Energy Absorption Capacity Of Beams Research Articles

Study on flexural behavior of concrete beams reinforced with hybrid high-strength and high-toughness (HSHT) and ordinary steel bars

To study the flexural behavior of high-strength and high-toughness (HSHT) reinforced concrete beams with negative Poisson’s ratio and special spiral grooves on the surface, fifteen beams of 250 mm × 450 mm × 3200 mm were designed and manufactured to conduct bending tests. The effects of different parameters, including the reinforcement ratio, compressive strength of concrete, loading mode, the number of HSHT steel bars in hybrid reinforcement, and longitudinal steel bars type, were studied on failure modes, crack patterns, flexural stiffness, flexural strength, ductility, and energy absorption capacity. The load versus mid-span deflection curves for concrete beams reinforced with HSHT steel bars can be divided into five stages. The concrete beams reinforced with HSHT steel bars can also bear higher residual strength (approximately 0.9 Fp) and exhibit superior crack width control ability. The peak load increases by a maximum of 22.9 % with the reinforcement ratio of HSHT steel bars increasing from 0.86 % to 1.08 %. Hybrid reinforcement can improve the service performance of concrete beams, take full advantage of HSHT steel bars, and increase the energy absorption capacity of beams. Based on strain analysis of cross-section, the flexural strength model of concrete beams reinforced with hybrid reinforcement was proposed by considering the ultimate compression strain. The calculation results show that the proposed model can accurately calculate the flexural strength of concrete beams reinforced with HSHT steel bars.

Experimental and Numerical Study of Energy Absorption Capacity of Glass Reinforced SCC Beams

Various experimental studies have been carried out on glass fiber reinforced concrete (GFRC), but in limited studies, the behavior of this type of concrete is evaluated using finite element method (FEM). In this study an analysis model is presented for predicting energy absorption capacity of glass fiber reinforced self-compacting concrete (GFRCSCC) beams and the results are compared with experimental study. For this purpose, the investigations are conducted in two experimental and numerical sections. In experimental section, the characteristics of fresh and hardened concrete have been evaluated using slump flow, V-funnel, L-box, T50, compressive strength, tensile strength and flexural strength tests. In numerical section, ABAQUS software has been used to simulate GFRCSCC beams. The concrete damage plasticity model has been used to simulated concrete material. The fiber contents are 0, 0.25, 0.75 and 1% of the mixed concrete by volume. The results show that the maximum increase in energy absorption capacity of beams compared to the plain concrete for 25, 35 and 45 concrete grade was 29, 33.2 and 53.75%, respectively. At last, the ultimate loads corresponding to the FEM are found to hold good agreement with experimental ultimate loads which validates the FEM.

A study on different techniques of restoration of fire damaged reinforced concrete flexural members

PurposeThe main aim of this research was to investigate the effectiveness of various strengthening techniques in restoring the structural performance of reinforced concrete (RC) beams damaged by elevated temperatures.Design/methodology/approachThree different strengthening techniques, namely, high-strength fibre reinforced concrete (HSFRC), ferrocement (FC) jacketing and externally bonded fibre-reinforced polymer (FRP) were used. Series of RC beams were casted, heated, strengthened and tested to investigate the influence of various variables. The variables of the study were type of strengthening and level of heat damage.FindingsExternally bonded FRP was found to be the best among the various techniques, especially with respect to strength and stiffness restoration. On the contrary, the FRP strengthening was not that effective in restoring the energy absorption capacity of beams compared to HSFRC and FC techniques of strengthening. The chosen strengthening techniques were able to restore the failure mode of beams to flexural failure, which was found to have changed to shear failure in case of heated unstrenghthened beams.Originality/valueThis research program has contributed to the fundamental understanding of designing post fire retrofit solutions for RC beams.

Flexural Behaviour of Bottom Ash Geopolymer Reinforced Concrete Beams

The present work deals with flexural behavior of bottom ash geopolymer reinforced concrete beam. A total of twelve beams were cast, in which six beams were control reinforced concrete beams and six beams were bottom ash geopolymer reinforced concrete (BAGPRC) beam. BAGPRC beam was cured at ambient temperature. The load carrying capacity, load deflection behavior, initial stiffness, ductility factor and energy absorption capacity of beams were arrived and compared with control reinforced cement concrete (RCC) specimens. The test result reveals that BAGPRC exhibited excellent performance over control RCC beam. However, ductility index and stiffness behavior of BAGPRC beam were comparable with control RCC beam.

Load-Deflection Characteristics Of Steel, Polypropylene And Hybrid Fiber Reinforced Concrete Beams

AbstractConcrete is the most widely used construction material because of its specialty of being cast into any desired shape. The main requirements of earthquake resistant structures are good ductility and energy absorption capacity. Fiber reinforced concrete possesses high flexural and tensile strength, improved ductility, and high energy absorption over the conventional concrete in sustaining dynamic loads. The aim of this paper is to compare the properties of concrete beams in which three types of fibers are added individually. Steel fibers, polypropylene fibers and hybrid fibers were added to concrete in the weight ratio of four percentages in the preparation of four beam specimens. The fourth specimen did not contain fibers and acted as a control specimen. The dimensions of the beam specimens were 150 mm × 150 mm × 700 mm. The reinforced concrete beams of M30 grade concrete were prepared for casting and testing. Various parameters such as load carrying capacity, stiffness degradation, ductility characteristics and energy absorption capacity of FRC beams were compared with that of RC beams. The companion specimens were cast and tested to study strength properties and then the results were compared. All the beams were tested under three point bending under Universal Testing Machine (UTM). The results were evaluated with respect to modulus of elasticity, first crack load, ultimate load, and ultimate deflection. The test result shows that use of hybrid fiber improves the flexural performance of the reinforced concrete beams. The flexural behavior and stiffness of the tested beams were calculated, and compared with respect to their load carrying capacities. Comparison was also made with theoretical calculations in order to determine the load-deflection curves of the tested beams. Results of the experimental programme were compared with theoretical predictions. Based on the results of the experimental programme, it can be concluded that the addition of steel, polypropylene and hybrid fibers by 4% by weight of cement (but 2.14 % by volume of cement) had the best effect on the stiffness and energy absorption capacity of the beams.

Experimental investigation of mechanical properties of hybrid fiber reinforced concrete samples and prediction of energy absorption capacity of beams by fuzzy-genetic model

There have been a great number of studies aiming to improve the mechanical qualities of concrete material which is a basic component of reinforced concrete bearing systems. Attempts to reinforce the concrete through fiber addition have an important place among these studies. This study is an experimental research on the mechanical features of hybrid fiber added concretes which are obtained using steel fibers and polypropylene (PP) fibers together in certain proportions. Test specimens consist of 180 cylindrical samples (150×300mm) and 90 prismatic (150×150×750mm) beams produced in C40 concrete class. The specimens were exposed to temperatures ranging from room temperature to 100, 200, 400, 600 and 800°C in a certain order following their cure periods of 7, 28 and 90days. It was observed that hybrid fiber addition has a significant contribution into the compressive strength, flexural strength and energy absorption capacity of the concrete. Significance of hybrid fiber addition was put forward for the increase in ductility of the concrete which displays a brittle behavior when forced to bending.In the experimental studies with a numerous test specimens, losing of data due to some reasons and being unable to receive data was considered as a problem to be solved. Therefore, a fuzzy-genetic model was suggested to predict not only the experimental gaps, but also the untested value ranges of experimental parameters. Model was taken consideration in three different applications and it showed a satisfactory performance in predicting data.