Abstract

This study, proposes a new lateral load resisting system for high-rise (Reinforced Concrete) RC frames, which includes friction damper-superelastic SMA wires. The proposed SMA-friction damper can not only regulate the mechanism of frictional energy dissipation components with its self-centering SMA wires according to the design method based on the proposed performance, which is able to provide a hysteretic behavior and high self-centering capacity with the lowest SMA consumption but also has some advantages such as simple configuration and economic application. In this paper, two high-rise 18 and 22-story RC frames were designed in two design modes of common and with the proposed damper. The nonlinear time history analysis subjected to 10 far-field earthquakes performed in Opensees software. The results of the analyses showed that using the proposed SMA-friction damper, in addition to the effective increase in ductility, lateral stiffness and lateral strength, provided an excellent self-centering capacity, which resulted to the significant reduction in the maximum drift and the residual deformations in the structure.

Abstract

'''In this paper, a suspended-zipper braced frame (SZBF) equipped with hybrid damper consisting of Added Damping and Stiffness (ADAS) metallic damper and shape memory alloy (SMA) wires is introduced. The proposed seismic-force-resisting system is designed by performance-based plastic design (PBPD) method, which in addition to a significant reduction in the residual displacement of the structure, can increase the collapse displacement amount by providing a suitable lateral strength and ductility compared to the conventional SZBF. A new method for designing the proposed hybrid damper is presented, in which two factors of highest hysteretic energy and the least consumption amount of SMA material is provided. The existing models in this paper are two high-rise 12- and 16-story SZBFs in two cases (a) with the conventional system and designed by force-based design method (b) with proposed hybrid damper and designed by the PBPD method. Seismic assessment of the proposed SZBF (PSZBF) by nonlinear static analysis is performed under two lateral load patterns of parabolic and uniform, in accordance with the FEMA-P695 in OpenSees software. Two parameters of the overstrength factor (Ω) and response modification coefficient (R) are evaluated from the analysis results. It is determined that the PSZBF does not lead to a significant change in the overstrength factor comparing to the conventional SZBF. Also, the PSZBF, in addition to reducing the consumption amount of used steel by about 7%, can increase the R parameter by about 50% compared to the conventional system.

Abstract

In this paper, a suspended-zipper braced frame (SZBF) equipped with hybrid damper consisting of Added Damping and Stiffness (ADAS) metallic damper and shape memory alloy (SMA) wires is introduced. The proposed seismic-force-resisting system is designed by performance-based plastic design (PBPD) method, which in addition to a significant reduction in the residual displacement of the structure, can increase the collapse displacement amount by providing a suitable lateral strength and ductility compared to the conventional SZBF. A new method for designing the proposed hybrid damper is presented, in which two factors of highest hysteretic energy and the least consumption amount of SMA material is provided. The existing models in this paper are two high-rise 12- and 16-story SZBFs in two cases (a) with the conventional system and designed by force-based design method (b) with proposed hybrid damper and designed by the PBPD method. Seismic assessment of the proposed SZBF (PSZBF) by nonlinear static analysis is performed under two lateral load patterns of parabolic and uniform, in accordance with the FEMA-P695 in OpenSees software. Two parameters of the overstrength factor (Ω) and response modification coefficient (R) are evaluated from the analysis results. It is determined that the PSZBF does not lead to a significant change in the overstrength factor comparing to the conventional SZBF. Also, the PSZBF, in addition to reducing the consumption amount of used steel by about 7%, can increase the R parameter by about 50% compared to the conventional system.

Abstract

Reinforced concrete (RC) shear walls are often used as the main lateral-resisting component in the seismic design of buildings. They provide a large percentage of the lateral stiffness of the structure, and therefore, they may experience large shear stresses at some point under earthquake loading. Consequentially, to accurately predict their behavior, it is recommended to use detailed finite element (FE) modeling with appropriate non-linear constitutive models for concrete and steel. However, such types of simulations are challenging and could significantly increase the computational time required to obtain the analysis results. In this paper, we study the viability of creating an artificial neural-network-based surrogate model of the RC shear wall that is able to capture its nonlinear behavior and predict the results obtained with a detailed FE model, offering a much lower computational effort. For this purpose, we develop a detailed parametric non-linear FE model based on well-established practices and validated studies using the OpenSees finite element software framework. The FE model consists of multi-layer shell elements with the vertical and transverse reinforcement included as smeared rebar layers. The concrete layers implement a damage mechanism with smeared crack constitutive model, whereas the rebar layers consider a uniaxial plasticity material law. The parametric FE model is used to build a large database of RC walls of different sizes and characteristics, with their corresponding lateral load capacity that is obtained through the detailed non-linear pushover analysis. Finally, the obtained database is used to train and validate the ANN-surrogate model. The developed model is able to accurately predict the lateral load capacity of RC shear walls without the need of detailed FE modeling, thus drastically reducing the complexity and the computational time required for the numerical solution and providing a reliable and robust analysis alternative, with only small compromise of accuracy.

Abstract