• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.457-470
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• 2020

The force resisting ability of a connection has direct implications on the overall response of a timber framed structure to various actions, thereby governing the integrity and safety of such constructions. The behavior of timber framed structures has been studied by many researchers by testing full-scale-connections in timber frames so as to establish consistent design provisions on the same. However, much emphasis in this approach has been unidirectional, that has focused on a particular connection configuration, with no research output stressing on the refinement of the existing connection details in order to optimize their performance. In this regard, addition of adhesive to dowelled timber connections is an economically effective technique that has a potential to improve their performance. Therefore, a comparative study to evaluate the performance of various full-scale timber frame Nailed connections (Bridled Tenon, Cross Halved, Dovetail Halved and Mortise Tenon) supplemented by adhesive with respect to Nailed-Only counterparts under tensile loading has been investigated in this paper. The load-deformation values measured have been used to calculate stiffness, load capacity and ductility in both the connection forms (with and without adhesion) which in turn have been compared to other configurations along with the observed failure modes. The observed load capacity of the tested models has also been compared to the design strengths predicted by National Design Specifications (NDS-2018) for timber construction. Additionally, the experimental behavior was validated by developing non-linear finite element models in ABAQUS. All the results showed incorporation of adhesive to be an efficient and an economical technique in significantly enhancing the performance of various timber nailed connections under tensile action. Thus, this research is novel in a sense that it not only explores the tensile behavior of different nailed joint configurations common in timber construction but also stresses on improvising the same in a logical manner hence making it distinctive in its approach.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.64-70
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• 2008

A full-scale field experiment is an important part in the design of ships and offshore structures. Full-scale tests in the ice-covered sea, however, are usually very expensive and difficult tasks. Model tests in a refrigerated ice tank may substitute this difficulty of full-scale field tests. One of the major tasks to perform proper model tests in an ice towing tank is to select a realistic material for model ice which shows correct similitude with natural sea ice. This study focuses on the testing material properties and the selection of model ice material which will be used in an ice model basin. The first Korean ice model basin will be constructed at the Maritime & Ocean Engineering Research Institute (MOERI) in 2009. With an application to the MOERI ice model basin, in this study the material properties of EG/AD/S model ice of IOT (Institute for Ocean Technology) Canada, were tested. Through comprehensive bending tests, the elastic modulus and the flexural strength of EG/AD/S model ice were evaluated and the results were compared with published test results from Canada. Instead of using an ice model basin, a cold room facility was used for making a model ice specimen. Since the cold room adopts a different freezing procedure to make model ice, the strength of the model ice specimen differs from the published test results. The reason for this difference is discussed and the future development for a making model ice is recommended.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.37-42
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• 2016

PURPOSES : The objective of this study is to determine the optimal frequency of ground penetrating radar (GPR) testing for detecting the voids under the pavement. METHODS : In order to determine the optimal frequency of GPR testing for void detection, a full-scale test section was constructed to simulate the actual size of voids under the pavement. Voids of various sizes were created by inserting styrofoam at varying depths under the pavement. Subsequently, 250-, 500-, and 800-MHz ground-coupled GPR testing was conducted in the test section and the resulting GPR signals were recorded. The change in the amplitude of these signals was evaluated by varying the GPR frequency, void size, and void depth. The optimum frequency was determined from the amplitude of the signals. RESULTS: The capacity of GPR to detect voids under the pavement was evaluated by using three different ground-coupled GPR frequencies. In the case of the B-scan GPR data, a parabolic shape occurred in the vicinity of the voids. The maximum GPR amplitude in the A-scan data was used to quantitatively determine the void-detection capacity. CONCLUSIONS: The 250-MHz GPR testing enabled the detection of 10 out of 12 simulated voids, whereas the 500-MHz testing allowed the detection of only five. Furthermore, the amplitude of GPR detection associated with 250-MHz testing is significantly higher than that of 500-MHz testing. This indicates that 250-MHz GPR testing is well-suited for the detection of voids located at depths ranging from 0.5~2.0 m. Testing at frequencies lower than 250 MHz is recommended for void detection at depths greater than 2 m.

• Wind and Structures
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• v.28 no.3
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• pp.181-190
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• 2019

Light-frame wood structures have the ability to carry gravity loads. However, their performance during severe wind storms has indicated weakness with respect to resisting uplift wind loads exerted on the roofs of residential houses. A common failure mode observed during almost all main hurricane events initiates at the roof-to-wall connections (RTWCs). The toe-nail connections typically used at these locations are weak with regard to resisting uplift loading. This issue has been investigated at the Insurance Research Lab for Better Homes, where full-scale testing was conducted of a house under appropriate simulated uplift wind loads. This paper describes the detailed and sophisticated numerical simulation performed for this full-scale test, following which the numerical predictions were compared with the experimental results. In the numerical model, the nonlinear behavior is concentrated at the RTWCs, which is simulated with the use of a multi-linear plastic element. The analysis was conducted on four sets of uplift loads applied during the physical testing: 30 m/sincreased by 5 m/sincrements to 45 m/s. At this level of uplift loading, the connections exhibited inelastic behavior. A comparison with the experimental results revealed the ability of the sophisticated numerical model to predict the nonlinear response of the roof under wind uplift loads that vary both in time and space. A further component of the study was an evaluation of the load sharing among the trusses under realistic, uniform, and code pressures. Both the numerical model and the tributary area method were used for the load-sharing calculations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.285-292
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• 2006

The objective of this study is to introduce the development of the first Korean full-scale APT(Accelerated Pavement Tester) and to compare the performances of general dense grade asphalt mixture and modified asphalt mixtures as the first running of the tester. The tests evaluated the rutting resistance for dense grade mixture and three different modified asphalt mixture under three different temperature conditions (25-30, 40, $50^{\circ}C$). The results of the testing were compared with the laboratory test results. Results of the tests indicated that the all the modified asphalt sections showed higher rutting resistance than the dense grade section. Especially, the difference was more noticeable at higher temperature condition. Additionally, $G^*/sin{\delta}$ is found out to be an important factor for permanent deformation prediction whereas the resilient modulus was not.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.1-7
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• 2010

Fatigue properties of composite materials are extremely important to design durable and reliable helicopter rotor blades. However, it is very difficult to apply conventional fatigue test loads in short period. Therefore, accelerating test speed and facilitating spectrum load realization are required. In this study, we have developed a fatigue testing method that uses a resonance of simply supported beam type blade specimen. This test consists in exciting the blade specimen with a frequency that corresponds to its natural frequency. In that case, the test specimen similar to a beam fixed between two pivot points starts vibrating and is significantly deformed. Resonant fatigue tests were performed by changing exciting vertical amplitude and frequency, and S-N curves of each composite materials were successfully obtained.

• Steel and Composite Structures
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• v.5 no.4
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• pp.259-269
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• 2005

Many slab-on-girder bridges around the world are being assessed because they are approaching the end of their anticipated design lives or codes are permitting higher allowable loads. Current analytical techniques assume that the concrete and steel components act independently, typically requiring full-scale load testing to more accurately predict the remaining strength or endurance of the structure. However, many of the load tests carried out on these types of bridges would be unnecessary if the degree of interaction resulting from friction at the steel-concrete interface could be adequately modeled. Experimental testing confirmed that interface friction has a negligible effect on the flexural capacity of a slab-on-girder beam however, it also showed that interface friction is significant under serviceability loading. This has led to the development of an improved analytical technique which is presented in this paper and referred to as the slab-on-girder mixed analysis service load assessment approach.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.142-149
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• 2000

The results of stand and field testing of a combustion chamber for a heavy-duty 150 MW gas turbine are discussed. The model represented one of 14 identical segments of a tubular multican combustor constructed in the scale 1:1. The model experiments were executed at a pressure smaller than in the real gas turbine. The combustion efficiency, pressure loss factor, pattern factor, liner wall temperature, flame radiation, fluctuating pressure, and NOx emission were measured at partial and full load for both model and on-site testing. The comparison of these items of information, received on similar modes in the stand and field tests, has allowed the development of a method of calculation and the improvement of gas turbine combustors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.265-268
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• 1997

In the recent day, fatigue life prediction techniques play a major role in the design of components in the ground vehicle industry. Full scale durability testing in the laboratory is an essential of any fatigue life evaluation of components or structures of the automotwe vehicle. Component testing is part~cularly important in today's highly competitive industries where the design to reduce weight and production costs must be balanced with the necessity to avoid expensive service failure. Generally, multi-axial road simulator is used to carry out the fatigue test and the vibration test. In this paper, the algorithm and software to realize the real road profile are developed. The validity of the software are verified by applying the belgian road, the city road, the highway, and the gravel road. The results of the above experiment show that the real road profiles are realized well after loth iteration.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.211-216
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• 2005

Resonance of railroad bridge can be broken out when natural frequency of the bridge coincides with exciting frequency of moving forces. In order to avoid aforementioned unpleasant response of the structure, exact determination of dynamic structural properties is important to understand dynamic behavior of the structure under moving train loads. In the present paper, a 25 meters long full scale IPC girder and 15m Precom girder models were fabricated as a test specimen and modal testing was carried out to evaluate modal parameters including natural frequencies and modal damping ratios. In the modal testing, a digitally controlled vibration exciter as well as an impact hammer is applied to obtain frequency response functions more exactly and the modal parameters are evaluated varying with structural status.