A case study of T-beams with hybrid section shear characteristics of reactive powder concrete

: As an extension of recent developments in concrete understanding, an extensive study is currently being conducted on the structural performance of reactive powder concrete (RPC). This article guides how to investigate the shear behavior of RPC T-beams and calculate their ultimate and breaking shear capacities. The mechanical features of this construction material and approach to revising the reactive powder shear hybrid segment T-beams are cast-o ﬀ in this motion and are investigated in this experimental study. To evaluate the e ﬀ ects of volumetric ratio of steel ﬁ bers, silica fume ratio, and tensile steel ratio, introductory section on the e ﬀ ective-ness of T-beam shearing reactive powder, the program of experimentation involved trying four beams. The research aimed to determine the de ﬂ ection conduct of the load, downtime approach, strain amount over the beams ’ depth, and failure form of cracks. In examining reaction powder ’ s mechanical characteristics mixtures, steel ﬁ ber volumetric ratio and silica fume volumetric ratio were also studied. Furthermore, a hybrid beam study revealed that by using reactive powder web and regular concrete in ﬂ ange e ﬀ ectively, T-beam concert is enhanced when associated with normal concrete T-beams by 12%. Hybrid beams have also revealed that using reactive powder ﬂ ange and usual concrete in a web e ﬀ ectively advances the show of T-beams when associated with standard concrete T-beams by 28%.


Introduction
Reactive powder concrete (RPC) is a high-performance cementitious material with imperfect shrinkage and creep, low permeability, ultra-high strength, and amplified corrosion resistance. In 2015, Yoo and Yoon [1] explored the influence of different fibers within the flexural conduct of strengthened UHPFRC beams. A moment's maximum capacity was unaffected by fiber geometry, although lengthy steel fibers pointedly improved post-peak reaction and flexibility. In 2016, Rahman et al. [2] added fibers to plastic concrete to increase its compressive and tensile strengths as well as to control cracking and enhance its durability. All these fibers are used in fiber-reinforced concrete throughout the world. RPC having all the ingredients in powder form is one of the modern types of ultra-high strength concrete where silica fume (SF) is used as pozzolana to achieve high strength. This article focuses on the effect of adding organic fibers (polypropylene) on compressive and tensile strengths of RPC. The organic fibers (polypropylene) produce RPC's compressive and tensile strengths. Furthermore, bending tests of plain RPC samples have been completed and characterized in the form of curves for load-deflection for fiber additions of 0.25-2% (with a 0.25% increment) by weight. In 2018, Alwash and Al-Sultan [3] studied the consequence of two types of fibers (steel fibers and polypropylene fibers) on flexural behavior as well as some important possession (compressive and splitting) assessment of RPC related to normal strength concrete. In 2021, Dawood and Abdullah arranged using different percentages of waste glass powder, steel slag, and SF, compressive and flexural strengths have been tested for such green mortar [4]. In 2022, AL-Shaar et al. presented finite element (FE) modeling using the ABAQUS program to investigate the numerical analysis of high-strength reinforcing steel with conventional strength in reinforced concrete beams under monotonic loading [5].

Production materials
There is computed normal concrete, and the relevance of a powder that reacts employing disparate preparations preceding the concert of beams in the casting-off products, cement [6], sand, gravel [7], and conventional water is processed without any additions. Also SF [8] and steel [10] fibers are cast-off for reactive powder concrete for RPC T-beams.

Steel fibers
Steel fibers with high performance were utilized in the study [10], and their attributes are listed in Table 3.

Steel reinforcement
Three 1,000 mm long specimens, each with insignificant diameter, are put on trial to determine the stress on middling yield f y and ultimate toughness f u [11] (Table 4).

Mixing concrete
In this study, two types of concrete compositions were discarded.

Typical concrete mixture
Cement, fine aggregate, coarse aggregate, and water were all thrown away in a conventional concrete composition, including molding the ordinary and web in hybrid beams. RPC1, RPC2, and RPC3 (normal, RPC1, RPC2, and RPC3).

Concrete mixes with reactive powders
The quantities of materials of all mixtures are given in Tables 5 and 6 ( Figure 1).

Mechanical properties of RPC
All the observations are shown in Table 7.

Inclined crack width
A fracture detection pocket microscope was cast-off to portion the major crack in the beam. Figure 3 shows the  ♣ The letter M denotes mix no. *SF weight as the total cement weight. ** SP, percent of binder weight. ***Ratio of total mixture volume.    Figure 3: Width of a load-inclined crack.  [12] f t ** (MPa) [13] f r *** (MPa) [14] E c **** (MPa) [ relation between loads and crack width. From this figure, it is clear that beams through a higher a/d ratio at an equal load level showed higher crack width. It is also observed   that figure beams with web reinforcement have a smaller crack width than those without web reinforcement. But at the load step just before failure, beams with web reinforcement showed higher crack width, and the failure did not occur suddenly.

Distribution of strains
The concrete strains in the middle of the spectrum part of the confirmed beams were unhurried on seven different points, as shown in numbers. Figure 4 depicts the location where the strain was measured for each beam. In Figure 5, for all beams, the tensile strain at the load path's middle length was measured.

Numerical element work
To analyze the beams, FEs are obsolete; the ABAQUS application provides choices for describing several types of material behavior; eight-node isoparametric brick pieces represent concrete. Employing four-node link components for steel reinforcement [16]. Figure 6 contains all details.

Displacement for specimens
Figures 7-10 express that the investigative data and computational load for these species' center beam deflection for direction Y are arranged correctly.

Concrete strain distribution
Figures 11-13 express the numerical concrete plastic-strain distribution of beams and damage. It can be seen from these figures that the largest strain occurred along the load path where the tending fracture occurred. Additionally, it showed that the position where the largest rate of strain followed was slightly below the midpoint of the load path, which corresponds to the location where the maximum crack width was confirmed in the exploratory study ( Figure 14). when the fibers' volume proportion increases from 0 to 0.5, 1.0, 1.5, and 2.0, respectively, and is associated with nonfibrous RPC beam. In addition, with the equivalent rise in fiber volume percentage, the final strength in shear of nonfibrous RPC specimens also increases by 87.3, 97.2, 118.3, and 132.4%, respectively. 3. When the SF content is the same amount diagonal cracking load is raised by 7.14 the RPC beams are increased from 5 to 10, 15, and 21.4%, respectively, while the total load rises by 6.06 and 9.09%. 4. Curves of load deflection for steel-fiber beams (0, 1, and 2%), an expression that as the steel fiber volumetric ratio rises, the deflection reduces at a given load level at all loading steps due to an upsurge in stiffness. 5. SF in concentrations ranging from 15 to 25% does not affect the major fracture capacity, ultimate shear, or RPC T-beams deflection in the middle of its span. The major fracture load, ultimate deflection of the mid-span, and shear strength, on the other hand, grow from 15 to 25% with percentages of 17, 10, and 15%, respectively. 6. RPC cylinders tested in compression had a peak strain of 0.0025. Peak strain was increased by 44, 60, 72, and 92% when portions of volume at 0.5, 1.0, 1.5, and 2.0% of steel fibers were added, resulting in 0.0036, 0.0040, 0.0043, and 0.0048, respectively.
7. The displacement curves and strain distribution figures used to describe the behavior of the FE models generally exhibit high agreement with the corresponding experimental curves.

Conflict of interest:
The authors state no conflict of interest.
Data availability statement: Most datasets generated and analyzed in this study are comprised in this submitted manuscript. The other datasets are available on reasonable request from the corresponding author with the attached information. Study of T-beams with hybrid section shear characteristics of concrete  9