Abstract
The control of vibrations and damage in traditional reinforced concrete (RC) buildings under earthquakes is a difficult task. It requires the use of innovative devices to enhance the seismic behavior of concrete buildings. In this paper, we design RC buildings with buckling restrained braces (BRBs) to achieve this objective. For this aim, three traditional RC framed structures with 3, 6, and 9 story levels are designed by using the well-known technique nondominated sorting genetic algorithm (NSGA-II) in order to reduce the cost and maximize the seismic performance. Then, equivalent RC buildings are designed but including buckling restrained braces. Both structural systems are subjected to several narrow-band ground motions recorded at soft soil sites of Mexico City scaled at different levels of intensities in terms of the spectral acceleration at first mode of vibration of the structure Sa(T1). Then, incremental dynamic analysis, seismic fragility, and structural reliability in terms of the maximum interstory drift are computed for all the buildings. For the three selected structures and the equivalent models with BRBs, it is concluded that the annual rate of exceedance is considerably reduced when BRBs are incorporated. For this reason, the structural reliability of the RC buildings with BRBs has a better behavior in comparison with the traditional reinforced concrete buildings. The use of BRBs is a good option to improve strength and seismic behavior and hence the structural reliability of RC buildings subjected to strong earthquake ground motions.
Highlights
In the past few years, an extensive amount of buildings has suffered damage due to medium and large earthquakes
Since the seismic design regulations recommend the control of maximum interstory drift as the main engineering demand parameter in order to achieve a good structural performance as Krawinkler and Gupta suggest [1], it is necessary to reduce the peak drift demands in reinforced concrete (RC) buildings. e displacement on traditional concrete buildings can be reduced by means of concentrically braces. e objective of the braces in structural frames is to increase the stiffness and to reduce the lateral displacements due to earthquakes [2, 3]
It is important to say that for the seismic design of all the buildings, the NSGA-II approach [20, 21] is used in order to reduce the cost and increase the structural capacity in accordance with the Mexico City Seismic Design Provisions (MCSDP). e 3D framed buildings in both type of structural systems are subjected to 30 ground motion records obtained from soft soil sites of Mexico City scaled at different spectral accelerations at first mode of vibration of the structure. us, a total of 3,600 seismic analyses have been performed. e numerical results of the analyses suggest that the seismic performance of reinforced concrete buildings with buckling restrained braces is superior to that of the structural behavior of traditional buildings indicating the advantages of this structural system
Summary
In the past few years, an extensive amount of buildings has suffered damage due to medium and large earthquakes. Several experimental tests have demonstrated that the cyclic behavior of the BRBs is stable and almost bilinear; in particular, Palazzo et al [18] concluded that it is feasible to design buckling restrained braces that are efficient, robust, virtually maintenancefree, durable, reasonably cheap, easy to produce, and made of basic and replaceable materials For this reason, the seismic response of reinforced concrete frames with buckling restrained braces has been studied, usually 2D systems are considered for the dynamic analyses; the advantages of BRBs on RC buildings in terms of structural fragility and reliability are not commonly assessed. E numerical results of the analyses suggest that the seismic performance of reinforced concrete buildings with buckling restrained braces is superior to that of the structural behavior of traditional buildings indicating the advantages of this structural system For this reason, BRBs can increase considerably the structural reliability when they are incorporated in reinforced concrete frames. The seismic reliability when both structural systems are subjected to narrow-band motions recorded in Mexico City is compared
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