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RISS 인기검색어
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- 저자 : E. Bojórquez (검색결과 4 건)
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Demands and distribution of hysteretic energy in moment resistant self-centering steel frames
Arturo López-Barraza,Sonia E. Ruiz,Alfredo Reyes-Salazar,Edén Bojórquez 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.5
Post-tensioned (PT) steel moment resisting frames (MRFs) with semi-rigid connections (SRC) can be used to control the hysteretic energy demands and to reduce the maximum inter-story drift (<i>γ</i>). In this study the seismic behavior of steel MRFs with PT connections is estimated by incremental nonlinear dynamic analysis in terms of dissipated hysteretic energy (<i>E<sub>H</sub></i>) demands. For this aim, five PT steel MRFs are subjected to 30 long duration earthquake ground motions recorded on soft soil sites. To assess the energy dissipated in the frames with PT connections, a new expression is proposed for the hysteretic behavior of semi-rigid connections validated by experimental tests. The performance was estimated not only for the global <i>E<sub>H</sub></i> demands in the steel frames; but also for, the distribution and demands of hysteretic energy in beams, columns and connections considering several levels of deformation. The results show that <i>E<sub>H</sub></i> varies with <i>γ</i>, and that most of <i>E<sub>H</sub></i> is dissipated by the connections. It is observed in all the cases a log-normal distribution of <i>E<sub>H</sub></i> through the building height. The largest demand of <i>E<sub>H</sub></i> occurs between 0.25 and 0.5 of the height. Finally, an equation is proposed to calculate the distribution of <i>E<sub>H</sub></i> in terms of the normalized height of the stories (<i>h</i>/<i>H</i>) and the inter-story drift.
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Energy-based damage index for steel structures
E. Bojórquez,A. Terán-Gilmore,S.E. Ruiz,A. Reyes-Salazar 국제구조공학회 2010 Steel and Composite Structures, An International J Vol.10 No.4
Ample research effort has been oriented into developing damage indices with the aim of estimating in a reasonable manner the consequences, in terms of structural damage and deterioration, of severe plastic cycling. Although several studies have been devoted to calibrate damage indices for steel and reinforced concrete members; currently, there is a challenge to study and calibrate the use of such indices for the practical evaluation of complex structures. The aim of this paper is to introduce an energy-based damage index for multi-degree-offreedom steel buildings that accounts explicitly for the effects of cumulative plastic deformation demands. The model has been developed by complementing the results obtained from experimental testing of steel members with those derived from analytical studies regarding the distribution of plastic demands on several steel frames designed according to the Mexico City Building Code. It is concluded that the approach discussed herein is a promising tool for practical structural evaluation of framed structures subjected to large energy demands.
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Response transformation factors for deterministic-based and reliability-based seismic design
Edén Bojórquez,Juan Bojórquez,Sonia E. Ruiz,Alfredo Reyes-Salazar,Juan Velázquez-Dimas 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.6
One of the main requirements of the seismic design codes must be its easy application by structural engineers. The use of practically-applicable models or simplified models as single-degree-offreedom (SDOF) systems is a good alternative to achieve this condition. In this study, deterministic and probabilistic response transformation factors are obtained to evaluate the response in terms of maximum ductility and maximum interstory drifts of multi-degree-of-freedom (MDOF) systems based on the response of equivalent SDOF systems. For this aim, five steel frames designed with the Mexican City Building Code (MCBC) as well as their corresponding equivalent SDOF systems (which represent the characteristics of the frames) are analyzed. Both structural systems are subjected to ground motions records. For the MDOF and the simplified systems, incremental dynamic analyses IDAs are developed in first place, then, structural demand hazard curves are obtained. The ratio between the IDAs curves corresponding to the MDOF systems and the curves corresponding to the simplified models are used to obtain deterministic response transformation factors. On the other hand, demand hazard curves are used to calculate probabilistic response transformation factors. It was found that both approaches give place to similar results.
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Seismic response estimation of steel buildings with deep columns and PMRF
Alfredo Reyes-Salazar,Manuel E. Soto-López,José R. Gaxiola-Camacho,Edén Bojórquez,Arturo Lopez-Barraza 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.4
The responses of steel buildings with perimeter moment resisting frames (PMRF) with medium size columns (W14) are estimated and compared with those of buildings with deep columns (W27), which are selected according to two criteria: equivalent resistance and equivalent weight. It is shown that buildings with W27 columns have no problems of lateral torsional, local or shear buckling in panel zone. Whether the response is larger for W14 or W27 columns, depends on the level of deformation, the response parameter and the structural modeling under consideration. Modeling buildings as two-dimensional structures result in an overestimation of the response. For multiple response parameters, the W14 columns produce larger responses for elastic behavior. The axial load on columns may be significantly larger for the buildings with W14 columns. The interstory displacements are always larger for W14 columns, particularly for equivalent weight and plane models, implying that using deep columns helps to reduce interstory displacements. This is particularly important for tall buildings where the design is usually controlled by the drift limit state. The interstory shears in interior gravity frames (GF) are significantly reduced when deep columns are used. This helps to counteract the no conservative effect that results in design practice, when lateral seismic loads are not considered in GF of steel buildings with PMRF. Thus, the behavior of steel buildings with deep columns, in general, may be superior to that of buildings with medium columns, using less weight and representing, therefore, a lower cost.
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