EXPERIMENTAL AND FINITE ELEMENT ANALYSIS OF THE CYCLIC BEHAVIOUR OF LINEAR DISSIPATIVE DEVICES

Abstract

In the past years, low-damage design of structures is becoming an efficient approach by engineers and researchers in order to mitigate the structural damage to buildings during a seismic event. To this aim, one of the most popular strategies is to endow framed structures with either viscous, hysteretic metallic, or viscoelastic devices. As an alternative to these systems, friction devices have been also studied, proving to be an effective solution. Steel braces endowed with linear dissipative devices based on friction can be used effectively both in the case of new and existing structures. Studies conducted on these devices stressed that their behaviour is mainly influenced by type of friction materials, loss of bolt preload and effect of disc springs. An experimental campaign has been performed at the Materials and Structures Laboratory of the University of Palermo on linear dissipative devices with different types of friction materials i.e., steel, thermal sprayed aluminium, and brass, to check their effectiveness. Finite element analysis using ABAQUS has been done to design, check the functionality, and get insight into the experimental results of the linear dissipative devices. An investigation has been done on the effectiveness of disc springs to limit the bolt preload variation in the device and the effect of thicknesses of plates on the functionality of linear friction dissipative device. The results showed that thermal sprayed aluminium, coupled with structural steel, is a good friction material as it provides stable hysteresis loops and high friction coefficient as compared to brass, and appropriately designed disc springs are able to limit bolt preload variation. The experimental results showed that the thermal sprayed aluminium provides a friction coefficient between 0.57 and 0.6 without significant variation even for a large number of cycles, while for the brass the friction coefficient at the beginning of the test was 0.25 and then it increased to 0.45 at the end of test, exhibiting large variation due to stick and slip phenomenon. The FEM analysis proved that the disc springs are able to minimize the variation of the contact pressure due to the Poisson effect and proper thickness of friction plates are important for the performance of friction device.