• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.343-350
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• 2017

The RC flat plate system has benefits such as a short construction time, an improvement of workability and a floor height reduction. In the case of long span slab, cracking damages and large deflections tend to occur due to the low flexural stiffness of flat plates. Specially, over-loading by self-weight of slab during construction increases short and long-term deflections. These problems may be solved by the use of void slab that has benefits of the reduced self-weight. In this study, to analyze an effect of self-weight reduction of void slab on slab deflections, the parametric study is performed. Including variable conditions such as a concrete strength, a slab construction cycle, the number of shored floors, a compressive reinforcement ratio and a tensile reinforcement ratio, slab construction loads and deflections are calculated by considering the construction stages, concrete cracking, and long-term effects. The short-term deflections during construction and the long-term deflections after construction of both of normal and void slabs are compared and the effects of void slab on the reduction of slab deflections are analyzed.

• Advances in concrete construction
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• v.5 no.5
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• pp.451-468
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• 2017

The problem of reducing the self-weight of reinforced concrete structures is very important issue. There are two approaches which may be used to reduced member weight. The first is tackled through reducing the cross sectional area by using voids and the second through using light weight materials. Reducing the weight of slabs is very important as it constitutes the effective portion of dead loads in the structural building. Eleven slab specimens was casted in this research. The slabs are made one way though using two simple supports. The tested specimens comprised three reference solid slabs and eight styropor block slabs having (23% and 29%) reduction in weight. The voids in slabs were made using styropor at the ineffective concrete zones in resisting the tensile stresses. All slab specimens have the dimensions ($1100{\times}600{\times}120mm$) except one solid specimens has depth 85 mm (to give reduction in weight of 29% which is equal to the styropor block slab reduction). Two loading positions or cases (A and B) (as two-line monotonic loads) with shear span to effective depth ratio of (a/d=3, 2) respectively, were used to trace the structural behavior of styropor block slab. The best results are obtained for styropor block slab strengthened by minimum shear reinforcement with weight reduction of (29%). The increase in the strength capacity was (8.6% and 5.7%) compared to the solid slabs under loading cases A and B respectively. Despite the appearance of cracks in styropor block slab with loads lesser than those in the solid slab, the development and width of cracks in styropor block slab is significantly restricted as a result of presence a mesh of reinforcement in upper concrete portion.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.138-143
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• 1998

The continuous casting process has been adopted increasingly in recent years to save both energy and labor. It has experienced a rapid development in the production of semi-finished steel products, replacing the conventional route of ingot casting plus rolling. To achieve this good merit, however, more studies about a heat transfer mechanism between roll and slab are needed. So this paper shows the results of the deformation behavior of steel cast slabs, which are about the solidification and heat transfer. This study is used to prevent internal cracks of a slab in a bending and unbending zone. The value of moving strand shell bulging between two supporting rollers under ferrostatic pressure and slab-self weight has been computed in terms of creep and elastic-plasticity. The high strand distributions in solidified shell undergoes a series of bulging are calculated with boundary condition a very closed to continuous steel cast slabs productions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.97-104
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• 2014

Hollow slab is a floor system which reduces the load of vertical structural members and earthquake load by decreasing self-weight of slab. Although hollow slab can reduce self-weight of slab remarkably, flexural strength and shear strength reduce due to the hollow section inside the slab, so it is very important to predict structural behavior. In spite of plenty of domestic and foreign studies on hollow slab, there is a shortage of research on shear performance according to shear reinforcement of one-way hollow slab. Therefore, this study aims to verify the need for shear reinforcement of one-way hollow slab by analyzing failure modes of one-way hollow slab depending on the state of shear reinforcement and comparing shear strengths of estimation formula and experimental value with one another.

• Geomechanics and Engineering
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• v.37 no.1
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• pp.1-8
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• 2024

Buckling failure is one of the classical types of catastrophic landslides developing on inclination-paralleled rock slopes, which is mainly governed by its self-weight, earthquake and ground water. However, nearly none of the existing studies fully consider the influence of slope self-weight, earthquake and ground water on the mechanical model of buckling failure. In this paper, based on energy equilibrium principle and elastoplastic slab theory, a thorough mechanical analysis on bucking slopes has been carried out. Furthermore, an analytical solution for slip bucking failure of rock slopes has been proposed, which fully considers the effect of slope self-weight, seismic force and hydrostatic pressure. Finally, the methodology is used to conduct comparative analysis with other analytical solutions for three practical buckling studies. The results show that the proposed approach is capable of providing a more accurate and reasonable evaluation for stability of rock slopes with potential buckling failure.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.391-398
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• 2012

This paper presents the shear capacities of biaxial hollow slab with donut type hollow sphere. Recently, various types of slab systems which can reduce self-weight of slabs have been studied for increasing constructions of taller and larger building structures. A biaxial hollow slab system is widely known as one of the effective slab system, which can reduce self-weight of slab. According to previous studies, the hollow slab has low shear strength, compared to solid slab. Also, the shear capacities of biaxial hollow slab are influenced by the shapes and materials of hollow spheres. However, the current code does not provide a clear computation method for the shear strength of hollow slab. To verify the shear capacities of this hollow slab, one-way shear tests were performed. Four test specimens were used for test parameters. One was conventional RC slab and others were hollow slabs. The test parameters included two different shapes and materials of plastic balls. The shape parameters were donut and non-donut forms and the material parameters were general plastic and glass fiber plastic. The results showed that the shear strengths varied depending on hollow shapes and materials used in the slab.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.86-92
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• 2017

The possibility to development of floor vibration problem is larger in case of long span structure under service loads. Therefore, to improve the vibration performance of the floor, increasing of its thickness is a common method. But, increasing of thickness can lead to increase of slab self weight and reduce the effectiveness of the building. For this reason, attention for voided slab which reduces the self-weight is increasing. Hence, voided deck slab combined with deck plate and polystyrene void foam which has buoyancy prevention capacity and much developed construct ability has bee developed. By using the developed voided slab, vibration performance of a mock-up building structure has been investigated in the current study. The results according to analysis showed that they can be implemented in living and bedroom which are considered as 1st grade on the basis of "Residential Evaluation Guidelines for Vibration of Buildings" by the Architectural Institute of Japan.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.257-264
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• 2002

This study presents a life-cycle cost (LCC) effectiveness of a concrete with lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. In this study, an optimum design for minimizing the life-cycle cost of concrete slab bridges is performed to evaluate the life cycle cost effectiveness of the lightweight concrete relative to conventional one from the standpoint of the value engineering. The data of physical properties for new concrete can be obtained from basic experimental researches. The material properties of conventional one are acquired by various reports. This study presents a LCC effectiveness of newly developed concrete, which is made by artificial lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. From the results of the numerical investigation, it may be positively stated that the new concrete lead to, the longer span length, the more economical slab bridges compared with structures using general concrete.

• Computers and Concrete
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• v.32 no.4
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• pp.351-363
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• 2023

Reducing the self-weight of reinforced concrete structures problem is discussed in this paper by using two types of self-weight reduction, the first is by using lightweight coarse aggregate (crushed brick) and the second is by using styropor block. Experimental and Numerical studies are conducted on (LWAC) lightweight aggregate reinforced concrete slabs, having styropor blocks with various sizes of blocks and the ratio of shear span to the effective depth (a/d). The experimental part included testing eleven lightweight concrete one-way simply supported slabs, comprising three as reference slabs (solid slabs) and eight as styropor block slabs (SBS) with a total reduction in cross-sectional area of (43.3% and 49.7%) were considered. The holes were formed by placing styropor at the ineffective concrete zones in resisting the tensile stresses. The length, width, and thickness of specimen dimensions were 1.1 m, 0.6 m, and 0.12 m respectively, except one specimen had a depth of 85 mm (which has a cross-sectional area equal to styropor block slab with a weight reduction of 49.7%). Two shear spans to effective depth ratios (a/d) of (3.125) for load case (A) and (a/d) of (2) for load case (B), (two-line monotonic loads) are considered. The test results showed under loading cases A and B (using minimum shear reinforcement and the reduction in cross-sectional area of styropor block slab by 29.1%) caused an increase in strength capacity by 60.4% and 54.6 % compared to the lightweight reference slab. Also, the best percentage of reduction in cross-sectional area is found to be 49.7%. Numerically, the computer program named (ANSYS) was used to study the behavior of these reinforced concrete slabs by using the finite element method. The results show acceptable agreement with the experimental test results. The average difference between experimental and numerical results is found to be (11.06%) in ultimate strength and (5.33%) in ultimate deflection.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.12-13
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• 2019

Flexible Table Form is being used more frequently at the level of formwork in construction site. However, one of the most common structural frameworks, the RC column-beam structure, is having problems in these factors. To improve this problems, this study developed support devices and proposed installation specifications to enable application of the one-way void slab method to flexible table form. It is expected that the effects of reducing the self-weight of the slab in the floor slab construction using flexible table form.