scholarly journals Shear Capacity of Textile-Reinforced Concrete Slabs without Shear Reinforcement

2019 ◽  
Vol 9 (7) ◽  
pp. 1382 ◽  
Author(s):  
Jan Bielak ◽  
Viviane Adam ◽  
Josef Hegger ◽  
Martin Classen
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Slenderness Ratio ◽  
Shear Capacity ◽  
Experimental Investigations ◽  
Textile Reinforced Concrete ◽  
Design Concepts ◽  
Shear Design ◽  
Reinforced Concrete Slabs ◽  
Relative Shear

A reliable and economic utilization of textile-reinforced concrete in construction requires appropriate design concepts. Unlike designs for bending, the development of models for shear is still the subject of current research. Especially for thin slabs, systematic experimental investigations are lacking. In this paper, the results of an experimental campaign on 27 carbon-textile reinforced slab segments tested in three-point bending are presented. The shear-span to depth ratio and member size were key variation parameters in this study. Increasing the structural depth of members led to a reduction in relative shear strength, while variation of shear slenderness controlled the efficiency of direct stress fields between load introduction and support. Interestingly, direct load transfer was activated up to a shear slenderness ratio of 4, which is significantly higher than in reinforced concrete (a/d < 2.5–3) and may result from the bond characteristics of the textile reinforcement. The experimental shear strengths were compared to predictions from existing models for shear of fiber-reinforced polymer (FRP)-reinforced concrete. The study shows that these FRP calculation models also predict the ultimate shear force for textile-reinforced concrete (TRC) tests presented in this paper with sufficient accuracy. Existing approaches for the size effect seem transferable as well. In order to validate the models for general use in TRC shear design, a compilation and comparison with larger experimental databases is required in future works.

scholarly journals State-of-the-Art Review on Experimental Investigations of Textile-Reinforced Concrete Exposed to High Temperatures

2021 ◽  
Vol 5 (11) ◽  
pp. 290
Author(s):  
Panagiotis Kapsalis ◽  
Tine Tysmans ◽  
Danny Van Hemelrijck ◽  
Thanasis Triantafillou
Keyword(s):  
Reinforced Concrete ◽  
High Temperatures ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Experimental Investigations ◽  
Textile Reinforced Concrete ◽  
Structural Applications ◽  
Promising Solution ◽  
Good Heat Resistance

Textile-reinforced concrete (TRC) is a promising composite material with enormous potential in structural applications because it offers the possibility to construct slender, lightweight, and robust elements. However, despite the good heat resistance of the inorganic matrices and the well-established knowledge on the high-temperature performance of the commonly used fibrous reinforcements, their application in TRC elements with very small thicknesses makes their effectiveness against thermal loads questionable. This paper presents a state-of-the-art review on the thermomechanical behavior of TRC, focusing on its mechanical performance both during and after exposure to high temperatures. The available knowledge from experimental investigations where TRC has been tested in thermomechanical conditions as a standalone material is compiled, and the results are compared. This comparative study identifies the key parameters that determine the mechanical response of TRC to increased temperatures, being the surface treatment of the textiles and the combination of thermal and mechanical loads. It is concluded that the uncoated carbon fibers are the most promising solution for a fire-safe TRC application. However, the knowledge gaps are still large, mainly due to the inconsistency of the testing methods and the stochastic behavior of phenomena related to heat treatment (such as spalling).

scholarly journals Deformations of R.C.Circular Slabs in Fire Condition

2018 ◽  
Vol 4 (4) ◽  
pp. 712 ◽  
Author(s):  
Abdelraouf Tawfik Kassem
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Slenderness Ratio ◽  
High Surface ◽  
High Surface Area ◽  
Concrete Slabs ◽  
Finite Element Models ◽  
Reinforced Concrete Slabs ◽  
Fire Condition ◽  
In Fire

Reinforced concrete slabs are elements in direct contact with superimposed loads, having high surface area and small thickness. Such a condition makes slabs highly vulnerable to fire conditions. Fire results in exaggerated deformations in reinforced concrete slabs, as a result of material deterioration and thermal induced stresses. The main objective of this paper is to deeply investigate how circular R.C. slabs, of different configurations, behave in fire condition. That objective has been achieved through finite element modelling. Thermal-structural finite element models have been prepared, using "Ansys". Finite element models used solid elements to model both thermal and structural slab behaviour. Structural loads had been applied, representing slab operational loads, then thermal loads were applied in accordance with ISO 843 fire curve. Outputs in the form of deflection profile and edge rotation have been extracted out of the models to present slab deformations. A parametric study has been conducted to figure out the significance of various parameters such as; slab depth, slenderness ratio, load ratio, and opening size; regarding slab deformations. It was found that deformational behaviour differs significantly for slabs of thickness equal or below 100 mm, than slabs of thickness equal or above 200 mm. On the other hand considerable changes in slabs behaviour take place after 30 minutes of fire exposure for slabs of thickness equals or below 100 mm, while such changes delay till 60 minutes for slabs of thickness equals or above 200 mm.

scholarly journals Flexural Strengthening of RC Structures with TRC—Experimental Observations, Design Approach and Application

2019 ◽  
Vol 9 (7) ◽  
pp. 1322 ◽  
Author(s):  
Silke Scheerer ◽  
Robert Zobel ◽  
Egbert Müller ◽  
Tilo Senckpiel-Peters ◽  
Angela Schmidt ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Design Model ◽  
Textile Reinforced Concrete ◽  
Bending Tests ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Reinforced Concrete Slabs ◽  
Open Questions ◽  
Basic Behavior ◽  
Strengthening Method

Today, the need for structural strengthening is more important than ever. Flexural strengthening with textile reinforced concrete (TRC) is a recommendable addition to already proven methods. In order to use this strengthening method in construction practice, a design model is required. This article gives a brief overview of the basic behavior of reinforced concrete slabs strengthened with TRC in bending tests as already observed by various researchers. Based on this, a design model was developed, which is presented in the main part of the paper. In addition to the model, its assumptions and limits are discussed. The paper is supplemented by selected application examples to show the possibilities of the described strengthening method. Finally, the article will give an outlook on open questions and current research.

Soft Insert for Support Modeling of Slightly Textile Reinforced Concrete

2018 ◽  
Vol 760 ◽  
pp. 158-163 ◽  
Author(s):  
Tomáš Vlach ◽  
Lenka Laiblová ◽  
Michal Ženíšek ◽  
Jakub Řepka ◽  
Petr Hájek
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Steel Plate ◽  
Testing Machine ◽  
Bending Test ◽  
Flexible Plate ◽  
Textile Reinforced Concrete ◽  
Concrete Element ◽  
Cross Sectional ◽  
The Difference

This paper presents a model of small experimental facade panel using four-point bending test. The facade panel with dimensions 100 x 360 mm and thickness approximately 18 mm was slightly reinforced using two layers of impregnated technical fabric from AR-glass roving. The amount of reinforcement in cross-sectional area of the concrete element is small and it is a reason of plastic joints initiation under the loading supports. The purpose of this experiment was validation of all used material parameters from the previous research in the program for nonlinear analysis of concrete and reinforced concrete Atena Engineering. For slightly reinforced concrete elements are monitored parameters better visible especially interaction between reinforcement and used concrete. The load transfer to the concrete element from the testing machine is typically modeled using some small steel plate. This paper shows the difference in results if we insert another flexible plate between the steel plate and the concrete element with a small defined stiffness.

scholarly journals Flexural and Shear Tests on Reinforced Concrete Bridge Deck Slab Segments with a Textile-Reinforced Concrete Strengthening Layer

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4210 ◽  
Author(s):  
Viviane Adam ◽  
Jan Bielak ◽  
Christian Dommes ◽  
Norbert Will ◽  
Josef Hegger
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Large Scale ◽  
Shear Failure ◽  
Bridge Deck ◽  
High Strength ◽  
Shear Capacity ◽  
Strengthening Effect ◽  
Textile Reinforced Concrete ◽  
Carbon Fibre Reinforced Polymer

Many older bridges feature capacity deficiencies. This is mainly due to changes in code provisions which came along with stricter design rules and increasing traffic, leading to higher loads on the structure. To address capacity deficiencies of bridges, refined structural analyses with more detailed design approaches can be applied. If bridge assessment does not provide sufficient capacity, strengthening can be a pertinent solution to extend the bridge’s service lifetime. For numerous cases, applying an extra layer of textile-reinforced concrete (TRC) can be a convenient method to achieve the required resistance. Here, carbon fibre-reinforced polymer reinforcement together with a high-performance mortar was used within the scope of developing a strengthening layer for bridge deck slabs, called SMART-DECK. Due to the high tensile strength of the carbon and its resistance to corrosion, a thin layer with high strength and low additional dead load can be realised. While the strengthening effect of TRC for slabs under flexural loading has already been investigated several times, the presented test programme also covered increase in shear capacity, which is the other crucial failure mode to be considered in design. A total of 14 large-scale tests on TRC-strengthened slab segments were tested under static and cyclic loading. The experimental study revealed high increases in capacity for both bending and shear failure.

Predicting the effect of stirrups on shear strength of reinforced normal-strength concrete (NSC) and high-strength concrete (HSC) slender beams using artificial intelligence

2006 ◽  
Vol 33 (8) ◽  
pp. 933-944 ◽  
Author(s):  
H El Chabib ◽  
M Nehdi ◽  
A Saïd
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
High Strength ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Design Parameters ◽  
Rc Beams ◽  
Shear Reinforcement ◽  
Strength Concrete ◽  
Shear Design

The exact effect that each of the basic shear design parameters exerts on the shear capacity of reinforced concrete (RC) beams without shear reinforcement (Vc) is still unclear. Previous research on this subject often yielded contradictory results, especially for reinforced high-strength concrete (HSC) beams. Furthermore, by simply adding Vc and the contribution of stirrups Vs to calculate the ultimate shear capacity Vu, current shear design practice assumes that the addition of stirrups does not alter the effect of shear design parameters on Vc. This paper investigates the validity of such a practice. Data on 656 reinforced concrete beams were used to train an artificial neural network model to predict the shear capacity of reinforced concrete beams and evaluate the performance of several existing shear strength calculation procedures. A parametric study revealed that the effect of shear reinforcement on the shear strength of RC beams decreases at a higher reinforcement ratio. It was also observed that the concrete contribution to shear resistance, Vc, in RC beams with shear reinforcement is noticeably larger than that in beams without shear reinforcement, and therefore most current shear design procedures provide conservative predictions for the shear strength of RC beams with shear reinforcement.Key words: analysis, artificial intelligence, beam depth, compressive strength, modeling, shear span, shear strength.

Innovative design concepts: Application of textile reinforced concrete to shell structures

2017 ◽  
Vol 19 (3) ◽  
pp. 637-646 ◽  
Author(s):  
Josef Hegger ◽  
Manfred Curbach ◽  
Alexander Stark ◽  
Sebastian Wilhelm ◽  
Kristina Farwig
Keyword(s):  
Reinforced Concrete ◽  
Shell Structures ◽  
Textile Reinforced Concrete ◽  
Innovative Design ◽  
Design Concepts

Combined effect of sustained load and freeze–thaw cycles on one-way concrete slabs reinforced with glass fibre – reinforced polymer

2013 ◽  
Vol 40 (11) ◽  
pp. 1060-1067 ◽  
Author(s):  
Hizia Bellakehal ◽  
Ali Zaidi ◽  
Radhouane Masmoudi ◽  
Mohamed Bouhicha
Keyword(s):  
Reinforced Concrete ◽  
Shear Capacity ◽  
Concrete Slabs ◽  
Thermal Cycles ◽  
Bending Tests ◽  
Freeze Thaw ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Significant Difference ◽  
Fibre Reinforced Polymer

Flexural behaviour of reinforced-concrete slabs has been widely investigated to characterize properties and behaviour of fibre-reinforced polymer (FRP) materials as reinforcement for concrete structures. However, the short- and long-term thermal effects on FRP bars owing to the significant difference between the bars’ coefficients of thermal expansion in the transverse and longitudinal directions are still to be evaluated and may affect the bond properties and the concrete cover thickness after multiple exposures to freeze–thaw cycles. This paper presents the thermostructural behaviour of one-way concrete slabs reinforced with glass FRP (GFRP) that have previously been subjected to mechanical loads of 20% and 30% of the ultimate flexural capacity of reinforced-concrete slabs, simultaneously with short freeze–thaw cycles. Series tests were conducted on FRP-reinforced concrete slabs 500 mm wide, 195–215 mm thick, and 2500 mm long. The thermal cycles were varied from −30 to 60 °C. Four-point bending tests were conducted up to failure of the slabs. The results show that the thermomechanical load applied before bending tests increases the performance of reinforced-concrete slabs, particularly the concrete shear capacity. The deflection predicted from CSA code and ACI guidelines are very close to those obtained from experimental tests; however, the CSA code overestimates the deflection at the service load. The applied thermal cycles have no big influence on the behaviour before shear failure of concrete slabs reinforced with GFRP bars.

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