• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.231-238
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• 2003

The overstrength factor and the ductility factor are the two important factors that determines response modification factors used in current seismic codes. The objective of this paper is to obtain the overstrength and ductility factors of special concentric braced frames. For this purpose pushover analysis is performed with model structures until the maximum inter-story drift reaches 2.5% of story height. According to the analysis results, the overstrength factors increase as the height of structures decreases and the span length increases. Ductility factors for mid-story structures turns out to be higher than the other structures and span length does not contribute much to ductility factors.

• International Journal of Concrete Structures and Materials
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• v.10 no.3
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• pp.355-371
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• 2016

In this study seismic performance of reinforced concrete staggered wall system structures were investigated and their behavior factors such as overstrength factors, ductility factors, and the response modification factors were evaluated from the overstrength and ductility factors. To this end, 5, 9, 15, and 25-story staggered wall system (SWS) structures were designed and were analyzed by nonlinear static and dynamic analyses to obtain their nonlinear force-displacement relationships. The response modification factors were computed based on the overstrength and the ductility capacities obtained from capacity envelopes. The analysis results showed that the 5- and 9-story SWS structures failed due to yielding of columns and walls located in the lower stories, whereas in the 15- and 25-story structures plastic hinges were more widely distributed throughout the stories. The computed response modification factors increased as the number of stories decreased, and the mean value turned out to be larger than the value specified in the design code.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.201-208
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• 2006

This study lotuses on the seismic behavior of 3-, 9-, and 20-story steel moment resisting frame (MRF) structures designed in accordance with the 2000 International Building Code using different Response Modification factors (R factors) 8, 9, 10, 11, and 12. For a detailed case study, 30 different structures were evaluated for twenty ground motions representing the hazard level which is equal to a 2% probability exceeding in 50 years (2% in 50 years). The results showed that the current R factors provide conservative designs for the 3- and 9-story buildings for the Collapse Prevention performance objective. However, the 20-story buildings designed without using the minimum requirement of spectral acceleration CS prescribed in the IBC 2000 did not satisfy the seismic performance for Collapse Prevention performance.

• Structural Engineering and Mechanics
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• v.71 no.4
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• pp.377-390
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• 2019

A method for estimating the floor response spectra (FRS) of elastic structures under earthquake excitations is proposed. The method is established based on a previously proposed direct estimation method for single degree of freedom systems, which generally overestimates the FRS of a structure, particularly in the resonance period range. A modification factor is introduced to modify the original method; the modification factor is expressed as a function of the period ratio and is determined through regression analysis on time history analysis results. Both real and artificial ground motions are considered in the analysis, and it is found that the modification factors obtained from the real and artificial ground motions are significantly different. This suggests that the effect of ground motion should be considered in the estimation of FRS. The modified FRS estimation method is further applied to a 10-story building structure, and it is verified that the proposed method can lead to a good estimation of FRS of multi-story buildings.

• Journal of Engineering Education Research
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• v.18 no.6
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• pp.64-69
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• 2015

A video-work story analysis system based on emotional state measurement includes a content provision unit which provides story content of a video-work, a display unit which displays content provided by the content provision unit, an emotional state measurement unit which measures a tense-relaxed emotional state of a viewer viewing the displayed story content, a story pattern analysis unit which analyzes the tense-relaxed emotional state measured from the emotional state measurement unit according to a scene in the story content provided by the content provision unit, and a story pattern display unit which prints out an analysis result or displays the analysis result as an image. The emotional state measurement unit measures a tense or relaxed emotional state through one or more analyses among a brainwave analysis, a vital sign analysis, or an ocular state analysis. A writer may obtain support in an additional scenario modification work, and an investor may obtain support in making a decision through the above description. Furthermore, the video-work story analysis system and analysis method based on emotional state measurement may extract a particular pattern with respect to a change in an emotional state of a viewer, compile statistics, and analyze a correlation between a story and an emotional state.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.29-37
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• 2002

The purpose of this study is to provide a fundamental data of earthquake resistant design through the estimation of the response modification factor and nonlinear displacement for moment resisting reinforced concrete frames by linear and nonlinear static analysis. The analysis models are designed in accordance with AIK code and then, estimated the response modification factor and nonlinear displacement of the buildings. The parameters such as story numbers(10, 20, 30), plan ratios(1:1, 1:2) and analysis types(2D, 3D) of building structure are chosen for use in this study. After comparing the results of linear and nonlinear static analysis, the response modification factor is obtained as the product of four factors: ductility factor, strength factor, damping factor and redundancy factor. The response modification factor are close to 3.5 in case of 2 span, 4.3 in case of 3 span and 5.0 in case 4 or more span models regardless number of stories and plan ratios. The nonlinear displacement is evaluated from the ratio of story drift angle(nonlinear drift/linear drift). The ratio of story drift angle increases as story numbers increase and the value varies from 5.85 to 9.34.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.1
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• pp.39-48
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• 2011

In this present study, a response modification factor for a lightweight steel panel-modular system which is not clarified in a current building code was proposed. As a component of the response modification factor, an over-strength factor and a ductility factor were drawn from the nonlinear static analysis curves of the systems modeled on the basis of the performance tests. The final response modification factor was then computed by modifying the previous response modification factor with a MDOF (Multi-Degree-Of-Freedom) base shear modification factor considering the MDOF dynamic behaviors. As a result of computation for the structures designed as a dual frame system, ranging from 2-story to 5-story, the value of 4 was estimated as a final response modification factor for a seismic design, considering the value of 5 as an upper limit of the number of stories.

• Earthquakes and Structures
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• v.5 no.1
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• pp.23-48
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• 2013

In this study, the effect of flexibility of superstructures and nonlinear characteristics of LRB (Lead Rubber Bearing) isolator on inelastic response of base isolated structures is investigated. To demonstrate the intensity of damage in superstructures, demand response modification factor without the consideration of damping reduction factor, demand RI, is used and the N2 method is applied to compute this factor. To evaluate the influence of superstructure flexibility on inelastic response of base isolated structures, different steel intermediate moment resisting frames with different heights have been investigated. In lead rubber bearing, the rubber provides flexibility and the lead is the source of damping; variations of aforementioned characteristics are also investigated on inelastic response of superstructures. It is observed that an increase in height of superstructure leads to higher value of demand RI till 4-story frame but afterward this factor remains constant; in other words, an increase in height until 4-story frame causes more damage in the superstructure but after that superstructure's damage is equal to the 4-story frame's. The results demonstrate that the low value of second stiffness (rubber stiffness in LRBs) tends to show a significant decrease in demand RI. Increase in value of characteristic strength (yield strength of the lead in LRBs) leads to decrease in the demand RI.

• Earthquakes and Structures
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• v.12 no.6
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• pp.643-652
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• 2017

One of the methods to strengthen the structures against the seismic lateral loading is the employment of the composite columns. A concrete-filled tube (CFT) has the cumulative advantages of steel and concrete. Concrete-filled steel tube columns have been widely used in the moment-resisting frame (MRF) structures, located in both non-seismic zones and high-risk seismic zones. In this paper, the results of studies on two important seismic parameters of ductility and the response modification factor (RMF) of the MRFs with CFT columns are submitted. While the studies are carried out, the effects of span length-story height ratio, the strength of materials and seismic behavior of MRFs are considered. In this regard, the ductility, RMF and the strength of 36 models of the steel MRFs with CFTs are analyzed. The fiber plastic hinges numerical simulation and pushover analysis method are used in the calculations. Based on the obtained results, the RMFs suitable for the 5-, 10- and 15- story frames are proposed.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.585-596
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• 2006

This study focuses on the seismic behavior of 3-, 9-, and 20-story steel moment resisting frame (MRF) structures designed in accordance with the 2000 International Building Code using different Response Modification factors (R factors), i.e., 8, 9, 10, 11, and 12. For a detailed case study, 30 different structures were evaluated for 20 ground motions representing the hazard level, which is equal to a 2% probability in 50 years (2% in 50 years). The results showed that the current R factors provide conservative designs for the 3- and 9-story buildings for the Collapse Prevention performance objective. the 20-story buildings, which were designed without using the minimum requirement of spectral acceleration CS prescribed in IBC 2000, did not satisfy the seismic performance for Collapse Prevention performance.