Self-weight Of Slab Research Articles

Structural Performance of Reinforced Concrete Double Layer Bamboo Bubble Slab Under Uniformly Distributed Load

The architectural use areas in the structure are formed by reinforced concrete (RC) slabs, which transport vertical loads to the beams, columns, load-bearing walls, and shear walls. The slab is an important structural member of reinforced concrete building structures and concrete-intensive parts of structural members. . The slab deflects significantly when the load acting on the slab or the clear span between columns is large. As a result, the slab's thickness increases to accommodate the load received. Since this slab's self-weight increases as the thickness increases, the slabs get heavier and causes the slab unable to withstand the load and to produce cracks on the surface. At the turn of the twentieth and twenty-first centuries, the creation of the bubble deck slab became an innovation to replace conventional slab. This study used bamboo as the bubble material in reinforced concrete bubble slab. This study examined and assessed the mechanical properties and structural behaviour of bamboo as a bubble in supported reinforced concrete double-layer bamboo bubble slab under a uniformly distributed load. In this research, 500 mm x 1250 mm x 175 mm supported reinforced concrete slabs C25 (1 sample) and C30 (1 sample) with double layer (DL) bamboo bubble slabs were constructed. Both samples were compared with the control sample (CS) for each slab type. It was found that the maximum displacement occurred at the centre of the slab, with 6.45 mm for DL25 and 6.89 mm for DL30. According to stress-strain analysis, the double layer bamboo slab produced a lower stress value than the control sample. Since the values were smaller than 2, DL25 and DL30 slab performed better for the ductility factor than CS25 and CS30. As a result, the displacement, ductility and section capacity were improved by employing bamboo as a bubble material in a reinforced concrete slab.

Comparative Study of and Voided Slab System and Conventional RCC Slab

This paper presents the flexural capacities of R.C.two-way hollow flat slabs with plastic voids. Recently, various types of slab systems which can reduce the self-weight of slabs have been studied as the height and span of building structures rapidly increase. To verify the flexural behaviour of this voided slab such as flexural stiffness, ultimate load, deflection, stresses and concrete compressive strain were studied.FEM model was created in ANSYS workbench 2022 for both conventional solid flat slab and voided slab. U-Boot beton from “daliform group building innovation Italy” was used as void former in this study. The dimensions of U-boot is 520×520mm and with 180mm and 160mm height. Dimension of FEM slab model is 8500×8500 mm with 500×500 column support at all four corners. Three different slab of 280mm, 300mm and 320mm was created. In addition, manual analysis of solid slab and voided slab was carried out using direct design method as per IS-456(2000). And further, design is checked to verify that it satisfies all design and serviceability criteria given as per IS-456(2000).Results obtain via theoretical calculation and FEM model simulation for both solid and voided slab were compared. The aim of this paper is to discuss and compare flexure behaviour of solid slab and voided slab and to study changes in inertia, stiffness and reduction in weight, of the slab by void formation.

Optimal Design of Bubble Deck Concrete Slabs: Sensitivity Analysis and Numerical Homogenization

The use of layered or hollow floors in the construction of buildings obviously reduces the self-weight of the slab, and their design requires some expertise. In the present work, a sensitivity analysis and numerical homogenization were used to select the most important characteristics of bubble deck floors that have a direct or indirect impact on their load capacity. From the extensive case study, conclusions were drawn regarding the optimal selection of geometry, materials, and the arrangement and size of air voids in such a way as to ensure high stiffness of the cross-section and at the same time maximally reduce the self-weight of the slabs. The conducted analyses showed that the height of the slab and the geometry of the voids had the greatest impact on the load-bearing capacity. The concrete class and reinforcement used are of secondary importance in the context of changes in load-bearing capacity. Both the type of steel and the amount of reinforcement has a rather small or negligible influence on the bubble deck stab stiffness. Of course, the geometry of the voids and their arrangement and shape have the greatest influence on the drop in the self-weight of the floor slabs. Based on the presented results of the sensitivity analysis combined with numerical homogenization, a set of the most important design parameters was ordered and selected for use in the optimization procedure.

Analysis of a ribbed slab without reinforcement using ANSYS

Concrete is widely used as a construction material in the world and consequently cement manufacturing industry ranks second in CO2 emission. To mitigate this environmental issue, this research focuses on reducing the self-weight of a concrete slab applying modern techniques to cut down the usage of cement, cutting carbon emissions from the cement manufacturing industries. The main goal of the study is to reduce the self-weight of concrete slabs and to eliminate steel reinforcement in concrete, and to use this stress profile to determine the isostatic path in concrete slabs. This would be achieved with high-strength concrete in the maximum bending stress path and replaces foam or other material in the minimum bending stress zone. In this work, the specimen considered for design and analysis is a slab having the dimension of 3 m x 3 m x 0.125 m. It slab uses 1% of steel fibers in concrete eliminating the need for reinforcement. Also, with the use of high-strength concrete in the maximum bending stress zone, the self-weight of the slab reduces up to 44%. The deformation of the slabs are well within the limits recommended by the codes released by Bureau of Indian Standards (BIS).

Flexural behavior of Two-Way voided slab

Slab is an essential part of a structure that consumes large quantity of concrete among all structural elements. Large self-weight of slab contrebutes to the larger dimensions of beams, columns & foundations which causes the increase in overall dead load and cost of structure. Voided slabs can be used as an economical and ecofriendly alternative to existing RCC slab systems. In voided slab concrete from the tension zone of the slab is removed partially; where concrete doesn’t have any structural benefit by creating voids using recycled plastic void formers. Therefore, self-weight of slab is decreased without changing the depth of slab, which in turns reduces the number of columns and offers more floor space for utilization. As it transfers lesser load on beams, columns & foundations, it reduces the overall sizes of all structural components and overall cost can be saved. In this study, finite element analysis is carried out using ANSYS Workbench 18.1. Five specimens are analyzed in this study out of which one of the slabs is a solid slab and the other four are voided slabs. Dice (cube) shaped voids are used as a void former in the biaxial voided slabs with variation in sizes and spacing between each other. The two-way flexural strength has been evaluated by applying sixteen point loading over full area of a slab. Load vs. deflection curves are plotted for each voided slab and compared it with solid slab. The flexural strength is evaluated using Rankine-Grashoff Theory and results are compared with the software results. The primary objective of the work is to study elastic behavior of voided slab and to compare it with solid slab. The present study proved that flexural behavior of voided slab with dice shaped void former shows good correlation with the solid slab system.

Bubble Deck Slab as an Innovative Biaxial Hollow Slab – A Review

Slab is the most important member in any building structure which consume large amount of concrete. The slab self-weight is large due to large consumption of concrete in producing slab. Therefore, bubble deck slab is an innovative and newly designed biaxial hollow slab system that had been introduced in order to overcome this problem. Bubble deck slab is a revolutionary method which was developed by Jorgen Bruenig from Denmark in the 1990s. The bubble deck slab had been designed and constructed with plastic hollow bubbles in the middle part of slab to eliminate the concrete which does not perform any structural function and at the same time reducing the slab self-weight. Thus, the self-weight of bubble deck slab can be reduced about 30-50% than conventional concrete slab; that can reduce the loads acting on columns, walls and foundations. Finally, the use of bubble deck slab can give many benefits as compared to conventional concrete slab such as improve the structural performance of slab, reduce the materials and cost, efficiency and faster construction time, and it is also a green product. The aim of this paper is to give some of the reviews from previous studies related to bubble deck slab.

Improvement of Structural Behaviour of Bubble Slab by Changing Bubble Thickness

Deflection of slab is the most important parameter by which we can calculate the depth of slab which is depend on total loads applied on the slab and span of slab between two column. The concept of bubble slab in which middle layer concrete is replaced by HDPE bubble which will helps to reduced its self-weight, deflection, moments & force reactions. The criteria of choosing suitable thickness of HDPE bubble are well mentioned in this paper with suitable examples so we can easily use that thickness value in practical on site. Static analysis of several models is done by finite element analysis method with tetra meshing by using Ansys ver. 15.0 as an analyzing tool. In this paper, results clearly specifies the structural behaviour change of bubble slab by changing its HDPE bubble thickness as well as its also specify the best thickness value of HDPE bubble. Bubble slab will be more useful on those structures in which intermediates columns is not required when the span of conventional slab is large then its deflection, moments & force reaction values is greater by which its depth is increased which makes conventional slab heavy so its total self-weight loads are transfer to column to footing which makes both increases in size & uneconomical. If we used the concept of bubble slab our nearly 35% self-weight of slab is reduced which positively effect on load transfer to other structural members and by this procedure whole structure will be more stable, durable & economical.

Behavior of Self Compacting Reinforced Concrete One Way Bubble Deck Slab

Reinforced concrete slab with plastic voids (Bubbled Deck system) is a new type of slabs which has two-dimensional arrangement of voids within the slab that is developed to decrease the slab self-weight while maintaining approximately the same load carrying capacity as compared with the solid slabs. Plastic voided slabs have the ability to reduce concrete amount by about 30 percent and this reduction is so important in terms of cost saving and enhancement the structural performance. In this research paper investigation is carried out to study the shear strength behavior of one-way bubble deck slab using self-compacting reinforced concrete. The experimental program consists of testing thirteen one-way slabs with dimensions of (1700 length, 700 width and 150 thick) mm. One of the tested slabs is a solid slab (without balls) is used as a reference, the remaining twelve bubbled slabs with ball diameter (73, 60) mm are divided into five groups according to the parameters of the experimental work, the parameters of the experimental work include: type of slab (bubble and solid slabs), ball diameter (73, 60) mm, shear reinforcement and spacing between balls. The experimental results showed that the bubbled slabs without shear reinforcement have a decrease in the ultimate load as compared to solid slab by about 3.7% to 14.3% and an increase in the deflection at ultimate load by about 10% to 22%, at the same time the first crack load decreases by about 15.3% to 42.4% as compared to solid slab due to decreases of moment of inertia of bubble slab compared to solid slab. Also, the results showed that the bubbled slabs withe shear reinforcement (multi-leg) have an increase in the ultimate load as compared to solid slab by about 35.4% to 57.3% and an increase in the deflection at ultimate load by about 1% to 15%, at the same time the first crack load decreases by about 2.8% to 27.4% as compared to solid slab.

Punching shear behavior of LWA bubble deck slab with different types of shear reinforcement

Punching shear is the most important problem in flat slabs, which usually requires strengthening for safety reasons. One of the most popular strengthening methods is the employment of shear reinforcement. Also, in order to reduce the self-weight of slabs, lightweight aggregate concrete as well as the bubble deck technology were used in this research. To study the influence of shear reinforcement type on lightweight aggregate voided slab behavior under punching shear, three slabs having the same geometrical and mechanical properties, with different shear reinforcement type (hook, inclined bar and stud) were cast and prepared for testing. As well as a control specimen with no shear reinforcement was used for comparison reason. The results showed that the inclined shear reinforcement has the most positive influence on slab behavior, between the three types of reinforcement that were adopted in the experimental work.

Structural behavior of reinforced concrete one-way slabs voided by polystyrene balls

In the last two decades, the use of voided (bubbled) slabs in constructions has been increased because of several advantages such as light self-weight, cost-saving, and accelerated construction schedules. However, the structural behavior of such slabs has not been adequately inspected, especially for one-way slabs. Therefore, this paper presented an experimental investigation to assess the effect of voids’ size on the structural behavior of one-way slabs. Four slabs were fabricated using self-compacting concrete. Three of them were bubbled slabs, containing 68 polystyrene balls with different sizes (60 mm, 70 mm, and 90 mm); these balls were regularly distributed inside the slabs. The fourth slab was conventional solid without balls and assigned as a control slab. The presence of balls led to reducing the self-weight of slabs, by about 6.4%–21.6%, compared with the solid slab. The slabs were subjected to the four-point loading up to collapse. The results stated that the use of balls with a size of 60 mm, which is equal to half thickness of slab, was the optimum where the reduction in the strength, compared to the control slab, was approximately nonexistent and the drops in stiffness, ductility, and toughness were relatively slight, smaller than 11.1%. For other sizes, the influence of balls became significant, especially for balls with a diameter of 90 mm where the reductions in strength, stiffness, ductility, and toughness reached, respectively, 21.3%, 23.7%, 67.0%, and 79%, in comparison with the control slab. Also, using 90 mm- diameter balls changed the failure mode from flexural to shear. Finally, the flexure and shear strengths of the slabs were determined per the ACI 318M-19 and EC2 codes. The predictions of the EC2 code were more accurate and less conservative than those of ACI 318M-19 code.

Vibration Analysis of Beam and Block Precast Slab System due to Human Vibrations

Beam and block precast slabs system are very efficient which generally give maximum structural performance where their voids based on the design of the unit soffit block allow a significant reduction of the whole slab self-weight. Initially for some combinations of components or the joint connection of the structural slab, this structural system may be susceptible to excessive vibrations that could effects the performance and also serviceability. Dynamic forces are excited from people walking and jumping which produced vibrations to the slab system in the buildings. Few studies concluded that human induced vibration on precast slabs system may be harmful to structural performance and mitigate the human comfort level. This study will investigate the vibration analysis of beam and block precast slab by using finite element method at the school building. Human activities which are excited from jumping and walking will induce the vibrations signal to the building. Laser Doppler Vibrometer (LDV) was used to measure the dynamic responses of slab towards the vibration sources. Five different points were assigned specifically where each of location will determine the behaviour of the entire slabs. The finite element analyses were developed in ABAQUS software and the data was further processed in MATLAB ModalV to assess the vibration criteria. The results indicated that the beam and block precast systems adequate enough to the vibration serviceability and human comfort criteria. The overall vibration level obtained was fell under VC-E curve which it is generally under the maximum permissible level of vibrations. The vibration level on the slab is acceptable within the limit that have been used by Gordon.

Curling effects on concrete slab-on-grade fracture

This paper discusses the effects of temperature curling on post-crack responses of concrete slabs-on-grade. The fracture process is idealized using traction–separation cohesive elements recently incorporated in ABAQUS based on the Fictitious Crack Model. Effects of curling alone as well as curling-plus-wheel load are investigated; the latter is carried out by considering two loading scenario: fixed temperature followed by increasing wheel load, and fixed wheel load followed by increasing temperature. In both loading cases, the effects of parameters, such as concrete age, notch size, slab size, slab self-weight, day time and night time temperature variation, concrete tensile strength and fracture energy have been conducted. When the slab is under curling-plus-load, it is observed that daytime curling significantly reduces the peak load capacity results in sudden failure of the slab whereas nighttime curling causes stable cracks and increases the peak load resisted by the slab. It is hoped that the application of fracture mechanics outlined in this study through a step-by-step approach may be extended to in situ pavement systems, thereby addressing the limitations in current pavement design procedures that exclusively rely on statistical algorithms for the prediction of pavement distresses.

슬림 프리캐스트 슬래브 데크를 사용한 I-슬래브 시스템의 휨 성능에 관한 실험적 연구

Recently, the interest in precast voided slab system for buildings is growing up according to the demand for high quality control and the increase in slab thickness. A hollow slab system is widely known as one of the effective slab system which can reduce self-weight of slab. However, in case of conventional precast voided slabs, It is uncertain to apply these slab system to two-way slabs because It have a rectangular shaped void-former. In this study, I-slab system that applies plate type and octagonal pillar type void-former on slim precast slab deck is developed, and then flexural capacity of the I-slab system Is evaluated by 4-pointed banding test. In addition, flexural capacities of I-slab system along the longitudinal and transverse axis are compared to verify the applicability of I-slab system to two-way slabs. Test results showed that I-slab had enough flexural strength and ductility for slab member. In addition, I-slab system Is found to be sufficiently possible to apply on two-way slabs.

Issues in simulating falling weight deflectometer test on concrete pavements

Falling Weight Deflectometer (FWD) produces pavement responses using a falling mass drop. This study investigated the features involved in the finite element modeling of FWD tests to help in the calibration of backcalculation. Falling mass, model size, subgrade damping, and boundary conditions were studied to reveal the significances of these factors on pavement responses. By modeling the falling mass in finite element models, this study has justified the idea that field-measured time history of impact force can be used as an alternative to falling mass. It is also concluded that subgrade damping, self-weight of slab, and boundary conditions are significant in modeling and interpretation of FWD finite element analysis. Finite element model with at least six times radius of relative stiffness is required to simulate dynamic responses of a continuously reinforced concrete slab.

전단 보강 유무에 따른 일방향 중공슬래브의 전단 성능 분석

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.

도넛형 중공슬래브의 휨 강도 및 휨 강성

This paper presents the flexural capacities of biaxial hollow slabs with donut type hollow shapes. Recently, various types of slab systems which can reduce self-weight of slabs have been studied as the height and width of building structures increase. A biaxial hollow slab system is widely known as one of the effective system which can reduce self-weight of slab. A biaxial hollow slab has hollow spheres within slabs in order to reduce self-weight of slabs. The capacities of biaxial hollow slab are influenced by the shapes, volume of hollow spheres. According to analytical studies, the hollow slab with donut type hollow sphere had good flexural capacities such as strength, stiffness and deflection. To verify the flexural capacities of this hollow slab such as strength and stiffness, flexural tests were performed. Three test specimens were planned to verify the effect of test parameters. One was conventional RC slab and others were donut type hollow slabs. The donut type hollow slabs have two different fixing methods of plastic balls. The one is used diagonal steel cage and the other is fixed with only its geometrical shapes without additional steel cage.

도넛형 이방향 중공슬래브 뚫림전단 강도 및 파괴거동에 대한 실험적 연구

This paper presents the punching shear strength and failure behavior of biaxial hollow slab with donut type hollow-shaper. Until now, various types of slab systems which can reduce self-weight of slabs have been studied as the height and width of building structures rapidly increase. 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 biaxial hollow slab has weakness in slab-column connection compared with solid slab. And previous studies pointed out reduced cross-section area of concrete by hollows as the cause. It is assumed in this study that the shape of hollows and the location of hollow-shaper exert influence on the punching shear strength of biaxial hollow slabs. Therefore, donut type hollow-shaper which was suggested as the optimal hollow shape in previous study was used in this study. To verify the punching shear strength and failure behaviour of donut type biaxial hollow slab, punching shear tests were conducted. 4 test specimens were used for test parameters. One was conventional RC slab and 3 were hollow slabs. The test parameter was the area of critical section which were determined by the number of hollow-shaper around the column. The punching shear strength of the donut type biaxial hollow slabs are 87%~103% of solid slabs and superior to generic biaxial hollow slabs. And punching shear cracks occurred at the first perimeter line of donut type hollows.

Parametric Study of R.C.C Voided and Solid Flat Plate Slab using SAP 2000

The use of flat plate slab is gaining much popularity amongst architects, because the flat plate slab system provides a way for the architect to achieve the concept of high and completely flat ceiling with no beam. As we know that, slab is one of the largest members consuming concrete, when the load acting on the slab is large or clear span between columns is more, the slab thickness is on increasing. It leads to consume more material such as concrete and steel, due to that self-weight of slab is increase. To avoid these disadvantages various studies carried out and researchers suggest voided flat plate slab system to reduce the self-weight of the slab. In this paper various parameters of the voided and solid flat plate slabs is calculated to compare the both systems. To evaluate the performance of the R.C.C voided and solid flat plate slabs, modelling of slabs is carried out using SAP 2000 having span ranging from 6x6 m to 14x14 m of 4x4 bay in both direction with thickness of the slabs 280 to 600 mm. The results drawn from the SAP 2000 are Reaction, Deflection, Moment and Reinforcement required for the voided and solid flat plate slabs. I. Introduction The flat plate floor systems are commonly used in multi-storey buildings, because flat plate floor system present advantages from technical and functional point of view. The self-weight of slab can reduce by replacing the middle height of the cross section of slab with void former. Here, to carry out the parametric study of voided flat plate slabs, different size of hollow void former( 180 to 450 mm ) is consider for various cases of slab thickness ( 280 to 600 mm). The modelling of voided flat plate slabs is carry out same as traditional flat plate slabs by applying the stiffness multiplication factor and modified self-weight of the voided flat plate slabs. The stiffness multiplication factor can be derived from the calculation of second moment of inertia of voided slab and solid slab.The other necessary checks are also done to prove that the voided slab can de model as solid flat slabs with necessary adjustment in certain parameters. The SAP 2000 results show that the behaviour of the voided flat plate slabs is almost same as that of solid voided flat slab in same condition. II. Reaction The main purpose of to carry out results for reaction is to confirm that the methodology that was adopted to perform the study of voided and solid flat slab is acceptable or not. It means that applied stiffness multiplication factor and modified self-weight of the voided slabs are correct or not. To perform the study, for different cases of voided and solid flat slabs are model in SAP 2000 ranging from 6x6 m to 14x14m having thickness 280 mm to 600 mm with spherical ball diameter 180 mm to 450mm respectively and slabs having 4 bays in both direction. For the punching shear criteria, the portion around the column is designed as the solid flat slabs without hollow void former. The results are taken at the centre of the slab considering only gravitational load.To validate the results of Reaction taken from SAP 2000 for voided flat slab, the numerical calculation is carry out of voided slab and the results are shown in Table -1. The Comparative results of reaction for voided and solid Flat slabs are shown in Table -2. The results have revealed that reaction of solid flat slab is higher than that of voided flat slab because of higher self-weight. Moreover, the values of reaction taken from SAP 2000 and by numerical calculation of interior bay are same for voided flat slab. From results it may be conclude that the methodology, which adopted to get the results are acceptable. Table -1 Result for validation of Reaction Slab Thk (mm) Ball Diameter (mm) Span (m) Reaction (KN)

The Deflection of Donut Type Hollow Slab Considering Crack Behaviors

Recently, various types of slab systems which can reduce self-weight of slabs have been studied as the height and width of building structures rapidly increase. A 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 with donut type hollow sphere had enough flexural strength. On the other hand, there were some differences in flexural stiffness and deflection between general RC slab and donut type hollow slab. The deflection of hollow slab was influenced by the shapes of hollow spheres due to its different second moment of inertia and amount of concrete surrounding bottom re-bar. Especially, the cracking behaviors also influence the deflection of slab. General RC slab deflection has been sufficiently investigated and some models to consider the crack behavior such as crack width, crack space, tension stiffening effect, bond-slip relationship. However, there is no study about the crack behavior on the hollow slab. Therefore, the purposes of this paper are to presents the cracking behavior of donut type hollow slab and to evaluate the deflection considering the crack behavior under flexural load.

Flexural Capacities of Reinforced Concrete Two-Way Bubbledeck Slabs of Plastic Spherical Voids

This paper presents the flexural capacities of R.C two way hollow slabs of plastic spherical voids, also known as BubbleDeck slab system. Recently, various types of slab systems which can reduce the self-weight of slabs have been studied as the height and width of building structures rapidly increase (1). A biaxial hollow slab system is widely known as one of the effective slab systems which can reduce the self-weight of slabs (1). A BubbleDeck slab has a two-dimensional arrangement of voids within the slabs to reduce self-weight (2). The behavior of BubbleDeck slabs is influenced by the ratio of bubble diameter to slab thickness. To verify the flexural behavior of this BubbleDeck slab such as ultimate load, deflection, concrete compressive strain and crack pattern, two-dimensional flexural tests were tested by using special loading frame. Six test of specimens were used. Two were a conventional RC slab and four were BubbleDeck slabs having void diameter to slab thickness ratios of (0.51, 0.64 and 0.80). Results have shown that the crack pattern and flexural behavior depend on the void diameter to slab thickness ratio. The ultimate load capacities for BubbleDeck slabs having bubble diameter to slab thickness of (0.٥1 and 0.64) were the same of solid slabs, while when bubble diameter to slab thickness of (0.80) the ultimate capacities were reduced by about (10%).