• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.331-340
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• 2004

This paper presents a feasibility study of a fresh air load reduction system by using an underground double floor space. The fresh air is introduced into the double slab space and passes through the opening bored into the footing beam. The air is cooled by the heat exchange with the inside surface of the double slab space in summer, and heated in winter. This system not only reduces sensible heat load of the fresh air by heat exchange with earth but also reduces latent heat load of the fresh air by ad/de-sorption of underground double slab concrete. In this paper, we used a model for evaluation of fresh air latent heat load reduction by hygroscopic of air to earth exchange system taking into account coupled heat and moisture transfer of underground double floor space. In conclusion it shows the validity of the proposed method for a design tool and the quantitative effect of the system.

• Computers and Concrete
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• v.21 no.5
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• pp.547-557
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• 2018

This paper measures the mechanical response of precast pavement joints under moving axle loads using the finite-element method, and the models were validated with results of field tests. In order to increase the ability to use the non-linear FE analysis for design and assessment of precast pavement subjected to moving axle load, this paper investigated the effects of different load transfer between the slabs using the ABAQUS finite-element package to solve the nonlinear explicit model equations. The assembly of the panels using dowels and groove-tongue keys has been studied to assess the efficiency of keyway joint system. Concrete damage plasticity model was used to calculate the effects of permanent damages related to the failure mechanisms. With aggregate interlock as the only load transferring system, Load transfer efficiency (LTE) is not acceptable when the axle load reaches to slab joints. The Finite-element modelling (FEM) results showed that keyway joints significantly reduced tensile stresses developed at the mid-slab. Increasing the thickness of the tongue the LTE was improved but with increasing the height of the tongue the LTE was decreased. Stresses are transferred to the adjacent slab efficiently when dowels are embedded within the model. When the axle load approaches joints, tensile damage occurs sooner than compressive damage, but the damage rate remains constant, then compressive damage increases significantly and become the major form of distress under the dowels.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.117-124
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• 2007

An experimental research has been performed to evaluate the load transfer capacity for the planar joints between existing and new slab in an apartment remodelling constructions expecially for enlarging the interior space. Post-installed dowel bars were used as a joint connector. The existing slabs were obtained from the existing apartment housing which will be demolished, and were retrofitted with carbon fiber plate. Test results showed that the planar joints with post-installed dowel bars behaved in full composite modes until ultimate capacity of test specimens, so sufficient ultimate and serviceability performance are confirmed.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.375-381
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• 2011

The passage of railway vehicles generates mechanical vibrations and noises. This problem can be mitigated by the 'floating slab track' that isolating from infrastructures by installing vibration isolator in the concrete slab track. In the previous researches, adjacent floating slab tracks are connected by dowel bar system. It has been reported that many dowel bars with less diameter show better load transfer efficiency (LTE) compared to small number of dowel bars with larger diameter under the condition of the same dowel area. In this study, dowel system is further considered as a concrete anchorage system and the design strength of the dowel system was evaluated based on ACI code 318-08 Appendix D. The design strength of dowel system is then verified against failure load test of floating slab system.

• Structural Engineering and Mechanics
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• v.53 no.4
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• pp.645-659
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• 2015

This research investigates the thermoelastic transient behavior of a thermally loaded slab made of a thermal diode-like material which has two directional thermal conductivity values (low and high). Finite difference analysis is used to obtain the elastic response of the slab based on the temperature solutions. It is found that the rate of heat transfer through the thickness of the slab decreases with reducing the ratio between the low and high thermal conductivity values (R). In addition, reducing R makes the slab less responsive to the thermal load when heated from the direction associated with the low thermal conductivity value.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.113-119
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• 2000

The R/C flat plate system provides architectural flexibility, clear space, reduced building height, simple formwork, which consequently enhance constructibility. One of the serious problems in the flat plate system is brittle punching shear failure due to transfer of shear force and unbalanced moments in column-slab joint. Recently, the flat plate system accompanied with shear walls to resist the lateral loads is applied to high-rise buidings. Although the flat plate system is not considered in design as part of the lateral load-resisting system, it is required that this system keeps the ductile behavior for the lateral displacement of the building. However, it is unclear whether the column-slab joint possesses ductility enough to survive the lateral deformation. The objective of this paper is to investigate the major parameters that influence the ductility of R/C flat plate system by examining the existing experiments on column-slab joint. The effects of gravity load and shear reinforcement on the ductility of the flat plate system are presented.

• Journal of the Korean Society for Railway
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• v.1 no.1 s.1
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• pp.30-39
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• 1998

The functions of diaphragms at abutments and piers of PSC box girder railway bridge are to transfer forces from the superstructure onto bearings or columns and to stiffen the superstructure cross-section against in -plane deformation. Due to stress disturbance at diaphragm, the design for the diaphragm using conventional design method is relatively irrational than those for other structural members. And, due to contribution to boundary condition of deck slab by the diaphragm, the behavior of deck slab near the diaphragm is different from that of the deck slab obtained from two dimensional analysis of the bridge, which is basis for the design of deck slab. In this paper, three dimensional behavior of deck slab near the diaphragm of prestressed concrete (PSC) box girder railway bridge constructed by the precast span method are analyzed by using three dimensional finite element modeling and using the strut-and-tie model design of the diaphragm are presented. The modeling techniques used in this paper can be applied effectively to examine the causes of cracks at deck slab near diaphragm and to design diaphragm rationally.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.278-285
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• 2013

The suppression of residual settlement is required on earthwork sections as concrete track is introduced. Use of pile-slab structure is one of the settlement restraining methods applied on soft ground. The slab distributes the upper embankment load and piles transfer the load from the slab to the stiff ground. While this method is very effective in terms of load transfer, it has not yet been established for dealing with the vibration transfer effects and interaction characteristics between a structure and the ground. It is possible that vibration caused by a moving train load is propagated in the upper embankment, because the slab acts as a reflection layer and waves are multi-reflected. In this present paper, wave propagation generated by a moving train load is evaluated in the time and frequency domains to consider a roadbed structure using an artificial impact load and field measured train load. The results confirmed the wave reflection effect on the pile-slab structure, if the embankment height is sufficient, vibration propagation can be stably restrained, whereas if the height is not sufficient, the vibration amplitude is increased.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.229-239
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• 2008

This paper compares the load transfer efficiency between precast concrete pavement specimen and typical concrete pavement specimen by means of laboratory and field tests. An experimental method was developed to evaluate the load transfer efficiency of the dowel bars buried in the concrete pocket and grouted with cement mortar. The test results showed that the load transfer efficiency of the specimen for the dowel bars repaired with grout was equivalent to that of the control specimen. In addition, a series of FWD field tests were conducted on the precast pavement to evaluate the joint stiffness. The field test results revealed that the central deflection of the precast slab slightly increased but the load transfer efficiencies at the joints were almost the same as those in the typical concrete pavement slab.

• Steel and Composite Structures
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• v.47 no.2
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• pp.203-216
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• 2023

The composite beam connections often encountered fracture failure in the welded bottom flange joint, and a bottom flange bolted connection has been proposed to increase the deformation ability of the bottom flange joint. The seismic performance of the bottom flange bolted composite beam connection was suffered from both the composite action of concrete slab and the asymmetric load transfer mechanisms between top and bottom beam flange joints. Thus, this paper presents a comprehensive numerical study on the working mechanism of the bottom flange bolted composite beam connections. Three available modelling methods and a new modelling method on the flange-stud-slab interactions were compared. The efficient numerical modeling method was selected and then applied to the parametric study. The influence of the composite slab, the bottom flange bolts, the shear composite ratio and the web hole shape on the seismic performance of the bottom flange bolted composite beam connections were investigated. A hogging strength calculation method was then proposed based on numerical results.