scholarly journals Analytical investigation of the seismic performance of special truss girder framing systems with new technologies

2020 ◽  
Author(s):  
Μαρία Ντίνα
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Seismic Performance ◽  
New Technologies ◽  
Analytical Investigation ◽  
Moment Frames ◽  
Special Truss Moment Frames

Αντικείμενο της Διατριβής αποτελεί η αναλυτική διερεύνηση της δυνατότητας βελτίωσης της αντισεισμικής συμπεριφοράς ειδικών δικτυωτών πλαισιακών συστημάτων (Special Truss Moment Frames, STMFs, από χάλυβα) μέσω της ενσωμάτωσης ράβδων κυκλικής διατομής από κράματα νικελίου-τιτανίου (μνήμης μορφής – shape memory alloy bars), οι οποίες αποτελούν εναλλακτικό σύστημα απορρόφησης της σεισμικής ενέργειας στο ειδικό τμήμα (special segment) των πλαισίων. Τούτο καθόσον διαθέτουν την δυνατότητα να ανακτήσουν την αρχική τους (απαραμόρφωτη) γεωμετρία μετά από μηχανική διαταραχή κατά την αποφόρτιση, μέσω του μετασχηματισμού φάσης των κρυσταλλικών δομών (ματερνσιτικής – ωστενιτικής). Ο επικρατών αντισεισμικός σχεδιασμός των STMFs με ειδικό μέρος ευρισκόμενο στο μέσο του ανοίγματος τους (με σκοπό την απορρόφηση σεισμικής ενέργειας) είναι η δημιουργία πλαστικών αρθρώσεων στις τέσσερεις γωνίες. Αυτός ο μηχανισμός προτείνεται να αντικατασταθεί μέσω της παραμόρφωσης των SMAs σε ένα ειδικό μέρος με αρθρώσεις στις κορυφές του. Τονίζεται ότι οι ράβδοι SMA θεωρούνται σε όλες τις αναλύσεις της Διατριβής ως μη λυγηρές, είτε λόγω μεγάλης διατομής είτε λόγω ενίσχυσης μέσω συστημάτων αποφυγής λυγισμού.

PERFORMANCE ASSESSMENT OF RC BEAM-COLUMN JOINT REINFORCED WITH DIFFERENT SUPER ELASTIC SHAPE MEMORY ALLOY TYPES

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mumtasirun Nahar ◽  
A.H.M.M. Billah ◽  
Habibur Rahman Kamal ◽  
Kamrul Islam
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Seismic Performance ◽  
Smart Materials ◽  
Plastic Hinge ◽  
Analytical Investigation ◽  
Rc Beam ◽  
Story Drift ◽  
Alloy Effect ◽  
Column Joint

Superelastic Shape Memory Alloys (SE SMAs) are smart materials that have the ability to undergo large inelastic deformation upon stress removal (superelasticity) or heating (shape-memory alloy effect). If such smart materials can be used in the plastic hinge regions of reinforced concrete (RC) beam-column joints as reinforcement, they can undergo large deformations during an earthquake and can return to their undeformed/ original shape after the earthquake. This paper represents the seismic performance of beam-column joint reinforced with three different types of SMA (e.g Ni-Ti, Cu-Al-Mn, Fe based) and compared the result with regular steel-RC beam-column joint. An analytical investigation has been considered to evaluate the seismic performance of smart RC beam-column joint and regular steel-RC joint under reversed cyclic loading. The performance of the beam-column joint is compared in terms of load-story drift ratio and energy dissipation capacity. All SMA-RC beam-column joints show nearly 40-60% higher displacement than steel-RC joint before yielding. Among three types of SMA Ni-Ti dissipate 24% higher energy than any other types of SMA.

Seismic Performance of Concrete Bridge Piers Reinforced with Hybrid Shape Memory Alloy (SMA) and Steel Bars

2019 ◽  
Vol 14 (01) ◽  
pp. 2050001
Author(s):  
Jize Mao ◽  
Daoguang Jia ◽  
Zailin Yang ◽  
Nailiang Xiang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Seismic Performance ◽  
Residual Deformation ◽  
Steel Reinforcement ◽  
Bridge Piers ◽  
Dissipated Energy ◽  
Concrete Bridge ◽  
Loss Of Function ◽  
Hybrid Reinforcement

Lack of corrosion resistance and post-earthquake resilience will inevitably result in a considerable loss of function for concrete bridge piers with conventional steel reinforcement. As an alternative to steel reinforcement, shape memory alloy (SMA)-based reinforcing bars are emerging for improving the seismic performance of concrete bridge piers. This paper presents an assessment of concrete bridge piers with different reinforcement alternatives, namely steel reinforcement, steel-SMA hybrid reinforcement and SMA reinforcement. The bridge piers with different reinforcements are designed having a same lateral resistance, or in other words, the flexural capacities of plastic hinges are designed equal. Based on this, numerical studies are conducted to investigate the relative performance of different bridge piers under seismic loadings. Seismic responses in terms of the maximum drift, residual drift as well as dissipated energy are obtained and compared. The results show that all the three cases with different reinforcements exhibit similar maximum drifts for different earthquake magnitudes. The SMA-reinforced bridge pier has the smallest post-earthquake residual displacement and dissipated energy, whereas the steel-reinforced pier shows the opposite responses. The steel-SMA hybrid reinforcement can achieve a reasonable balance between the residual deformation and energy dissipation.

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