• Structural Engineering and Mechanics
• /
• 제59권5호
• /
• pp.821-840
• /
• 2016

A simple design process is proposed for supplemental viscous dampers based on structural safety redundancy. In this process, the safety redundancy of the primary structure without a damper is assessed by the capacity and response spectra. The required damping ratio that should be provided by the supplemental dampers is estimated by taking the structural safety redundancy as a design target. The arrangement of dampers is determined according to the drift distribution obtained by performing pushover analysis. A benchmark model is used to illustrate and verify the validity of this design process. The results show that the structural safety redundancy of the structure provided by the viscous dampers increases to approximately twice that of the structure without a damper and is close to the design target. Compared with the existing design methods, the proposed process can estimate the elastic-plastic response of a structure more easily by using static calculation, and determine the required damping ratio more directly without iterative calculation or graphical process. It can be concluded that the proposed process is simple and effective.

• Structural Engineering and Mechanics
• /
• 제59권1호
• /
• pp.15-36
• /
• 2016

The components of the seismic behavior factor of RC frames are expected to change as structural redundancy increases. Most researches indicate that increasing redundancy is desirable in response to stochastic events such as earthquake loading. The present paper investigated the effect of redundancy on a fixed plan for seismic behavior factor components and the nonlinear behavior of RC frames. The 3D RC moment resistant frames with equal lateral resistance were designed to examine the role of redundancy in earthquake-resistant design and to distinguish it from total overstrength capacity. The seismic behavior factor and dynamic behavior of structures under natural strong ground motions were numerically evaluated as the judging criteria for structural seismic behavior. The results indicate that increasing redundancy alone in a fixed plan cannot be defined as a criterion for improving the structural seismic behavior.

• Computational Structural Engineering : An International Journal
• /
• 제1권2호
• /
• pp.137-137
• /
• 2001

The reliability/redundancy of structural system has become a serious concern among engineers and researchers after structural failures in Northridge and Kobe earthquakes. The reliability/redundancy factor, ρ, in current codes considers only member force and floor area and has received much criticism from dissatisfied engineers. Within a reliability framework. the redundancy is investigated for dual systems of primary shear walls and secondary moment frames and steel moment frame systems. Probabilistic performance analyses are carried out baled on nonlinear responses under SAC ground motion. The effects of structural configuration, ductilily capacity, 3-D motion, and uncertainty of demand verses capacity are investigated. Important redundancy-contributing factors are identified and a uniform-risk redundancy factor is developed for design. The result are compared with the p factor and its inconsistency is pointed out.

• 대한조선학회논문집
• /
• 제52권2호
• /
• pp.161-169
• /
• 2015

According to SOLAS Regulation XII/6.5.3 and IMO GBS functional requirement(IMO, 2010), the structural redundancy of multi-bay stiffened panel in cargo area of bulk carrier should be provided enough in order to endure the initial design load though one bay of the stiffened panel is damaged due to plastic deformation or fatigue crack. To satisfy structural redundancy, Harmonized Common Structural Rules (hereinafter CSR-H, IACS, 2014) proposed to use 1.15 instead of 1.0 for buckling usage factor of stiffened panel in cargo area. This paper shows that buckling usage factor in CSR-H for structural redundancy is somewhat conservative considering the ultimate strength calculated by using nonlinear FEA for the damaged condition which is only one bay's plastic deformation due to colliding by weigh object like a bucket. Also, this paper presents that increasing of plate thickness only is more effective to get enough structural redundancy.

• Earthquakes and Structures
• /
• 제8권5호
• /
• pp.995-1016
• /
• 2015

The reliability or the safety index is a measure of how far a structure is from the state of collapse. Also it defined as the probability that a structure will not fail in its lifetime. Having any increase in the reliability index is typically interpreted as increasing in the safety of structures. On the other hand most of researchers acknowledged that one of the most effective means of increasing both the reliability and the safety of structures is to increase the structural redundancy. They also acknowledged that increasing the number of vertical seismic framing will make structural system more reliable and safer against stochastic events such as earthquakes. In this paper the reliability index and the behavior factor of a numbers of three dimensional RC moment resisting frames with the same story area, equal lateral resistant as well as different redundancy has been evaluated numerically using both deterministic and probabilistic approaches. Study on the reliability index and the behavior factor in the case study models of this research illustrated that the changes of these two factors do not have always the same manner due to the increasing of the structural redundancy. In some cases, structures with larger reliability index have smaller behavior factor. Also assuming the same ultimate lateral resistance of structures which causes an increase to a certain level of redundancy can enhance behavior factor of structures. However any further increase in the redundancy of that certain level might decrease the behavior factor. Furthermore, the results of this study illustrate that concerning any increase in the structural redundancy will make the reliability index of structure to be larger.

• 한국정보과학회논문지:데이타베이스
• /
• 제32권2호
• /
• pp.177-192
• /
• 2005

본 논문에서는 XML 데이타를 릴레이션으로 분할 저장할 경우, 분할된 XML 데이타로부터 질의 결과 XML 문서를 재구성하는데 소모되는 질의 처리비용을 줄이기 위한 구조적 중복 방법을 소개한다. 기본 아이디어는 주어진 질의 패턴을 분석하여, 적절한 데이타들을 중복시킴으로서 질의 처리 성능을 향상시키는 것이다. 이러한 구조적 중복 방법으로 실질적으로 유효할 수 있는 ID, VALUE, SUBTREE의 세 가지 유형의 특성을 분석하였다. 본 논문에서는 추가적으로 주어진 XML 데이타와 질의들이 매우 크고 복잡할 경우 최적의 중복 집합을 팎는 것이 매우 어려운 작업이 될 수 있으므로, 이를 위한 경험적 탐색 방법을 소개한다. 마지막으로 몇 가지 실험을 통하여, 중복 데이타를 사용함으로 발생하는 XML 질의 처리비용과 제안된 탐색 방법의 효율성을 분석한다. 중복 데이타를 사용함으로 XML 판독 질의는 빨라지지만, XML 갱신 질의는 중복 데이타의 갱신 일관성 비용 때문에 느려지는 것은 당연하다. 하지만 실험 결과는 매우 과도한 갱신 비용의 경우에도 in-place ID 중복은 효율적이며, 갱신 비용이 매우 과도하지만 않다면 multiple-place SUBTREE 중복은 판독 질의 처리 성능을 크게 향상시킬 수 있음을 보여주었다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1993년도 가을 학술발표회논문집
• /
• pp.240-247
• /
• 1993

The precise prediction of reserved carrying capacity of bridge as a system is extremely difficult especially when the bridges are highly redundant and significantly deteriorated or damaged. This paper is intended to propose a new approach for the evaluation of reserved system carrying capacity of bridges in terms of equivalent system-strength, which may be defined as a bridge system-strength corresponding to the system reliability of the bridge. This can be derived from an inverse process based on the concept of FOSM form of system reliability index. It may be emphasized that this approach is very useful for the evaluation of the deterministic system redundancy and reserve strength which are measured in terms of either probabilistic system redundancy factor and reserve factor or deterministic system redundancy factor and reserve factor. The system reliability of bridges is formulated as a parallel-series model obtained from the FAM(Failure Mode Approach) based on the major failure mechanisms. AFOSM and IST methods are used for the reliability analysis of the proposed models. The proposed approach and method for the system redundancy and reserve safety/strength are applied to the safety assessment of actual RC and steel box-girder bridges. The results of the evaluation of reserved system safety or bridge system-strength in terms of the system redundancy and the system safety/strength are significantly different from those of element reliability-based or conventional methods.

• Structural Engineering and Mechanics
• /
• 제52권6호
• /
• pp.1177-1191
• /
• 2014

Reinforced concrete (RC) shear walls are one of the most commonly used lateral-load resisting systems in high-rise buildings. RC Parallel redundancy walls studied herein consist of two parts nested to each other. These two parts have different mechanical behaviors and energy dissipation mechanisms. In this paper, experimental studies of four 1/2-scale specimens representing this concept, which are subjected to in-plane cyclic loading, are presented and test results are discussed. Two specimens consist of a wall frame with barbell-shaped walls embedded in it, and the other two consist of a wall frame and braced walls nested each other. The research mainly focuses on the failure mechanism, strength, hysteresis loop, energy dissipation capacity and stiffness of these walls. Results show that the RC parallel redundancy wall is an efficient lateral load resisting component that acts as a "dual" system with good ductility and energy dissipation capacity. One main part absorbs a greater degree of the energy exerted by an earthquake and fails first, whereas the other part can still behave as an independent role in bearing loads after earthquakes.

• Structural Engineering and Mechanics
• /
• 제27권6호
• /
• pp.651-670
• /
• 2007

An experimental study to evaluate a redundancy capacity in simple span two plate-girder bridges, which are generally classified as a non-redundant load path structure, has been performed under the condition that one of the two girders is seriously damaged. The bottom lateral bracing was selected as an experimental parameter and two 1/5-scale bridge specimens with and without bottom lateral bracing have been prepared. The loading tests were first performed on the intact specimens without cracked girder within elastic range. Thereafter, the ultimate loading tests were conducted on the damaged specimens with an induced crack at the center of a girder. The test results showed that the cross beams and concrete deck redistributed partly the applied load to the uncracked girder, but the lateral bracing system played a significant role of the load redistribution when a girder was damaged. The redundancy was evaluated based on the test results and an appropriate redundancy level was evaluated when the lateral bracing was provided in a seriously damaged simple span two-girder steel bridge.

• Earthquakes and Structures
• /
• 제4권6호
• /
• pp.649-670
• /
• 2013

It is known that a base-isolated building exhibits a large response to a long-duration, long-period wave and an inter-connected system without base-isolation shows a large response to a pulse-type wave. To compensate for each deficiency, a new hybrid passive control system is investigated in which a base-isolated building is connected to another building (free wall) with oil dampers. It is demonstrated that the present hybrid passive control system is effective both for pulse-type ground motions and long-duration and long-period ground motions and has high redundancy and robustness for a broad range of disturbances.