• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.167-172
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• 2001

Hollow core slabs generally have not been used for a bridge slab or a parking in Korea. In this study, high performance hollow core slabs, which has been the most thick one in domestic are re-designed and examined for practical use. Flexural tests were performed on four 315mm deep hollow core slabs to investigate adaptability for high vehicle live loadings and composite action with topping concrete. The precast slabs were reinforced with 10-l/2 inch dia-strands at the lower of slab and 4-l/2 inch dia-strands at tile upper of slab, and cast with 80mm deep topping concrete. Those tested hollow core slabs showed ductile failure behaviors which were conform to the current Ultimate Strength Design Method for a span of l0m up to the live load of 1, 000 kg/$m^2$.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.311-314
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• 2005

This research aims to analyze of prestressed composite hollow-core slab and box type steel beam. The smeared crack model used in abaqus for the modeling of hollow core reinforced concrete, including cracking of the concrete, rebar and concrete interaction using the tension stiffening concept, and rebar yield. The structure modeled is a simply supported hollow core spancrete slab subjected spa-h beams and prestressed in one direction. The hollow core spancrete slab is subjected to four-point bending. The concrete-rebar interaction that occur as the concrete begins to crack are of major importance in determining the spancrete slab's response between its initial, deformation and its collapse. This smeared crack model used in analysis involved non-liner concrete analysis concept.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.397-400
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• 2004

This research aims to estimate the shear strength of the composition of prestressed hollow-core slab and steel beam. The shear strength of prestressed hollow-core slab combined with the steel beam decreases, as the beam deflection increases to a considerable extent. Existing studies on the shear strength of prestressed hollow-core slab are mostly limited to 265mrn- and larger thickness slab on concrete beam. This study investigates the slab of 100mm-thickness combined with steel beam instead of concrete beam. Five shear connector methods are proposed and the shear strength is estimated with or without the beam deflection for each composition method, respectively. Finally the reduction coefficient $(\beta)$ for the transverse shear stress$(\tau_{zx})$, which is critical for the failure of prestressed hollow-core slab, is proposed.

• Structural Monitoring and Maintenance
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• v.6 no.4
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• pp.269-289
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• 2019

This study investigated experimentally the response of thick reinforced concrete specimens having hollow cores with critical parameters. The investigation includes testing of twelve specimens that are solid and hollow-core slab models. Each specimen consists of two pieces, the piece dimensions are (1.2 m) length, (0.3 m) width and (20 cm) thickness tested under both monotonic and repeated loading. The test program is carried out to study the effects of load type, core diameters, core shape, number of cores, and steel fiber existence. Load versus deflection at mid span, failure modes, and crack patterns were obtained during the test. The test results showed that core shape and core number has remarkable influenced on cracking pattern, ultimate load, and failure mode. Also, when considering repeated loading protocol, the ultimate load capacity, load at yielding, and ductility is reduced.

• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.535-546
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• 2018

The objective of this study is to understand the behaviour of hollow core slabs strengthened with FRP and hybrid techniques through numerical and analytical studies. Different strengthening techniques considered in this study are (i) External Bonding (EB) of Carbon Fiber Reinforced Polymer (CFRP) laminates, (ii) Near Surface Mounting (NSM) of CFRP laminates, (iii) Bonded Overlay (BO) using concrete layer, and (iv) hybrid strengthening which is a combination of bonded overlay and NSM or EB. In the numerical studies, three-dimensional Finite Element (FE) models of hollow core slabs were developed considering material and geometrical nonlinearities, and a phased nonlinear analysis was carried out. The analytical calculations were carried out using Response-2000 program which is based on Modified Compression Field Theory (MCFT). Both the numerical and analytical models predicted the behaviour in agreement with experimental results. Parametric studies indicated that increase in the bonded overlay thickness increases the peak load capacity without reducing the displacement ductility. The increase in FRP strengthening ratio increased the capacity but reduced the displacement ductility. The hybrid strengthening technique was found to increase the capacity of the hollow core slabs by more than 100% without compromise in ductility when compared to their individual strengthening schemes.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3303-3306
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• 2014

A facile and effective approach has been developed to prepare hybrid hollow microspheres, via consecutive processes of pickering mini-emulsion polymerization for core-shell formation, and calcination of the sacrificial core. The resulting hollow composite particles have mono-layered shells. The morphology and size characteristics of synthesized composite particles were investigated, using dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements.

• Structural Engineering and Mechanics
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• v.81 no.1
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• pp.59-68
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• 2022

Prestressed prefabricated hollow core concrete slabs with spans of 5 m and 10 m are commonly used since last century and still in service due to the advantage of construction convenience and durability. However, the end slabs are regularly subjected to cracks at the top and fail with brittleness due to the asymmetric boundary conditions. To better maintain such widely used type of hollow core slabs, the effect of asymmetric constraint in the end slabs are systematically studied through detailed nonlinear finite element analyses and experimental data. Experimental tests of slabs with four prestressed tendons and seven prestressed tendons with different boundary conditions were conducted. Results observe three failure modes of the slabs: the bending failure mode, shear and torsion failure mode, and transverse failure mode. Detailed nonlinear finite element models are developed to well match the failure modes and to reveal potential damage scenarios with asymmetric boundary conditions. Recommendations regarding ultimate capacity of the slabs with asymmetric boundary conditions are made to ensure a safe and rational design of prestressed concrete hollow slabs for short span bridges.

• Computers and Concrete
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• v.19 no.5
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• pp.567-577
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• 2017

This study presents investigation of the behavior of moderately thick reinforced concrete slabs having hollow cores with different parameters. The experimental part of this investigation includes testing eight specimens of solid and hollow-core slab models having (2.05 m) length, (0.6 m) width and (25 cm) thickness under two monotonic line loads. Load versus deflection was recorded during test at mid span and under load. Numerically, the finite element method is used to study the behavior of these reinforced concrete slabs by using ANSYS computer program. The specimens of slab models are modeled by using (SOLID65) element to represent concrete slabs and (LINK180) element to represent the steel bars as discrete axial members between concrete nodes. The finite element analysis has showed good agreement with the experimental results with difference of (4.71%-8.68%) in ultimate loads. A parametric study have been carried out by using ANSYS program to investigate the effects of concrete compressive strength, size and shape of core, type of applied load and effect of removing top steel reinforcement.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.425-430
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• 1996

The purpose of this study is to investigate the behavior of the bearing precast concrete (pc) wall structure with hollow core based on experimental tests. In order to evaluate the cyclic performance of the pc walls. Too one story pc walls and ond one reinforced concrete wall are made. The experimental results of pc walls were compared with those values of reinforced concrete (rc) wall. The structural behaviors of pc wall structure with hollow core are similar to those of reinforced concrete bearing wall structure. This study shows that the pc wall with hollow core could be treated as rc wall when designs the pc wall structure against lateral loads

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.63-69
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• 2009

This paper provides the engineer with a simple design method dealing with situations arise where in-situ reinforced concrete joints are cast between hollow core units. Using finite element method, hollow core slabs with wide in-situ RC joints under point load and line loads are analysed. In addition, some important behavioural characteristics of the floor slab subjected to line and point loads are investigated. In-situ reinforced concrete joint causes reduction of load distribution for remote units because distance to the remote units from the point of load is increased, while the portion of load distribution carried by loaded unit increases. Also, it was turned out load distribution factors for point load and line loads are almost same. Finally, we suggest a simple analytical method, which can determine load distribution factors using normalized deflections by regression analysis for design purposes.