Numerical and experimental investigation of a new model of friction damper in diagonal brace under cyclic loading

Abstract

Owing to the performance of prefabricated friction dampers, which are rapidly increasing, the resistance of structural systems against earthquakes increases and depreciates the energies generated by earthquakes in the structure. It is important to use passive control systems to control the vibrations of a structure at a single level. However, in the design, they cannot depreciate the incoming energy from earthquakes at different levels. Friction dampers focus on displacement variables and are mostly used in steel structures according to the rules of a Coulomb damper or a friction brake that converts kinetic energy into heat through friction. In this study, a new type of friction damper, called a flat cylindrical friction damper, was designed using brake pads in a diagonal brace. The performance and seismic resistance of this system, as well as the amount of energy loss, were investigated. In this study, 18 laboratory tests were conducted using the universal device to check the research variables, their hysteresis diagrams were shown, and the configuration of the damper was designed such that grooved bolt connections and twin steel cables of different sizes and thicknesses were used. Moreover, the way the internal and external components are placed in the damper is such that innovation in tension and pressure has been created. In addition, the movement of the cylindrical element in the damper increased the amount of friction, owing to the presence of two types of brake pads with friction coefficients of 0.11 and 0.16 and the bolt connections. This demonstrates the damper performance under different sliding forces at different friction levels. The geometric dimensions, thickness of the brake pad, number and size of bolts, diameter of cables, sliding force, and location of the damper were among the variables investigated in this study. Brake pads, steel cables, and bolt connections are important and economically affordable. The seismic performance of the intended frame was investigated using 80 different damper models and the placement of the research variables. The desired optimal models were modelled using Abaqus software, analysed, and designed. This system aims to reduce the relative horizontal displacement of floors and increase the amount of energy absorption. An increase in theaxial-force created in multiple loading cycles always causes damage to damper components and frames. In this study, we used a special multi-level geometry to reduce the axial-force created in the damper, the relative displacement of the frame, and damages in the elements, as well as increase the ductility. The results show that the friction surfaces of steel plates and brake pads is very high due to the displacement and damping of the cables. Additionally, with the consumption of energy and its absorption by the damper in cyclic loads, displacement is easily controlled. The seismic response of the structures in terms of frame and damper displacement, base shear forces, and energy absorption is also observed. Numerical studies confirmed that the intended damper is an independent seismic-resistant member in critical building structures when high seismic performance or seismic resilience during moderate and strong earthquakes is desirable.