Combined Behavior of Reinforced Concrete Out-of-Plane Parts Beams Encased with Steel Section

Compressive behaviour of thin-walled square tubular columns filled with high-strength steel section and precast compound concrete segments

This research investigates the behavior of RC beam column joints reinforced with steel sections. The study deals with the strengthening of RC joints by different steel sections. The investigation included a theoretical analysis through a performing of simulation of beam-column joints laced with steel sections by using FEA. Implementation of the parametric study included reinforcing the concrete beam with steel sections in many configurations. Shapes and length were the most variables in this study, and many shapes were used, such as I-section, box section, and plates, beside the concrete compressive strength variable. The most recent study revealed the possibility of the method to enhance the efficiency of the joint in resisting the loads while the offering many additional features such as higher ductility, stiffness, and energy absorption. The results showed that strengthening by the steel section enhanced the flexural strength of the joint, but these enhancements were to a certain limit due to the concrete strength limitation. The ultimate strength enhancement was 49%, which is considered a good index for the joint efficiency. The use of compressive strength in small amounts led to the enhancements being limited due to the weakness of the concrete. Strengthening the flexural side of the beam by adding a steel section requires stronger concrete to provide more contribution for the steel section to resist more flexural loads. The increase in the compressive strength of the concrete made the improvements reach their peaks. Strengthening by I-shaped and box steel sections showed that the enhancement due to the existence of the I section was greater than that of the box one. Doi: 10.28991/CEJ-2023-09-03-015 Full Text: PDF

Structural performance of fiber-reinforced SCC beams containing Stalite lightweight aggregates

Structural behavior of reinforced concrete beams with out of plane part

The use of composite systems comprising of concrete and conventional steel is commonly used in a multi-story steel frame with hot-rolled steel section. However, the use of cold-formed steel section designed as composite beam is yet to be established. Cold-formed steel (CFS) is usually categorized as a slender section which tends to buckle and deform. The strength of this section is usually reduced significantly as the section is very thin. However, all these problems can be significantly improved by designing the section as composite construction by integrating concrete and steel with the use of rebar as a shear connector. Therefore, this paper presents experimental works on the structural performance of cold-formed steel (CFS) section with self-compacting concrete (SCC) as a composite beam by means of the shear connection mechanism of the proposed using reinforcement bar. A specimen was carried out where the behavior of encased double cold-formed steel composite beam with composite slab was tested until failure. The proposed shear connector of size 12 mm was embedded in CFS and encased in SCC with a compressive strength of 40 N/mm2. The specimen comprised of two parallel CFS attached together to form encased beam with a concrete slab. Based on the experimental results it was found that the proposed composite system using bent-up rebar as shear connector showed slightly higher results than expected with ultimate moment capacity of 358.3 kNm for experimental and 341 kNm for predicted results. The failure mode was recorded as ductile which make it suitable to be used in the seismic zone.

Effect of structural parameters on low-velocity impact behavior of aluminum honeycomb sandwich structures with CFRP face sheets

Service Limit State Control of Permanent Deflection for Steel Sections in Flexure

This paper aims to experimentally investigate and compare the structural behavior of reinforced concrete straight beam and other beams there made with one, two, and three out of plane parts. The study focused on the effect of the number and location of the out plane parts on the beams mid span deflection, and rotation, as well as the ductility index, cracking loads, and failure modes. Four beams were manufactured with a cross-sectional width of 150 mm and a depth of 200 mm, and 2000 mm in length. All the beams were made with normal strength concrete and constant longitudinal reinforcement ratio 0.011 for negative and positive moment. All the beam specimens were clamped by a special steel fixed ends and subjected to the two-point load up to their failure. The obtained results presented that the load bearing capacity of straight beam was higher than the beams with out of plane parts. Furthermore, the beam with two out of plane parts has capacity higher than the beams with one and three out of plane part by 5.86%, and 55.07%. In addition, the results showed that the ductility increased with increasing number of out of plane parts by 5.52%, and 32.71% as copared with the beam with one out of plane part.

Flexural behavior of preflex sfrc-encased steel joist composite beams

This paper investigates the possibility of strengthening a ferrocement RC beam with steel wire mesh under static loading. This experimental study included testing ten normal and high-strength concrete specimens made with ferrocement. The main parameters were the steel wire mesh layers 4, 8, and 10 in addition to the compressive strength and shear to span to depth ratio of 1.8 and 2.5. The cracking load, ultimate load, deflections, initial stiffness, energy absorption, diagonal and compressive strains, and crack pattern and failure modes of such beams were discussed. The outcomes exhibited that the beams behave linearly until they reach about 21.5% of the ultimate strength for the normal concrete beam and 23.2% for the high-strength concrete beam. The steel wire mesh presence affected the ultimate strength of the concrete beam, which increased the cracking load by an average of 15.5% for the high-strength RC beam and by 24.2% for normal-strength RC ones. The ultimate load was increased by an average of 40% for the high-strength strengthened beams and with less percentage for the normal ones, which was 31%. The ratio affected the ultimate load-carrying capacity and maximum displacement directly, which increase led to a decrease in the ultimate load-carrying capacity. The strengthening by steel wire mesh enhanced the initial stiffness, ductility, and energy absorption. Doi: 10.28991/CEJ-2022-08-05-04 Full Text: PDF

In this study, the structural behavior and performance of the dapped end beams with composite section under effect of static and repeated loads was investigated by experimentally tested and included ten simply supported beams with dapped in one of ends. The parameters that have been taken into consideration represented by studying the effect of reparation longitudinal tensile reinforcement by steel sections, effect of repeated loads, different types of composite steel sections, and influence of increased the shear span to depth ratio (a/d) more than one on the composite dapped end region. The study focused on determining the first cracking load, ultimate strength (Pu), deflection at service and ultimate load, failure mode, load-deflection behavior, ductility ratios, and crack pattern at failure load.
 The results presented that using the composite I-section instead of normal section in dapped end beams developed the shear capacity for dapped end region and enhanced the first crack appearances about 33.33, and 39.42 % for shear span to depth ratio 1.0, and 1.5 respectively.

Impact of anchored holes technique on behavior of reinforced concrete beams strengthened with different CFRP sheet lengths and widths

The impacts of numerous important factors on the Energy Absorption (EA) of torsional Reinforced Concrete (RC) beams strengthened with external FRP is the main purpose and innovation of the current research. A total of 81 datasets were collected from previous studies, focused on the investigation of EA behaviour. The impact of nine different parameters on the Torsional EA of RC-beams was examined and evaluated, namely the concrete compressive strength (f'c), steel yield strength (fy), FRP thickness (tFRP), width-to-depth of the beam section (b/h), horizontal (ρh) and vertical (ρv) steel ratio, angle of twist (θu), ultimate torque (Tu), and FRP ultimate strength (fy-FRP). For the evaluation of the energy absorption capacity at different levels, Response Surface Methodology (RSM) was implemented in this study. Also, to fit the measured results, Quadratic and Line models were created. The results show that the RSM technique is a highly significant tool that can be applied not only to energy absorption-related problems examined in this research, but also to other engineering problems. An agreement is observed between Pareto and standardized charts with the literature showing that the EA capacity of the torsional FRP-RC beams is mostly affected by the concrete compressive strength, followed by the vertical reinforcement ratio. The newly suggested model in this article exhibits a satisfactory correlation co-efficient (R), of about 80%, with an adequate level of accuracy. The obtained results also reveal that the EA acts as a safety index for the FRP-strengthened RC beams exposed to torsional loadings to avoid sudden structural damage. Doi: 10.28991/cej-2020-SP(EMCE)-07 Full Text: PDF

The impact of the welded wire mesh as internal reinforcement on the flexural behavior of RC beams exposed to elevated temperature

Push-out tests on bolted shear connectors in composite cold-formed steel beams