• Journal of Power System Engineering
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• v.15 no.4
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• pp.19-24
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• 2011

The operational efficiency of domestic gas turbine is about 25% and it is now in the trend of the gradual growth in spite of the severe temperature, frequent starting and shutdown according to the environmental management and the energy-efficient use. Rotor bolts of gas turbine in power plants have been the cause of defects because these gas turbines have been operated for a long time under the high pressure and temperature environment experiencing the aging change and stress concentration of the bonded part. The connection parts of the bolt revealed various failure shape and these parts were elongated under very low pressure when operated in the relaxed condition. The cause is in the lack of the metal distribution in the bottle lack area and the cap screw of the bolt is broken totally in case that the nut is fastened in most cases. Gas turbine rotor bolts are connected to the rotor wheel and these bolts caused the vibration, the bulk accident of the rotor in the event that the coupling power among these bolts was relaxed. Therefore, we would like to evaluate the soundness of the main part of the gas turbine rotor bolt through the measurement of the inner condition change along with the mechanic deterioration and temperature, stress in the gas turbine rotor material.

• Steel and Composite Structures
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• v.48 no.5
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• pp.547-564
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• 2023

This study investigates the effect of bolt preloading on the rotational stiffness of stainless steel end-plate connections. An experimental programme incorporating 11 full-scale joint specimens are carried out comparing the behaviours of fully pre-tensioned (PT) and snug-tightened (ST) flush/extended end-plate connections, made of austenitic or lean duplex stainless steels. It is observed from the tests that the presence of bolt preloading leads to a significant increase in the rotational stiffness. A parallel finite element analysis (FEA) validated against the test results demonstrates that the geometric imperfection of end-plate has a strong influence on the moment-rotation response of preloaded end-plate connections, which is crucial to explain the observed "two-stage" behaviour of these connections. Based on the data obtained from the tests and FE parametric study, the performance of the Eurocode 3 predictive model is evaluated, which exhibits a significant deviation in predicting the rotational stiffness of stainless steel end-plate connections. A modified bi-linear model, which incorporates three key properties, is therefore proposed to enable a better prediction. Finally, the effect of bolt preloading is demonstrated at the system (structure) level considering the serviceability of semi-continuous stainless steel beams with end-plate connections.

• 건축구조
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• v.22 no.3
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• pp.31-42
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• 2015

• 건축구조
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• v.22 no.4
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• pp.25-34
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• 2015

• Steel and Composite Structures
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• v.18 no.6
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• pp.1423-1450
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• 2015

The paper presents the details and results of an experimental study on bolted end-plate joints of industrial type steel building frames. The investigated joints are commonly used in Lindab-Astron industrial buildings and are optimized for manufacturing, erection and durability. The aim of the research was to provide an experimental background for the design model development by studying load-bearing capacity of joints, bolt force distribution, and end-plate deformations. Because of the special joint details, (i.e., joints with four bolts in one bolt-row and HammerHead arrangements), the Eurocode 3 standardized component model had to be improved and extended. The experimental programme included six different end-plate and bolt arrangements and covered sixteen specimens. The steel grade of test specimens was S355, the bolt diameter M20, whereas the bolt grade was 8.8 and 10.9 for the two series. The end-plate thickness varied between 12 mm and 24 mm. The specimens were investigated under pure bending conditions using a four-point-bending test arrangement. In all tests the typical displacements and the bolt force distribution were measured. The end-plate plastic deformations were measured after the tests by an automatic measuring device. The measured data were presented and evaluated by the moment-bolt-row force and moment-distance from centre of compression diagrams and by the deformed end-plate surfaces. From the results the typical failure modes and the joint behaviour were specified and presented. Furthermore the influence of the end-plate thickness and the pretension of the bolts on the behaviour of bolted joints were analysed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.43-50
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• 2008

The analysis and results of flexural behavior for steel composite beam with built-up cross-section considering bolt deformation are presented in this paper. The bolt deformation and the restrict effect due to bolt-connection and friction are considered to investigate the flexural behavior of steel composite beam. Nonlinear spring element in ABAQUS is used to consider bolt deformation, also the results are compared with those in case bolt deformations are ignored. The displacement, bending stresses and shear stresses are calculated by F.E. model, and these results are compared with the analytical value of no interaction beam, partial interaction beam and full interaction beam. As a result of analysis, the behavior of composite beam is more dependant on the composite rate than the friction of the steel. When the composite rate is more than 50%, the behavior of composite beam considering the effects of bolt deformation is similar to that of fully composite beam.

• Earthquakes and Structures
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• v.25 no.5
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• pp.307-323
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• 2023

This study compares two prominent design provisions, National Design Specification (NDS) and Eurocode 5, on load-carrying capacity calculations and failure analysis for mortise-tenon joints. Design procedures of double-shear connection from both provisions were used to calculate load-carrying capacity of mortise-tenon joints with eight different bolt sizes. From this calculation, the result was validated using finite element analysis and failure criteria models. Although both provisions share similar failure modes, their distinct calculation methods significantly influence the design load-carrying capacity values. Notably, Eurocode 5 predicts a 6% higher design load-carrying capacity for mortise-tenon joints with varying bolt diameters under horizontal loads and 14% higher under vertical loads compared to NDS. However, the results from failure criteria models indicate that NDS closely aligns with the actual load-carrying capacity. This indicates that Eurocode 5 presents a less conservative design and potentially requires fewer fasteners in the final timber connection design. This evaluation initiates the potential for the development of a wider range of timber connections, including mortise-tenon joints with wooden pegs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.9-17
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• 2012

This study is dealt with the experimental seam strength of deep corrugated steel plate which is used as underpasses, storm sewers and other buried applications. The soil-metal structure using deep corrugated plate should be sufficient to ensure safety for compressive loading. The experimental and theoretical results on the seam strength are accumulated enough to take the design guideline, even if the seam strength at the bolt connected lap joint in construction site can be varied depending on the connection detailing and the thickness of plate. In this study, compressive behavior of bolted lap jointed plates using various connection detail such as gasket, slot hole, washer was experimentally analyzed. From the test, failure pattern with an increases in the thickness of specimens was changed from plate bearing to bolt shearing. In case of thicker plates than 6.0mm, the structural performance of lap joint using gasket and slot hole is more effective than it of the plate adopted washer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.2
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• pp.49-57
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• 2012

Recently, in field of bridge construction, modular technology has been studied to reduce construction period. However, main stream of the study is limited to the pier, girder and deck of bridge, which are huge or main members. Studies on incidental facilities like concrete barrier is out of sight. Thus, in this study, connection system of concrete barrier was developed to apply to modular bridges and static experiment was performed in order to verify structural capability of proposed system. Variables of experiment are composed of bolt direction such as vertical and horizontal. The experimentation due to the designed variables was conducted by comparison with a standard concrete barrier, which is a traditional barrier. As a result, vertical joint way of the bolt showed nearly identical structural performance and healthy to standard specimen's. it can be applied to modular bridges.

• Steel and Composite Structures
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• v.46 no.3
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• pp.403-416
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• 2023

This paper summarised and re-examined the theoretical basis of the commonly used design rule developed by Cochrane in the 1920s to consider staggered bolt holes in tension members, i.e., the s²/4g rule. The rule was derived assuming that the term two times the bolt hole diameter (2d₀) in Cochrane's original equation could be neglected, and assuming a value of 0.5 for the fractional deduction of a staggered hole in assessing the net section area. Although the s²/4g rule generally provides good predictions of the staggered net section area, the above-mentioned assumptions used in developing the rule are doubtful, in particular for a connection with a small gauge-to-bolt-hole diameter (g/d₀) ratio. It was found that the omission of 2d₀ in Cochrane's original equation appreciably overestimates the net section area of a staggered bolted connection with a small g/d₀ ratio. However, the assumed value of 0.5 for the fractional deduction of a staggered hole underestimates the staggered net section area for small g/d₀ ratios. To improve the applicability of the above two assumptions, a modified design equation, which covers a full range of g/d₀ ratio, was proposed to accurately predict the staggered net section area and was validated by the existing test data from the literature and numerical data derived from this study. Finally, a reliability analysis of the test and numerical data was conducted, and the results showed that the reliability of the modified design equation for evaluating the net section resistance of staggered bolted connections can be achieved with the partial factor of 1.25.