Effects of Fibres on Improvement the Cracking in Concrete Slabs

2014 ◽  
Vol 1025-1026 ◽  
pp. 997-1004
Author(s):  
Arton Dautaj ◽  
Naser Kabashi ◽  
Cene Krasniqi ◽  
Patriot Ahmeti
Keyword(s):  
Structural Design ◽  
Composite Structures ◽  
Concrete Slab ◽  
Concrete Slabs ◽  
Design Requirement ◽  
Polypropylene Fibres ◽  
Hardening Process ◽  
Traditional Definition ◽  
Definition Of ◽  
Concrete Elements

The behaviour of concrete elements under loads, hydrated process and several conditions is one of the actually problems on improvement of structures or elements of structures. In this paper we analyze the problem of cracking, such a result of loading and hardening process of concrete. One of the way for improvement is using the polypropylene fibres , and creating the composite materials In this case of studies we used experimental examinations of concrete slab, such a model, for - slab (referent model) - slab with different percent of fibres The most of comparing results are on comparing the effect of fibres in improvement of energy capacity of concrete elements, and following the crack situation, or decreasing the dimensions of cracks. One of the most important value based on the behavior of the structure is ductility. The ductility is a structural design requirement in most design codes. The traditional definition of ductility cannot be applied to composite structures, but will be analyzed on the increasing the dissipations of energy. Several methods are used on the analyzing of this problem and propose to calculate the absorption the energy in concrete slab and to analyze the positions of cracks.

scholarly journals Experimental evaluation on the structural behavior of truss shear connectors in composite steel-concrete beams

2019 ◽  
Vol 12 (5) ◽  
pp. 1157-1182 ◽  
Author(s):  
W. C. S. BARBOSA ◽  
L. M. BEZERRA ◽  
L. CHATER ◽  
O. R. O. CAVALCANTE
Keyword(s):  
Composite Structures ◽  
Concrete Slab ◽  
Experimental Studies ◽  
Experimental Models ◽  
Concrete Slabs ◽  
Shear Connectors ◽  
Reinforced Concrete Slabs ◽  
Constituent Material ◽  
Steel Composite ◽  
Stud Connector

Abstract The composite structures have great advantages in terms of structural and constructive aspects, with the shear connectors being decisive for obtaining the interaction between the structural elements and for the distribution of the stresses in the structure, taking advantage of the potentiality of each constituent material of the composite structure (steel and concrete). This work, through experimental studies, presents the development of a shear connector (Truss connector) proposed for use in a concrete-steel composite beam. The proposed connector is easy to implement and can serve as a viable alternative to the use of stud or U connectors. It was idealized a connector geometry that would provide low production cost, ease of execution, higher values of resistant load, efficiency as regards the relative sliding resistance between the metal profile and the concrete slab, as well as the efficiency regarding the resistance to the spacing of the slabs in relation to the metal profile (uplift). In order to evaluate the behavior of Truss connectors, 6 experimental models were constructed for push-out tests, 3 with 12.5 mm diameter Truss connectors and 3 with 19.0 mm diameter stud bolt connectors. The behavior of the models was investigated with respect to the loads of rupture, the transversal displacements between the concrete slabs and the relative vertical slide between the reinforced concrete slabs and the metallic profiles of the models. The results of the experimental analyzes provided an overview of the operation of the Truss and stud bolt connectors, with significant results that showed advantages of the Truss connector in relation to the stud connector considering the parameters analyzed in this work.

scholarly journals Changes to structural solutions and their effect on radon functionality on the structures base on the ground

2020 ◽  
Vol 172 ◽  
pp. 05011
Author(s):  
Ari-Veikko Kettunen
Keyword(s):  
Thermal Insulation ◽  
Structural Design ◽  
Concrete Slab ◽  
Moisture Diffusion ◽  
Concrete Slabs ◽  
Diffusion Flow ◽  
Conservation Of Energy ◽  
Radon Diffusion ◽  
Floor Structure ◽  
Structural Solutions

The structural design in terms of radon of the ground-supported base floor solutions currently used in Finland are largely based on the extensive measurements conducted in the 1980s and the 1990s. In addition to ventilating/underpressurising the base of the building, the instructions in Finland and other European countries i.e. Denmark [1] focus on the adequate sealing of the base floor structure in order to prevent the air containing radon from the soil from entering the rooms at harmful levels with air flows. According to the Finnish radon guidelines, the transmission of radon by means of diffusion is prevented by using a sufficiently thick concrete slab. The structural solutions used in base floors have, however, developed significantly over the decades. The thickness of thermal insulation of a ground-supported base floor slab has been increased significantly especially due to reasons related to the conservation of energy. In the 1980s, the polystyrene layer in the base floor was 50...100 mm, whereas it currently is 200 mm. This change reduces the ground temperature under the thermal insulation, thereby also reducing the moisture diffusion flow from the ground to the concrete slab of the base floor. As a result, the current concrete slabs used in the base floor will be significantly drier than those of the 1980s after the construction humidity has dried. Underfloor heating, which is nowadays used in Finland very commonly, also impacts the moisture of the concrete slab by increasing the concrete slab’s temperature and drying it further. The measurements now conducted on concrete have shown that the radon diffusion permeability of dry concrete (Rh approximately 50%) is so high that stopping the radon diffusion flow solely by means of an 80-mm concrete slab may not be an adequate solution in some cases.

scholarly journals Effect of the Geometrical Constraints to the Wenner Four-Point Electrical Resistivity Test of Reinforced Concrete Slabs

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4622
Author(s):  
Kevin Paolo V. Robles ◽  
Jurng-Jae Yee ◽  
Seong-Hoon Kee
Keyword(s):  
Experimental Investigation ◽  
Electrical Resistivity ◽  
Reinforced Concrete ◽  
Concrete Slab ◽  
Plain Concrete ◽  
Electrode Spacing ◽  
Concrete Slabs ◽  
Reinforced Concrete Slabs ◽  
Spacing Ratio ◽  
Geometrical Constraints

The main objectives of this study are to evaluate the effect of geometrical constraints of plain concrete and reinforced concrete slabs on the Wenner four-point concrete electrical resistivity (ER) test through numerical and experimental investigation and to propose measurement recommendations for laboratory and field specimens. First, a series of numerical simulations was performed using a 3D finite element model to investigate the effects of geometrical constraints (the dimension of concrete slabs, the electrode spacing and configuration, and the distance of the electrode to the edges of concrete slabs) on ER measurements of concrete. Next, a reinforced concrete slab specimen (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)) was used for experimental investigation and validation of the numerical simulation results. Based on the analytical and experimental results, it is concluded that measured ER values of regularly shaped concrete elements are strongly dependent on the distance-to-spacing ratio of ER probes (i.e., distance of the electrode in ER probes to the edges and/or the bottom of the concrete slabs normalized by the electrode spacing). For the plain concrete, it is inferred that the thickness of the concrete member should be at least three times the electrode spacing. In addition, the distance should be more than twice the electrode spacing to make the edge effect almost negligible. It is observed that the findings from the plain concrete are also valid for the reinforced concrete. However, for the reinforced concrete, the ER values are also affected by the presence of reinforcing steel and saturation of concrete, which could cause disruptions in ER measurements

Finite Element Analysis of Composite Ceramic-Concrete Slab Constructions Exposed to Fire

2016 ◽  
Vol 861 ◽  
pp. 88-95
Author(s):  
Balázs Nagy ◽  
Elek Tóth
Keyword(s):  
Composite Structures ◽  
Elevated Temperatures ◽  
Cfd Simulation ◽  
Concrete Slab ◽  
Composite Ceramic ◽  
Reinforced Concrete Beam ◽  
Element Analysis ◽  
Standard Fire ◽  
Using Data ◽  
Dynamics Simulations

In this research, conjugated thermal and fluid dynamics simulations are presented on a modern hollow clay slab blocks filled pre-stressed reinforced concrete beam slab construction. The simulation parameters were set from Eurocode standards and calibrated using data from standardized fire tests of the same slab construction. We evaluated the temperature distributions of the slabs under transient conditions against standard fire load. Knowing the temperature distribution against time at certain points of the structure, the loss of load bearing capacity of the structure is definable at elevated temperatures. The results demonstrated that we could pre-establish the thermal behavior of complex composite structures exposed to fire using thermal and CFD simulation tools. Our results and method of fire resistance tests can contribute to fire safety planning of buildings.

scholarly journals Longitudinal shear capacity of the slabs of composite beams

1976 ◽  
Vol 3 (4) ◽  
pp. 514-522 ◽  
Author(s):  
M. N. El-Ghazzi ◽  
H. Robinson ◽  
I. A. S. Elkholy
Keyword(s):  
Composite Beam ◽  
Shear Failure ◽  
Concrete Slab ◽  
Compressive Force ◽  
Longitudinal Shear ◽  
Composite Beams ◽  
Shear Capacity ◽  
Slab Width ◽  
Two Parameters ◽  
Concrete Elements

The longitudinal shear failure of the slab of composite beams is constrained to occur at a predetermined shear surface. A method for calculating the longitudinal shear capacity of the slab of simply-supported steel–concrete composite beams is presented. The method is based on analyzing the stresses at failure of the concrete elements located at the slab shear surface.A design chart based on estimating the transverse normal stress required within the concrete slab to achieve the full ultimate flexural capacity of the composite beam is proposed. Alternatively, using elastic–plastic stress distribution across the concrete slab, the longitudinal compressive force due to bending and hence the applied moment can be predicted for any longitudinal shear capacity of the slab. The proposed design and analysis when compared to previous tests and analysis showed good agreement.The slab width and the shear span of the composite beam are found to be two important parameters which cannot be neglected when estimating the longitudinal shear capacity of the slab. These two parameters have been neglected in the empirical solutions previously adopted.

scholarly journals Examples of Solutions for Steel-Concrete Composite Structures in Bridge Engineering / Przykłady Konstrukcji Zespolonych W Budownictwie Mostowym

2015 ◽  
Vol 16 (1) ◽  
pp. 51-68
Author(s):  
Kazimierz Flaga ◽  
Kazimierz Furtak
Keyword(s):  
Structural Design ◽  
Composite Structures ◽  
Concrete Structures ◽  
Design Analysis ◽  
Bridge Engineering ◽  
Structural Composition ◽  
Points Of View

Abstract The aim of the article [1] was to discuss the application of steel-concrete composite structures in bridge engineering in the aspect of structural design, analysis and execution. It was pointed out that the concept of steel-concrete structural composition is far from exhausted and new solutions interesting from the engineering, scientific and aesthetic points of view of are constantly emerging. These latest trends are presented against the background of the solutions executed in Poland and abroad. Particular attention is focused on structures of double composition and steel-concrete structures. Concrete filled steel tubular (CFST) structures are highlighted.

Emotion and Virtue

2020 ◽  
Author(s):  
Gopal Sreenivasan
Keyword(s):  
Virtue Ethics ◽  
Moral Psychology ◽  
Character Trait ◽  
Full Measure ◽  
Traditional Definition ◽  
Definition Of

What must a person be like to possess a virtue in full measure? What sort of psychological constitution does one need to be an exemplar of compassion, say, or of courage? Focusing on these two examples, this book ingeniously argues that certain emotion traits play an indispensable role in virtue. With exemplars of compassion, for instance, this role is played by a modified sympathy trait, which is central to enabling these exemplars to be reliably correct judges of the compassionate thing to do in various practical situations. Indeed, according to the book, the virtue of compassion is, in a sense, a modified sympathy trait, just as courage is a modified fear trait. While the book upholds the traditional definition of virtue as a species of character trait, it discards other traditional precepts. For example, the book rejects the unity of the virtues and raises new questions about when virtue should be taught. Unlike orthodox virtue ethics, moreover, this account does not aspire to rival consequentialism and deontology. Instead the book repudiates the ambitions of virtue imperialism, and makes significant contributions to moral psychology and the theory of virtue alike.

Moment and shear transfer between columns and concrete slabs

1990 ◽  
Vol 17 (4) ◽  
pp. 621-628
Author(s):  
Amin Ghali ◽  
Adel A. Elgabry
Keyword(s):  
Shear Strength ◽  
Structural Design ◽  
American Concrete Institute ◽  
Punching Shear ◽  
Vertical Shear ◽  
Concrete Slabs ◽  
Finite Element Analyses ◽  
Shear Transfer ◽  
Flat Slabs ◽  
Punching Failure

Gravity and horizontal forces cause the transfer of vertical shear and moments between concrete flat slabs and their supporting columns. These forces can cause punching failure. Design equations for safety against punching given in the Canadian Standards Association and the American Concrete Institute codes are critically reviewed. It is shown that the equations give in some cases incorrect stresses which do not satisfy equilibrium. A modification is suggested which makes the equations applicable to all cases. The paper also discusses the codes' approach of sharing the resistance to transferred moment between resistances by flexure and by eccentricity of shear, using the coefficient γv. Comparisons are made with the result of finite element analyses. It is concluded that the code equations, with the suggested modification, are adequate, provided that appropriate values are used for the coefficient γv. Key words: columns, connections, flat concrete plates, moments, punching shear, reinforced concrete, shear strength, slabs, structural design.

scholarly journals Ductility and flexure of lightweight expanded clay basalt fiber reinforced concrete slab

2021 ◽  
Vol 17 (1) ◽  
pp. 74-81
Author(s):  
Vera V. Galishnikova ◽  
Alireza Heidari ◽  
Paschal C. Chiadighikaobi ◽  
Adegoke Adedapo Muritala ◽  
Dafe Aniekan Emiri
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Basalt Fiber ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Lightweight Aggregate Concrete ◽  
Concrete Slabs ◽  
Reinforced Concrete Slab ◽  
Chopped Basalt Fiber

Relevance. The load on a reinforced concrete slab with high strength lightweight aggregate concrete leads to increased brittleness and contributes to large deflection or flexure of slabs. The addition of fibers to the concrete mix can improve its mechanical properties including flexure, deformation, toughness, ductility, and cracks. The aims of this work are to investigate the flexure and ductility of lightweight expanded clay concrete slabs reinforced with basalt fiber polymers, and to check the effects of basalt fiber mesh on the ductility and flexure. Methods. The ductility and flexural/deflection tests were done on nine engineered cementitious composite (expanded clay concrete) slabs with dimensions length 1500 mm, width 500 mm, thickness 65 mm. These nine slabs are divided in three reinforcement methods types: three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm (first slab type); three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm plus dispersed chopped basalt fiber plus basalt fiber polymer (mesh) of cells 2525 mm (second slab type); three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm plus dispersed basalt fiber of length 20 mm, diameter 15 m (third slab type). The results obtained showed physical deflection of the three types of slab with cracks. The maximum flexural load for first slab type is 16.2 KN with 8,075 mm deflection, second slab type is 24.7 KN with 17,26 mm deflection and third slab type 3 is 32 KN with 15,29 mm deflection. The ductility of the concrete slab improved with the addition of dispersed chopped basalt fiber and basalt mesh.

scholarly journals IDENTIFIKASI FAKTOR PENGARUH DOMINAN KETERLAMBATAN PROYEK AKIBAT RANTAI PASOK PADA PENGADAAN PELAT BETON PRACETAK

2020 ◽  
Vol 3 (4) ◽  
pp. 1295
Author(s):  
Firena Bian Saputri ◽  
Basuki Anondho
Keyword(s):  
Supply Chain ◽  
Human Error ◽  
Concrete Slab ◽  
Precast Concrete ◽  
Influence Factors ◽  
Concrete Slabs ◽  
Literature Study ◽  
Factors Affecting ◽  
Project Duration ◽  
Speed Up

One way that can be done to speed up the duration of the project is to use precast concrete slabs. However, the use of precast concrete slab elements in the project can be ineffective if in the order stage, production stage, until the delivery stage of precast concrete elements to the project site is not managed properly, which can cause delays in project duration. Therefore, the use of precast concrete slabs is very dependent on the supply chain management. To anticipate this risk, it is necessary to identify what are the dominant factors in the supply chain that affect the procurement of precast concrete slabs which can cause delays in project duration. The initial influence factors were collected through a literature study and interviews with a number of practitioners, followed by a survey using a questionnaire to a number of project actors in projects using precast concrete slabs. The Likert scale 1-5 is used to measure the level of influence of a factor identified on project delays. By using factor analysis techniques, as many as three groups of dominant supply chain factors affecting the procurement of precast concrete slabs were found, namely special factors, technical factors, and human error factors.ABSTRAKSalah satu cara yang dapat dilakukan demi mempercepat durasi proyek adalah menggunakan pelat beton pracetak. Namun, penggunaan elemen pelat beton pracetak di proyek bisa tidak efektif apabila dalam tahap pemesanan, tahap produksi, hingga tahap pengiriman elemen beton pracetak ke lokasi proyek tidak dikelola dengan baik, sehingga dapat menyebabkan keterlambatan durasi proyek. Oleh sebab itu, penggunaan pelat beton pracetak sangat bergantung pada manajemen rantai pasokannya. Untuk mengantisipasi risiko tersebut, perlu adanya identifikasi mengenai faktor dominan apa saja pada rantai pasok yang mempengaruhi pengadaan pelat beton pracetak yang dapat menyebabkan keterlambatan durasi proyek. Faktor pengaruh awal dikumpulkan melalui studi literatur dan wawancara kepada sejumlah praktisi, dilanjutkan dengan survei menggunakan kuesioner kepada sejumlah pelaku proyek di proyek yang menggunakan pelat beton pracetak. Skala Likert 1-5 digunakan untuk mengukur tingkat pengaruh suatu faktor yang diidentifikasi terhadap keterlambatan proyek. Dengan menggunakan teknik analisis faktor, sebanyak tiga kelompok faktor dominan rantai pasok yang berpengaruh pada proses pengadaan pelat beton pracetak ditemukan, yaitu faktor khusus, faktor teknis, dan faktor human error.

Sign in / Sign up

Export Citation Format

Share Document