presentation av examensarbeten - chalmers · corrosion were examined. no strong correlation between...

AVDELNINGEN FÖR KONSTRUKTIONSTEKNIKARKITEKTUR OCH SAMHÄLLSBYGGNADSTEKNIK

Välkomna till årets gemensamma redovisning av examensarbeten

Avdelningen för konstruktionsteknik på Chalmers utexaminerar ett relativt stort antal examensarbeten varje år. Som ett led i vår strävan för ett starkare samarbete till industrin och en effektivare kunskaps- och erfarenhetsöver-föring anordnar vi tillsammans med Konstruktionscentrum på Chalmers en workshop där examens-arbeten genomförda under våren 2019 presenteras. Vi hoppas därigenom att öka möjligheten för branschföreträdare att närvara vid redovisningarna för att ta del av presentationerna och bidra till diskussionen.

Vi har förnyat processen med att initiera examensarbeten för att ytterligare stärka samarbetet mellan högskola och näringslivet. Målsättningen är att alla examensarbeten skall vara initierade i samverkan mellan Chalmers och olika aktörer i näringslivet, och ha en stark anknytning till de forskningsprojekt som bedrivs av forskargrupperna på avdelningen.

Mycket välkomna!

Chalmers kartor, http://maps.chalmers.se/, sök efter SB-H3/SB-H4, SB-H5, SB-H6 hörsal

Presentation av examensarbeten Tid: Tisdag 11 Juni, 8.00 - 14.00 Plats: SB-huset, Sven Hultins gata 6

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Master’s thesis seminars - June, 11th 2019 Session 1, 08:00-09:00 Room SB-H3 Room SB-H4

Crack comparison in radon proof concrete slab

Abstract: Health problems may occur if humans are exposed to radioactive gas e.g. radon. Therefore, concrete foundations have to be designed in a way to prevent radon to penetrate to the environment inside. The purpose of this thesis was to investigate different compositions of a concrete slab, to find the most efficient solution when designing with respect to crack widths. An analytical analysis was performed where various compositions of concrete and reinforcement layouts were investigated. When increasing the concrete strength or the dimension of the reinforcing bar, a larger reinforcement amount is required to meet the crack limitations. However, the crack width is reduced with increased concrete strength if the same reinforcement diameter can be used.

Student Isabelle Persson

Opponents Malin Andersson & Emma Pettersson

Supervisors

Ingemar Löfgren (Chalmers), Oscar Stanser (Integra)

Examiner

Ingemar Löfgren

No Presentation

Welcome to the master’s thesis seminar day!

Room SB-H5 Room SB-H6

Stability and Dynamic Properties of Tall Timber Structures

Abstract: The dynamic response i.e. acceleration in tall timber structures is essential in the design and dependent of mass, stiffness and damping. The aim is to find a structural concept that makes a taller structure than the usual today feasible via a parametric study of mass and stiffness. With a combination of numerical and analytical methods, accelerations are calculated and evaluated against human comfort-criteria. An outrigger bracing system has been found the most efficient. Results show that a pure timber building of 15-storeys can be achieved and 20-storeys when adding concrete floors at the top. Students

Joakim Larsson & Ahmad Alalwan

Opponents

Ole Netek, Felix Dubrefjord

Supervisors

Thomas Hallgren (COWI), Robert Jockwer

Examiner

Mohammad Al-Emrani

Effect of Cracks and Fibres on Reinforcement Corrosion

Abstract: Reinforcement in concrete edge beams on road bridges often corrode due to cracks and de-icing salts. In this study, the corrosion pattern and corrosion level of rebars extracted from plain concrete and fibre reinforced concrete beams subjected to 3-years corrosion were examined.

No strong correlation between transverse crack width and corrosion level was found. However, the relative frequency of higher corrosion level increased with target transverse crack width. The results were used for a suggestion of a design of an edge beam, where fibres are included in the concrete mixture.

Students

Rebecca Henriksson & Marie Åhs

Opponents

Viktoria Bodén & Stina Lundin

Supervisors

Björn Thomasson (Sweco), Magnus Bäckström (Sweco) & Teresa E Chen (Chalmers)

Examiner Karin Lundgren

Master’s thesis seminars - June, 11th 2019 Session 2, 09:00-10:00


Structural Behaviour of Steel Fibre Reinforced Concrete Floors

Abstract: Steel fibre reinforced concrete (SFRC) as a complex structural material has several advantages in comparison to ordinary concrete that makes it an attractive alternative for industrial floors if cracking can be controlled. A significant discrepancy has been recognized between experimental results and proposed design methods. This difference could spring from factors such as arching action phenomenon in pile supported slabs, which normally is neglected in design. Hence, numerical models using 3D non-linear FEA have been implemented to investigate the structural behaviour of SFRC in mentioned case. The evaluated capacities exhibited a significant difference between numerical models and proposed design methods which is further discussed in the thesis. Students Ahmad Arafat, Amir Khorsandi

Opponents Mohammad Raihan Abir, Sarah Gratwick

Supervisors Ingemar Löfgren (Thomas Betong), David Fall (NCC)

Examiner Ingemar Löfgren

Assessment and Optimization of Fibre Reinforced Glulam Beams

Abstract: Embedding CFRP in glulam beams can increase the stiffness and hence reduce the section height in flexural structural elements. CFRP strengthening can be used for design and construction of pedestrian timber bridges, offering a sustainable solution. Various reinforcement configurations were evaluated, based on price and production factors. A parametric study considering the span length, amount and E-modulus of CFRP, and pre-camber was performed. The results showed that a height reduction of at least 25% was possible with a small amount of reinforcement. In conclusion, the concept proved itself to be viable and increases the areas of application for timber structures.

Students

Adam Lennell & Christoffer Jonsson

Opponents

Jonathan Söderqvist & Lars Scheidegger

Supervisors

Magnus Bäckström (Sweco) & Georgi Nedev (Sweco)

Examiner

Reza Haghani Dogaheh


Impact of connections on the system behaviour and reliability of timber structures

Abstract: For CLT structures, stiffness and strength of connections is of high importance for the global structural behaviour. The aim is to develop guidance for a more reliable design of CLT systems, by accounting for the variability of the properties of applied connections.

The effects of the variation of properties decrease with the number of elements in the structure, provided that sufficient ductility of the connections is guaranteed. For insufficient load-redistribution between the elements however, the variation of connections can lead to unpredictable global failure, which should be considered in Eurocode.

Students

Michaela Henriksson & Anna Rosenberg

Opponents

Petter Öhman & Simon Nilsson

Supervisor

Robert Jockwer (Chalmers)

Examiner

Mohammad Al-Emrani

Loop connections in heavily reinforced concrete frame corners

Abstract: The concept of loop connections is often preferred by contractors, over a more conventional detailing, requested mainly from a working environment safety aspect. However, this may result in higher radial stresses and cracking within the corner. Today this solution is used within the field of building construction and the objective of this study is to evaluate whether this is applicable also in structures with higher reinforcement ratio, such as tunnels and bridges. Finite element analyses were verified against experimental data and available regulations; no significant reduction in capacity was found.

Students Jenny Berglund & Malin Ivarsson Holmström

Opponents Joakim Larsson & Ahmad Alalwan

Supervisor Christoffer Svedholm (ELU)

Examiner Karin Lundgren



Reinforced concrete beams subjected to drop weight impact - Experimental study of the influence of reinforcement properties on the structural response

Abstract: There is a need to increase the understanding of the structural response of concrete structures subjected to impact loading. Therefore, Structural Engineering at Chalmers is conducting experiments using a drop weight hitting a concrete beam. The main objective of this thesis is to support this research by evaluating the influence of damaged reinforcement on the plastic deformation capacity.

The evaluation showed that using damaged reinforcement resulted in a smaller plastic deformation, a slight increase in maximum load capacity and a decrease in residual capacity after the impact.

Students

Malin Andersson & Emma Pettersson

Opponent

Isabelle Persson

Supervisor

Morgan Johansson (Norconsult)

Examiner

Joosef Leppänen

An Innovative Application of FRP Composites in Bridge Strengthening and Repair

Abstract:

With bridge loads expected to increase, the SUREBridge group proposed a method to increase the load-bearing capacity of an existing concrete bridge superstructure through the application of carbon and glass FRP. This thesis aimed to replicate the experimental results of this proposal through FE modelling in ABAQUS and DIANA, and determine the economic benefits of the retrofit through a comparative life cycle cost analysis. It was concluded that the ultimate flexural capacity could be increased by 160%, and the design is an economical alternative to typical refurbishment solutions.

Students

Sarah Gratwick & Mohammad Raihan Abir

Opponents

Ahmad Arafat & Amir Khorsandi

Supervisors

Johan Söderman (ÅF), Jincheng Yang

Examiner

Reza Haghani Dogaheh


Finite element analysis of T-stub components in tension – A study of model parameters and their influence on time and accuracy

Abstract: When assessing bolted steel joints, finite element analysis can be performed to achieve the ultimate capacity. For an insufficient representation of reality, the results obtained by finite element solution may be inaccurate.

A study of FE-parameters with respect to ultimate load and time efficiency of FE-analysis, followed by an investigation of geometric parameters affecting the failure mode in a T-stub, are performed.

Through this, an insight for further modelling is provided. While different FE-parameters have a significant influence on time, the accuracy of the predicted ultimate load is barely affected.

Students

Felix Dubrefjord & Ole Netek

Opponents

Malin Ivarsson Holmström & Jenny Berglund

Supervisors

David Wesley (ÅF Byggnadskonstruktion) & Mohammad Al-Emrani

Examiner

Mohammad Al-Emrani

A study on 2D-graphic statics methods Implementing a graphical and algebraic method of 2D-graphic statics in a parametric

environment for conceptual design

Abstract: Interest in computational structural design with complex geometry is increasing. In addition, there exist a lack of understanding between the structural form and force relation, potentially leading to inefficient structures and material waste. The purpose of the thesis was to implement and compare different 2D-graphic statics approaches, which can be used as form-finding methods to create an informed design process.

Graphic statics strengthen visual impact and communication between disciplines that may support a creative design exploration. Furthermore, the graphical nature allows the engineer to reflect outside a numerical mindset.

Students Gabriel Borg & Albin Johnsson

Opponent Johan Örnborg

Supervisors Isak Berneheim (Sweco), Carl Hoff (Sweco)

Examiner Mats Ander



Evaluation of crack width predictions in Eurocode 2 using Digital Image Correlation

Abstract:

A correct prediction of crack widths in reinforced concrete elements in SLS is important in terms of keeping the proper functionality of the structure. The purpose of this thesis was to investigate the accuracy of crack widths prediction using Eurocode 2 through experiments and Digital Image Correlation (DIC) measurements. A comparison of results between three-point bending tests of reinforced concrete beams and Eurocode 2 crack widths calculations was performed. The achieved results from DIC and EC 2 calculations seem to accurately correspond with each other. However, it can be noted that in some cases EC 2 approach underestimates the crack widths in the beams.

Student

Przemyslaw Smereka

Opponent

Julius Kandt

Supervisors

Mario Plos, Morgan Johansson (Norconsult)

Examiner

Mario Plos

Designing multiple span pedestrian SLT-bridges - A parameter study considering dynamic effects

Abstract:

In light weight constructions the dynamic response will be more crucial in design compared to heaver material. Eurocode does not contain a adequate design process for dynamic effects, making it very conservative. The purpose of this thesis was to develop the dynamic design process for SLT bridges by finding crucial, influencing parameters that affect the acceleration. A parameterized model to use for testing has been created that performs frequency and acceleration analysis. The results show correlation between multiple parameters. Recommendations for an optimized dynamic design are given.

Students

Linnea Amundsson and Sabiha Fasth

Opponent

Antonia Ramböl Bryntesson

Supervisors

Staffan Lindén (Cowi), Robert Jockwer (Chalmers)

Examiner

Robert Kliger


Stability design of steel structures - Comparison of approaches presented in Eurocode 3 on how to consider

imperfections and second-order effects

Abstract: Today, there are no detailed guidelines in Eurocode 3 on how the stability design approaches should be implemented and how they differ in result. This leaves many questions regarding interpretation for the designer and creates need for increased understanding. Therefore, the purpose of this thesis project was to understand, explore and compare the approaches in dealing with imperfections and second-order effects.

Studies showed that the approaches for frame design produce different results. For stocky frames the differences in utilization ratios were around 10 %, while for very slender frames the differences were up to 30 %.

Students

Viktoria Bodén & Stina Lundin

Opponents

Rebecca Henriksson & Marie Åhs

Supervisors

Svante Severinsson (ELU), Christoffer Svedholm (ELU)

Examiner

Mohammad Al-Emrani

Flexible formwork for concrete shells - Development of a computational framework for design, optimization and

construction of interacting cable and membrane structures

Abstract: One of the complications with shell construction in any material today is the complexity of the building process, especially to construct and build the formwork and/or guide work. This often leads to unsatisfactory building time and increased cost. In a quest to rationalize this process, a concept based on flexible formwork is explored.

A computational framework has been developed, with functions for form finding and analysis of cables, membranes and shells. The theoretical predictions have been evaluated in a case study, with the construction of a full scale concrete pavilion. These comparisons showed good correspondence in general, the main difference was a significantly stiffer response in the experiment compared to the models.

Student Johan Örnborg

Opponents Gabriel Borg & Albin Johnsson

Supervisor Mats Ander

Examiner Mats Ander



Structural optimization for effective strut-and-tie models - Design of support crossbeams in single girder concrete bridges

Abstract:

Experience from engineering practice indicates that the strut and tie method is over-conservative in some cases. Therefore, there is a need to investigate if the method can be improved. The objective of this thesis was to investigate if the method can be improved using bi-directional evolutionary optimization. The final designs, obtained from simulations, are translated into optimized strut and tie models which then are further investigated.

It was found that the needed reinforcement amount decreased using this method, compared to conventional strut and tie method.

Students

Simon Nilsson & Petter Öhman

Opponents

Michaela Henriksson & Anna Rosenberg

Supervisors

Max Fredriksson (Inhouse Tech), Mario Plos & Alexandre Mathern

Examiner

Mario Plos

Managing Temporary Works - A summary of exciting problems and solutions

Abstract:

In recent years, there have been a series of accidents regarding temporary works in Sweden, while other countries seem to have fared better. In the thesis, interviews with different stakeholders within the temporary work industry are presented alongside a literature study into the important temporary work elements and European Standards. Furthermore, a study of the most recent accidents has been summarised. In addition, a case study was performed to further investigate some claims by the interviewing partners and suggestions in the regulating standards. The conclusion is presented as a list of suggestions on how to improve the temporary works industry and the regulations surrounding temporary works.

Students

Lars Scheidegger & Jonathan Söderqvist

Opponents

Christopher Jonsson & Adam Lenell

Supervisors

Jimmy Lovén (VBK), David Salekärr (Serneke) & Robert Kliger

Examiner

Robert Kliger


Inventory of knowledge needs with regard to explosions in a densified urban environment

Abstract: In densified environments buildings gets more exposed to explosion risks from e.g. dangerous goods traffic. This thesis aims to identify potential needs for increased knowledge regarding explosions in densified urban environments. The thesis includes literature studies, risk analysis reviews, explosion response calculations and interviews with stakeholders with different interests in what improvements are needed. It is agreed that increased knowledge is needed. In the thesis different types of priority needs are identified. Increased understanding of what is reasonable loads to considered is an improvement among many more that is suggested in the thesis.

Student

Emma Dahlén

Opponents

Hanna Geiger & Olena Shkundalova

Supervisor

Morgan Johansson (Norconsult, Chalmers)

Examiner

Morgan Johansson

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Thank you all!

presentation av examensarbeten - chalmers · corrosion were examined. no strong correlation between...

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