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.

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.

Seismic Performance of RC Frame with Shape Memory Alloy Bracing Bars

2011 ◽  
Vol 71-78 ◽  
pp. 37-40
Author(s):  
Wen I Liao
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Seismic Performance ◽  
Rc Frame ◽  
Test Results ◽  
Base Shear ◽  
Rc Frames ◽  
Story Drift ◽  
Bracing System ◽  
Force Displacement

In this study, high seismic performance RC frames have been proposed to have Shape Memory Alloy (SMA) bars acting as a kind of structural bracing system at both sides of a frame to increase the energy dissipation capacity of the RC frame. The type of SMA bar used in the study is the Superelastic SMA bar. The force-displacement hysteretic loops of the RC frame with SMA bars under seismic loading are presented and compared with the test results of the bare RC frame. Test results show that the SMA bars can effectively reduce the maximum story drift of the tested frame. It was found that the reduction of story drift and base shear was depending on the characteristic of the input ground motions.

Experimental Validation and Numerical Simulation of Shape Memory Flat Wire Actuators

2014 ◽  
Author(s):  
Alexander Czechowicz ◽  
Sven Langbein
Keyword(s):  
Shape Memory Alloy ◽  
Boundary Conditions ◽  
Shape Memory ◽  
Smart Materials ◽  
Empirical Data ◽  
Dynamic Properties ◽  
Fatigue Behavior ◽  
Different Boundary Conditions ◽  
Heating And Cooling ◽  
Actual Shape

Shape memory alloys (SMA) are thermally activated smart materials. Due to their ability to change into a previously imprinted actual shape through the means of thermal activation, they are suitable as actuators for mechatronical systems. Despite of the advantages shape memory alloy actuators provide, these elements are only seldom integrated by engineers into mechatronical systems. Reasons are the complex characteristics, especially at different boundary conditions and the missing simulation- and design tools. Also the lack of knowledge and empirical data are a reason why development projects with shape memory actuators often lead to failures. This paper deals with the dynamic properties of SMA-actuators (Shape Memory Alloy) — characterized by their rate of heating and cooling procedures — that today can only be described insufficiently for different boundary conditions. Based on an analysis of energy fluxes into and out of the actuator, a numerical model of flat-wire used in a bow-like structure, implemented in MATLAB/SIMULINK, is presented. Different actuation parameters, depending on the actuator-geometry and temperature are considered in the simulation in real time. Additionally this publication sums up the needed empirical data (e.g. fatigue behavior) in order to validate the numerical two dimensional model and presents empirical data on SMA flat wire material.

Shape memory alloy–actuated prestressed composites with application to morphing automotive fender skirts

2018 ◽  
Vol 30 (3) ◽  
pp. 479-494 ◽  
Author(s):  
Venkata Siva C Chillara ◽  
Leon M Headings ◽  
Ryohei Tsuruta ◽  
Eiji Itakura ◽  
Umesh Gandhi ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Design Procedure ◽  
Building Blocks ◽  
Smart Composite ◽  
Thermally Induced ◽  
One Dimensional ◽  
Flat Shape

This work presents smart laminated composites that enable morphing vehicle structures. Morphing panels can be effective for drag reduction, for example, adaptive fender skirts. Mechanical prestress provides tailored curvature in composites without the drawbacks of thermally induced residual stress. When driven by smart materials such as shape memory alloys, mechanically-prestressed composites can serve as building blocks for morphing structures. An analytical energy-based model is presented to calculate the curved shape of a composite as a function of force applied by an embedded actuator. Shape transition is modeled by providing the actuation force as an input to a one-dimensional thermomechanical constitutive model of a shape memory alloy wire. A design procedure, based on the analytical model, is presented for morphing fender skirts comprising radially configured smart composite elements. A half-scale fender skirt for a compact passenger car is designed, fabricated, and tested. The demonstrator has a domed unactuated shape and morphs to a flat shape when actuated using shape memory alloys. Rapid actuation is demonstrated by coupling shape memory alloys with integrated quick-release latches; the latches reduce actuation time by 95%. The demonstrator is 62% lighter than an equivalent dome-shaped steel fender skirt.

Evaluation of the Mechanical Properties of Glass/Epoxy Composite by Embedding Shape Memory Alloy and Nanoclay

2021 ◽  
Vol 1019 ◽  
pp. 3-11
Author(s):  
Niranjan Pattar ◽  
S.F. Patil ◽  
Pratik Patil ◽  
Iranna Anikivi ◽  
Shridhar Hiremath
Keyword(s):  
Electron Microscopy ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Smart Materials ◽  
Epoxy Composite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Clay Concentration ◽  
Impact Characteristics

Embedding smart materials in the composite to enhance mechanical strength have become a research hotspot owing to their unique properties. The present research also focus on novel way to fabricate composite by embedding Shape Memory Alloy (SMA) wire and montmorillonite (MMT) nanoclay by varying clay concentration (0-7 wt.%). The extent of dispersion of nanoclay in epoxy resin was studied using Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD). Fabricated samples were examined for tensile, flexural and impact characteristics. Scanning Electron Microscopy (SEM) was used to study the adhesion, delamination and damage occurred within the composite due to tensile loading. Results shows that the tensile strength, flexural strength and impact energy of SMA/MMT/glass/epoxy composite was improved by 23%, 21% and 57% respectively, when it was compared with composite with glass/epoxy composite.

scholarly journals Seismic Assessment of RC Bridge Columns Retrofitted with Near-Surface Mounted Shape Memory Alloy Technique

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1701 ◽  
Author(s):  
Ammar Abbass ◽  
Reza Attarnejad ◽  
Mehdi Ghassemieh
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Plastic Hinge ◽  
Bridge Columns ◽  
Near Surface ◽  
New Approach ◽  
Seismic Rehabilitation ◽  
Bridge Column ◽  
Near Surface Mounted ◽  
Fiber Element Modeling

From past earthquakes, it has been found that the large residual displacement of bridges after seismic events could be one of the major causes of instability and serviceability disruption of the bridge. The shape memory alloy bars have the ability to reduce permanent deformations of concrete structures. This paper represents a new approach for retrofitting and seismic rehabilitation of previously designed bridge columns. In this concept, the RC bridge column was divided into three zones. The first zone in the critical region of the column where the plastic hinge is possible to occur was retrofitted with near-surface mounted shape memory alloy technique and wrapped with FRP sheets. The second zone, being above the plastic hinge, was confined with Fiber-Reinforced Polymer (FRP) jacket only, and the rest of the column left without any retrofitting. For this purpose, five types of shape memory alloy bars were used. One rectangular and one circular RC bridge column was selected and retrofitted with this proposed technique. The retrofitted columns were numerically investigated under nonlinear static and lateral cyclic loading using 2D fiber element modeling in OpenSees software. The results were normalized and compared with the as-built column. The results indicated that the relative self-centering capacity of RC bridge piers retrofitted with this new approach was highly greater than that of the as-built column. In addition, enhancements in strength and ductility were observed.

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