Ahmad Jabbar Hussain Alshimmeri

Over the past ten years, cold-formed steel two-channel sections featuring edge-stiffened castellated cellular web apertures have been developed and are now widely used in New Zealand. Previous research on vertical compression has shown that using edge-stiffened web openings in these channel sections increases their vertical load capacity. Subsequent studies expanded to include hexagram web holes; however, the literature still lacks investigations on the effect of applied vertical pressure on web openings in two-channel sections with perforated webs. This research addresses that gap. The aim of this study is to evaluate the structural response of symmetrical castellated two-channel (2C) sections. Six specimens of castellated 2C beams made of cold-formed steel and encased in reactive powder concrete with diagonal reinforcement on both sides were examined. The concrete encasement and reinforcement enhanced the beam’s resistance to buckling, bending, and both horizontal and vertical shear, and also improved joint performance. Two concentrated loads were applied at the beam center to investigate the structural behavior of each specimen. The results showed that the presence of a joint gap enhanced load resistance. The ultimate load increased by 6.75% compared with the reference specimen SCB2C-rLG20% in G3, by 30.86% compared with SCB2C-rL in G2, and by 1064.73% compared with SCB2C/R1 in G1. The specimen with a 30% gap demonstrated the best load capacity and the highest ductility compared with the reference specimen and the other specimens.

This study investigates the analytical approach of web reinforcement techniques, including high-strength concrete and laced reinforcement, to enrich improvement for the structural behavior of these beams. The analysis compares an unmodified cellular beam (LB1) with a web-reinforced beam (LB2), including the improvements in load-carrying capacity. The study considers the effects of reinforcement on critical design limit states, such as flexural strength, Vierendeel bending, web post-buckling, and shear resistance. The outcomes reveal significant enhancements in LB2’s structural behavior, with over a 100% increase in flexural strength and local axial force capacity and a 165% increase in web post-buckling strength. This research validates the effectiveness of web reinforcement techniques in concentrating on the limitations of cellular beams and maximizing their potential in structural applications.

This study's primary objective is to examine the structural behavior of using 2C-Cold produced. Section Castellated beams when subjected to monotonic load till failure. The experimental program testing. Seven Fabricated samples of castellated steel beams and one sample, which is a non-castellated steel beam (reference beam), were tested as supported beams under concentrated loads at two points over a clear span length (1730 mm). All castellated steel beams were similar in all properties and dimensions except the breadth of the upper and lower flanges. The current study considers the implications of modifying the width of the top and bottom flanges on how these beams behave. The findings showed that the ratio of the tested Castellated beams' ultimate load-carrying capacity to the non-castellated reference beam (R1) ranged from 99.3 to 117.2%, and the ratio of the tested beams' ultimate deflection to the same reference beam (R1) ranged from 72.6 to 103.2%. Increasing the breadth of the top and bottom flanges has a direct relationship with castellated beam stiffness and ultimate load. Finally, adjusting the flange width between the top and bottom flanges reduces castellated beam rigidity and ultimate load.

This paper examines the experimental flexural performance of the strengthening composite concrete asymmetrical castellated steel beam of double channel shape by connecting two castellated hot rolled steel channels back-to-back using bolts along its length to obtain a built-up I-shaped form with a new total beam depth heightened by 52.4%. This research tested four specimens: the first was a reference specimen without any strengthening techniques; the second was strengthened with RPC (Reactive Powder Concrete) in the steel web region; the third was strengthened by RPC reinforced with a lacing rebar. Also, this study investigated the welding effects in web posts for the top and bottom parts of the castellated steel in the fourth specimen. All specimens were tested under simply supported conditions by applying two-point static loads on the concrete deck slab of the composite beams. The ultimate load deflection, stiffness, ductility, energy absorption capacity, and failure mode were investigated and discussed. According to the experimental results, the ultimate load capacity increased 24.01% and 48.34% in the second and third specimens, respectively, with increased stiffness, ductility, and energy absorption capacity compared with the first specimen. In contrast, the ultimate load capacity decreased by 11.02 % in the fourth specimen (strengthening without welding in web posts), reducing stiffness and ductility compared with the first specimen (reference).

Current numerical research was devoted to investigating the effect of castellated steel beams without and with strengthening. The composite concrete asymmetrical double hot rolled steel channels bolted back to back to obtain a built-up I-shape form are used in this study. The top half part of the steel is smaller than the bottom half part, and the two parts were connected by bolting and welding. The ABAQUS/2019 program employed the same length and conditions of loading for four models: The first model is the reference without castellated and strengthening; the second model was castellated without strengthened; the third model was castellated and strengthened with reactive powder concrete encased in the steel web, and the fourth model was castellated and strengthened with reactive powder concrete and lacing steel rebar's welded diagonally on two sides of the steel web. According to the Numerical results, there was an increase in ultimate load capacity compared to the reference model of about 22.74%, 51.65%, and 77.98% in the second, third, and fourth models, respectively; also, there is a reduction in deflection of 55.52%, 58.74, and 60.55% in the second, third, and fourth models, respectively, compared to the level deflection at ultimate load for the reference model, with an increase in stiffness and ductility. In comparison to the I section, the fabrication of a castellated steel beam from the double channel is more cost-effective in terms of cutting steel loss at the ends of the castellated beam, this is due to the feature of rotation and reflection of the steel channel section during cutting and forming to castellated shape.

Precast reinforced concrete (RC) girders with dapped ends are used in order to reduce the overall depths of concrete floors and bridge decking and meet architectural requirements. The structural requirements by reducing the depths of these girders result in stress concentrations within the recessed zones. Thus, girders with dapped ends require special details for the strengthening systems. The use of open transverse holes in RC sections is for the passage of various service lines such as telecommunication cables, gas lines, water pipes, electricity cables, etc. The behaviours of RC girders with dapped ends and openings strengthened by bolts subjected to two vertical concentrated loads were numerically simulated by utilising commercial finite element software ANSYS. The numerical results from the simulated models were identical and compatible with those experimental results stated in literature. The validation of the numerical results with those experimental ones was based on the statistical analysis by including the calculations of the correlation coefficients, arithmetic means, and standard deviations for all the simulated girder models in terms of loads and deflections. The obtained numerical results showed that an increase in the compressive strength of concrete by 20% would cause an increase in the loading resistance of the models by 13% and a decrease in the deflection by 21%, respectively. Also, it was indicated that the type of section, i.e., the change of the section from solid to open (with transverse openings), would decrease the resistance of the section by 8–16% and increase the deflections by 15–20%. Similarly, an increase in the number of holes would result in the decreases in the load resistance by up to 6% and the increases in the deflections by up to 24% under the same applied loads. Strengthening openings using vertical bolts has an important role in enhancing the resistance of the models by 8–20% and decreasing the deflections by 20–30%. The failure patterns were hybrid, e.g., flexure and shear, and identical with the experimental ones. Finally, the effect of using the cylindrical compressive strength of concrete as a mechanical parameter on the structural behaviours of the simulated models was investigated, which could improve the resistance loading and decrease the deflections of the models.

Nowadays, castellated steel beams are widely used for various structural purposes. Castellated beams are structural members made by thermally cutting a rolled c

This paper studies the flexural experimental behavior of an asymmetric castellated composite beam with an encased steel web by RPC (reactive powder concrete) ca

This paper studies the flexural experimental behavior of an asymmetric castellated composite beam with an encased steel web by RPC (reactive powder concrete) with and without lacing rebar effect using a gap between the two parts of the steel web. The cross section made from steel beams and concrete deck slabs. The steel beam (asymmetric section) made from two parts of the tee section; the top part cut is from IPE 180 and the bottom part cut from IPE 200. The RPC was used to connect the steel web without welding. From the results, the difference in ultimate service load capacity using gaps (0%, 10%, and 20%) from web depth equals (+8.36%) with a gap of (20%) from total depth, a decrease equal to (-18.59%) with a gap equal to 0% gap, and a decrease equal to (-2.96%) with a gap equal to 10% gap.

Non-prismatic reinforced concrete (RC) beams are widely used for various practical purposes, including enhancing architectural aesthetics and increasing the overall thickness in the support area above the column, which gives high assurance to services that this will not result in the distortion of construction features and can reduce heights. The hollow sections (recess) can also be used for the maintenance of large structural sections and the safe passage of utility lines of water, gas, telecommunications, electricity, etc. They are generally used in large and complex civil engineering works like bridges. This study conducted a numerical study using the commercial finite element software ANSYS version 15 for analysing RC beams, hollow longitudinally sectioned and retrofitted with carbon fibre reinforced polymers (CFRPs), which were subjected to concentrated vertical loads. The numerical analysis results on the simulated beam models were in excellent agreements with the previous experimental test results. This convergence was confirmed by a statistical analysis, which considered the correlation coefficients, individual arithmetic means and standard deviations for all the calculated deflections of the simulated beam models. A proposed numerical simulation model with the hypotheses can be considered suitable for modelling the behaviours of simple supported non-prismatic RC beams under vertical concentrated loads. The numerical results showed that altering the cross-section from solid to hollow could reduce the load carrying capacities of the beams by up to 53% and increase the corresponding deflections by up to 40%, respectively. Using steel pipes for making recesses could enhance the loading capacity by up to 56%, increase the ductility, and reduce the corresponding deflections by up to 30%, respectively. Finally, it was found that bonding the CFRP sheets in the lower middle tensile areas of the hollow beams could improve the resistance and reduce the deformations by up to 27%. The failure patterns for all the numerical models were shear failure. The cylinder compressive strength could be used as a mechanical parameter for modelling and assessing the structural behaviours of the beam models, as its increase could improve the load carrying capacities and reduce the deflections by 30–50%.