Equivalent viscous damping for steel concentrically braced frame structures

Abstract

The direct displacement based seismic design procedure utilises equivalent viscous damping expressions to represent the effect of energy dissipation of a structural system. Various expressions for the equivalent viscous damping of different structural systems are available in the literature, but the structural systems examined in the past have not included concentrically braced frame structures. Thus, this study describes the development of an equivalent viscous damping equation for concentrically braced frame structures based on the hysteretic response of 15 different single storey models. Initially, equivalent viscous damping is calculated based on the area based approach and then corrected for the earthquake excitation. An iterative procedure is adopted to calibrate the equivalent viscous damping expression to the results of inelastic time history analyses using a number of spectrum-compatible real accelerograms. From the results of this research, a new damping expression is developed as a function of the ductility and the non dimensional slenderness ratio.

Seismic Performance of High-Rise Steel MRFS With Outrigger and Belt Trusses Through Nonlinear Dynamic Fe Simulations

“…Additionally, a detailed approach is currently almost unfeasible if the response of an entire mega-frame system has to be investigated. By contrast, the complex contribution of bolted [22][23][24][25][28][29][30] and welded [20,21,31,32] joints can be easily incorporated into classical fiber-based FE models, able to represent the interaction among connection components in an equivalent manner. Thus, mechanical representations have been assumed in this research to include global response and potential failure mechanisms of these systems, as discussed later on.…”

“…Fig. 3 shows a schematic of the modeling approach used for brace and gusset-plate connections [20,21,31,32]. The model consists of two inelastic force-based beam-column elements, each of which having five integration points and a discretized fiber section.…”

“…The model consists of two inelastic force-based beam-column elements, each of which having five integration points and a discretized fiber section. In order to capture the effects of gusset end restraint [20,21,31,32], the present paper takes advantage of an additional inelastic force-based beam-column element of length 2t -where t is the thickness of the gusset plate -at each end of the brace. A set of rigid elements is included to represent the confined portions of beam, column and gusset plate, as shown by [20,21,31,32].…”

Dissipating Effect of Glazed Curtain Wall Stick System Installed on High-Rise Mega-Braced Frame-Core Buildings Under Nonlinear Seismic Excitation

“…On the other hand, the insight on the well-known physical phenomena allows their easy calibration into classical fiber-based FE models, saving significant computational time. In this light, since a three-dimensional approach would be extremely onerous to investigate the full-scale mega-frame dynamic response, the contribution of the resisting frame system was easily incorporated into classical fibre force-based [13] FE models, able to represent bolted [14,15,16,17,18] and welded [11,19,20,21] connections, and the other members besides. By contrast, aiming to develop a qualified façade numerical model and to understand the phenomena underpinning the mechanical global behavior, detailed brickbased FE simulations were performed in order to assess the aluminium frame deformability, the interaction between glass panels and aluminium frame, the gasket mechanical distortion and the transom-to-mullion connection stiffness.…”

Evaluation of sensitivity of CBFs for types of Bracing and story numbers

“…So, structures can dissipate most of the earthquake's energy throughout deection and entering into an inelastic phase of response of structures [1][2][3][4].…”