• Earthquakes and Structures
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• v.26 no.5
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• pp.383-400
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• 2024

For a conventionally repaired frame-supported-transfer-slab (FSTS) reinforced concrete (RC) structure, both the transfer slab and the beam-to-column and transfer slab-to-column joints remain vulnerable to secondary earthquakes. Aimed at improving the seismic performance of a damaged FSTS RC structure, an innovative retrofitting scheme is proposed, which adopts the sector lead rubber dampers (SLRDs) at joints after the damaged FSTS RC structure is repaired by conventional approaches. In this paper, a series of quasi-static cyclic tests was conducted on a large-scale retrofitted FSTS RC structure. The seismic performance was evaluated and the key test results, including deformation characteristics, damage pattern, hysteretic behaviour, bearing capacity and strains on key components, were reported in detail. The test results indicated that the SLRDs started to dissipate energy under the service level earthquake, and thus prevented damages on the beam-to-column and transfer slab-to-column joints during the secondary earthquakes and shifted the plastic hinges away from the beam ends. The retrofitting scheme of using SLRDs also achieved the seismic design concept of 'strong joint, weak component'. The FSTS RC structure retrofitted by the SLRDs could recover more than 85% bearing capacity of its undamaged counterpart. The hysteresis curves were featured by the inverse "S" shape, indicating good bearing capacity and hysteresis performance. The deformation capacity of the damaged FSTS RC structure retrofitted by the SLRDs met the corresponding codified requirements for the case of the maximum considered earthquake, as set out in the Chinese seismic design code. The stability of the FSTS RC structure retrofitted by the SLRDs, which was revealed by the developed stains of the RC frame and transfer slab, was improved compared with the undamaged FSTS RC structure.

• Fire Science and Engineering
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• v.27 no.3
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• pp.66-71
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• 2013

The purpose of this study is to assess the criteria on a floor hinge and door closer for the optimum design of the access door of a smoke control room. The door opening force due to differential pressure is 60.75 N, 40.5 N, 32.91 N and 12.66 N when the differential pressure is 60 Pa, 40 Pa, 32.5 Pa and 12.5 Pa, respectively. The door opening force of the floor hinge and door closer to which the criteria of KS F 2806 are applied is 27.5 N, 40 N, 75 N, 100 N and 125 N for the Nos. 1, 2, 3, 4 and 5 class floor hinges and door closers, respectively. This study compared the differential pressure and opening force limits of floor hinges and door closers with the values specified in NFSC 501A and found that they exceeded the criteria specified in NFSC 501A. Therefore, it is necessary to reflect the differential pressure and smoke control wind speeds as well as the opening forces specified in NFSC 501A on the design of floor hinges and door closers. The installation conditions of floor hinges and door closers of access doors differ depending on the type and name of a smoke control damper. This study found that Nos. 1, 2 and 3 floor hinges and door closers could be installed for access doors with low differential pressure and that Nos. 1 and 2 floor hinges and door closers could be installed for access doors with normal differential pressure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.113-125
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• 2017

In spite of bulk literature about the tuning of TMD, the effectiveness of TMD in reducing the seismic response of engineering structures is still in a row. This paper deals with the optimum tuning parameters of a passive TMD and simulated on MATLAB with a ten-story numerical shear building. A weighted multi-objective optimization method based on computer experiment consisting of coupled with central composite design(CCD) central composite design and response surface methodology(RSM) was applied to find out the optimum tuning parameters of TMD. After the optimization, the so-conceived TMD turns out to be optimal with respect to the specific seismic event, hence allowing for an optimum reduction in seismic response. The method was employed on above structure by assuming first the El Centro seismic input as a sort of benchmark excitation, and then additional recent strong-motion earthquakes. It is found that the RSM based weighted multi-objective optimized damper improves frequency responses and root mean square displacements of the structure without TMD by 31.6% and 82.3% under El Centro earthquake, respectively, and has an equal or higher performance than the conventionally designed dampers with respect to frequency responses and root mean square displacements and when applied to earthquakes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.275-281
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• 2015

In this study, vertical motion of a Tuned Liquid Column Damper(TLCD) is measured by a variable voltage measurement system in the electric field and design parameters of the TLCD are determined. First, nonlinear damping term of the TLCD is replaced as the equivalent viscous damping term. The natural frequency and damping ratio of dynamic characteristics of the TLCD are verified. In addition, a novel liquid level measurement system is developed for measuring vertical motion of the TLCD. For the experimental achievement, experimental characterizations of natural frequency and damping ratio of the TLCD are undertaken utilizing the developed variable voltage sensing. Also, shake table testing is performed to determine the dynamic characteristics of the TLCD. As a result, the feasibility of the proposed liquid level measurement system is verified by comparison with the capacitive type wavemeter.

• Steel and Composite Structures
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• v.20 no.4
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• pp.801-812
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• 2016

In an actual design, none of the structures with shear behaviors will be designed for torsional moments. Any failure or damages to roofs, infills, shear walls, and braces caused by an earthquake, will inevitably result in relocation of center of mass and rigidity of the structure. With these changes, the dynamic characteristics of structure could be changed during an earthquake at any moment. The main objective of this paper is to obtain the relationship between time-varying eccentricity of load and corner lateral displacement. In this study, various methods have been used to determine the structural response for time-varying lateral corner displacement. As will be seen below, some of the structural calculation methods result in a significant deviation from the actual results, although these methods include the interaction effects of modes. Controlling the lateral displacement of structure can be performed in different ways such as, passive dampers, friction dampers, semi-active systems including the MR damper and active Systems. Selecting and locating these control systems is very important to bring the maximum safety with minimum cost into the structure. According to this study will be show the relation between the corner lateral displacements of structure and time-varying eccentricity by different kind of methods during an earthquake. This study will show that the response of the structure at the corners due to an earthquake can be very destructive and because of changing the eccentricity of load, calculating the maximum possible response of system can be carried out by this method. Finally, some kind of systems must be used for controlling these displacements. The results shows that, the CQC, DSC and exact methods is comply each other but the results of Vanmark method is not comfortable for these kind of buildings.

• Journal of the Korean Solar Energy Society
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• v.36 no.6
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• pp.1-12
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• 2016

A control algorithm for a 100 kW wind turbine is designed in this study. The wind turbine is operating as a variable speed variable pitch (VSVP) status. Also, this wind turbine is a permanent magnet synchronous generator (PMSG) Type. For the medium capacity wind turbine considered in this study, it was found that the optimum tip speed ratios to achieve the maximum power coefficients varied with wind speeds. Therefore a commercial blade element momentum theory and multi-body dynamics based program was implemented to consider the variation of aerodynamic coefficients with respect to Reynolds numbers and to find out the power and thrust coefficients with respect tip speed ratio and blade pitch angles. In the end a basic power controller was designed for below rated, transition and above rated regions, and a load reduction algorithm was designed to reduce tower vibration by the nacelle motion. As a result, damage equivalent Load (DEL) of tower fore-aft has been reduced by 32%. From dynamic simulations in the commercial program, the controller was found to work properly as designed. Experimental validation of the control algorithm will be done in the future.

• Fire Science and Engineering
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• v.31 no.1
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• pp.1-9
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• 2017

This study conducted Testing, Adjusting, and Balancing (TAB), which is a type of field performance evaluation experiment of a zone smoke-control system, at a railway underground transit passage installed with a zone smoke- control system to find problems and improvements for ensuring performance. TAB for the smoke control system was classified into several procedures, such as design data review, duct leakage test, field measurement of the airflow rate, velocity of the fan and duct, and a smoke test. Through the duct leakage test, the system leakage ratio was examined to prove the duct sealing. The iImprovement of the smoke control airflow problems due to the lack of fan static pressure loss was the secured performance. The performance of the smoke control fan was secured by improvements of the smoke control airflow rate problems caused by the loss of static pressure in the intake duct. The smoke test in the smoke control zone confirmed that the damper operating schedule subject was influenced by natural wind or train wind.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1231-1237
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• 2014

It is essential to perform driving performance tests of military vehicles on rough terrain. A full car test is limited by cost and time constraints, because of which a dynamic analysis via computer simulation is preferred. In this study, a vehicle model is developed using MSC.ADAMS, a commercial multibody analysis program, and compared via experiments. FTire is modeled using the results of a tire performance test to obtain the vertical stiffness. A nonlinear damper is modeled by a characteristic experiment. Leaf springs are modeled with beam force elements and consisted to a vehicle model. The vertical force and acceleration response of the wheel are identified when vehicle is passing over a simple bump as well as a sinusoidal road. The developed vehicle model is verified with the results of a full car test.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.1
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• pp.33-44
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• 1995

As the occupant safety receives more attention from automobile industries. protection systems have been developed quite well. Developed protection systems must be evaluated through real tests in crash environment Since the real tests are extremely expensive. computer simulations are replaced for some prediction of the real test In the computer simulation. it is very crucial to express the real environment precisely in the modeling precess. The energy absorbing(EA) steering system has a very important rote in vehicle crashes because the occupant can hit the system directly. In this study. the EA steering system is modeled precisely. analyzed for the safely and designed by an optimization technology. First. the EA steering system is disassembled by parts and modeled by segments and joints. The segments are modeled by rigid bodies in motion and they have resistances in contact. Spring-damper elements and force-deflection curves are utilized to represent the joints. The body block test is cal lied out to validate. the modeling. When the test results are not enough for the detailed modeling. the differences between tests and simulations are minimized to calculate unknown parameters using optimization. The established model is applied to a crash simulation of a full-car model and tuned again. After the modeling is finished. components of the steering system are designed by an optimization algorithm. In the optimization process. the compound injury of a driver is defined and minimized to determine the chracteristics of the components. The second. order approximation algorithm has been adopted for the optimization.

• Advances in biomechanics and applications
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• v.1 no.3
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• pp.169-185
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• 2014

Computational multibody models of the elbow can provide a versatile tool to study joint mechanics, cartilage loading, ligament function and the effects of joint trauma and orthopaedic repair. An efficiently developed computational model can assist surgeons and other investigators in the design and evaluation of treatments for elbow injuries, and contribute to improvements in patient care. The purpose of this study was to develop an anatomically correct elbow joint model and validate the model against experimental data. The elbow model was constrained by multiple bundles of non-linear ligaments, three-dimensional deformable contacts between articulating geometries, and applied external loads. The developed anatomical computational models of the joint can then be incorporated into neuro-musculoskeletal models within a multibody framework. In the approach presented here, volume images of two cadaver elbows were generated by computed tomography (CT) and one elbow by magnetic resonance imaging (MRI) to construct the three-dimensional bone geometries for the model. The ligaments and triceps tendon were represented with non-linear spring-damper elements as a function of stiffness, ligament length and ligament zero-load length. Articular cartilage was represented as uniform thickness solids that allowed prediction of compliant contact forces. As a final step, the subject specific model was validated by comparing predicted kinematics and triceps tendon forces to experimentally obtained data of the identically loaded cadaver elbow. The maximum root mean square (RMS) error between the predicted and measured kinematics during the complete testing cycle was 4.9 mm medial-lateral translational of the radius relative to the humerus (for Specimen 2 in this study) and 5.30 internal-external rotation of the radius relative to the humerus (for Specimen 3 in this study). The maximum RMS error for triceps tendon force was 7.6 N (for Specimen 3).