• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.71-76
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• 2005

This paper describes basic structural design for the large floating crane barge of fixed undulation type. Structural analysis was performed separately after dividing the floating crane into two parts, The crane part was composed of jib boom, back stay and back tower and the barge part supported the crane part. The structural strength for jib boom structural members are in compliance with JIS B 8821 and scantling of all barge structural members are in compliance with the requirement of KR (Korean Register of Shipping) Steel Barges and Rules for Classification of Steel Ships. For the structural analysis of large floating crane, MSC/NASTRAN and MSC/PATRAN software were used.

• Structural Engineering and Mechanics
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• v.73 no.4
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• pp.463-479
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• 2020

This paper is aimed to address a simultaneous optimization of the size, shape, and topology of steel lattice towers through a combination of the radial basis function (RBF) neural networks and the artificial bee colony (ABC) metaheuristic algorithm to reduce the computational time because mere metaheuristic optimization algorithms require much time for calculations. To verify the results, use has been made of the CIGRE Tower and a 132 kV transmission towers as numerical examples both based on the design requirements of the ASCE10-97, and the size, shape, and topology have been optimized (in both cases) once by the RBF neural network and once by the MSTOWER analyzer. A comparison of the results shows that the neural network-based method has been able to yield acceptable results through much less computational time.

• Journal of the Korean Professional Engineers Association
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• v.15 no.4
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• pp.12-24
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• 1982

East Parts of Bangladesh have been benifited by low cost energy generated by domestic natural gas but West parts where energy generated by imported fuel. Bangladesh Government authority has very much concerned to transmit the low cost electricity to the West from the East for past several years. To solve such concerns, cross-country 230kv double circuits Power transmission line was proposed, however there was a big obstacle for the realization of this line to cross the Jamuna river which has 12 km long width with a deep muddy river bed. A consultant engineering firm named Merz-Mclellan anyway finalized this plan and a world-wide bid was announced on June 31, 1979. Due to the expected difficulty to construct the towers on sea like area, only three construction groups have participated. including a Korean joint venture organization of Samsung-Korean Developement corporation-Kolon Electric Machinery company. After 3 months bid evaluation, contract was awarded to Korean Consosium and KEM Co was in charge of designing steel towers with anchor bolts and base plates beside to electrical engineering field. Then KEM Co have faced and over-comed many unenpected technical difficulties such as forced eccentricity joint on base plate, distorsion issue of 60mm thick plates welding, threading anchor bolts, tad heat treatment of some anchor bolts, disagreement from Consultant Engineer on multiplying factor of leg stresses for 45$^{\circ}$ wind and on reducing O.L.F for wind loads on cables for such 1220km long spans. After spending two years long period for designing and engineering towers, base plates, and anchor bolts, first shipment of tower was finally realized on Nov. 8, 1981 and on the other hand KDD has proceeded concrete caisson work on schedule at Jamuna river site and expected to complete tower erection and stringing of cables within this year of 1982 which was original completion target.

• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.119-129
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• 2015

Due to reduced self weight and alleviated wind effect, the multi-column wind towers that consist of a number of circular tubes as vertical members interconnected with horizontal brace members can be a substitute for the large-scale single cylinder wind towers. It is critical to guarantee strengths of tubular joints where vertical and horizontal members are structurally connected in order to make the whole multi-column system behave as a single tower structure. In this study, strength evaluation has been conducted for T-type tubular joints that are applicable in multi-column towers. Four of available design codes, i.e., AISC, Eurocode3, ISO 19902, CIDECT have been investigated and predictor equations in the considered design codes were validated and discussed through parametric numerical study on slenderness ratios of chords and braces at joints.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.6-14
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• 2014

This paper has an aim to evaluate microstructure and fracture toughness of TMCP steel weldment applied for off-shore wind tower with the focus on the effect of heat input on the weldment with various welding processes; FCAW(13kJ/cm and 30kJ/cm), SAW(62kJ/cm), and EGW(177kJ/cm). Based on experimental results developed from this study, it was found that the impact toughness of top side for TMCP steel weldments with heat input up to 62 kJ/cm satisfied the required minimum value except the EGW(177kJ/cm). The heat input and microstructure are the main factors of impact toughness. The heat input of 13kJ/cm on back side with low heat input increased the amount of grain boundary ferrite which has low impact toughness, and heat input of 177kJ/cm on top side is significant enough to produce the austenite grain growth. The compositions and sizes of inclusions which are the dominant factors for the formation of acicular ferrite were analyzed by OM and EDS. As the heat input increased, the inclusions also grew and a nucleation site decreased. The size of nonmetallic inclusions and the crack width was nearly similar, therefore the inclusions were related with the crack propagation.

• Journal of Korean Society of Steel Construction
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• v.19 no.2
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• pp.191-199
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• 2007

This paper presents a closing method for a cable-stayed bridge erected by the free cantilever method to produce the initial equilibrium configuration at the final construction stage. To realize the initial equilibrium condition in cable-stayed bridge by the cantilever method, compatibility conditions for vertical displacements, rotational angles, and axial displacements at the closing section of both side girders should be satisfied. In this paper, it was shown that it can be accomplished by using some applicable loads during construction such as the pull-up force of the derrick crane, some cable tension forces, and jacking force at the pylon. The proposed method was applied to a construction stage analysis of a sample bridge to demonstrate its validity, and it was acknowledged that the tower was considerably affected by the compatibility condition for axial displacement in the closing step.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.19-26
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• 2024

In this study, the compressive behavior of a 1/12.5 scale model of a wind tower support structure connection was experimentally analyzed. A high-performance cementitious grout with a compressive strength of 140 MPa was used to fill the connection, and experiments were conducted with shear key spacing, the shape, and connection length as variables. When the number of shear keys in the connection is the same, the smaller the spacing of the shear keys than the length of the connection, the higher the shear strength, and for the same spacing and connection length, the higher the height of the shear keys, the higher the strength. In addition, it was found that the strength showed a linear behaviour until the connection slip reached 1.0 mm, and it reached the maximum strength at 7.0 mm connection slip showing a non-linear behaviour as the load increased. It was found that the failure mode changed from interfacial shear failure to grout failure as the strength increased according to the shape and spacing of the shear key, and brittle failure did not occur due to steel fibers.

• Steel and Composite Structures
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• v.21 no.5
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• pp.963-980
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• 2016

The jib system with middle strut is widely used to achieve the large arm length in the large scale tower crane and the deployability in the mobile construction crane. In this paper, an analytical solution for the out-of-plane buckling of the jib system with middle strut is proposed. To obtain the analytical expression of the buckling characteristic equation, the method of differential equation was adopted by establishing the bending and torsional differential equation of the jib system under the instability critical state. Compared with the numerical solutions of the finite element software ANSYS, the analytical results in this work agree well with them. Therefore, the correctness of the results in this work can be confirmed. Then the influences of the lateral stiffness of the cable fixed joint, the dip angle of the strut, the inertia moment of the strut, and the horizontal position of the cable fixed joint on the out-of-plane buckling behavior of the jib system were investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.171-176
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• 2011

The purposes of the research were to evaluate system performance and response of building structure under external load for full scale modal-testing-tower applied toggle bracing and lead rubber damper(LRD). The dynamic properties of the structure were measured before and after installing damper under harmonic excitation using the AMD and the results were compared. The harmonic excitation condition is to increase 0.01Hz sine sweep signal from 0.49Hz to 0.63Hz. As a result of measuring resonant frequency, before installing damper is 0.55Hz and after installing damper is 0.62Hz. The experimental results after installing damper were also distinguished from simulation results and the main cause of this results is temperature dependency property of rubber material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.298-303
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• 2016

Owing to the advantages of reduced weight and wind effect, the space-framed towers that consist of vertical and horizontal members of circular hollow tubular sections have been adopted widely for various purposes. It is critical to guarantee the strengths of tubular joints where vertical and horizontal members are connected structurally to make the entire space-framed system behave as a single tower structure. In this study, a strength evaluation was conducted for T-type tubular joints subjected to the concurrent action of compression and bending. Three of the available design codes, i.e., AISC, Eurocode 3, ISO 19902 were investigated and a design equation was suggested for an ultimate strength interaction between the axial force and bending moment based on nonlinear finite element analyses by selecting the slenderness ratios at the joints as major parameters.