Assessment of seismic response reduction factor for moment resisting RC frames
01 Nov 2017-Vol. 263, Iss: 3, pp 032034
About: The article was published on 2017-11-01 and is currently open access. It has received 6 citations till now. The article focuses on the topics: Moment (mathematics).
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01 Jan 2021
TL;DR: In this paper, the authors evaluated the nonlinear response of reinforced concrete (RC) frames with two types of brick infills viz., unreinforced brick masonry infill (URM) and semi-interlocked bricks masonry (SIM) together with lintel beams, subjected to seismic loads.
Abstract: The primary focus of this study is to evaluate the nonlinear response of reinforced concrete (RC) frames with two types of brick infills viz., unreinforced brick masonry infill (URM) and semi-interlocked brick masonry infill (SIM) together with lintel beams, subjected to seismic loads. The seismic response is quantified in terms of response reduction factor and base shear. Infill walls are modeled using double strut nonlinear cyclic element. Nonlinear static adaptive pushover analysis is performed in the finite element program SeismoStruct. The response reduction factor (R) is computed from adaptive pushover analysis and performance for all models is obtained. The results showed that the average R factor of the RC framed structure with semi-interlocked masonry (SIM) is 1.31 times higher than the RC frame with unreinforced masonry (URM) infill. The R value of the bare frame with the lintel beam is found to be less than the corresponding value recommended in the Indian Standard Code. The results obtained in this study highlight that if the impacts of lintel beams and various brick infill scenarios are considered in the RC frames then the R values used for the design of RC frame buildings with infills would be underestimated (i.e., the evaluated R values are greater than the R values used for the design purpose).
8 citations
TL;DR: In this paper , a high-rise G+10-storey L-shaped building is considered, and different R factors were used in the building design, considering buildings subjected to both unidirectional and bidirectional seismic loading scenarios.
Abstract: Several design codes consider the non-linear response of a building by using one of the most important seismic parameters, called the response reduction factor (R). The lack of a detailed description of the R factor selection creates the need for a deeper study. This paper emphasises a methodology for the selection of a proper R factor based on resilience aspects. Unsymmetrical/irregular buildings have become the most common in recent times due to aesthetic purposes. However, because of the complexity due to the torsional effect, the selection of the R factor is even more difficult for this type of building. Therefore, a high-rise G+10-storey L-shaped building is herein considered. The building has re-entrant corners based on the structural/plan arrangement. Different R factors were used in the building design, considering buildings subjected to both unidirectional and bidirectional seismic loading scenarios. The building response with respect to various R factors (R equal to 3, 4, 5 and 6) in terms of its performance level, functionality, damage ratio and resilience was assessed at two design levels, i.e., design basic earthquake (DBE) and maximum considered earthquake (MCE). The study concludes that, considering the above criteria along with the resilience aspect, a maximum R factor up to 4 can be recommended for unidirectional loading, whereas for bidirectional loading, the maximum recommended R factor is 3.
5 citations
23 Oct 2018
4 citations
Cites background or methods from "Assessment of seismic response redu..."
...For a structural system, over strength factor (Ro) vary as a function of seismic zone and building period [13]....
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...[13] examined the response reduction factors for moment resisting RC frames designed according to Indian codes....
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TL;DR: In this article , a high-rise building with multiple response reduction factors (R = 3, 4, 5, and 6) was developed and five potential recovery paths (RP-1 to RP-5) that matched the realistic scenario were used to estimate the building's functionality.
Abstract: The selection of an adequate response reduction factor (R) in the seismic design of a reinforced concrete building is critical to the building’s seismic response. To construct a robust structure, the R factor should be chosen based on the building’s resilience performance. Since no background was provided for the selection of R factors, the study focuses on the right selection of R factors in relation to the building’s functionality, performance level, and resilience. In this study, a high-rise building with multiple R factors (R = 3, 4, 5, and 6) is developed. Five potential recovery paths (RP-1 to RP-5) that matched the realistic scenario were used to estimate the building’s functionality. The building was subjected to uni and bi-directional loadings, and two design levels, Design Basic Earthquake (DBE) and Maximum Considered Earthquake were used to monitor the building’s response. According to the findings, a decrease in the lateral design force with the highest R results in a high ductility requirement and a substantial loss of resilience. The maximum R factor can be recommended under uni-directional loading up to 6, in which the building’s resilience is almost 50%, whereas under bi-directional loading and taking the recommended R factor decreased from 6 to 4.
3 citations
TL;DR: In this paper , a high-rise building was designed with various response reduction factors (R = 3, 4, 5, and 6) to estimate the building's functionality, five different recovery paths (RP-1 to RP-5), which match the real scenario, were used.
Abstract: In the seismic design of a reinforced concrete building, selecting appropriate response reduction factor (R) is vital for the building’s seismic response. Indian Standard (IS) 1893-2016 provides R values of 3 and 5 for ordinary moment resisting frames and special moment resisting frames, respectively. As R factors are used to incorporate the building’s non-linearity, R factor selection should be based on the building’s performance in terms of resilience. Since IS does not provide any clause on the background for selecting R factors for the design aspects, the study emphasizes the appropriate selection of R factors with respect to a building’s functionality, performance level, and resilience. In this study, a high-rise building was designed with various R factors (R = 3, 4, 5, and 6). To estimate the building’s functionality, five different recovery paths (RP-1 to RP-5), which match the real scenario, were used. The response of the building in each case was observed at two design levels, Design Basic Earthquake (DBE) level and MCE level. Variations in ductility demand, performance level, and resilience for each building case at each design level were observed. The R factor was used to obtain lateral design force at the DBE level by reducing the actual base shear placed on the structure. The reduction in the lateral design force with maximum R yielded high ductility demand and high loss of resilience. The result shows that the considered building can be designed with a maximum R of 6 since its resilience is almost 50%; hence, recovery is possible at a high cost. The performance level of the building at R = 6 lies at CP-C for the MCE design level. Considering the building’s resilience and performance level aspects, the maximum R factor was found to be 6. This helps the stakeholder and designer in the selection of R, based on the requirements of building functionality, performance level, and resilience.
2 citations
References
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27 Mar 1992
TL;DR: In this paper, the causes and effects of earthquakes: Seismicity, Structural Response, Seismic Action, and Seismical Action in Member Design principles of member design.
Abstract: Causes and Effects of Earthquakes: Seismicity--Structural Response--Seismic Action. Principles of Member Design. Reinforced Concrete Ductile Frames. Structural Walls. Dual Systems. Masonry Structures. Reinforced Concrete Buildings with Restricted Ductility. Foundation Structures. Appendices. Symbols. References. Index.
3,086 citations
TL;DR: The main parameters that affect the magnitude of strength reductions are discussed in this paper, and the evaluation of the results indicates that strength reduction are primarily influenced by the maximum tolerable displacement ductility demand, the period of the system and the soil conditions at the site.
Abstract: Strength reduction factors which permit estimation of inelastic strength demands from elastic strength demands are evaluated. Results from various investigations of strength reduction factors carried out over the last 30 years are reviewed, and their results are presented in a common format which facilitates their comparison. The main parameters that affect the magnitude of strength reductions are discussed. The evaluation of the results indicates that strength reductions are primarily influenced by the maximum tolerable displacement ductility demand, the period of the system and the soil conditions at the site. Simplified expressions of strength reduction factors to estimate inelastic design spectra as functions of these primary‐influencing parameters are presented.
570 citations
01 Jan 1993
152 citations
TL;DR: In this paper, the response modification factor plays a key role in the seismic design of new buildings in the United States, and the values assigned to this factor are based on engineering judgment and have little sound technical basis.
Abstract: The response modification factor plays a key role in the seismic design of new buildings in the United States. To date, the values assigned to this factor are based on engineering judgment and have little sound technical basis. Any improvement in the reliability of modern earthquake-resistant buildings in the United States will require the systematic evaluation of the building response characteristics that most affect the values assigned to the factor. To this end, a draft formulation that represents the response modification factor as the product of factors related to reserve strength, ductility, and redundancy is presented in the paper. Pertinent data from various analytical and experimental studies on reserve strength and ductility are also presented.
105 citations