Non-linear Response in Reinforced Concrete related to Cryogenic Conditions Fredrik Jenseg Eriksen Civil and Environmental Engineering (2 year) Submission date: June 2014 Supervisor: Jan Arve Øverli, KT Norwegian University of Science and Technology Department of Structural Engineering Non-linear Response in Reinforced Concrete related to Cryogenic Conditions Fredrik Jenseg Eriksen Civil and Environmental Engineering Submission date: June 2014 Principal Supervisor: Jeovan Freitas, DNV GL Principal Supervisor: Bente Skovseth Nyhus, Dr. Techn. Olav Olsen AS Assistant Supervisor: Jan Arve Øverli, NTNU Norwegian University of Science and Technology Department of Structural Engineering iii Department of Structural Engineering ACCESSIBILITY Faculty of Engineering Science and Technology NTNU- Norwegian University of Science and Technology OPEN OPEND MASTER THESIS 2014 SUBJECT AREA: DATE: NO. OF PAGES: NON-LINEAR FINITE 10.06.14 ELEMENT ANALYSIS “NON-LINEAR RESPONSE IN REINFORCED CONCRETE RELATED TO CRYOGENIC CONDITIONS” “IKKE-LINEÆR RESPONS FOR ARMERT BETONG UTSATT FOR KRYOGENISKE TEMPERATURLASTER” BY: FREDRIK JENSEG ERIKSEN RESPONSIBLE TEACHER: JAN ARVE ØVERLI PRINCIPAL SUPERVISOR: JEOVAN FRITAS PRINCIPAL SUPERVISOR: BENTE SKOVSETH NYHUS CARRIED OUT AT: NTNU SUMMARY: A reinforced outer concrete containment tank exposed for liquefied natural gas was the basis for this study. The containment tank was analysed both linearly and non-linearly by use of two different finite element programs; Abaqus and Sestra/ShellDesign. The main goal for this study was to examine whether a given concrete containment tank would fulfil the formal rules and regulations regarding, the residual compressive zone and the crack width limitation, without a thermal corner protection. Non-linear analyses were carried out by use of temperature dependent material properties. The results showed an acceptable residual compressive zone for both the wall and the slab, but the required limit crack width was exceeded by 100 % (0.5 mm). The residual compressive zone will ensure impermeability and the outer containment tank will withstand a major leak event. Abaqus proved itself to be a good tool for non-linear analysis due to a cryogenic condition. The results from Abaqus were compared to a similar model created and analysed with Sestra/ShellDesign. Some unfavourable peak values was found at the edges of the thermal load. The non-linear reinforcement stresses were however reliable for the tests ran without any concrete tensile capacity, and should be considered a solid basis for further studies for Sestra/ ShellDesign due to a cryogenic liquid spill condition. v MASTER THESIS, SPRING 2014 for FREDRIK JENSEG ERIKSEN Non-linear Response in Reinforced Concrete related to Cryogenic Conditions The storage of liquefied natural gas at low temperatures is a relevant and challenging scenario. It is feasible to cool gas into a liquid form, and then store it in a steel inner tank with a concrete containment tank as a surrounding load carrier. In case of a leakage from the steel inner tank, the outer containment tank needs to be liquid proof and serve as a catch basin. Therefore, it is crucial to determine the thermal properties of the materials involved, and how they interact with each other. In cryogenic conditions, the difference in material behavior between concrete and reinforcement with resulting internal forces have to be considered as well as the more external non-linear redistribution of stress resultants. The assignment will be to analyze a representative storage tank by use of finite element method. Non-linear temperature dependent materials will be used and analyzed by Abaqus and Sestra/ShellDesign. The non-linear results achieved from these applications should be compared and important parameters that affect the results should be identified. The advantages and disadvantages using Abaqus vs. ShellDesign should be addressed. The proposed thesis should be developed based on the following assumptions: 1. The geometry of the tank and the loads should be the same as defined in reference (1). An alternative geometry could also be used, defined in (2). DNV GL shall approve the final geometry. 2. Shell based elements should be used for all finite element models. Additional solid elements model could be considered in Abaqus, if shell elements are insufficient. 3. A steady-state temperature flow scenario with linear gradient variation over thickness should be assumed. 4. All material properties (concrete and steel) shall be defined by DNV GL. The thesis should be delivered by existing guidelines. Deadline June 10.2014 Supervisors Jeovan Freitas (DNV GL) Bente Skovseth Nyhus (Dr. Techn. Olav Olsen AS) Jan Arve Øverli (NTNU) vii Preface This Master’s thesis was written at the Department of Structural Engineering at the Norwegian University of Science and Technology in Trondheim, during the spring 2014. The assignment was provided by Ph.d. Jeovan Freitas at DNV GL, who also has been of great assistance with Abaqus modelling and general guidance. M.Sc. Bente Skovseth Nyhus at Dr. Techn. Olav Olsen has been at great help in all matters regarding Sestra and ShellDesign. I would also like to thank M.Sc. Hege Berg Thurman, the Head of Concrete Sections at DNV GL, for making this interesting master thesis available for me, including the Patran model I acquired for the Sestra/ShellDesign analyses. Creating the Abaqus model has been essential for this thesis, and very time consuming. A literature study was done in the Abaqus Analysis User’s Manual, and a great number of analyses were run in order to evolve a dependable model. Some software issues were met regarding the analyses in Sestra/ShellDesign. These issues were solved by great assistance from Bente Skovseth Nyhus, and I am very grateful for her time invested in these issues. I would also like to thank my fellow students at 2-46D, Bendik, Tor Jørgen, Olav and Kenth. Together, we have created a great environment that has overcome all errors and perplexities.