Concrete Hollow Floor Research Articles

Identifying the evolution of through cracks in iron-reinforced hollow slabs under the influence of a standard fire temperature mode

The object of this study is the fire resistance of reinforced concrete hollow slabs at the onset of the limit state of loss of integrity. The problem of accurate modeling of the formation and development of cracks in concrete was investigated. The paper reports an analysis of the results of the stress-strain state of a reinforced concrete hollow slab during fire exposure for devising a method for evaluating the fire resistance of such structures upon the onset of the limit state of loss of integrity. According to EN 1992-1-2, the determination of fire resistance of structures is provided by calculation methods, however, there is no such procedure for reinforced concrete hollow slabs. Many scientific works offer refined methods for evaluating only the loss of load-bearing and heat-insulating capabilities, leaving aside the issue of loss of integrity. Thus, this can lead to a biased evaluation of reinforced concrete hollow floor slabs according to the criterion of the limit state of loss of integrity, which in turn can put under a threat to the fire safety of buildings, which threatens the life and health of people. According to the results of the calculation, a parameter has been determined, according to which the onset of the limit state of fire resistance, in particular, the loss of integrity, was established. Summarizing the damage distributions, it was assumed that in the case of reaching the critical plastic deformation of 2.5e-3 in concrete finite elements, they are excluded from the general set of finite elements. Thus, in the case of the formation of through cracks, the removal of finite elements is taken as a parameter to identify the onset of the limit state of loss of integrity. According to the results of the computational experiment, it was established that through cracks in a fragment of a reinforced concrete hollow slab are formed in 44 min. According to the results of the research, the method of evaluating the fire resistance of such structures based on the onset of the limit state of loss of integrity has been substantiated. Such a method could be applied during design, which provides an opportunity to determine the limit of fire resistance in reinforced concrete hollow slabs

Method of manufacturing reinforced concrete floor slabs using non-removable void formers

The article provides a critical analysis of the work on the manufacture of monolithic reinforced concrete, relying on the contour, hollow floor slabs using box-shaped, spherical and tubular hollow-formers. The paper proposes a method of manufacturing monolithic reinforced concrete hollow floor slabs based on the contour using circular tubular polyethylene cardboard holders of rectangular or square shape in plan. The subject of the research is a method of continuous production of reinforced concrete floor slabs with round voids based on the contour using non-removable void formers, their technical and economic efficiency of solutions to reduce the weight of monolithic floor slabs by reducing the resources for their production. The technical and economic feasibility of manufacturing monolithic reinforced concrete floor slabs based on the contour with the use of non-retrievable void formers from round pipes of square and rectangular shape in plan has been substantiated. Materials for the manufacture of void former are proposed. The technical result has been determined - the maximum weight reduction of the proposed hollow core slabs compared to solid slabs.

An effective treatment method for phosphogypsum.

Phosphogypsum (PG) accumulation occupies huge amounts of land resources and results in serious environmental risks. A new recycling product, the phosphogypsum embedded filler (PGEF) made with calcination-modified phosphogypsum, was developed. The preparation process, hydration mechanism of PG, basic physical performances, environmental safety, engineering application, and cost analysis of the PGEF were studied. The results showed that the stress performance and thermal insulation property of the products were satisfied. Environmental performance tests established their findings that the application of PGEF prepared with calcination-modified PG does not cause any secondary contamination. In addition, the cost of PGEF is far lesser than that of the same volume of reinforced concrete. PGEF prepared with calcination-modified PG has shown a perfect application in cast-in situ concrete hollow floor structure.

Heat Analysis of Assembled Steel-truss Concrete Hollow Floor

The numerical analysis software ABAQUS has been used to study the temperature field of an assembled steel-truss concrete hollow floor in this paper to simulate the assembled steel-truss concrete hollow floor under thermal coupling under the ISO-834 standard heating curve. The distribution principle of temperature field for different sections in the floor system has been obtained to provide a reference for the study of the mechanical properties of assembled steel-truss concrete hollow floor.

Structural condition assessment of a reinforced concrete driveway

The reinforced concrete structure of a driveway built in the eighties of the 20th century is under consideration. It is a single-storey structure with a length of approx. 66.00 m, made in the form of a reinforced concrete skeletal structure, consisting of 7 frames with cantilevers, spaced at 9.00 m: 3 frames in the horizontal part of the driveway are three-span ones, and 4 in the sloping part are single-span frames. The driveway frame main beams have a rectangular cross-section and are based on pillars that have been placed on the spread footing these elements form a monolithic structure. Prefabricated reinforced concrete hollow floor plates were laid on them in the central part of the driveway, and in the outer parts the driveway floor was made of hollow clay slab blocks (Ackerman type). At the time of investigation, the upper layers of the driveway consisted of a surface waterproofing layer, a concrete slab of approx. 10 cm thickness made on a 1 cm sand layer. However, no internal waterproofing layer was found as was in the original design. The paper describes the process of determining the current technical condition of the reinforced concrete driveway structure, paying attention to the design and construction of the object, its operation (including the issues of durability of concrete under the conditions of possible impacts of the marine environment). Static and strength calculations were also performed (supported by concrete and reinforcement tests) and the conditions for further operation of the driveway were analyzed as well as concepts of rehabilitation.

Calculation and Numerical Simulation of the Torsional Problems of Hollow Floor’s Boundary Beam

As a new form of floor, the cast-in-place reinforced concrete hollow floor has the advantages on functions, structural and economic performances.It is a great technological innovation in the field of building structure in our country. This paper studies the torsional problems of the hollow floor boundary beam, and derives the torque’s calculation formula of boundary beam. Then the paper compares the results with the numerical simulation. The results show that both the error is small, the theoretical derivation formula has certain feasibility.

Thermal Isolation Character of Reinforced Concrete Hollow Floor

Reinforced Concrete Hollow floor system was named by its typical inner core and worked as an excellent horizontal bearing structure. It has fine mechanical ability and good thermal isolation character. The author compared reinforced concrete hollow floors and traditional reinforced concrete floor. And studied their development in long span or large loaded building.

The Experimental Study on Mechanical Performance of Multi-Span Column-Supported Assembly Box Concrete Hollow Floor

Assembly box concrete hollow floor sructure is a new-style whole structure that are constituted by the a cross section of a concrete box composed of small prefabricated components (concrete superposition box) and a cast-in-place concrete rib beam.The internal force distribution law was analyzed in this paper, based on the static load experiment with a multi span column-supported assembly box concrete hollow floor.The findings prove that the prefabricated boxs and cast-in-situ concrete ribbed beams are able to form a whole to jointly bear external forces, that the internal force distribution law is basically the same with the solid cast-in-situ concrete floor with no beams, and that the floor structure can be simplified to the column strip and middle strip.The specific distribution ratios between the minus moment and the plus moment of the column strip and middle strip respectively are as follows. For the angel area floor(contianed edge beams), the ratio of midspan section is 0.537:0.463, the ratio of support section is 0.816:0.184; for the edge area floor(contianed edge beams), the ratio of midspan section is 0.51:0.49, the ratio of support section is 0.808：0.192; for the inner area floor, the ratio of midspan section is 0.55:0.45, the ratio of support section is 0.75:0.25.

The Method of Sandwich Plate about Thin-Wall Cast-in-Site Reinforced Concrete Hollow Floor

Treat the upper plate and lower plate of ribbed hollow floor as the surfaces of sandwich panel, and the ribbed hollow layer as the central layer of sandwich panel; consider the bending stiffness of the surfaces and transverse shear deformation of the central layer; use Hoff laminated theory; based on the same stiffness principle; establish sandwich panel structure model of hollow floor; Derive partial differential equations of cast-in-place reinforced concrete two-way ribbed and thin-walled hollow floor under vertical uniform load and present the analytic solution of the equations with two opposite clamped edges and others simply supported edges. Analyze the mechanical properties of hollow floor. The results are very close to the results of using finite element method.

Cast<i> - In Situ</i> Concrete Hollow Plates, the Application of the Teaching Building

The design and construction characteristics of cast-in-situ concrete hollow floor are introduced and the difficulties of the construction system are discussed in this paper. Based on the analysis of the engineering, the construction technology is introduced and its application is evaluated.

Joint Construction of Assembled Integrally Floor

This article expounds the floor ends and sides joint constructions of prestressed concrete floor and prestressed concrete hollow floor with added surface，as well as prestressed concrete hollow floor without added surface，and the comparation are available。Finally，some new construction methods are raised based on improving the seismic performance of integrally assembled prestressed concrete floor。

Shear-Lag Phenomenon in Cast-in-Site Reinforced Concrete Hollow Floor System

Shear-lag phenomenon exits in many long-web structure especially when the stiffness of web is much larger than that of the flange’s. In this paper, Energy-Variation Method is applied to interpret shear-lag phenomenon in cast-in-site reinforced concrete hollow floor system. Finite Element Method (FEM) and is then used to validate the analysis results. The solution for the variation equation for effective flange width is proposed by solving the differential equations using proper boundary conditions.

Study on Mechanical Behaviors of New Reinforced Concrete Hollow Floor Slab

In this paper a new type of reinforced concrete four-way rib hollow slab was proposed by the authors first. Further in order to research on the mechanical properties of the new floor slab the other two common slabs were compared with the new one, that was two-way rib hollow slab and solid slab. The rational finite element (FE) models of the three kinds of slabs supported by four corner columns were built up respectively by ANSYS. The deflection and stress of the three kinds of slabs under three load cases were calculated separately, on the basis of which thorough comparisons and analysis were carried out. The study results showed that the new reinforced concrete four-way rib hollow floor slab has superior mechanical properties.

Experimental Research of Assembly-Box Concrete Hollow Floor System under Gravity Load

Assembly-box concrete hollow floor is a new kind of cellular voided floor structure, in which a lot of prefabricated box-shaped interior forms are placed regularly on the formwork before the floor concrete is cast. The new type of box-shaped filler is termed assembly-box and could behave as load-bearing elements. Such floor system has many advantages, such as low self-weight, good mechanical behavior, equally flexural stiffness in two directions and high voided rate. The characteristic of this floor structure is the combination of precast assembly-box and cast-in orthogonal grids of ribs. For the purpose of understanding the behavior of this floor, a test has been carried out with three scale specimens under vertical loading. All experimental values provide essentially the same result that a typical flexural failure occurred under ultimate load and the structural system of assembly-box hollow could behave like an overall cast-in hollow floor. A part of the top plate in assembly-box could be viewed as the flange of rib beam during the process of structural design.

High sound and thermal insulation constructions with dB‐deck

The new Belgian requirements demand DnT,w⩾58 dB and L'nT,w⩽50 dB between apartments for enhanced acoustic comfort. At the same time the Energy Performance Regulations impose strict requirements for the thermal insulation between apartments. Higher demands on sound insulation can be realized in practice by using higher surface weights for walls and floors and by applying failure free floating floors. However requiring higher weights for floors is in contradiction with the technique of concrete hollow floor elements. A thermal and acoustical solution was found in the development of dB‐deck, a prefab double floor element with intermediate supporting elastic pads, cutting structural vibration paths between superposed apartments. In combination with double walls without anchors (allowing for a high sound reduction index and no structural transmission in the horizontal sense), this construction technique allowed for DnT,w>63 dB and L'nT,w<47 dB without a floating floor in experimental setups This solution was developed by a team of the BBRI, KULeuven, and CDM for an important producer of hollow floor elements. This technique has now been used for real constructions. The paper presents technical details, the results of the acoustical measurements and the acoustical advantages and difficulties met in the construction of this apartment block.