• Journal of Korean Society of Steel Construction
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• v.16 no.6 s.73
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• pp.793-805
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• 2004

The main objective of this paper is to evaluate the ductility and strength factors that are key components of the response modification factor for special steel moment-resistant frames. The ductility factors for special steel moment-resistant frames were calculated by multiplying the ductility factor for SDOF systems and the MDOF modification factors. Ductility factors were computed for elastic and perfectly plastic SDOF systems undergoing different levels of inelastic deformation and periods when subjected to a large number of recorded earthquake ground motions. Based on the results of the regression analysis, simplified expressions were proposed to compute the ductility factors. Based on previous studies, the MDOF modification factors were also proposed to account for the MDOF systems. Strength factors for special steel moment resisting frames were estimated from the results of the nonlinear static analysis. A total of 36 sample steel frames were designed to investigate the ductility and strength factors considering design parameters such as number of stories (4, 8, and 16 stories), seismic zone factors (Z = 0.075, 0.2, and 0.4), framing system (Perimeter Frames, PF and Distributed Frames, DF), and failure mechanism (Strong-Column Weak Beam, SCWB, and Weak-Column Strong-Beam, WCSB). The effects of these design parameters on the ductility and strength factors for special steel moment-resisting frames were investigated.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.1
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• pp.11-18
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• 2011

The connection type of steel moment frames in the country is mostly fabricated in factories so that it is fairly ductile due to good quality control. Based on references, the domestic connection satisfies the performance limit for steel intermediate moment frames specified by the AISC. However, the current KBC2009 building code specifies various systems for steel moment frames such as ordinary, intermediate, and special moment frames while the former KBC2005 only did so for a ductile moment frame. This induces the necessity of investigating which system is appropriate in the country when the domestic connection is applied. Therefore, this study was aimed at finding a proper design method by comparing the ductile moment frame in KBC2005 and the intermediate moment frames in KBC2009. The results showed that seismic design parameters for the ductile moment frames can be reasonable for satisfying the performance objective.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.6 s.40
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• pp.13-22
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• 2004

Ductiluty factor has played an important role in seismic design as it is key component of response modification factor(R). In this stuty, ductility factors() are calculated by multiplying ductility factor for SDOF systems() and MDOF modification factors(). Ductility factors() for SDOF systems are computed from nonlinear dynamic analysis undergoing different level of displacement ductiluty demands and period when subjected to a large number of recorded earthquake ground motions. The MDOF modification factors() are proposed to account for the MDOF systems, based on previous studies. A total of 108 prototype steel frames are designed to investigate the ductility factors considering the number of stories(4, 8 and 16-stories), framing system(Perimeter Frames, PF and Distributed Frames, DF), failure mechanism(Strong-Column Weak-Beam, SCWB and Weak-Column Strong-Beam, WCSB), soil profiles(SA, SC and SE in UBC 1997) and seismic zone factors(Z=0.075, 0.2 and 0.4 in UBC 1997). It is shown that the number of stories, failure mechanisms (SCWB, WCSB), and soil profiles have great influence on the ductility factors, however, the structural system(Perimeter frames, Distributed frames), and seismic zones have no influence on the ductility factors.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.221-229
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• 2013

To find the influence of incident angle of wave on the moment of 3 storied steel moment resisting frame which is placed on the concrete rectangular pontoon, the fluid dynamic analysis is carried out, varying the period of wave from 5 to 15 second by 2 seconds. As increasing incident angle of wave to longitudinal axis, the influence of RAO-rolling is increased. The moment of longitudinal frame is increased apparently by the wave pressure when the incident angle is $0^{\circ}$. And the moment of the frame due to the wave pressure is decreased as the incident angle is increased. But the moment of frame due to acceleration caused from pitching and rolling is increased. It is shown that the increased moment when incident angle is $90^{\circ}$ is much greater than that of incident angle $0^{\circ}$.

• Journal of Navigation and Port Research
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• v.36 no.3
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• pp.215-223
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• 2012

To examine the interaction of the floating pontoon with a steel moment resisting frame, the static structural analysis is carried out, in which the pressure load are calculated from the forgoing fluid dynamic analysis, varying the period of wave from 3 to 15 second and for 3 cases of depth of pontoon, 1.5, 2.0, 2.5m. As results, it has shown that RAO-pitch has the linear relationship with the increase of moment of the frame and the curvature of pontoon is reversely proportional to the stiffness of pontoon. By synthesizing these results, an estimation method is proposed, which predicts the moment of frame of the different depth of pontoon based on the analysis result of an arbitrary depth of a floating pontoon. The estimation result shows considerably good agreement, compared with the analysis result.

• Journal of Korean Association for Spatial Structures
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• v.11 no.1
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• pp.57-66
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• 2011

For the lateral load resistance of a RC frame in a medium risk seismic zone, the strength of lower story beams and columns should be larger than those of the upper stories. However, the lateral loads can be accommodated by redistributing design beam moments vertically as well as horizontally so all beams end up with identical strengths. This paper looks at the impact of the vertical redistribution of beam moments to provide identical beam strength over as many floors as possible. Two-bay six-story RC frame was designed with and without vertical beam moment redistribution and its seismic performance were evaluated by using push-over limit analysis and by non-linear time history dynamic analysis. Analytical results show that with the use of vertical beam moment redistribution the increase in the ductility demand is similar to the proportion of moment redistribution applied, but this additional demand is below the ductility capacity of well detailed RC members.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.457-468
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• 2006

An experimental study was performed to investigate the maximum energy dissipation and the ductility capacity of shear-dominated steel plate walls with thin web plates. Three specimens of three-story plate walls with thin web plates were tested. The parameters for the test specimens were the aspect ratio of the web plate and the shear strength of the column. A concentrically braced frame and a moment-resisting frme were a also tested for comparison. The steel plate walls exhibited much better ductility and energy dissipation capacity than the concentrically braced frame and the moment-resisting frame. The results showed that unlike other structural systems, the sh as well as strength, and can therefore be used as an effective earthquake-resisting system. A method of predicting the energy dissipation capacity of a steel plate wall was proposed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.509-516
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• 2010

In this study a seismic retrofit scheme for the reinforced concrete moment framed structures was investigated using steel bracing and moment frames. The analysis model structure is a 3-story 3-bay moment frame structure designed only for gravity load. The stress/strain concentration in brace-RC frame connection was investigated using finite element analysis. To prevent premature joint failure, steel moment frames were placed inside of middle bay of the RC frame. Two types of braces, steel braces and buckling restrained braces(BRBs), were used for retrofit, and the ductility and the strength of the structure before and after the retrofit were compared using nonlinear static and dynamic analyses. According to the analysis results, the strength and ductility of the structure retrofitted by the moment frames and braces increased significantly. The added steel frame did not contribute significantly to the increase of lateral strength mainly because the size is relatively small.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.5
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• pp.1-9
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• 2007

This study summarizes the results of a research project aimed at investigating the inelastic rotation capacity of beam-column connections of reinforced concrete moment frames. A total of 91 test specimens for beam-column joint connections were examined in detail, and 28 specimens were classified as special moment frame connections based on the design and detailing requirements in the ACI 318-02 Provisions. Then the acceptance criteria, originally defined for steel moment frame connections in the AISC-02 Seismic Provisions, were used to evaluate the joint connections of concrete moment frames. Twenty-seven out of 28 test specimens that satisfy the design requirements for special moment frame structures provide sufficient strength and are ductile up to a plastic rotation of 0.03 rad. without any major degradation in strength. Joint shear stress, column-to-beam flexural strength ratio, and transverse reinforcement ratio in a joint all play a key role in good performance of the connections.

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.261-269
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• 2003

The length of the links in an eccentrically braced frame will dictate the behavior of the frame. Link length controls the yielding mechanism and the ultimate failure mode. For short links, the links' shear forces reach the plastic shear capacity before the end moments reach the plastic moment capacity, and the links yields in the shear, forming a shear hinges. These links are termed "shear links." For long links, the end moments reach the plastic moment capacity before the links' shear forces reach the plastic shear capacity, forming moment hinges. These links are termed moment links." In long links, flexural yielding dominates the response, and very high bending strains are required at the link ends to produce large link deformations. In a shear links, the shear force is constant along the length of the links, and the inelastic shear strain are is uniformly distributed over the length of the links. This permits the development of large inelastic link deformations without the development of excessively high local strains. However, The use of eccentrically braced steel frames for the purpose of architectural cionsiderations such as openings and doors, areis dictating the use of longer links, though. Little data areis available on the behavior of long links under cyclic loading conditions. In This paper documents the results of an experimental program is that was conducted to assess the response of moment links in eccentrically braced frames. Sixteen specimens awere tested using a cyclic load.