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You searched for subject:(Steel strength degradation). Showing records 1 – 3 of 3 total matches.

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KTH

1. Ghasemi, Rohollah. Hydrogen-assisted stress corrosion cracking of high strength steel.

Degree: Chemical Science and Engineering (CHE), 2011, KTH

In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of micro-structure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under free corrosion potential and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate(1×10-6s-1) in 1 wt% and 3.5 wt% NaCl solutions under free corrosion potential. It was con-firmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.

Subjects/Keywords: Hydrogen embrittlement; hydrogen induced cracking; stress corrosion cracking; high strength steel; uniform corrosion; SSRT; hydrogen charging; fractography; hydrogen degradation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Ghasemi, R. (2011). Hydrogen-assisted stress corrosion cracking of high strength steel. (Thesis). KTH. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50416

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Ghasemi, Rohollah. “Hydrogen-assisted stress corrosion cracking of high strength steel.” 2011. Thesis, KTH. Accessed December 16, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50416.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Ghasemi, Rohollah. “Hydrogen-assisted stress corrosion cracking of high strength steel.” 2011. Web. 16 Dec 2019.

Vancouver:

Ghasemi R. Hydrogen-assisted stress corrosion cracking of high strength steel. [Internet] [Thesis]. KTH; 2011. [cited 2019 Dec 16]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50416.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ghasemi R. Hydrogen-assisted stress corrosion cracking of high strength steel. [Thesis]. KTH; 2011. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50416

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Skalomenos, Konstantinos. Seismic performance of plane moment resisting frames with concrete filled steel tube columns and steel I beams.

Degree: 2014, University of Patras; Πανεπιστήμιο Πατρών

The purpose of this research is to investigate the seismic behavior of plane moment resisting frames (MRFs) consisting of concrete filled steel tube (CFT) columns and steel I beams through targeted studies utilizing advanced computational methodologies calibrated on the basis of existing experimental results and to propose a preliminary performance-based seismic design method for this kind of frames.A computational study is conducted first to investigate the nonlinear cyclic response of square concrete-filled steel tubes (CFT) in bending and compression. An accurate nonlinear finite element model is created and its validity is established by comparing its results with those of existing experiments. Using this finite element model, extensive parametric studies are performed to provide information on the hysteretic and deteriorating behavior of CFT columns. Thus, on the basis of this computational study, three simple yet sufficiently accurate concentrated plasticity hysteretic models for simulating the cyclic behavior of square concrete-filled steel tube (CFT) columns, are developed.The seismic behavior of plane MRFs consisting of I steel beams and CFT columns is investigated next. More specifically, the effect of modelling details of each individual component of CFT-MRFs, such as the CFT columns, the beam-column connections, the panel zones and the steel I beams, on their seismic behavior is studied through comparisons against available experimental results. Then, fragility curves are constructed for composite frames for various levels of modelling sophistication through nonlinear time history analyses involving three typical CFT-MRFs which have been designed according to the European seismic design codes. On the basis of these fragility curves, one can select the appropriate modelling level of sophistication that can lead to the desired seismic behavior for a given seismic intensity. The third part of this work deals with the establishment of all the necessary ingredients for this kind of composite frames to be seismically designed by the performance-based hybrid force-displacement (HFD) seismic design method, which combines the advantages of the well-known force-based and displacement-based seismic design methods. Thus, extensive parametric studies are conducted involving nonlinear dynamic analysis of 96 frames under 100 seismic motions in order to create a databank with the response quantities of interest. Based on regression analysis, simple formulae for estimating the maximum roof displacement, the maximum inter-storey drift ratio, the maximum rotation ductility along the height of the frame and the behavior factor are developed.Comparison of the proposed design method with those adopted by current seismic design codes demonstrates that the proposed procedure seems to be more rational and controls deformation better than current seismic design codes. Nonlinear time history analyses proved the consistency of the proposed method to accurately estimate inelastic deformation demands and the tendency of the current…

Subjects/Keywords: Κοιλοδοκοί γεμισμένοι με σκυρόδεμα; Σύμμικτα υποστυλώματα; Πεπερασμένα στοιχεία; Φαινόμενα απομείωσης αντοχής και δυσκαμψίας; Υστερητικά μοντέλα; Συγκεντρωμένη πλαστιμότητα; Καμπύλες τρωτότητας; Καμπτικά επίπεδα πλαίσια; Παραμετρικές μελέτες; Αντισεισμικός σχεδιασμός; Υβριδική μέθοδος σχεδιασμού; Συντελεστής συμπεριφοράς; Καθολική πλαστιμότητα κορυφής; Επιτελεστικότητα; Concrete filled steel tube; Composite columns; Finite elements; Deterioration effects; Strength and stiffness degradation; Hysteretic models; Concentrated plasticity; Fragility curves; Moment resisting frames; Parametric studies; Seismic design; Hybrid seismic design method; Behavior factor or strength reduction factor; Roof ductility; Performance - based design

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Skalomenos, K. (2014). Seismic performance of plane moment resisting frames with concrete filled steel tube columns and steel I beams. (Thesis). University of Patras; Πανεπιστήμιο Πατρών. Retrieved from http://hdl.handle.net/10442/hedi/35563

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Skalomenos, Konstantinos. “Seismic performance of plane moment resisting frames with concrete filled steel tube columns and steel I beams.” 2014. Thesis, University of Patras; Πανεπιστήμιο Πατρών. Accessed December 16, 2019. http://hdl.handle.net/10442/hedi/35563.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Skalomenos, Konstantinos. “Seismic performance of plane moment resisting frames with concrete filled steel tube columns and steel I beams.” 2014. Web. 16 Dec 2019.

Vancouver:

Skalomenos K. Seismic performance of plane moment resisting frames with concrete filled steel tube columns and steel I beams. [Internet] [Thesis]. University of Patras; Πανεπιστήμιο Πατρών; 2014. [cited 2019 Dec 16]. Available from: http://hdl.handle.net/10442/hedi/35563.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Skalomenos K. Seismic performance of plane moment resisting frames with concrete filled steel tube columns and steel I beams. [Thesis]. University of Patras; Πανεπιστήμιο Πατρών; 2014. Available from: http://hdl.handle.net/10442/hedi/35563

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

3. Loulelis, Dimitris. Αντισεισμικός σχεδιασμός επίπεδων μεταλλικών πλαισίων με ιδιομορφικούς συντελεστές συμπεριφοράς και τρεις στάθμες επιτελεστικότητας.

Degree: 2015, University of Patras; Πανεπιστήμιο Πατρών

In this thesis a new performance - based seismic design method of planar steel frames is presented. Two groups of planar steel frames are examined, moment resisting frames including the contribution of the panel - zone and steel frames with buckling restrained braces. The steel frames are subjected to far - field seismic ground records corresponding in the 4 soil classes A,B,C and D of the Eurocode 8. The seismic records have been scaled properly in order the interstorey drift or ductility demands to comply with the targeted performance levels, as they are specified in SEAOC2000 or FEMA. The purpose of this research is the construction of an equivalent, linear multi - degree of freedom system, which substitutes the real nonlinear multi - degree of freedom structure. The equivalent linear system has the same mass and stiffness with the initial real structure and can approximate the seismic response of the non - linear system with the aid of the modal damping ratios which quantify the work of the material and geometrical non - linearities. The modal damping ratios for the first significant modes are identified through an iterative procedure, where the transfer function of the system is computed while the system is fed with damping until the transfer function satisfies certain criteria of monotony. The modal damping ratios are finally identified from the arithmetical solution of a set of non - linear algebric equations.\ Having found the modal damping ratios, the pseudo - response spectra are constructed for each value of the modal damping ratios. With the aid of these spectra, the strength reduction factors different for each mode can be computed. Since the seismic records have been properly scaled, the modal damping ratios and the modal strength reduction factors correspond to the performance levels of the SEAOC2000 or the FEMA. The design base shear is computed with linear response spectrum analysis with the usage of the modal strength reduction factors. In addition to that the results from the moment resisting frames including the panel - zone effect are compared with the moment resisting frames without pane - zone. The purpose is to note the rotational contribution of the panel - zone and to quantify this contribution in the absorption of energy. Comparison of the proposed design method with those adopted by current seismic design codes demonstrates that the proposed method seems more rational and controls deformation better than current seismic design codes. Non - linear analyses are performed in order to validate the proposed method and to prove that the inelastic deformation demands can be accurately estimated while current seismic codes tend to overestimate the maximum inter - storey drift ratio along the height of the frames.

Στην παρούσα διατριβή παρουσιάζεται μία νέα μέθοδος αντισεισμικού σχεδιασμού επίπεδων μεταλλικών πλαισίων με βάση την επιτελεστικότητα. Εξετάζονται δύο ομάδες επίπεδων κανονικών μεταλλικών πλαισίων, πλαίσια καμπτικά στα οποία λαμβάνεται υπόψη η επίδραση του κομβοελάσματος του…

Subjects/Keywords: Αντισεισμικός σχεδιασμός; Σχεδιασμός με βάση την επιτελεστικότητα; Συνάρτηση μεταφοράς; Μετασχηματισμός Fourier; Επεξεργασία σήματος; Ιδιομορφικοί συντελεστές συμπεριφοράς; Ισοδύναμη ιδιομορφική απόσβεση; Ισοδύναμο ελαστικό σύστημα; Ζώνη κόμβου σε διάτμηση; Απομείωση αντοχής χάλυβα; Γωνιακή παραμόρφωση ορόφου; Πλαστιμότητα; Seismic design; Performance based design; Transfer function; Fourier transform; Signal processing; Modal strength reduction factors; Equivalent modal damping; Equivalent linear system; Panel zone; Steel strength degradation; Inter-storey drift; Ductility

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Loulelis, D. (2015). Αντισεισμικός σχεδιασμός επίπεδων μεταλλικών πλαισίων με ιδιομορφικούς συντελεστές συμπεριφοράς και τρεις στάθμες επιτελεστικότητας. (Thesis). University of Patras; Πανεπιστήμιο Πατρών. Retrieved from http://hdl.handle.net/10442/hedi/36834

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Loulelis, Dimitris. “Αντισεισμικός σχεδιασμός επίπεδων μεταλλικών πλαισίων με ιδιομορφικούς συντελεστές συμπεριφοράς και τρεις στάθμες επιτελεστικότητας.” 2015. Thesis, University of Patras; Πανεπιστήμιο Πατρών. Accessed December 16, 2019. http://hdl.handle.net/10442/hedi/36834.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Loulelis, Dimitris. “Αντισεισμικός σχεδιασμός επίπεδων μεταλλικών πλαισίων με ιδιομορφικούς συντελεστές συμπεριφοράς και τρεις στάθμες επιτελεστικότητας.” 2015. Web. 16 Dec 2019.

Vancouver:

Loulelis D. Αντισεισμικός σχεδιασμός επίπεδων μεταλλικών πλαισίων με ιδιομορφικούς συντελεστές συμπεριφοράς και τρεις στάθμες επιτελεστικότητας. [Internet] [Thesis]. University of Patras; Πανεπιστήμιο Πατρών; 2015. [cited 2019 Dec 16]. Available from: http://hdl.handle.net/10442/hedi/36834.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Loulelis D. Αντισεισμικός σχεδιασμός επίπεδων μεταλλικών πλαισίων με ιδιομορφικούς συντελεστές συμπεριφοράς και τρεις στάθμες επιτελεστικότητας. [Thesis]. University of Patras; Πανεπιστήμιο Πατρών; 2015. Available from: http://hdl.handle.net/10442/hedi/36834

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.