Multi-objective Performance-Based Design Optimization of a Controlled Rocking Steel Braced Frame System

Author(s):  
Henry V. Burton ◽  
Ji Yun Lee ◽  
Saber Moradi ◽  
Shahrzad Dastmalchi
2017 ◽  
Vol 33 (4) ◽  
pp. 1533-1554 ◽  
Author(s):  
Mehrdad Shokrabadi ◽  
Henry V. Burton

This paper investigates the effectiveness of various ground motion intensity measures (IMs) in estimating the structural response of two types of rocking systems: (a) a controlled rocking steel braced frame system with self-centering action and (b) a rocking spine system for reinforced concrete infill frames. The IMs are evaluated based on the dispersion in engineering demand parameter (EDP) predictions (efficiency) and the sensitivity of the conditional distributions of EDPs to the distributions of the magnitudes, distances and spectral shape parameter (ε) of ground motion records (sufficiency). The EDPs include maximum transient and residual story drifts and peak floor accelerations. The spectral acceleration averaged over a range of periods (Sa avg) is most effective for predicting transient and residual drift demands and peak ground acceleration (PGA) is generally the best predictor of peak floor accelerations. The proximity of the frequency range most affecting an EDP to that best reflected in an IM is found to be a good indicator of the performance of that IM.


2014 ◽  
Vol 43 (11) ◽  
pp. 1725-1742 ◽  
Author(s):  
Matthew R. Eatherton ◽  
Jerome F. Hajjar

2022 ◽  
pp. 136943322110509
Author(s):  
Maryam Hafezi ◽  
Armin Aziminejad ◽  
Mohammad Reza Mansoori ◽  
Mahmood Hosseini ◽  
Abdolreza Sarvghad Moghadam

Self-centering controlled rocking steel braced-frame (SC-CR-SBF) is proposed as an earthquake-resistant system with low damage. Pre-stressed vertical strands provide a self-centering mechanism in the system and energy absorbing fuses restrict maximum displacement. Presence of asymmetry in structures can highlight the advantages of employing this structural system. Moreover, these days designing and constructing asymmetric and irregular structures is inevitable and as a result of architectural attractiveness and requirements of different functions of buildings, they are of great importance. Consequently, in these types of structures in order to minimize seismic responses, particular measures should be taken into consideration. Proper distribution of strength and stiffness throughout the plan of structures with self-centering systems can play a considerable role in resolving problems associated with asymmetry in these structures. In this study, the asymmetric buildings with 10% and 20% mass eccentricities and having different arrangements of centers were simulated. The models were analyzed under a set of 22 bidirectional far-field ground-motion records and corresponding responses of maximum roof drift, acceleration and rotation of the roof diaphragms of the structures with different arrangements of the center of mass, stiffness and strength were computed and studied. Results show that proper distribution of stiffness and strength throughout the plan of the structures with SC-CR-SBF system reduces the maximum roof drift as well as the rotation of the roof diaphragm. With appropriate arrangement of the centers, maximum drift response of the asymmetric structure decreases as much as roughly 20% and the ratio of the maximum drift response of the asymmetric structure to the response of the similar symmetric structure with the same overall stiffness and strength was 1.1. In other words, maximum drift response of the asymmetric structure with SC-CR-SBF system is acceptably close to the one for the symmetric building.


2021 ◽  
Vol 151 ◽  
pp. 106977
Author(s):  
Mohammad Gholami ◽  
Elnaz Zare ◽  
Mojtaba Gorji Azandariani ◽  
Reza Moradifard

2014 ◽  
Vol 540 ◽  
pp. 197-200
Author(s):  
Chang Jiao Hu ◽  
Xin Wu Wang

With the purpose of comprehending the seismic performance of steel-braced frame system better and more comprehensivly, the paper overviewed and summarized the hysteretic performance,ductility and energy dissipation performance of the steel-braced frame based on a large number of abroad documents.The force was on the seismic performance of steel-braced frame in different supporting forms and the insufficiency in the research.


2020 ◽  
Vol 5 (1) ◽  
pp. 40-50
Author(s):  
Kashif Salman ◽  
Dookie Kim ◽  
Ataullah Maher ◽  
Abdul Latif

Author(s):  
J. Schiffmann

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.


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