Experimental and numerical evaluation of compression confinement techniques for HSC beams reinforced with different ratios of high strength steel reinforcement

This work presents experimental and numerical research to evaluate the compression confinement techniques of HSC beams reinforced with different ratios of high-strength steel reinforcement. Twelve specimens of high-strength reinforced concrete beams with two different compression confinement techniques were tested experimentally. The first method is used carbon fiber reinforced polymers sheets (CFRPs) around the compression zone, CF, and the steel fibers reinforced concrete is used in the compression zone by 1% of volume fraction, SF, in the second case. A 3-D finite element analysis was done; using the ANSYS program to simulate and idealize all experimental specimens. The numerical and experimental results of the RC beams were validated and compared in this work. The results showed that there is a good idealization using 3-D finite element models with the experimental specimens. Also, it was found that using the suggested techniques can increase the strength ratio and increase the ductility index depending on the tensile reinforcement ratios. Moreover, the energy absorption and the mode of failure were enhanced

The Influence of Strain Rate Behavior on Laminated Glass Interlayer Types for Cured and Uncured Polymers

Recent explosions and impact events have highlighted the exposure of civil structures, prompting the need for resilient new constructions and retrofitting of existing ones. Laminated glass panels, particularly in glazed facades, are increasingly used to enhance blast resistance. However, the understanding of glass fragments and their interaction with the interlayer is still incomplete. This paper investigates experimentally the quasi-static and dynamic responses of cured and uncured polymers for seven different materials—two different products of polyvinyl butyral (PVB), two ethylene vinyl acetate products (EVA), one product of thermoplastic polyurethane (TPU), and two SentryGlas products (SG)—that were tested between 21 and 32 °C (69.8 and 89.6 °F), which is the recommended room temperature. In these experiments, the responses of PVB, EVA, TPU, and SG were evaluated under a quasi-static strain rate of 0.033 s−1 and compared to the results under a relatively higher strain rate of 2 s−1. Moreover, the high strain rate loading of the materials was accomplished using a drop-weight testing appliance to evaluate the engineering stress–strain response under strain rates between 20 and 50 s−1. The results demonstrated that with strain rates of 20 s−1, PVB behaved like a material with viscoelastic characteristics, but at 45 s−1 strain rates, PVB became a non-elastic material. SG, on the other hand, offered both a high stiffness and a high level of transparency, making it a very good alternative to PVB in structural applications. In contrast, after the maximum stress point, the response to the failure of the seven materials differed significantly. The tests provided ample information for evaluating alternative approaches to modeling these different materials in blast events

Investigation of the Effect of Crumb Rubber on the Static and Dynamic Response of Reinforced Concrete Panels

Increasing the mass of a wall system as well as the ability to absorb energy can improve the blast resistance. The role of ductile materials attached externally to the wall tension side has been studied extensively to improve ductility and resistance. In the present study, the use of hyperelastic materials, added internally to wall systems, was analyzed to determine the static resistance of those systems. In this paper, adding shredded rubber to the concrete mix as a replacement for coarse aggregates traditionally used in designing concrete mixes was investigated. The use of shredded rubber to replace coarse aggregates is hypothesized to enhance the concrete wall panels’ blast-resistant by increasing the ductility. In the evaluation of rubber contents, the normal concrete design without rubber was compared to concrete mixes with two rubber contents. Static resistance functions were developed by evaluating the performance of concrete cylinders and concrete wall full-scale specimens with coarse aggregate partially replaced by rubber under simulated uniform loading by a loading tree. According to the results of the test, there was a reduction in compressive strength of specimens due to rubber, which caused the specimens to crack more easily during testing. Increased rubber content decreased the walls’ maximum load and overall resistance. Furthermore, the mode of failure of rubberized concrete specimens was significantly different from those without any rubber

Investigation of the Effect of Crumb Rubber on the Static and Dynamic Response of Reinforced Concrete Panels

Increasing the mass of a wall system as well as the ability to absorb energy can improve the blast resistance. The role of ductile materials attached externally to the wall tension side has been studied extensively to improve ductility and resistance. In the present study, the use of hyperelastic materials, added internally to wall systems, was analyzed to determine the static resistance of those systems. In this paper, adding shredded rubber to the concrete mix as a replacement for coarse aggregates traditionally used in designing concrete mixes was investigated. The use of shredded rubber to replace coarse aggregates is hypothesized to enhance the concrete wall panels’ blast-resistant by increasing the ductility. In the evaluation of rubber contents, the normal concrete design without rubber was compared to concrete mixes with two rubber contents. Static resistance functions were developed by evaluating the performance of concrete cylinders and concrete wall full-scale specimens with coarse aggregate partially replaced by rubber under simulated uniform loading by a loading tree. According to the results of the test, there was a reduction in compressive strength of specimens due to rubber, which caused the specimens to crack more easily during testing. Increased rubber content decreased the walls’ maximum load and overall resistance. Furthermore, the mode of failure of rubberized concrete specimens was significantly different from those without any rubber

A Low Cost Multiband Microstrip Antenna for Wireless Applications

International audienceThis study deals with a new research work on a low cost multiband printed antenna which can be used for three operating frequency bands GSM900/PCS/WIFI/Bluetooth. The achieved antenna is mounted on an FR-4 substrate. In this study, the solts technique is used to obtain the multiband behavior. The different solts are inserted in the radiator face and the back face that is the ground. The whole circuit is optimized taking into account the good matching of the input impedance in the operating frequency bands with a stable radiation pattern. In order to optimize the proposed antenna structure we have used CST-MW and to compare the obtained simulation results we have conducted another electromagnetic simulation by using HFSS solver. The final circuit validated into simulation has been fabricated and tested which permits to validate the proposed multiband antenna