• Steel and Composite Structures
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• 제45권2호
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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.

• 한국강구조학회 논문집
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• 제16권3호통권70호
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• pp.325-332
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• 2004

강합성거더 교량의 단면은 강거더와 콘크리트 슬래브의 합성정도에 따라 각각 비합성, 부분합성 그리고 완전합성 단면들로 구분 할 수 있다. 국내의 경우 강합성거더 교량의 단면을 합성시키기 위하여 일반적으로 전단 연결재 중 스터드를 사용하도록 규정하고 있고, 진단 연결재가 없는 경우 즉 비합성 단면의 경우에는 바닥판 앵커를 설치하도록 경험적으로 규정하고 있다. 그러나 바닥판 앵커를 사용한 단면의 실제 거동은 비합성 거동이 아닌 부분합성의 거동을 나타낸다. 그러한 이유로 본 연구에서는 바닥판 앵커를 사용한 플레이트거더교의 부분합성에 관한 해석 및 실험연구를 수행하였다. 실험연구를 통해서 바닥판 앵커의 초기강성을 산정하였고, 해석연구를 통해서 바닥판 앵커를 사용한 단순 및 2경간 연속 플레이트거더교의 합성정도를 비교$\cdot$분석하였다. 또한, 실험에 의해 산정된 강성 값에 근거하여, 2경간 연속 플레이트거더교에 바닥판 앵커를 적용하였을 때 발생할 수 있는 내부지점부 콘크리트의 인장응력 저감 효과를 검토하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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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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• 제14권4호
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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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.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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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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• 제69권1호
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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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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• 제24권1호
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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.