• Journal of Korean Association for Spatial Structures
• /
• v.18 no.4
• /
• pp.105-111
• /
• 2018

In this study, the seismic performance and behavior characteristics of the upper truss structure of the large stadium are analyzed by nonlinear dynamic analysis. In the nonlinear dynamic analysis, the earthquake records were generated by site response analysis to simulate the nonlinear behavior of the relevant soil condition where the structure is located. Nonlinear dynamic analysis was performed using Perform-3D and the nonlinear properties of the substructure and the superstructure were determined in accordance with KISTEC guideline. According to the analysis results, excessive deformation occurred in the upper truss element, and plastic hinges exceeded the target performance in some members. Buckling-restrained brace is used for seismic retrofit of stadium structures and the analysis results shows the interstory drift satisfies the target performance level with dissipating the seismic energy efficiently.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.23 no.1
• /
• pp.1-8
• /
• 2019

In this study, the effectiveness of a multi-action hybrid damper (MHD) composed of lead rubber bearing (LRB) and friction pad was verified in terms of seismic performance improvement of a frame structure. The LRB and the friction elements are connected in series, so the LRB governs the intial small deformation and the friction determines large deformation behavior. Cyclic loading tests were conducted by using a half scale steel frame structure with the MHD, and the results indicated that the structure became to have the stable trilinear hysteresis with large initial stiffness and first yielding due to the LRB, and the second yielding due to the friction. The MHD could significantly increase the energy dissipation capacity of the structure and the hysteresis curves obtained by tests were almost identical to the analytically estimated ones.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.28 no.5
• /
• pp.257-266
• /
• 2024

Due to seismically deficient details, existing reinforced concrete structures have low lateral resistance capacities. Since these building structures suffer an increase in axial loads to the main structural element due to the green retrofit (e.g., energy equipment/device, roof garden) for CO₂ reduction and vertical extension, building capacities are reduced. This paper proposes a machine-learning-based methodology for allowable ranges of axial loading ratio to reinforced concrete columns using simple structural details. The methodology consists of a two-step procedure: (1) a machine-learning-based failure detection model and (2) column damage limits proposed by previous researchers. To demonstrate this proposed method, the existing building structure built in the 1990s was selected, and the allowable range for the target structure was computed for exterior and interior columns.

• International conference on construction engineering and project management
• /
• 2015.10a
• /
• pp.532-536
• /
• 2015

This paper presents an automated computer vision-based system to update BIM data by leveraging multi-modal visual data collected from existing buildings under inspection. Currently, visual inspections are conducted for building envelopes or mechanical systems, and auditors analyze energy-related contextual information to examine if their performance is maintained as expected by the design. By translating 3D surface thermal profiles into energy performance metrics such as actual R-values at point-level and by mapping such properties to the associated BIM elements using XML Document Object Model (DOM), the proposed method shortens the energy performance modeling gap between the architectural information in the as-designed BIM and the as-is building condition, which improve the reliability of building energy analysis. The experimental results on existing buildings show that (1) the point-level thermography-based thermal resistance measurement can be automatically matched with the associated BIM elements; and (2) their corresponding thermal properties are automatically updated in gbXML schema. This paper provides practitioners with insight to uncover the fundamentals of how multi-modal visual data can be used to improve the accuracy of building energy modeling for retrofit analysis. Open research challenges and lessons learned from real-world case studies are discussed in detail.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.25 no.6
• /
• pp.525-532
• /
• 2012

The recently constructed buildings are ensuring seismic safety with enhanced design criteria. But, the buildings unapplied enhanced design criteria are very weak. In this study, steel grid shear wall is proposed as a solution of seismic retrofit to ensure safety of the existing buildings for the earthquake. And the structural performance experiments were carried out under axial force and cyclic lateral loads. The two specimens were made of a reference RC frame and steel grid shear wall in-filled RC frame. The test setup configured with two dynamic actuators, for the axial force with a 500kN capacity actuator and for the cyclic lateral load applied with the 2,000kN actuator. Compared with control specimen, the strength, stiffness, ductility, energy dissipation capacity of the seismic retrofit structures is evaluated.

• Earthquakes and Structures
• /
• v.1 no.1
• /
• pp.93-108
• /
• 2010

This paper investigates the seismic performance of existing reinforced concrete frames with wide beams mainly designed for gravity loads, as typically found in the seismic-prone Mediterranean area before the introduction of modern codes. The seismic capacity is evaluated in terms of the overall amount of input energy that the frame can dissipate/absorb up to collapse. This approach provides a quantitative evaluation that can be useful for selecting and designing an appropriate retrofit strategy. Six prototype frames representative of past construction practices in the southern part of Spain are designed, and the corresponding non-linear numerical models are developed and calibrated with purposely conducted tests on wide beam-column subassemblages. The models are subjected to sixteen earthquake records until collapse by applying the incremental dynamic analysis method. It is found that the ultimate energy dissipation capacity at the story level is markedly low (about 1.36 times the product of the lateral yield strength and yield displacement of the story), giving values for the maximum amount of energy that the frame can dissipate which are from one fourth to half of that required in moderate-seismicity regions.

• Earthquakes and Structures
• /
• v.13 no.2
• /
• pp.177-191
• /
• 2017

In the present study, exterior beam column sub-assemblages are designed in accordance with the codal stipulations prevailed at different times prior to the introduction of modern seismic provisions, viz., i) Gravity load designed with straight bar anchorage (SP1), ii) Gravity load designed with compression anchorage (SP1-D), iii) designed for seismic load but not detailed for ductility (SP2), and iv) designed for seismic load and detailed for ductility (SP3). Comparative seismic performance of these exterior beam-column sub-assemblages are evaluated through experimental investigations carried out under repeated reverse cyclic loading. Seismic performance parameters like load-displacement hysteresis behavior, energy dissipation, strength and stiffness degradation, and joint shear deformation of the specimens are evaluated. It is found from the experimental studies that with the evolution of the design methods, from gravity load designed to non-ductile and then to ductile detailed specimens, a marked improvement in damage resilience is observed. The gravity load designed specimens SP1 and SP1-D respectively dissipated only one-tenth and one-sixth of the energy dissipated by SP3. The specimen SP3 showcased tremendous improvement in the energy dissipation capacity of nearly 2.56 times that of SP2. Irrespective of the level of design and detailing, energy dissipation is finally manifested through the damage in the joint region. The present study underlines the seismic deficiency of beam-column sub-assemblages of different design evolutions and highlights the need for their strengthening/retrofit to make them fit for seismic event.

• Journal of the Korea Concrete Institute
• /
• v.11 no.5
• /
• pp.107-118
• /
• 1999

10 RC bridge piers have been made on a 1/3.4 scale model, and six piers of them were retrofitted with glassfiber. The have been tested in the quasi-static cyclic load so as to investigate their seismic enhancement before and after retrofitting with glassfibers. The objective of this experimental study is to investigate how to strength the ductility of reinforced concrete bridge piers which have been nonseismically designed and constructed in Korea before 1992. Important test parameters are axial load, load pattern, retrofit type. Glassfiber sheets were used for retrofitting in the plastic hinge region of concrete piers. The nonlinear behavior of bridge columns have been evaluated through their yield and ultimate strength, energy dissipation, displacement ductility and load-deflection characteristics under quasi-static cyclic loads. It can be concluded from the test that concrete piers strengthened with glassfibers have been enhanced for their ductile behavior by approximate 50%.

• International Journal of Advanced Culture Technology
• /
• v.8 no.2
• /
• pp.260-269
• /
• 2020

The Steam Assisted Gravity Drainage (SAGD) process is an enhanced method to extract oil from bitumen which involves surface and central process facilities. This paper describes the Central Process Facilities (CPF) of SAGD and proposes several retrofit plans to the Heat Exchanger Network (HEN). In this approach, the process integration scheme is applied to estimate the energy saving in HENs, and various cases are modeled in favor of a commercial simulator. Throughout this work, a minimum approach temperature of 10℃ is assumed. The results reveal that, due to the HEN optimization using process integration, the heating and cooling duties can be reduced to 29.68MW and 1.886MW, respectively. Compared with the Husky case, all cases considered in this study indicate a potential reduction of at least 6% in total cost, including investment and operation costs.

• Journal of Energy Engineering
• /
• v.4 no.1
• /
• pp.140-152
• /
• 1995

대부분의 기존 화력발전소는 기동정지가 빈번하지 않고 부하는 정상운전시에 일정하게 운전된다. 그러나, 최근에 원자력발전소 운전과 다양한 형태의 전력소비가 이루어지고 있어 발전소에 대한 효율적인 운전이 요구되어지고 있다. 따라서, 일일기동정지 및 주말기동정지 운전이 이루어지고 있으며, 발전소의 기동, 정지 및 부하변동이 자주 일어나며, 이러한 운전형태는 수처리시스템에 영향을 미치게 된다. P 화력발전소는 일일기동정지 운전개념으로 설계되었으며, 수처리설비중의 하나인 약품주입 제어시스템은 수질을 일정한 설정치로 유지시키지 못하였으며, 현장기술자가 PID 제어기 대신에 F(x) 함수를 갖는 제어시스템으로 설계변경하였으나 시험운전 결과는 만족스런 성능을 나타내지 않았다. 본 논문에서는 제어성능을 개선하기 위한 퍼지약품주입시스템을 제안하고 시뮬레이션으로 타당성을 입증하였다.