• 한국태양에너지학회 논문집
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• 제23권4호
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• pp.89-96
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• 2003

In planning a building retrofit, energy conservation, thermal comfort and economic benefits should be considered. In this study, retrofit effects of exterior insulating method on preventing condensation, saving energy were analyzed through the heat transfer simulation, energy simulation in the apartment house retrofitted by exterior insulating method cheaper than other retrofit methods. The results of this study show that the retrofit using exterior insulating method can prevent the condensation at the corner walls and save about 20% of annual heating load. The LCC analysis revealed to be effective to select a dryvit system for a building retrofit.

• Structural Engineering and Mechanics
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• 제53권1호
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• pp.1-16
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• 2015

Due to design codes and regulations and the variety of building plans in Turkey, it is very often seen that band-type windows are left for ventilation and lightening of the basements of buildings which are used for various purposes such as workplaces and storage. Therefore when the necessary support measures cannot be given, short columns are subjected to very high shear forces and so damage occurs. One of the precautions to avoid the damage of short column mechanisms in buildings where band-type windows are in the basement is to strengthen the short columns with fiber reinforced polymer (FRP). In this study, the effect of the FRP retrofitting process of the short columns around band-windowed structures, which are found especially in basement areas, is analyzed in accordance with Turkish Seismic Code 2007 (TSC 2007). Three different models which are bare frame, frame with short columns and retrofitted short columns with FRP, are created and analyzed according to TSC 2007 performance analysis methods to understand the effects of band windows in basements and the effect of FRP retrofitting.

• Earthquakes and Structures
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• 제9권3호
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• pp.563-576
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• 2015

Over the past few decades, seismic retrofitting of structural systems has been significantly improved by the adoption of various methods such as FRP composite wraps, base isolation systems, and passive/active damper control systems. In parallel with this trend, probabilistic risk assessment (PRA) for structural and nonstructural components has become necessary for risk mitigation and the achievement of reliable designs in performance-based earthquake engineering. The primary objective of the present study was to evaluate the effect on piping fragility at T-joints due to seismic retrofitting of structural systems with passive energy-dissipation devices (i.e., linear viscous dampers). Three mid-rise building types were considered: without any seismic retrofitting; with distributed damper systems; with optimal placement of dampers. The results showed that the probability of piping system failure was considerably reduced in a Multi Degree of Freedom (MDOF) building retrofitted with optimal passive damper systems at lower floor levels. This effect of damper systems on piping fragility became insignificant as the floor level increased.

• 한국공작기계학회논문집
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• 제14권6호
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• pp.8-15
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• 2005

The new square electro-magnetic chuck, which can be used for the clamping devices on a grinding machine, is developed in this study to improve the convenience of grinding works. The various kinds of structures are recommended to find the most adequate magnetic characteristics through the analytical approach using finite element methods. The analyzed results are retrofitted to solve the drawbacks of previous models step by step by considering the magnetic fields, strength and distribution of drag force, and thermal deformations of chuck such as high parallelism and flatness. Finally the best recommended models is designed to satisfy the KS specifications required fur the commercial magnetic chuck. The prototype chuck with this dimensions and structures is manufactured. For this final model, the experimental verifications are investigated whether the KS specifications are satisfied.

• Earthquakes and Structures
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• 제10권3호
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• pp.589-611
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• 2016

This paper presents an analytical study aimed at evaluating the seismic performance of steel moment resisting frames (MRFs) retrofitted with different approaches. For this, 3, 6 and 12 storey MRFs having four equal bays of 5 m were selected as the case study models. The models were designed with lateral stiffness insufficient to satisfy code drift and hinge limitations in zones with high seismic hazard. Three different retrofit strategies including traditional diagonal bracing system and energy dissipation devices such as buckling restrained braces and viscoelastic dampers were used for seismic upgrading of the existing structures. In the nonlinear time history analysis, a set of ground motions representative of the design earthquake with 10% exceedance probability in fifty years was taken into consideration. Considering the local and global deformations, the results in terms of inter-storey drift index, global damage index, plastic hinge formations, base shear demand and roof drift time history were compared. It was observed that both buckling-restrained braces and viscoelastic dampers allowed for an efficient reduction in the demands of the upgraded frames as compared to traditional braces.

• Earthquakes and Structures
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• 제13권2호
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• pp.137-150
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• 2017

This paper focuses on the post-earthquake serviceability of steel arch bridges installed with three types of seismic dampers suffered mainshock-aftershock sequences. Two post-earthquake serviceability verification methods for the steel arch bridges are compared. The energy-absorbing properties of three types of seismic dampers, including the buckling restrained brace, the shear panel damper and the shape memory alloy damper, are investigated under major earthquakes. Repeated earthquakes are applied to the steel arch bridges to examine the influence of the aftershocks to the structures with and without dampers. The relative displacement is proposed for the horizontal transverse components in such complicated structures. Results indicate that the strain-based verification method is more conservative than the displacement-base verification method in evaluating the post-earthquake serviceability of structures and the seismic performance of the retrofitted structure is significantly improved.

• Structural Engineering and Mechanics
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• 제70권2호
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• pp.133-141
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• 2019

The aim of the present paper is to present the cyclic behavior of strengthened reinforced concrete shear wall test specimen, which was reinforced with cold drawn welded wire mesh fabric. Two reinforced concrete shear wall specimens have been tested in the present study. The walls were tested under reversed cyclic loading with loading applied near the tip of the walls. The control wall is tested in its original state to serve as a baseline for the evaluation of the repair and strengthening techniques. The two test specimens include a control wall and a repaired wall. The control wall test specimen was designed and detailed to simulate non-ductile reinforced concrete shear walls that do not meet the modern seismic provisions. The response of the original wall was associated with the brittle failure. The control shear wall was repaired by addition of the reinforcements and the concrete and then it was reloaded. The effectiveness of the repair technique was investigated. Test results indicate that there can be a near full restoration of the walls' strength. The data from this test, augmenting other data available in the literature, will be useful in calibrating improved analytical methods as they are developed.

• Computers and Concrete
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• 제27권1호
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• pp.41-54
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• 2021

This paper introduced three new strengthening systems for isolated footings: BFRP wrapping system, CFRP wrapping system, and steel jacketing system. The proposed systems are more practical than the current traditional methods, which involves installing many dowel bars and splicing reinforcing steels to join new and old concrete segments. In the proposed three new systems, BFRP wraps, CFRP wraps, or steel jackets are installed on the exterior surface of the enlarged footing, with construction adhesive or a few steel dowels being applied to the contact surfaces. To investigate the effectiveness of three systems, forty-four models were constructed in ABAQUS, with different parameters being considered. All footings investigated failed in punching shear, including original and retrofitted footings. According to FEA results and parametric studies, the three strengthening systems were capable of improving the punching shear resistance of footings. By introducing a new factor η, the punching shear equation in Eurocode 2 was modified to predict the punching shear resistances of the strengthened footings. A linear formula was developed to present the relationship between the new factor η and the investigated parameters.

• 한국정밀공학회지
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• 제13권12호
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• pp.99-105
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• 1996

Increasing demands on precision machining of free-form surfaces have necessitated the tool to move not only with position error as small as possible, but also with smoothly varying feedrates. In this paper, linear, circular and spline interpolators were developed in reference-pulse type using PC. M-SAM and M-DAM were designed by the comparison and analysis of previous interpolation methods. Spline interpolator was designed to follow the free-form curves. To apply to the real cutting process, constant feedrate compensation and acceleration-deceleration compensation were conceived. Finally, its performance was tested using retrofitted milling machine. As a result, new interpolation algorithm is favorable in precision machining of free-form curves.

• 한국지진공학회논문집
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• 제14권1호
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• pp.63-70
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• 2010

본 연구는 반복 횡하중 하에서 CFRP(Carbon Fiber Reinforced Polymer) Sheet로 보강된 철근콘크리트 프레임면내 조적벽체의 전단내력을 평가하여 국내 조적벽체 학교 건축물에 적합한 CFRP Sheet 보강 방안을 제안하는 것에 그 목적이 있다. 조적 허리벽이 있는 1층, 1경간, 1/2 스케일의 시험체를 4개 제작하여 CFRP Sheet의 보강량을 변수로 실험을 수행하였으며 이를 통하여 보강량에 따른 강도와 강성의 변화를 분석하였다. 실험 결과 CFRP Sheet는 시험체의 내력과 강성을 향상시켰으며 특히 기둥과 조적벽을 모두 보강하는 방법을 통한 보강방법에 있어 그 적용성을 확인할 수 있었다.