Investigation of the seismic performance of a single story – Single bay special truss moment frame with SMAs incorporated

The present work deals with the improvement of the seismic performance of a Single Story-Single Bay Special Truss Moment Frame (STMF) by incorporating Shape Memory Alloys (SMAs) as dissipation devices in the special segment, which can recover their initial geometry after mechanical distortion by unloading through the phase transformation (martensitic-austenitic phase). STMFs were initially designed with a special segment located in the middle of the truss to dissipate the input energy through the formation of plastic hinges at the four corners of the chord members. This mechanism is replaced with the input energy dissipation through the SMA deformation in a pin-ended special segment. In what follows, the frame at hand is examined incorporating SMA bars per diagonal of either 0.025 m or 0.035 m in diameter, restrained against buckling, simulated via a 4-DOF mechanical model consisting of two lumped masses, under selected ground motions. To further evaluate the performance of the frame with SMAs incorporated and at the same time verify the model, a non-linear dynamic time-history analysis is conducted using SeismoStruct Finite Element software. The response of the proposed system is compared with the one of the conventional one. Results show that the proposed system leads to a decrease of the maximum displacement and potentially allows a much lighter construction. © 2021 Institution of Structural Engineer

A new rate-dependent constitutive model of superelastic shape memory alloys and its simple application in a special truss moment frame simulation

In this work, a new constitutive model of the behavior of shape-memory alloys is presented, based on earlier models, showing a very good agreement with the existing experimental results. A simple approximate application concerning the use of these alloys modelled as dissipation devices in a special truss-moment frame is demonstrated. The results obtained are considered sufficiently encouraging as a motivation for the ongoing work. © 2018 Maria I. Ntina and Dimitrios S. Sophianopoulos

STRUCTURAL APPLICATIONS OF SHAPE MEMORY ALLOYS FOR SEISMIC RESILIENCE ENHANCEMENT

Shape Memory Alloys (SMAs) are metallic materials with advanced properties enabling them to recover their initial geometry by the application of heat or by unloading which indicates the shape memory and the superelastic effect respectively, through the phase change (austenitic-martensitic). The discovery of their special nature was made in the 1960s. It was noticed that they possessed a shape recovery capability, apart from their good mechanical properties, a characteristic that since then has made SMAs popular in a wide range of industrial fields. As far as engineering applications are concerned, research studies of implementations of the SMAs have increased in recent years. In the present paper a comprehensive and thorough look is attempted to familiarize with their use for structural engineering purposes while particular emphasis is shown to their deployment towards improving buildings’ seismic resilience. In this framework, recent advances in scientific research are summarized and presented aiming to provide an up-to-date scientific knowledge, highlighting thus also the SMA potential in construction sector. © 2022, Jordan University of Science and Technology. All rights reserved