• International Journal of High-Rise Buildings
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• v.3 no.2
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• pp.121-145
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• 2014

The story shear force distributions of most seismic design codes generally reflect the influences of higher vibration modes based on the elastic deformations of structures. However, as the seismic design allows for the plastic behavior of a structure, the story shear force distribution shall be effective after it is yielded due to earthquake excitation. Hence this study conducted numerical analyses on the story shear force distributions of most seismic design codes to find out the characteristics of how a structure is damaged between stories. Analysis results show that the more forces are distributed onto high stories, the lower its concentration is and the more energy is absorbed. From the results, this study proposes the optimum story shear force distribution and its calculation formula that make the damages uniformly distributed onto whole stories. Consequently, the story damage distribution from the optimum calculation formula was considerably more stable than existing seismic design codes.

• Structural Engineering and Mechanics
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• v.76 no.3
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• pp.311-324
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• 2020

Until now, a comparative study on fully and partially-connected steel shear walls leading to enhancing strength and stiffness reduction of partially-connected steel plate shear wall structures has not been reported. In this paper a number of 4-story and 8-story steel plate shear walls, are considered with three different connection details of infill plate to surrounding frame. The specimens are modeled using nonlinear finite element method verified excellently with the experimental results and analyzed under monotonic loading. A comparison between initial stiffness and shear strength of models as well as percentage of shear force by model boundary frame and infill plate are performed. Moreover, a comparison between energy dissipation, ductility factor and distribution of Von-Mises stresses of models are presented. According to the results, the initial stiffness, shear resistance, energy dissipation and ductility of the models with beam-only connected infill plates (SSW-BO) is found to be about 53%, 12%, 15% and 48% on average smaller than those of models with fully-connected infill plates (SPSW), respectively. However, performance characteristics of semi-supported steel shear walls (SSSW) containing secondary columns by simultaneously decreasing boundary frame strength and increasing thickness of infill plates are comparable to those of SPSWs. Results show that by using secondary columns as well as increasing thickness of infill plates, the stress demands on boundary frame decreases substantially by as much as 35%. A significant increase in infill plate share on shear capacity by as much as 95% and 72% progress for the 4-story SSW-BO and 8-story SSSW8, respectively, as compared with non-strengthened counterparts. A similar trend is achieved by strengthening secondary columns of 4-story SSSW leading to an increase of 50% in shear force contribution of infill plate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.578-581
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• 2007

In this study, the seismic control performance of energy dissipation devices installed in a shear all-frame structure is investigated through nonlinear time history analysis of a 12-story building. Inelastic shear walls are modeled using the multiple vertical line element model (MVLEM) and inelastic columns and girders were modeled using fiber beam elements. For a seismic load increased by 38% compared to the design load, the seismic control performance was analyzed based on the results of a nonlinear time history analysis in terms of the inter-story drift, the story shear and the flexural strain. Friction type dampers was found to performs best if they are installed in the form of a brace adjacent to the shear wall with the friction force of 15 % of the maximum story shear force induced in the original building structure without dampers.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.4
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• pp.191-199
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• 2016

Piloti-type building is one of typical vertical atypical buildings. These buildings can fail by weak-story or flexible-story mechanism on the first story. They should be designed by taking into account the special seismic load, but those less than six stories are not required to confirm the seismic performance from structural engineers in Korea. For this reason, small-size pilloti-type RC buildings need to be checked for seismic performance. Based on this background, this study performed nonlinear dynamic analysis using the PERFORM-3D for small-size pilloti-type RC buildings and assessed their seismic performance. Examples are two through four story buildings with and without walls in the first story. The walls and columns in the first story satisfied the target performance in the basic of flexural behavior due to quite a large size and reinforcement. However, wall shear demands exceed shear strength in some buildings. When designed for KBC2009, wall shear strength exceed shear demand in some buildings, but still does not in others. Consequently, wall shear must be carefully checked in both existing and new small-size pilloti-type RC buildings.

• Earthquakes and Structures
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• v.17 no.1
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• pp.63-73
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• 2019

This paper studies damage detection as an optimization problem. A new objective function based on changes in natural frequencies, and Natural Frequency Vector Assurance Criterion (NFVAC) was developed. Due to their easy and fast acquisition, natural frequencies were utilized to detect structural damages. Moreover, they are sensitive to stiffness reduction. The method presented here consists of two stages. Firstly, Finite Element Model (FEM) is updated. Secondly, damage severities and locations are determined. To minimize the proposed objective function, a new bio-inspired optimization algorithm called salp swarm was employed. Efficiency of the method presented here is validated by three experimental examples. The first example relates to three-story shear frame with two single damage cases in the first story. The second relates to a five-story shear frame with single and multiple damage cases in the first and third stories. The last one relates to a large-scale eight-story shear frame with minor damage case in the first and third stories. Moreover, the performance of Salp Swarm Algorithm (SSA) was compared with Particle Swarm Optimization (PSO). The results show that better accuracy is obtained using SSA than using PSO. The obtained results clearly indicate that the proposed method can be used to determine accurately and efficiently both damage location and severity in multi-story shear frames.

• Computers and Concrete
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• v.10 no.2
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• pp.173-196
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• 2012

Experimental results of cyclic reversed lateral force test on a two-story reinforced concrete shear wall sub-assemblage are simulated analytically by using the PERFORM-3D program. A comparison of experimental and analytical results leads to the following conclusions: (1) "Shear Wall" and "General Wall" models with "Concrete shear" cannot simulate the pinching phenomena due to shear and show larger amounts of inelastic energy absorption than those in the experiment. (2) Modeling a story-height wall by using two or more "General Wall" elements with "Diagonal shear" in the vertical direction induces the phenomenon of swelling-out at the belly, leading to the erroneous simulation of shear behaviors. In application to tall building structures, it is recommended to use one element of "General Wall" with "Diagonal shear" for the full height of a story. (3) In the plastic hinge area, concrete deformations of analytical models overestimate elongation and underestimate shortening when compared with experimental results.

• Structural Engineering and Mechanics
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• v.48 no.2
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• pp.173-193
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• 2013

In this paper, influence of geometric configurations of multi-story bracing on shear lag behaviour of braced tube structures is investigated. The shear lag of 24-, 36- and 72-story braced tube structures are assessed considering all possible configurations of overall X and Chevron bracing types. Based on the analytical results, empirical equations, useful for the preliminary design phase, are proposed to provide the optimum number of stories that braced, in order to exert minimum shear lag on structures. Studying the interaction behaviour of a tube and different bracing types along with paying attention to the shear lag behaviour, a better explanation about the reasons behind the efficiency of a specific bracing module in decreasing the shear lag is developed. The analytical results show that there are distinct differences between the anatomy of braced tube structures with X and Chevron bracing regarding the shear lag behaviour.

• Journal of Power System Engineering
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• v.7 no.1
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• pp.60-67
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• 2003

This paper introduces basic study how to restrain the vibration of a four story shear structure. We have modeled a four story shear structure mathematically and have identified each parameters by experiment. We have gotten a reduced nominal model through modal analyzing method and the $H_{\infty}$ control theory is used in the control system design to get the robust controller. It's shown that the desirable performances is confirmed through the mathematical simulation. And a designed controller applying the $H_{\infty}$ control theory shows the good performance for the impulse disturbance through the simulation results. That is, the robustness of this control system is confirmed for the ability of disturbance rejection and modeling error.

• Earthquakes and Structures
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• v.14 no.6
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• pp.589-598
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• 2018

An attempt is conducted to explore the relationship between the macroscopic global damage and the local damage of shear-type RC frames. A story damage index, which can be expressed as multi-variate functions of modal parameters, is deduced based on the tridiagonal matrix of the shear-type frame. The global damage model is also originated from structural modal parameters. Due to the connection of modal damage indexes, the relationship between the macroscopic global damage and the local story damage is reasonably established. In order to validate the derivation, a case study is carried out via an 8-story shear-type frame. The sensitivities of modal damage indexes to the location and severity of local story damages are studied. The evolution of the global damage is investigated as well. Results show that the global damage is sensitive to the degree of story damage, but it's not sensitive to its location. As the number of the damaged stories increases, more and more modes will be involved. Meanwhile, the global damage evolution curve changes from the concave shape to the S-type and then finally transforms into the convex shape. Through the proposed story damage, modal damage and global damage model, a multi-level damage assessment method is established.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.465-472
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• 2000

Seismic isolation technique has been applied mainly in low rise buildings and its seismic performance was satisfactory during Kobe Earthquake. However, in the case of medium and/or high-rise buildings, mid-story isolation could be more technically feasible than base isolation to reduce earthquake forces. In this paper, the seismic effectiveness of mid-story isolation in medium and/or high-rise shear building as well as low rise shear building was evaluated analytically. After verifying the effectiveness of mid-story isolation technique, this method also applied in residential-commercial building. It was found that mid-story isolation, that is isolation between upper residential area and lower commercial area, could reduce inter-story drift and floor shear forces comparing to the conventional fixed base.