Experimental Investigations of Reinforced Concrete Beams with Innovative Truss-Shaped Reinforcement System.

Adam Stolarski,Jacek Zychowicz

doi:10.3390/ma14071652

Adam Stolarski, Jacek Zychowicz

Open Access

https://doi.org/10.3390/ma14071652

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Abstract

The purpose of the work is an experimental analysis of the behavior of reinforced concrete beams with a new, patented system of truss-shaped reinforcement. Experimental tests of reinforced concrete beams with conventional reinforcement and with truss-shaped, mass equivalent reinforcement, with two different values of longitudinal reinforcement ratio, were carried out. The testing results of the load-carrying capacity and displacements of beams are presented. The cracking and failure mechanism of beams with a new truss-shaped reinforcement system was also analyzed. The test results for conventionally reinforced beams and with truss-shaped reinforcement were compared. The test results show that the use of the truss reinforcement has an influence on increasing the load-carrying capacity of beams. The amount of this increase depends on the total longitudinal reinforcement ratio and reaches as much as 95% for beams with a low reinforcement ratio and 12% for beams with a higher reinforcement ratio. Based on the investigation of the cracking mechanism, it can be concluded that the failure of the beams with transverse truss-shaped reinforcement occurs with a greater number of smaller cracks, which are more evenly distributed along the length of the cracking zone, and have a shorter range over the cross-section depth, which results in their smaller opening widths. The comparative analysis shows the effectiveness of the proposed reinforcement system, justifying the high potential possibilities of its use for the reinforcement of concrete structural elements.

Highlights

IntroductionConcrete structures reinforced with inserts made of high-strength materials are the most commonly used in the building structures of the world
The results showed that adding fibers to the compression zone of the section led to a higher ductility in both glass fiber-reinforced polymer (GFRP) rebar and steel rebar reinforced beams, while adding fibers to the tensile zone led to a higher ultimate flexural strength
The originality of the proposed reinforcement system consists in the truss shaping of diagonal transverse bars and the permanent connection of the reinforcement bars at all connection points

Summary

Introduction

Concrete structures reinforced with inserts made of high-strength materials are the most commonly used in the building structures of the world. The development of reinforced concrete began with the commonly known inventions of Joseph-Louis Lambot, Joseph Monier, William Boutland Wilkinson, and Francois Hennebique in the nineteenth century. In the pioneering invention of Khan [1], a reinforcement system called “Khan Trussed Bar System” was presented. Khan, noticing that concrete has a high compressive strength and a low tensile strength, conducted scientific engineering experiments and created the concept of reinforcement for reinforced concrete elements, with bent bars attached to the longitudinal reinforcement at an angle of 45 degrees. The features and application of this reinforcement system have been described by the Trussed Concrete Steel Company [2] and e.g., in the review paper by Salmon and Elliott [3]

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