Structural Effects of Heat Treatment Holding-Time on Dynamic and Damping Behaviour of an Fe-28Mn-6Si-5Cr Shape Memory Alloy

The paper reports the structural effects of holding time period, during heat treatment, on the dynamic and damping behavior of a Fe-28Mn-6Si-5Cr (mass. %) shape memory alloy. After casting and hot rolling, solution treatment at 1050 oC was applied for five holding times, 2, 4, 6, 8 and 10 hours, followed by water quenching. The specimens were analyzed by scanning electron microscopy and X-ray diffraction which emphasized that only the 2-hours solution treated specimens contained ε-hexagonal close packed (hcp) martensite and experienced the highest internal friction value. These specimens were tested on a special device which transformed both tension and compression into tensile strain applied to the specimens and proved to be a promising solution for anti-seismic damper.

Behavior of multidirectional friction dampers

Earthquakes are catastrophic events causing loss of lives, injuries, and extensive losses in properties. Majority of the life and property losses of earthquakes are dependent on the incapabilities of the building stock to resist earthquakes. Although unsuitable design, analyses, and production techniques play a major role as the main reasons for the poor performance of buildings against earthquakes, buildings constructed in accordance with building codes also suffer from the devastating impact of earthquakes. In this context, the lack of proper management and adequate damping of the energy caused by earthquakes is a major cause of structural damage in earthquakes. The efficiency of conventional basic elements in structures with energy damping is very limited and may not be sufficient for the damping of a large amount of earthquake-induced energy. Thanks to the rapid advances in technology and associated engineering techniques, numerous new products, and production and calculation techniques are underway to mitigate the devastating effects of earthquakes on buildings. In this study, it was aimed to theoretically and experimentally investigate the performance of a versatile friction-type seismic damper that eliminates earthquake energy. The damper is designed using a spherical surface friction joint to respond to all loads regardless of the loading direction. The damper can be easily adjusted to the desired capacity by means of bolt tensioning elements. Experiments have been carried out for various shear loads and damping parameters. Furthermore, numerical analysis of the model was carried out by use of the finite element method. The results of this study revealed that the shear load capacity of the device did not change at different frequencies. Analyzing the effect of the equipment on a structure, it was understood that it reduces roof displacement and periods of the structure. The analysis revealed that the damper significantly improved the earthquake performance of the structure.

Recent advances in the technologies of connection for panel structures: Design and cost analysis of different solutions with X-shaped dissipative connectors

In this work, a recently patented seismic damper to be applied to structures composed by systems of panels is presented. In particular, the article is devoted to characterize the behaviour of the proposed connector by means of an experimental and numerical analysis and to provide some information about the cost of the elements needed to realize the damper, accounting for the manufacturing process. The experimental analysis has regarded five specimens tested under different loading conditions, and it has been used as a term of comparison with the classical systems of connection currently employed in these structures. Afterwards, in the article, a design criterion able to control the capacity and ductility of the device by simply varying the shape of the damper is presented and its accuracy is evaluated by performing finite element analyses. The results of the experimental and finite element analyses are very promising in terms of cyclic behaviour and energy dissipation capacity and reveal that the design of the element can be accurately controlled by means of the proposed approach. Furthermore, the cost estimate has revealed that the proposed damper is also cheaper than the classical solutions with a cost reduction of about 40%.

Seismic Testing of In-Plane Flexural Damper in Arched-Shape

This study proposes an innovative displacement-dependent metallic yielding damper for seismic protection of building structures. The damper is designed to deform inelastically under in-plane flexural bending and becomes energy-dissipative with an improved efficiency in terms of material utilization, as compared with those designed to bend in an out-of-plane manner. Both component test and seismic performance test of the proposed damper have been conducted in this study. Hysteresis of the component test indicates consistent and effective energy-dissipative characteristics of the damper. The contour of cracks on the surface of the damper after testing is well correlated with the stress distribution obtained from numerical analysis. Moreover, excellent seismic performance of the proposed in-plane arched damper has been demonstrated via a series of shaking table tests on a five-story model structure. Experimental results indicate that, with the dampers implemented, the acceleration responses in both peak and root-mean-squares of all floors are significantly reduced and more pronounced with the earthquake intensity increased. Effectiveness of the seismic damper is also revealed from the increase of the effective modal damping of all modes identified.