Displacement-based design procedure of damped braces for the seismic retrofitting of r.c. framed buildings

2014 ◽  
Vol 13 (7) ◽  
pp. 2121-2143 ◽  
Author(s):  
Fabio Mazza ◽  
Alfonso Vulcano
2012 ◽  
Vol 217-219 ◽  
pp. 1114-1118 ◽  
Author(s):  
Marco Valente

This study presents a displacement-based design procedure for seismic retrofitting of steel frames using buckling-restrained braces (BRB) to meet a given target displacement in the framework of the capacity spectrum method. The seismic performance of a six-storey steel frame equipped with BRB is investigated. Different storey-wise BRB distribution methods are proposed and the influence on the results of the design procedure is analyzed. Nonlinear dynamic analyses demonstrate the efficacy of the design procedure showing the improvements achieved by the retrofitting intervention using BRB. The maximum top displacement registered for the retrofitted frame under earthquake excitation coincides with the target displacement obtained in accordance with the design procedure. The introduction of buckling-restrained braces enhances the earthquake resistance of the steel frame, providing significant energy dissipation and the stiffness needed to satisfy structural drift limits.


2021 ◽  
Vol 13 (4) ◽  
pp. 1864
Author(s):  
Vincenzo Manfredi ◽  
Giuseppe Santarsiero ◽  
Angelo Masi ◽  
Giuseppe Ventura

In Italy as well as in other earthquake-prone countries, the large number of existing buildings requiring seismic retrofitting calls for sustainable solutions able to reduce both costs and downtime. To this purpose, in this paper, the High-Performance Dissipating Frame system (HPDF), a new strengthening solution for the seismic rehabilitation of existing buildings, is presented. HPDF is based on external precast reinforced concrete (RC) frames rigidly connected to the existing structures and equipped with shear damper devices in order to provide high dissipation capacity. The proposed solution permits: (i) to increase sustainability through works made up from the outside without removing/demolishing infills/other non-structural components, (ii) rapid execution by adopting precast resisting members mutually restrained with steel connections, and (iii) effectiveness due to shear damper devices able to dissipate a large amount of shaking energy. In the paper, a displacement-based design procedure is proposed and applied to a numerical example.


Author(s):  
Andrea Belleri ◽  
Simone Labò

AbstractThe seismic performance of precast portal frames typical of the industrial and commercial sector could be generally improved by providing additional mechanical devices at the beam-to-column joint. Such devices could provide an additional degree of fixity and energy dissipation in a joint generally characterized by a dry hinged connection, adopted to speed-up the construction phase. Another advantage of placing additional devices at the beam-to-column joint is the possibility to act as a fuse, concentrating the seismic damage on few sacrificial and replaceable elements. A procedure to design precast portal frames adopting additional devices is provided herein. The procedure moves from the Displacement-Based Design methodology proposed by M.J.N. Priestley, and it is applicable for both the design of new structures and the retrofit of existing ones. After the derivation of the required analytical formulations, the procedure is applied to select the additional devices for a new and an existing structural system. The validation through non-linear time history analyses allows to highlight the advantages and drawbacks of the considered devices and to prove the effectiveness of the proposed design procedure.


2019 ◽  
Vol 22 (16) ◽  
pp. 3420-3434 ◽  
Author(s):  
Gang Li ◽  
Li-Hua Zhu ◽  
Hong-Nan Li

Passive energy dissipation devices have been proved to be effective and low-cost means of structural control, and a variety of dampers have been developed over the past decades. Hysteretic dampers with hardening post-yielding stiffness have multiphased energy dissipation characteristics because of their hardening behavior, which can compensate for stiffness loss and postpone the collapse of damaged structures. In this article, a hysteretic model is proposed for hysteretic dampers with hardening post-yielding stiffnesses, and a formula is derived for equivalent yield strength expressed by the additional damping of the structure. A procedure is developed for displacement-based seismic design that transforms the relatively complex damping into an acceptable yield strength. A numerical example is only presented for demonstrating the design process and simply validating the proposed method. The results show that the proposed procedure is easy to implement and could produce adequate hysteretic dampers with hardening post-yielding stiffness hardening behavior. The maximum displacement responses of the existing structure retrofitted using the proposed procedure satisfy the expected performance objective well. Thus, this procedure could be an alternative to seismic retrofitting for structures with energy dissipation systems.


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