety of faying surfaces and bolt types, accompanying testing to ensure realistic input data for FEA, long-term testing to establish loss of pretension forces during the lifetime and fatigue tests.• Bending test of the friction and flange connection in a down-scaled tower. • Feasibility of production of the tower segments in the laboratory and at the production plant. • Monitoring of the existing tower to access a stress variation during the operation. • FEA analysis of experimental results and a complete case study of the monitored tower. Numerical examples for design of the friction connection are given for the sake of illustration and to encourage use of the new connection

Place, publisher, year, edition, pages
Brussells: European Commission Joint Research Centre, 2012. p. 168
Series
EUR Scientific and Technical Research series
National Category
Building Technologies
Research subject
Steel Structures; Centre - Centre for High Performance Steel (CHS)
Identifiers
urn:nbn:se:ltu:diva-24782 (URN)10.2777/39656 (DOI)c7f1ba62-da45-495a-9a8f-0c4987713b77 (Local ID)978-92-79-22434-8 (ISBN)c7f1ba62-da45-495a-9a8f-0c4987713b77 (Archive number)c7f1ba62-da45-495a-9a8f-0c4987713b77 (OAI)
Note

Godkänd; 2012; 20120427 (milan)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-03-29Bibliographically approved
Limam, M. & Veljkovic, M. (2011). Analysis of a column friction connection using high strength bolts (ed.). Paper presented at International Conference on Advances in Mechanical Engineering and Mechanics : 18/12/2010 - 20/12/2010. Paper presented at International Conference on Advances in Mechanical Engineering and Mechanics : 18/12/2010 - 20/12/2010.
Open this publication in new window or tab >>Analysis of a column friction connection using high strength bolts
2011 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

Use of high-strength friction connections is investigated in the HISTWIN project (2006-2009), High-Strength Steel Towerfor Wind Turbine where a new type of assembling connection between two tower segments is used. The connection is amore competitive solution compared to the traditional flange connection. The new type of connection is a lap frictionconnection. Inner tower segment has long opened slotted holes and the other tower segment has high-strength boltspreinstalled in the no and the cover plate have holes with normal clearance.The contact surface modelling of the friction connection is presented here by using ABAQUS FE software. A connection ofa rectangular column is considered. The main principles of the connection modelling are the same as those investigated intubular towers. This column is chosen for the sake of simplicity but still having possibility of addressing main issues of finiteelement modelling. Various levels of pretension forces and its influence on the bolt behaviour and loss of the pre-tensionforce in the bolt are considered. Comparison is made between a lap connection with one shear plane and a butt connectionhaving two shear planes. The various geometries of the connection are investigated on a rectangular column in tension.A short parametric study is made to evaluate influence of number of bolts and the pretension force on the column failuremode. Resistance according European codes, EN1993-1-8, for the preloaded bolts is compared with the FE

Keywords
Steel Structures, Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-40748 (URN)ffd5491a-2301-41ce-9add-7ccf2d78d23e (Local ID)ffd5491a-2301-41ce-9add-7ccf2d78d23e (Archive number)ffd5491a-2301-41ce-9add-7ccf2d78d23e (OAI)
Conference
International Conference on Advances in Mechanical Engineering and Mechanics : 18/12/2010 - 20/12/2010
Note
Godkänd; 2010; 20110628 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-06-08Bibliographically approved
Limam, M. (2011). FE modelling of friction connections in tubular tower for wind turbines (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>FE modelling of friction connections in tubular tower for wind turbines
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

During the last few decades the demand for renewable energy has led to a myriad of innovative solutions. The present assembling solution between two segments of a tubular tower is accomplished by conventional ring flange connection. This connection suffers from economical and technological barriers. One possible improvement could be achieved by implementing friction connections. Performance of this connection exposed to static loading is considered in this thesis. FEM is used as the main tool to improve understanding of the friction connection behaviour for application in towers for wind turbines. This new solution consists of the upper tower segment, where normal clearance holes are made and where bolts can be pre-installed, and the lower tower segment where opened slotted holes are made. It is easier to produce and 80% less expensive than traditional flange connection which leads to a total reduction of 10% to 15% of the tower costs.The influence of the level of assembling tolerances and the loss of pretension force in the bolts has been thoroughly investigated by a large number of FE models in the search for a model that is the most successful match with regards to its comparison with test data. Experiments are performed in an international project financed by RFCS, HISTWIN.The starting point is a small scale friction connection, best described as a single shear lap joint. This specimen represents a strip of the friction connection of a tubular tower. The ability of the FE models to capture three-dimensional contact problems, with realistic modelling of the assembling process and effects of the secondary bending during the loading are investigated. Resistance according to European codes, EN 1993-1-8, for the preloaded bolts is compared with the FE solutions.The second type of specimen is a down-scaled bending test of the beam. The test is used to check the performance of the connection and to calibrate the FE model. A very realistic FE model is created and compared with results from experiments. Failure modes and the respective ultimate resistances are predicted by FEA. The same model is used to investigate the influence of the gap between tubular segments and the influence of residual stresses generated in the segment which contains slotted holes on the tower resistance in bending, as well as in compression and tension.

Abstract [sv]

Efterfrågan på förnyelsebar energi har under de senaste decennierna drivit fram ett stort antal innovativa lösningar. Idag är flänsar den vanligaste lösningen vid skarvar i rörformade vindkraftstorn. Det är en lösning som har både ekonomiska och tekniska brister. Friktionskoppling kunde vara en möjlig förbättring. I detta arbete studeras hur en sådan koppling skulle fungera under statisk last. FEM används som det viktigaste verktyget för att skapa förståelse för hur en sådan friktionskoppling fungerar i ett rörformat vindkrafttorn. Den föreslagna friktionskopplingen består av en övre del som har hål med bultar i längs nedre kanten, och en undre del som har skåror. Det är en konstruktion som är enklare att tillverka och som kostar 80% mindre än en traditionell flänskoppling. Det ger en total besparing för ett torn på mellan 10 och 15%. Betydelsen av det extra spelrum som tillåts för att förenkla monteringen och vad förlusten av förspänning i bultarna betyder har studerats i ett antal FEMmodeller för att hitta en modell som ger så bra överensstämmelse som möjligt med mätdata från försök gjorda i projektet HISTWIN som finansierats av RFCS. Första försöket är en liten del av hela friktionskopplingen, enklast beskriven som ett skjuvförband. FEM-modellens förmåga att beskriva den tredimensionella kontakten, en realistisk sammanfogning samt de olika böjfenomen som uppträder undersöks. De förspända bultarnas bärförmåga enligt Europakoden EN 1993-1-8 jämförs med FEM-lösningen. Den andra modellen är ett nedskalat böjtest på en balk. Modellen används för att undersöka hur friktionskopplingen fungerar och för att kalibrera FEMmodellen. En mycket realistisk FEM-modell skapas och beräkningsresultaten jämförs med gjorda försök. FEM-beräkningen ger både brottmod och brottlast. Samma modell används också för att studera betydelsen av glappet mellan de olika delarna i tornet samt betydelsen av spänningstillståndet i delen med skårorna när den belastas i både tryck och drag.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2011. p. 154
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Keywords
Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-26304 (URN)d9a85385-3152-4273-a992-96d325841b55 (Local ID)978-91-7439-344-6 (ISBN)d9a85385-3152-4273-a992-96d325841b55 (Archive number)d9a85385-3152-4273-a992-96d325841b55 (OAI)
Note

Godkänd; 2011; 20111109 (marlim); LICENTIATSEMINARIUM Ämnesområde: Stålbyggnad/Steel Structures Examinator: Professor Milan Veljkovic, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Assistant Professor Jean-Francois Demonceau, Dép. Architecture, Géologie, Environnement et Construction, Université de Liège, Belgium Tid: Torsdag den 8 december 2011 kl 13.00 Plats: F1031, Luleå tekniska universitet

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-24Bibliographically approved
Limam, M., Veljkovic, M., Bernspång, L., Rebelo, C. & silva, L. S. (2011). Modeling three dimensional friction connection for wind towers using finite element methods (ed.). In: (Ed.), (Ed.), Proceedings of the 6th European Conference on Steel and Composite Structures: Eurosteel 2011, August 31 - September 2, 2011, Budapest, Hungary. Paper presented at European Conference on Steel and Composite Structures : 31/08/2011 - 02/09/2011. Budapest: European Convention for Constructional Steelwork, ECCS
Open this publication in new window or tab >>Modeling three dimensional friction connection for wind towers using finite element methods
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2011 (English)In: Proceedings of the 6th European Conference on Steel and Composite Structures: Eurosteel 2011, August 31 - September 2, 2011, Budapest, Hungary, Budapest: European Convention for Constructional Steelwork, ECCS , 2011Conference paper, Published paper (Refereed)
Abstract [en]

The tubular steel towers supporting wind turbines account for about 15 to 20% of the total installation costs and their optimization may lead to substantial savings with regard to costs and use of material. An innovative solution for assembling joints of a tubular tower for wind turbines has been studied in an European research project called HISTWIN (High-Strength Steel Tower for Wind Turbine). This solution is simpler to produce and 80% less expensive than the traditional flange connection.The paper deals with connections used to assemble sections of tubular steel towers supporting wind turbines. The starting point is a rather simple lap joint connection .This connection is chosen for the sake of simplicity but still having possibility of general conclusions. After that more realistic connection between two tower segments is presented, each section has about 3m high and 2 m in diameter and they are connected by 222 M30 high-strength bolts.Modeling such FE models, which consists of several parts in contact, requires knowledge in contact mechanics with friction, meshing techniques as well as stability and convergence algorithms.A short parametric study is made to evaluate influence of number of bolts and the pretension force on the tubular tower failure mode.Results of FEA and resistance according to European codes, series EN1993-1-8 is considered. Keywords: Finite Element Model, Gap, High Strength Friction Grip Connection, Tubular Steel Tower, contact.

Place, publisher, year, edition, pages
Budapest: European Convention for Constructional Steelwork, ECCS, 2011
Keywords
Steel Structures, Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Building Technologies Infrastructure Engineering
Research subject
Steel Structures; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-38617 (URN)d0f6878e-afbf-4522-a874-f97d5320b264 (Local ID)978-92-9147-103-4 (ISBN)d0f6878e-afbf-4522-a874-f97d5320b264 (Archive number)d0f6878e-afbf-4522-a874-f97d5320b264 (OAI)
Conference
European Conference on Steel and Composite Structures : 31/08/2011 - 02/09/2011
Note
Godkänd; 2011; 20110601 (marlim)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-06-08Bibliographically approved
Veljkovic, M., Limam, M., Heistermann, C., Rebelo, C. & Simoes da Silva, L. (2010). Feasibility study of friction connection in tubular towers for wind turbines (ed.). In: (Ed.), Steel structures: culture & sustainability 2010: international symposium, Istanbul, 21 - 23 September 2010. Paper presented at International Symposium Steel Structures : Culture & Sustainability 21/09/2010 - 23/09/2010. Istanbul: Turkish Constructional Steelwork Association
Open this publication in new window or tab >>Feasibility study of friction connection in tubular towers for wind turbines
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2010 (English)In: Steel structures: culture & sustainability 2010: international symposium, Istanbul, 21 - 23 September 2010, Istanbul: Turkish Constructional Steelwork Association , 2010Conference paper, Published paper (Refereed)
Abstract [en]

In steel tubular towers flange connections are used to assemble two segments of the tower. As an alternative for these fatigue-sensitive joints a new type of friction connection has been investigated both in laboratory and at a production plant where the feasibility study was performed. The specimen used in the feasibility test consists of two tower segments, each about 3m high and 2 m in diameter. The segments are connected by 222 M30 high-strength bolts. The production process and tolerances achieved are briefly explained. The assembling process is modeled using a realistic FEA model to predict the stress in the segments during pretensioning. A simplified FE analysis was performed to assess the influence of the compressive strength of the specimens. This paper presents results of a short parametric study on the influence of the gap between two tower segments exploring possibilities to use higher-strength steel in the towers. Keywords: Finite Element Model, Gap, High Strength Friction Grip Connection, Tubular Steel Tower, Wind Energy Converter

Place, publisher, year, edition, pages
Istanbul: Turkish Constructional Steelwork Association, 2010
Keywords
Steel Structures, Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Building Technologies
Research subject
Steel Structures; Centre - Centre for High Performance Steel (CHS)
Identifiers
urn:nbn:se:ltu:diva-32165 (URN)68fd2c94-c0ce-4f80-a044-97e5dc8db556 (Local ID)978-975-92461-2-9 (ISBN)68fd2c94-c0ce-4f80-a044-97e5dc8db556 (Archive number)68fd2c94-c0ce-4f80-a044-97e5dc8db556 (OAI)
Conference
International Symposium Steel Structures : Culture & Sustainability 21/09/2010 - 23/09/2010
Note

Godkänd; 2010; 20110628 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-03-29Bibliographically approved
Limam, M., Veljkovic, M., Pak, D. & Naumes, J. (2010). Towards better understanding of a friction connection in tubular towers for wind turbines (ed.). In: (Ed.), Brian Uy (Ed.), Proceedings of the 4th International Conference on Steel and Composite Structures: 21 - 23 July 2010, Sydney, Australia. Paper presented at International Conference on Steel and Composite Structures : 21/07/2010 - 23/07/2010 (pp. 507-512). Singapore: Research Publishing Services
Open this publication in new window or tab >>Towards better understanding of a friction connection in tubular towers for wind turbines
2010 (English)In: Proceedings of the 4th International Conference on Steel and Composite Structures: 21 - 23 July 2010, Sydney, Australia / [ed] Brian Uy, Singapore: Research Publishing Services, 2010, p. 507-512Conference paper, Published paper (Refereed)
Abstract [en]

The present assembling detail between two segments of the tubular tower segments used in to support wind turbines is accomplished by flange connection. This type of connection suffers from a rather low fatigue resistance class, in the range of 40 MPa. To remedy this drawback a new friction joint has been developed in the recently finished international RFCS research project HISTWIN (High-Strength Steel Tower for Wind Turbine). In order to study the behaviour of both type of joints, conventional ring-flange connections and friction connection, eight "Four point bending tests" of down-scaled tubular tower section were performed. The behaviour of tests using the friction connection is described in this paper. A short summary of the experimental and numerical work, performed at RWTH and LTU, respectively, is presented in this paper.

Place, publisher, year, edition, pages
Singapore: Research Publishing Services, 2010
Keywords
Steel Structures, Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Building Technologies
Research subject
Steel Structures
Identifiers
urn:nbn:se:ltu:diva-39510 (URN)10.3850/978-981-08-6218-3_SS-Th018 (DOI)e4bb73f1-c49b-4790-b447-b986548f3626 (Local ID)978-981-086218-3 (ISBN)e4bb73f1-c49b-4790-b447-b986548f3626 (Archive number)e4bb73f1-c49b-4790-b447-b986548f3626 (OAI)
Conference
International Conference on Steel and Composite Structures : 21/07/2010 - 23/07/2010
Note
Godkänd; 2010; 20110601 (marlim)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-06-08Bibliographically approved
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