• Steel and Composite Structures
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• v.45 no.2
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• pp.219-230
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• 2022

The aim of this paper is to study the mechanical behaviors of the cold-formed thin-walled steel and reinforced concrete sandwich composite slab (CTS&RC-SCS) under vertical loads and to develop the calculation methods of its flexural bearing capacity and section stiffness. Two CTS&RC-SCS specimens were designed and manufactured to carry out the static loading test, and meanwhile, the numerical simulation analyses based on finite element method were implemented. The comparison between experimental results and numerical analysis results shows that the CTS&RC-SCS has good flexural capacity and ductility, and the accuracy and rationality of the numerical simulation analysis are verified. Further, the variable parameter analysis results indicate that neither increasing the concrete strength grade nor increasing the thickness of C-sections can significantly improve the flexural capacity of CTS&RC-SCS. With the increase of the ratio of longitudinal bars and the thickness of the composite slab, the flexural capacity of CTS&RC-SCS will be significantly increased. On the basis of experimental research and numerical analysis above, the calculation formula of the flexural capacity of CTS&RC-SCS was deduced according to the plastic section design theory, and section stiffness calculation formula was proposed according to the theory of transformed section. In terms of the ultimate flexural capacity and mid-span deflection, the calculated values based on the formulas and the experimental values are in good agreement.

• Journal of Korean Society of Steel Construction
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• v.16 no.3 s.70
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• pp.325-332
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• 2004

Cross sections of steel-plate girder bridges are divided into three cross sections of non-composite, partially composite, and fully composite sections, according to their composite characteristics. The Korean provision for the partially and fully composite sections specifies general usage of the stud of shear connectors, whereas the one for the non-composite section specifies empirical usage of slab anchors. However, the actual behavior of the cross sections of steel-plate girder bridges using slab anchors is close not to the non-composite action, but to the partially composite action. Therefore analytical and experimental studies on partial composites of steel-plate girder bridges using slab anchors are performed in this study. Intial stiffness of the slab anchor is obtained by the experimental study for the first time, and the composite characteristic of simple-span and two-span continuous steel-plate girder bridges is investigated by the finite element analyses for the second time. Based on the obtained initial stiffness, the reduction effect of tensile stresses in the concrete-slab on the intermediate support of the continuous bridge is also considered herein.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.36-43
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• 2005

Stiffness reduction factor of slab in flat-plate structure is proposed in comparison with UCB test result. Then analysis of structural system of flat-plate apartment buildings is carried out by using effective beam width method and finite element method. Effective beam width method overestimates the lateral stiffness of the system where columns are arranged atypically and overestimates the stiffness of slab-wall joint.

• Tribology and Lubricants
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• v.14 no.4
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• pp.44-50
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• 1998

This paper describes the simulation of the levitation force between permanent magnet and high Tc(critical temperature) superconductor(HTSC). Levitation force is evaluated numerically on the basis of the magnetic vector potential method and the critical state model. The superconductor is approximated to 2-D slab model. By performing computations, the following characteristics have been investigated: the process of the generation of hysteresis, the various hysteretic behaviors. The characteristics of hysteresis are important for the application to magnetic bearing, for the damping and the nonlinear stiffness is related to hysteresis.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.191-194
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• 2005

Recently the heavy weight impact noise transmitted slab vibration has been recognized as an important issue. The aim of this study is to find the path of vibration transmission, comparing the numerical analysis with the field test results. Additionally the effect of stiffening beam element under slab, as a method to increase the stiffness of slab, will be shown concerning natural frequencies.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.191-198
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• 2003

Flat slab system has been adopted in many buildings constructed recently because of the advantage of reduced floor heights to meet the economical and architectural demands. Structural engineers commonly use the equivalent frame method(EFM) with equivalent beams proposed by Jacob S. Grossman in practical engineering for the analysis of flat slab structures. However, in many cases, when it is difficult to use the EFM, it is necessary to use a refined finite element model for an accurate analysis. But it would take significant amount of computational time and memory if the entire building structure were subdivided into a finer mesh. An efficient analytical method is proposed in this study to obtain accurate results in significantly reduced computational time. The proposed method employs super elements developed using the matrix condensation technique and fictitious beams are used in the development of super elements to enforce the compatibility at the interfaces of super elements. The stiffness degradation of flat slab system considered in the EFM was taken into account by reducing the elastic modulus of floor slabs in this study. Static and dynamic analyses of example structures were peformed and the efficiency and accuracy of the proposed method were verified by comparing the results with those of the refined finite element model and the EFM.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.1-10
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• 2019

In the construction of flat plate slabs, which are widely used for tall buildings but have relatively low flexural stiffness, serviceability problems such as excessive deflections and cracks are of great concern. To prevent excessive deflections at service load levels, current design codes require the minimum slab thickness, but the requirement could be unconservative because it is independent on loading and elastic modulus of concrete, both of which have significant effects on slab deflections. In the present study, to investigate the effects of the construction load of shored slabs, reduced flexural stiffness and moment distribution of early-age slabs, and creep and shrinkage of concrete on immediate and time-dependent deflections, numerical analysis was performed using the previously developed numerical models. A parametric study was performed for various design and construction conditions of practical ranges, and a new minimum permissible thickness of flat plate slabs was proposed satisfying the serviceability requirement for deflection. The proposed minimum slab thickness was compared with current design code provisions and numerical analysis results, and it agreed well with the numerical analysis results.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.922-927
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• 2004

The bending moment and settlement of the slab track can be reduced by the installation of small numbers of micro piles beneath the track. This paper presents the effect of micro pile installation on the reduction of bending moment and settlement of slab track, estimated by a numerical method. The slab track is modeled as a plate based on the Mindlin's plate theory, and soil and piles are modeled as Winkler and coupled springs, respectively. The stiffness of piles is obtained by the approximate analytical method proposed by Randolph and Wroth. and the modulus of subgrade reaction is adopted to evaluate Winkler spring constant. From the analysis results, the effect of the micro pile installation is significant to considerably reduce the settlement of slab track. However, for the proper reduction of bending moments in a slab track, the pile arrangement should be reasonably taken into account to prevent the stress concentration at pile location.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.79-82
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• 2005

This study reports on the structural characteristics of slab-column connections using an ultra-high-strength-fiber-reinforced concrete from new and retrospective data. The parameters investigated were the ' puddling ' of ultra-high-strength-fiber-reinforced concrete and the use of high-strength concrete in the slab. The effects of these parameters on the punching shear capacity, negative moment cracking, and stiffness of the two-way slab specimens are investigated. Furthermore, the ACI Code (2002), the CSA Standard (1994), the BS Standard (1985) and the CEB-FIP Code (1990) predictions are compared to the experimental results obtained from some slab-column connections tested in this experiment and those tested by other investigators. The beneficial effects of the ultra-high-strength-fiber-reinforced concrete puddling and of the use of high-strength concrete are demonstrated. It is also concluded that the punching shear strength of slab-column connections is a function of the flexural reinforcement ratio.

• Steel and Composite Structures
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• v.24 no.1
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• pp.113-128
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• 2017

This paper highlights a study undertaken on the free vibration of a precast steel-concrete composite slab panel for track support. The steel-concrete composite slab track is an evolvement from the slab track, a form of ballastless track which is becoming increasingly attractive to asset owners as they seek to reduce lifecycle costs and deal with increasing rail traffic speeds. The slender nature of the slab panel due to its reduced depth of construction makes it susceptible to vibration problems. The aim of the study is driven by the need to address the limited research available to date on the dynamic behaviour of steel-concrete composite slab panels for track support. Free vibration analysis of the track slab has been carried out using ABAQUS. Both eigenfrequencies and eigenmodes have been extracted using the Lanczos method. The fundamental natural frequencies of the slab panel have been identified together with corresponding mode shapes. To investigate the sensitivity of the natural frequencies and mode shapes, parametric studies have been established, considering concrete strength and mass and steel's modulus of elasticity. This study is the world first to observe crossover phenomena that result in the inversion of the natural orders without interaction. It also reveals that replacement of the steel with aluminium or carbon fibre sheeting can only marginally reduce the natural frequencies of the slab panel.