Slab Panels Research Articles

Effectiveness of Different Configurations of Ferrocement Retrofitting for Seismic Protection of Confined Masonry: A Numerical Study

A ferrocement layer, which consists of a wire mesh and cement mortar, is a popular retrofitting method for existing structural elements, particularly wall or slab panels. This paper presents a study on the effectiveness of different configurations of ferrocement for seismic retrofitting of confined masonry through finite element analysis. The masonry panel was modeled using expanded brick-unit elements, where the element was expanded in size by as much as half of the mortar thickness, and an interacting zero-thickness interface was applied to mimic the elastic-plastic and damage behavior during tension, shear, and compression. The concrete damage plasticity (CDP) model was used to model the confining reinforced concrete frame and overlay mortar in the ferrocement layer, and the reinforcing bars and wire mesh were modeled using elastic-plastic behavior. In the present numerical study, nine models were subjected to cyclic and pushover shear test simulations, considering the effects of the number of ferrocement layers and the wire mesh orientation. The volumetric ratio of the wire mesh to the masonry (ρwm) ranged from 0.48% to 1.92%, whereas the ratio of the mortar overlay to the masonry (ρmo) varies from 10.42% to 41.66%. Based on the increase in the lateral strength, the model with the largest volume of the ferrocement layer exhibited the largest increase in strength. However, the most cost-effective retrofitting configuration was presented by model DS-1-45, in which a single layer of ferrocement was applied on both sides of the wall using 45° of wire mesh orientation. The DS-1-45 model provided a lateral strength increase of more than 6 times compared to the original unreinforced model. Doi: 10.28991/CEJ-2024-010-09-02 Full Text: PDF

COMPARATIVE STUDY OF FLAT SLAB DESIGN USING VARIOUS INTERNATIONAL CODES

The structural function of beamless floor system is to collect the gravity load and other load such as wind load etc. and to transfer to the vertical structural elements i.e. column through the combined capacity in flexure and shear. In Flat slab, the slab is directly supported on the columns. Moments and shear values are usually the largest over the columns. However, when spans are relatively small and imposed load is low, the thickness of slab can be increased to reduce the stresses at slab-column joint which would result in providing greater effective depth for negative moments occurring near the column. With increasing span and live load intensity, the thickness requirement increases which does not give economical solution. So, to tackle this problem flaring of the column at top is done such that the plan geometry at the column head is similar to that of the column. The column capital is intended primarily to increase the capacity of the slab to resist punching shear. The column capital stiffens the slab, which help in controlling the floor deflection. Thus, the floor span can be increased to some extent. Beyond a certain range of span, further stiffening of the slab is required which is achieved by increasing the slab thickness of the slab panel around the column capital. This portion of the slab is known as drop panel. For flat slabs and flat plates supported directly by columns, shear may be the critical factor in design. In almost all tests of such structures, failures have been due to shear or perhaps shear and torsion. These conditions are particularly serious around the exterior columns. In the present study, attempt has been made to understand different methods of analysis of flat slab and parameters, which governs the design parameters of the flat slab. Attempts have been made to study the provisions of flat slab in well-known international standards such as ACI 318, EC-2 and IS 456:2000. Keywords: Flat slab, drop panel, Column head, IS 456:2000, ACI 318, EC-2

Electrochemical study on the effect of high volume fly ash on the corrosion of reinforcement in self compacting concrete slab panels

Electrochemical study on the effect of high volume fly ash on the corrosion of reinforcement in self compacting concrete slab panels

Influence of arch action on load-carrying capacity of double-sized industrial precast slabs: A combined numerical and experimental study

The precast industry offers slab panels of different geometries according to the field conditions. These slab panels are popular in temporary constructions and beneficial in sustainability but have some financial limitations and local constraints. For a long time, the construction industry has used the arch action method, which restricts the stresses to the compression zone in concrete members and develops the required load-carrying capacity. For the same motives, industrial buildings have preferred semi-circular precast roofs, but the morphology was not suitable. For the proposed slab in this research, firstly, the typical industrial precast slab panel was doubled in width to minimize the time and efforts required for its casting, curing, and placement. Secondly, that doubled-in-width slab was provided with the arch action to confine the stresses to compression and benefit from the section entirely. Lastly, the top of the slab was kept flat to take advantage of the roof space. All these changes aimed for structural stability, reduced material's weight, improved load-carrying capacity, appropriate mobilization, and financial viability. A numerical approach and practical testing were adopted using the finite element modeling software, ABAQUS, to analyze load–deflection responses of both slabs through the concrete damage plasticity model. The proposed slab exhibited better performance as its capacity enhanced by about 1.5 times that of a typical slab. Although the volume of the material in the proposed slab increased slightly from 0.040 m3 to 0.045 m3, the reductions in joint filler materials, reinforcements, and efforts required for mixing and lifting machinery compensated for this increase significantly. Hence, the slab can be recommended for the industry to save the costs while taking heavier loads efficiently.

In-plane seismic performance of precast concrete hollow-core slab panels for basement walls

In building structures, exterior basement walls should resist the soil pressure type earthquake load transmitted by the ground. Thus, the structural performance of the exterior basement walls is affected by in-plane seismic performance as well as out-of-plane load resistance. In the present study, for better constructability and cost-effectiveness of the exterior basement walls, conventional reinforced concrete walls were replaced with precast hollow core slab (HCS) panels. To investigate the in-plane earthquake load resistance of HCS for exterior basement walls, cyclic lateral loading test and numerical analysis were performed on four HCS panels with in-plane double curvature. The test and analysis results showed that the structural behavior of the HCS panels was significantly affected by the panel layout. In the test specimens using a single panel, flexural compression failure occurred at the bottom of the panel, and shear friction damage occurred at the upper and lower parts of the panel. In the test specimens using double panels, failure mode was governed by direct shear. The load-carrying capacity of the test specimens using double panels was greater than two times that of the test specimens using a single panel, because the load transfer changed from flexure into direct shear in the wall specimens using double panels. Further, to use HCS panels for exterior basement walls, a design method for prediction of in-plane seismic performance and yield displacement of HCS panels was proposed.

Experimental and numerical investigation on the behavior of concrete sandwich slab panel for a structural system

This paper proposes a simplified methodology based on a concentrated plasticity model to develop numerical analysis of concrete sandwich slab panels for structural systems. Also, a proposal for the determination of experimental damage and its evolution within concrete sandwich panels is formulated. To validate the proposed methodology, an experimental study was carried out on full-scale slab panels to analyze the flexural behavior. Eight specimens were subjected to three- and four-point bending tests. A cycle loading protocol with unloading up to zero load was performed. These specimens, constructed with either one or two joined panels, were used to assess the group action. Mechanical properties for structural analysis—such as strength, stiffness, degree of composite action, and effective moment of inertia—were determined. The tested specimens exhibit significant stiffness degradation, indicating a notable evolution of damage even at small plastic displacements. The proposed methodology proves to be effective and reliable for predicting the behavior of concrete sandwich panels under bending moments. The numerical simulations performed show an adequate description of slab panel behavior until the ultimate load, regardless of its simplicity.

Evaluation of strength parameters of plain and reinforced concrete with the addition of polypropylene fibers

This research investigates the influence of incorporating small-diameter polypropylene fibers on the mechanical properties of concrete. The studied concrete properties include compressive strength, tensile strength, flexural strength (both plain and reinforced), shear strength, and the mitigation of shrinkage cracks. A total of 92 specimens were meticulously fabricated in the laboratory, comprising cylinders (12 inches in length and 6 inches in diameter), beams (20 x 4 x 4 inches), larger beams (60 x 9 x 9 inches), and slab panels (48 x 48 x 4 inches). During the specimen casting process, a consistent mix with a ratio of 1:2:4 and a water-cement ratio of 0.60 was consistently applied. The polypropylene fiber content varied at 0%, 0.2%, 0.4%, and 0.6% for each property examination. Results indicate a positive impact on all concrete properties studied upon the addition of polypropylene fibers. However, the optimal percentage of polypropylene fibers exhibited variability for each variable and property under investigation. This research contributes insights into the nuanced effects of polypropylene fibers on concrete properties, providing a basis for further exploration and practical application in optimizing concrete performance and durability.

Load-carrying mechanisms of 3D post-tensioned precast concrete sub-structure under internal column removal scenario

To shed light on structural response of a post-tensioned precast concrete (PTPC) sub-structure under an internal column removal scenario, a large three-dimensional (3D) beam-slab assembly was tested under twenty-four-point quasi-static loading. The specimen was a two-by-two bay floor with primary beams, secondary beams and slabs. The primary and secondary beams were designed with precast concrete using wet-connection joints in which post-tensioned (PT) tendons were used in the primary beams only. Besides, precast half planks were employed for the slab panels. A proper restraint system along the four sides was designed to facilitate mobilization of all load-carrying mechanisms in the sub-structure. The test results, including the load-displacement curve, joint rotation and deflection profile, crack pattern and failure mode, and load redistribution, are presented and discussed in detail. The test results revealed the distinctive roles of different load-carrying mechanisms in the sub-structure at different stages. In addition, a simplified analytical method was developed to predict the flexural and tensile capacities of the 3D sub-structure. The method could predict the respective contributions of individual members such as the primary beams, secondary beams and slabs, thereby allowing structural engineers to control the behaviour of the 3D sub-structure at different stages.

Panorama of approaches to reuse concrete pieces: identification and critical comparison

Practices that reuse concrete pieces in new building or infrastructure projects are currently diversifying as concrete reuse gains more and more relevance for sustainability. The present research provides a yet missing identification of the main approaches to these practices and introduces a new set of criteria to compare them. Five types of sourced concrete pieces are identified, three resulting from careful deconstruction and two from demolition. The study shows that approaches allowing the best re-utilization rate of the structural capacities of the concrete pieces are less compatible with current demolition practices, in contrast to approaches reusing debris. The reuse of wall and slab panels, beams, and columns is a promising approach as it implies a low to medium level of constraints on the new design while recovering the capabilities of discarded reinforced concrete equivalently. A few dozen built precedents have already applied this approach to precast components, but applications reusing cast-in-place concrete are lacking, despite considerable CO2 emissions reduction.

Flexural stiffness of lightweight steel-concrete slab panels made of low-density foam concrete

Lightweight steel-concrete structures (LSCS) are a type of steel-concrete structures where the filling concrete is monolithic (pouring) foam concrete with density 100-1000 kg/m3, the profile steel is lightweight steel thin-walled structures (LSTS), and fiber cement panels perform the function of non-removable formwork. As a rule, these structures are made of structural and heat-insulating foam concrete, which has good insulation and technical characteristics and sufficient strength. The object of the study is lightweight steel-concrete slab panels, which are one of the special cases of LSCS, made of monolithic foam concrete with density of 400 kg/m3. An analysis of the bending stiffness of LSBC slab panels by comparing the experimental data with analytical calculations was carried out. It was found that bendable LSCS made of monolithic foam concrete with density of 400 kg/m3 operate in physical nonlinear way. It was shown that the bending stiffness of LSCS floor panels can be determined as the sum of stiffnesses of profiled steel and foam concrete at the linear stage of work. The reliability of the proposed methodology within the limits of linear operation was demonstrated. It was proved both experimentally and theoretically that the bending stiffness of panels based on LSCS is higher than the bending stiffness of similar panels made of lightweight thin-walled steel (LTSS) by about 30%.

Structural integrity of reinforced concrete slabs of some selected existing buildings based on field assessment

Quality assurance and reinforcement detailing may affect the primary function of a reinforced concrete slab to transfer the load upon it by bending. This paper is focused on a probability-based approach to investigate the structural integrity of the reinforced concrete slabs of two selected buildings at a university campus. The in situ strength of all accessible floor slabs was measured using the Schmidt rebound hammer and Ultrasonic pulse velocity tester. The loadings on the slabs were analysed using Orion Software on the structural layouts of the two buildings. The integrity of the slabs, measured by their reliability indices, considering the yielding of the steel and deflection criteria, were estimated using the first-order reliability procedure. The computed indices were related to a target reliability index of 3.8 for the ultimate limit state and 1.5 for the serviceability limit state, chosen for a 50-years reference period of Class RC2 structural members according to BS EN 1990:2002+A1:2005. Generally, the safety indices decrease as the applied loads/moments increase for all the slabs in the two buildings. Although the estimated safety indices reveal that the slabs are over-designed, some of the slab panels in one of the buildings will fail the deflection criterion when loaded to about 80% of their ultimate capacity. Based on this assessment, a disparity in quality assurance between the two buildings has been established.

Analytical Comparison of Conventional Slab and Voided Slab Using Ansys 14.5 – A Review

Abstract: Reinforced concrete slab with plastic voids is a new and innovative type of structural, concrete slab system developed to allow for lighter self weight of thestructure while maintaining similar load carrying capacity of a solid slab. In this study the design process for plastic voided slab is compared with reinforced concrete solid flat slab through a design comparison of typical bays with the same thickness. Also, the finite element analysis of the slab panels has been carried out byusing ANSYS Workbench 14.5 to find out the deformation. The primary objective of the work is to obtain optimum slab system with the above stated parameters. Also, the finite element analysis of the slab panels has been carried out byusing ANSYS Workbench 14.5 to find out the deformation. The primary objective of the work is to obtain optimum slab system with the above stated parameters.

Simple Slab Elements for Environmentally Friendly Construction Technology

Concrete industry poses a great threat to the environment not only by its consumption of natural resources, but also in its role on the global emission of carbon dioxide in the atmosphere from cement industries which in turn results into global warming. In light of these scenarios, serious interventions have to be incorporated in designs to promote sustainable construction and prevent environmental pollution and degradation. In order to minimize the use of cement, a study has been done by developing simple soil arch elements which can be used to support the topping concrete slab of around 30 mm thick. The technique utilizes the semi-prefab technology and therefore eliminates the use of shuttering for slab panel construction. Through this study, it has been shown that the consumption of cement is reduced to 49.32% while the timber formwork is reduced to 60.00%. The technique is recommended for application in upper floor slab casting as it reduces the cost of construction and is environmentally friendly.

Experimental Investigation of Bamboo Reinforced With Conventional Slab Panel

The requirement for building materials is rising gradually. Concrete is embedded in steel to strengthen the tensile carrying properties. However the price of steel is increasing day by day, this attempt is made by providing low cost locally available, ecofriendly material as a replacement of Steel.In this study the properties of bamboo as a reinforced material has been studied. Various properties like surface treatment, bond strength; flexural strength has been investigated through experimentation. Surface treatment is done by using different material and bond strength has been investigated. Total 27 slab panel has been casted as per the codal provision. The effect of total replacement of steel reinforcement by bamboo in flexural behavior, load –deflection characteristic has been observed. Finally the recommendation based on the result for slab panel is proposed.

An Experimental Evaluation of Impact Strength of Fiber Reinfoced Concrete by using Drop Weight Test Method

Abstract: Using the Drop weight test method on slab panels with various types of fibre and their various proportions, this research examines the impact resistance of reinforced concrete's fibre resistance. The results of the IS drop weight test method, which measured the impact qualities of objects travelling at low and high speeds as well as the spilling and scabbing areas, are discussed in the current review study. The most frequently employed test. The results will be increases with the fibers added in percentages.

Analytically Design and Tested the Flat Slab with Drop and Without Drop under Punching Shear Strength Considerations

Abstract: Two types of flat slab are tested one having drop and another having no drop. Shape of openings-(circular, rectangular and square) having sizes of openings (500mm dia, 400mm x 500mm, 445mm x 445mm) respectively. Dimension of slab panel is (6000mmx 6000mm x 220mm) and the drop having size (3000mmx 3000mm). size of column – (500mmx 500mm). The provision of location of openings is at center of the slab panel. Software CSI Safe16 is used to analytically design and check the result. End result is based on punching shear value, deflection, Maximum shear force and maximum bending moment.

Review on seismic performance evaluation of precast concrete buildings

Precast concrete multistoried building systems have become a reliable solution for mass housing projects. Literature on the failure of precast buildings during past earthquakes reports poor connections and improper ductility considerations. This paper emphasizes the role of various ductile framed connections (emulate monolithic and hybrid connections), shear wall systems and diaphragm slab panel connections in lateral load transfer. The sequential development of these systems, codes and standards recommendations and construction practices in various parts of the world are discussed in detail. Experimental and analytical studies are also pointed out in developing these precast ductile systems. The importance of ties, the requirement for splicing and anchoring inserts, and their code requirements are also highlighted. The advancement of experimental studies and numerical computing technics helped in the understanding of linear and nonlinear behaviour of precast systems. Developing and implementing local building codes and procedures to ensure safety against catastrophic failures is an ultimate disaster mitigation measure.

Review on Analysis of Structure and Design of Steel Bridge Using Staad Pro Software

Abstract: In this study the T-beam bridge is to be analysis on the staad pro sofware. A T-beam bridge is composite concrete structure which is composed of slab panel, longitudinal girder and cross girder. This project looks on the work of analysis and design of bridge deck and beam on software the specific bridge model is taken of a particular span and carriageway width the bridge is subjected to different IRC loadings like IRC Class AA, IRC Class 70R tracked loading etc. in order to obtain maximum bending moment and shear force. From the analysis it is observed and understand the behavior of bridge deck under different loading condition and comparing the result. The different codes of design will be use in this project are IRC 5-2015,IRC 6-2016, IRC 112-2011, IRC 21-2000.

Flexural Behaviour of Two Ribbed SFRC Slab Reinforced with GFRP Bars

This study presents the results of an experimental investigation on the application of steel fibres (SF) in combination with glass fibre reinforced polymer (GFRP) bars as the steel reinforcement replacement in a ribbed slab structure. The promising ability of steel fibre reinforced concrete (SFRC) to reduce the formation of cracks and increase the tensile strength of concrete has made it an attractive composite material for numerous civil construction applications. However, previous research had shown that the performance of the steel fibres on their own to replace steel reinforcements is still in doubt. Therefore, the GFRP bar is chosen due to its structural performance with flexural reinforcement with less weight and corrosion resistance. The influence of the steel fibres and GFRP bars on the two-ribbed slab flexural performance was investigated. Three (3) numbers of slab panels were cast, consisting of one solid SFRC slab (solid-SF), one SFRC ribbed slab (rib-SF), and one SFRC ribbed slab reinforced with GFRP bars (rib-SF-GFRP). All slab samples measuring 1000 mm x 1500 mm x 75 mm thickness were tested under bending and the results showed that the SFRC ribbed slab reinforced with GFRP (rib-SF-GFRP) is efficient in the flexural performance by exhibiting the highest first crack and ultimate load.

Modeling of Composite Structures in Fire Using a Coupled Skeletal Frame and Floor System Analysis: Slab Panel Method

This paper presents a proposed design methodology which combines the fire beam element (FBE) for skeletal frame analysis with the slab panel method (SPM) for floor experiencing catenary action. The methodology enables the two systems to interact with each other to provide a simplistic manner to design a full composite structure. The design methodology consists of an iterative process in which (1) the SPM is used to design the composite slab and provides the loads on the support beams of the skeletal structure, and then (2) the FBE analysis, implemented in OpenSees version 2.5.0, determines the deflection of the edge support beams which are used to update the SPM calculations. The existing two-dimensional (2D) FBE finite-element matrices are updated for a three-dimensional FBE, while the SPM is modified to allowing the interaction between the FBE analysis and the SPM. Three validation studies of the FBE analysis show that the FBE analysis is able to capture the behavior of the skeletal structure adequately, as long as the support edge beams of the slab panel have sufficient strength to support the slab panel. The application of the design methodology to an office building serves as a proof on concept and demonstrates that the deflection of the edge beams does have a significant impact on the predicted ultimate load-carrying capacity of the slab panel.