Normal Strength Concrete Beams Research Articles

Numerical Analysis of Combined Effect Hybrid Fibres and Fire Insulation on the Fire Resistance Performance of SCC Beams

The use of self-compacting concrete in structural members has become increasingly prevalent in various construction applications. However, these structures are susceptible to one of the most hazardous disasters, which is the fire. This paper presents a numerical investigation of the fire resistance performance of self-compacting reinforced concrete (SCC) beams, as well as a parametric study to assess the impact of hybrid fibres and fire insulation on enhancing their performance under fire conditions. The study is conducted by developing a 3D finite element (FE) model using ANSYS software, where temperatures are applied according to the ISO834 standard fire. Geometric and material nonlinearities are considered in the evaluation of the behaviour of beams under fire conditions. The developed FE model is validated by comparing the predicted results with those of the experimental tests in literature. The fire resistance performance of SCC beams was compared with that of normal strength concrete (NSC) beams. The parametric study is conducted using three types of fire insulation, namely Tyfo WR-AFP, CAFCO 300, and Carboline Type-5MD. The results showed that SCC beam has lower fire resistance performance than the NSC beam. However, the incorporation of hybrid fibres allows a 17% improvement in the fire resistance of SCC beams. The use of fire insulations has increased the fire resistance time of SCC beams, and more particularly Carboline Type-5MD insulation with an increase of 28%. The combined use of hybrid fibres and fire insulation improved the fire resistance of SCC beams by 43%.

Experimental study on the flexural behaviour of lap-spliced rapid hardening concrete beams

Rapid-hardening concrete (RHC) has recently garnered significant attention because of its potential to expedite construction schedules and enhance structural performance. However, the flexural behaviour of lap-spliced RHC beams requires further investigation to provide valuable insights into the performance of this innovative construction material and splice technique. This study examined the flexural behavior of 22 lap-spliced RHC beams with varying lap splice lengths and compared them with four normal-strength concrete (NSC) beams. The key parameters investigated included lap splice length, concrete type, concrete cover, bar diameter, and splice end shape. The flexural performance of the beams was evaluated by analysing the load-deflection response, crack patterns, reinforcement strain distribution, and failure modes. Rapid-hardening concrete beams were tested three days after casting, whereas normal-strength concrete beams were tested 28 days later. The results of the study revealed that lap-spliced RHC beams exhibited increased ductility and load capacity by an average of 76 % and 32 %, respectively. In addition, the lap splice length in RHC beams could be reduced by up to 30 %.

Innovative Method for Reinforcing Beams with Different Types of Concrete Using Cross-Rod Steel Bracing Under Pure Torsion

This study aimed to investigate the effectiveness of an innovative way to reinforce the concrete beams using cross-rod steel bracing under pure torsion. The experimental program consists of casting and testing eighteen concrete beams made of three types of concrete in the form of three groups, with the same dimensions for all beams (200×200×2000) mm. The parameters of the study included concrete types (normal strength, high strength, and steel fiber), as well as the number of internally cross rods (4, 8, 12, 16, 20). The experimental results showed that the number of internally cross-rod reinforcements and concrete type had an effect on ultimate torque, crack width, toughness, and stiffness. The torsional capacity of all concrete beams increased with the increase in internally cross-rod reinforcement. The ultimate torque of normal-strength concrete beams, high-strength concrete beams, and steel fiber concrete beams reinforced with twenty internally cross rods increased (88.34%, 53.20%, and 40.60%), respectively, compared to beams without cross rods in each type of concrete beam. Increasing the internally cross rod in all concrete beams effectively inhibited the development of crack width and improved torsional stiffness, especially in fibrous concrete beams that contained steel fiber. The torsional toughness of all concrete beams increased with the increase of internally cross-rod reinforcement, and it was higher in steel fiber concrete beams. The steel fiber concrete beams reinforced with internally cross-rod steel bracing have better torsional properties compared to ordinary concrete beams and high-strength concrete beams. Doi: 10.28991/CEJ-2024-010-04-06 Full Text: PDF

Experimental investigation on UHPC-NSC composite beams

A hybrid beam composed of ultra-high performance concrete (UHPC) and normal strength concrete (NSC), is experimentally evaluated. The layout optimizes cost and performance by placing the UHPC full-depth section at mid-span of the hybrid beam. The length of the UHPC section compared to the span length (Lu/L) as well as the angle between the UHPC and NSC interface is varied experimentally, and the performance evaluated against fully NSC and fully UHPC control beams. The fully UHPC beam (BU) had an ultimate load 63.5% higher compared to the NSC beam (B). All three hybrid UHPC-NSC beams B0.5, B0.6, and B0.5I, having Lu/L ≥ 0.5, achieved ultimate loads of 92.3%, 95.8% and 94.2% of the fully UHPC beam ultimate load respectively. The failure of the hybrid beam with the inclined joint (B0.5I) was more gradual when compared with the beam with the straight joint (B0.5) having the same volume of UHPC. The hot joint between UHPC and NSC in the hybrid beams showed no joint separation. The developed 3D FE model was able to predict the load-deflection behaviour as well as crack locations and crack localization. In hybrid UHPC-NSC beams, steel yielding can initiate near the UHPC-NSC joint location, where unlike within the UHPC portion, the steel rebars are required to carry the entire tensile force. An analytical method is proposed to provide conservative design loads considering the different failures expected from the hybrid UHPC-NSC beam.

Behavior of Fire-damaged RC Beams After Strengthening with Various Techniques

High temperatures during a fire can significantly degrade the structural capacity of concrete. However, in many cases, it is possible to restore and strengthen fire-damaged concrete rather than completely rebuild damaged structures. The study considered two types of concrete (normal 25 MPa and high-strength 65 MPa) with two types of strengthening techniques: carbon-fiber-reinforced polymers (CFRP) sheets with different thicknesses of 1.5 and 2.5 mm and slurry-infiltrated fibrous concrete (SIFCON) jacketing with different fiber sizes of 20 and 30 mm. The numerical simulations and analyses were conducted to capture the complex behavior of fire-damaged concrete members (beams). A fire-damaged concrete beam subjected to an extreme or critical fire Exposure time (2 hours) was evaluated and modified using a finite element simulation approach. The simulation process included three stages: the first, subjecting the concrete beam to thermal loading; the second, reflecting the fire distribution map to another model of applying mechanical loading; and the third, involving the application of strengthening to the damaged model. The results showed that the strengthening using CFRP with a thickness of 2.5 improved the load-carrying capacity compared with SIFCON in both types of concrete. 200% improvement for the normal-strength concrete beam and a 136% improvement for the high-strength concrete beam, compared to the damaged beams. Doi: 10.28991/CEJ-2024-010-01-012 Full Text: PDF

Flexural and cracking performance of ultra-high performance concrete beams with high-strength steel reinforcements

In this study, the flexural and cracking performance of ultra-high performance concrete (UHPC) beams reinforced with high-strength steel reinforcement (HSSR) is investigated. Four beam specimens, including two UHPC beams and two normal-strength concrete (NSC) beams with different HSSR ratios were tested under flexure. The effect of concrete type and HSSR ratio on the flexural behaviour was evaluated. The failure mode, load-deflection response, stiffness, ductility and strain of the concrete and HSSR were discussed. Test results show that UHPC coupled with HSSR achieved better flexural performance and the ability to limit the development of the crack. The flexural capacity, deflection and stiffness for the UHPC beams were increased but the ductility was decreased as the HSSR ratio increased. The flexural behaviors of UHPC beams were predicted by section analysis. The flexural performance of HSSR-UHPC beams should consider the contribution of steel fibre to the tensile strength. Considering the influence of steel fibre, an equation was proposed to predict the average crack spacing. UHPC beams showed excellent agreement with the experimental results. The maximum crack width of 630 MPa reinforced UHPC beams was calculated by NF P 18-710 in accordance with the test results.

Shear behavior of normal and high-strength concrete beams reinforced with BFRP bars and basalt macro fibers

This research examined the effect of basalt macro fibers (BMF) on the shear resistance and behavior of normal-strength concrete (NSC) and high-strength concrete (HSC) beams longitudinally reinforced with basalt fiber reinforced polymer (BFRP) bars. Twelve BFRP reinforced concrete beams (BFRP-RC) were cast and tested under two-point loads without and with BFRP stirrups. The volume fraction (Vf) of BMF, the concrete compressive strength (fc′), and the existence of stirrups were all evaluated. Three volume fractions of BMF were used (0 %, 0.75 %, 1.5 %) with three classes of concrete compressive strength (30 MPa, 60 MPa, and 90 MPa). The results indicated that adding BMF to BFRP-reinforced-NSC and BFRP-reinforced-HSC beams enhanced the shear resistance. For concrete classes C30 and C90 shear resistance increased by 38 % and 62 %, respectively, when 0.75 % BMF was added, and it increased by 81 % and 115 %, respectively, when 1.5 % BMF was added. The enhancement of shear resistance due to the addition of BMF to BFRP-reinforced-HSC beams was more effective than in BFRP-Reinforced-NSC beams. Moreover, the addition of BMF enhanced the shear resistance of both stirrup-equipped and stirrup-less beams. The experimental results showed that the shear resistance of BFRP-reinforced-HSC beams due to the addition of BMF rather than stirrups is comparable, if not better, with stirrups. For instance, the shear resistance of the beam reinforced with 1.5 % of BMF is more than the beam reinforced with the minimum amount of BFRP stirrups. The post-cracking stiffness of all beams remarkably increased due to BMF addition. Furthermore, the effect of novel BMF on the mechanical properties of concrete was investigated.Additionally, an equation to predict the concrete contribution to the shear strength of FRP-RC beams was developed using the experimental shear strength of the tested beams and the experimental results of 217 FRP-RC beams without stirrups published in the literature. The proposed equation is combined with Said et al. and Narayanan and Darwish expressions to account for FRP stirrups and BMF contributions in the shear strength of the BFRP-RC beams. The mean value and the coefficient of variance (CV) of experimental to predicted ultimate shear strength of the beams (Vu,exp/Vu,pred) were 1.12 and 7.64%, respectively.

Characterization of interface properties for modeling the shear behavior of T-beams strengthened with ultra high-performance concrete

The application of Ultra high-performance concrete (UHPC) lateral layers on normal-strength concrete (NSC) beams substantially improves their shear performance. However, the impact of the NSC-UHPC interface properties on the shear performance has been scarcely studied and may hinder the strengthening efficiency and modify the failure mode. This study has characterized the complete shear and tensile behavior of interface specimens and evaluated the effect of anchors at the interface. Then, the complete curves of the interface allowed calibration of an interface concrete fracture (CF) model that was introduced in finite element (FE) simulations replicating the shear behavior of UHPC-strengthened T-beams tested in the same project. Parametric studies were then made with FE simulations. Results showed the FE simulations with the CF model better capture the stiffness evolution and failure mode of strengthened beams than that with the perfect bond model. The increase of UHPC layer thickness up to 80 mm and anchor spacing at the interface smaller than 300 mm considerably increased the stiffness and shear capacity of the strengthened beams. Existing dead load on beams did not impair UHPC strengthening and a substantial increase in shear capacity can still be achieved in real-size strengthened T-beams.

Flexural behavior and bond coefficient of BFRP bar reinforced normal and high strength concrete beams

Basalt fiber-reinforced polymer (BFRP) bars are emerging as potential non-metallic reinforcements for concrete structures due to the wide availability of their raw materials, their environmentally friendly manufacturing process, and their excellent mechanical and durability properties. This paper focuses on the flexural and deflection response of normal and high-strength concrete (HSC) beams reinforced with BFRP bars. A total of fifteen simply supported concrete beams were tested under four-point loading on a flexural span of 2.5 m. The study parameters were the reinforcement ratio, BFRP bar size, concrete strength and bar type (BFRP, GFRP and Steel). The experimental results were compared to ACI 440.1R-15 predictions. The prediction of ultimate moment capacity was in good agreement with the experimental result, while the cracking moment was overestimated. Furthermore, the mid-span deflection was significantly underestimated at service and ultimate loads. Modification in the empirical equations was proposed to enhance the predictions of mid-span deflection at service load. The bond coefficient kb used for predicting the crack width was estimated at 0.89 and 1.12 for BFRP-reinforced normal and high-strength beams.

Effect of the NSM material and area on the flexural response of normal strength concrete beams internally reinforced with GFRP and steel bars

Strengthening the steel-reinforced concrete (RC) beams by fiber-reinforced polymer (FRP) elements have become common several years ago. Recently, the RC beams internally reinforced with FRP reinforcement, especially Glass FRP (GFRP) bars, became popular worldwide. The carbon FRP (CFRP) elements (strips and bars) were recently used to strengthen the internally GFRP RC beams. In contrast, using the GFRP elements to upgrade the RC beams, especially those with GFRP bars as the main tensile reinforcement, was rarely studied. In this paper, the GFRP bars were implemented as near-surface mounted (NSM) elements to upgrade the beams reinforced in their tension side with GFRP or steel bars. All beams were experimentally loaded in flexure using a four-point loading scheme. The experimentally studied parameters were the main tensile reinforcement area, NSM area, and main reinforcement properties. Moreover, a numerical model was established and validated using the available experimental data to investigate the impact of main and NSM materials properties and areas on RC beam response. The experimental results highlighted that increasing the internal and NSM GFRP area by 96% and 100 % increased the beam capacity by 61.6% and 59.7%, respectively, which underlined a slightly higher efficiency of the main reinforcement than NSM bars on the beam load capacity. In addition, substituting the main steel with GFRP bars for the beams upgraded with NSM GFRP reinforcement enhanced their capacities by 11.33–15.1%. This emphasized the great effect of the linear response of the FRP materials and their higher tensile strengths than steel on the interaction between the main and NSM reinforcement, especially after the steel yielding. The FE results showed the highest load capacity using CFRP and GFRP bars as main and NSM reinforcement for the simulated beams. Conversely, using CFRP bars as NSM strengthening was more efficient than GFRP bars for the RC beams with steel or GFRP bars.

Experimental Investigation of Compound Effect of Flexural and Torsion on Fiber-Reinforced Concrete Beams

Fiber-reinforced concrete is widely acknowledged for its ability to resist cracking effectively and limit its propagation. By preventing cracks from spreading, the addition of fiber composites to concrete can enhance its extensibility and tensile strength, not only at the initial point of cracking but also at its maximum capacity. Additionally, the fibers in fiber-reinforced concrete are capable of binding the matrix, even when exposed to significant cracking. However, there is limited information available about the behavior of fiber-reinforced concrete under a bending moment combined with torsion. This study aims to investigate the structural behavior of fiber-reinforced concrete members subjected to a bending moment with a torsion to moment ratio equal to 1. Synthetic and steel fibers of 1.0% content with different lengths (19, 35, and 55 mm for synthetic fiber and 13 mm for straight and hook steel fibers) were mixed with concrete mixtures to examine the effects of fiber lengths and types on the concrete beam performance. Test results indicated that the fiber-reinforced concrete beams showed higher cracking moments than the normal-strength concrete beam. The steel fiber with a hooked configuration reinforced beam showed increased moment capacity and total torsional toughness higher than that of the straight steel fiber-reinforced beam. The synthetic fiber of a 55 mm length reinforced beam exhibited the highest first-crack and ultimate moment values among other tested beams. The test results were compared with past research models for the moment capacity of beams under the compound effect of bending and torsion and we modified these values with another factor that represented the fiber length influence on beam capacity, as suggested in past research. The comparison between the ultimate moment of the test results and the moment predicted from the modified past research model presented a good correlation.

Numerical Assessment on Continuous Reinforced Normal-Strength Concrete and High-Strength Concrete Beams

High-strength concrete (HSC) has been broadly applied to various civil structures for its advantages including high compressive strength and excellent durability and creep resistance. However, the brittleness of HSC raises concern about its use in practice. So far study on continuous reinforced HSC beams is limited. This work investigates the structural response of reinforced HSC continuous beams, and the results are compared with those of the counterparts made of normal-strength concrete (NSC). By applying a finite element method verified by experimental data, a comprehensive assessment is performed on two-span reinforced NSC and HSC (compressive strengths of 30, 60 and 90 MPa) continuous beams. A wide range of flexural reinforcement ratios are used to cover both under-reinforced and over-reinforced beams. The results show that reinforced HSC beams exhibit better flexural performance in terms of ultimate load, deformation, flexural ductility and moment redistribution, when compared to reinforced NSC beams. Formulae relating flexural ductility and moment redistribution with either neutral axis depth or tensile steel strain are suggested.

Behavior of High Strength Concrete Columns Intersected by Normal Strength Concrete Beams

Under axial compression stress, ten column specimens were investigated, one of which was an isolated column specimen, while the others were beam-column specimens with varying concrete strengths intersected with normal strength concrete. The column axial strength and behaviour were studied with the following parameters: different ratios of column concrete strength to beam concrete strength ( / ) (1, 1.58 and 1.89), different confinement ratios (ties) at the column location that intersected with the beam (0, 0.0049, and 0.0098), and the effects of confining beam-column joint by beams on two sides of the column. The experimental results demonstrated that the strength of the inner beam-column joint depends on the confining of the beam-column joint by ties. The ties change the failure location from the beam-column joint to the upper and lower column. The existence of ties overcomes the problem of normal concrete strength between high strength concrete (HSC). The proposed method is compared with ACI and CSA equations to show the efficiency of the models. ACI model gave significantly underestimated results.

ЧИСЛЕННОЕ ИССЛЕДОВАНИЕ ПОВЕДЕНИЯ ЖЕЛЕЗОБЕТОННЫХ БАЛОК ПРИ ВЫСОКИХ ТЕМПЕРАТУРАХ

The numerical study focuses on analyzing the structural response of reinforced concrete (RC) beams at high temperatures. Gaining more insight into the behavior of reinforced concrete (RC) structures at high temperatures and the material properties of steel reinforcement and concrete are the main goals of this research. To conduct this analysis, finite element analysis (FEA) using the ABAQUS software package is adopted. FEA allows for the simulation of the behavior of the RC beam under fire by inputting relevant parameters, such as material properties, dimensions, and temperature. The program calculates the temperature distribution within the structure and predicts the resulting structural responses. Two phases are applied: before and after exposure to fire. Both normal-strength concrete (NSC) beams and high-strength concrete (HSC) beams are considered. The results indicate that high temperatures have a detrimental effect on the overall behavior of concrete beams. At 600°C, the residual strength of HSC beams is shown to be twice that of NSC beams.

Flexural behaviour and cost effectiveness of layered UHPC-NC composite beams

This paper presents a pilot numerical study to investigate the flexural performance of simply-supported layered ultra-high performance concrete (UHPC)-normal strength concrete (NC) beams consisting of two UHPC layers with an NC core layer sandwiched in between. A three-dimensional finite element model (FEM) is developed for the beam and is validated against the existing experimental results of UHPC-NC bi-layer composite beams. The effects of the bonding between UHPC and NC layers, the fraction of UHPC and NC in the beam, and the mechanical properties of UHPC material on the flexural performance of the beam are discussed in detail. Numerical results show that the flexural behavior of the layered UHPC-NC beam is significantly influenced by the interfacial bonding between UHPC and NC layers that is represented by the cohesive stiffness which should be higher than 3 to avoid possible delamination failure in the beam. The material cost effectiveness of the layered UHPC-NC beam is also evaluated. It is found that with properly designed UHPC layer thickness, the beam with a thick NC core layer can not only sustain the same loading as a pure UHPC beam with the same thickness but is also much less costly, indicating the excellent mechanical performance and great cost effectiveness of the proposed layered UHPC-NC beam.

Evaluating the Efficiency of Epoxy Injection Technique for Repairing Normal and High Strength Concrete Beams - A Critical Review

Concrete deficiency is a very common issue and has several forms, including cracks in a plastic or hardened state. Various materials and methods are used nowadays for repairing because repairing is cost-effective, can rehabilitate deteriorated structures, and increases the overall structural life cycle. Epoxy injection is one technique used for repairing cracks with 0.05mm width. The main objective of this review is to evaluate the efficiency of this technique for normal and high-strength concrete beams and investigate the factors that affect the improvement ratio of repaired samples, such as; the depth of the beam, the number of drilled holes for injection, reinforcement distribution, the viscosity of the epoxy and width of the crack. The results proved that epoxy injection is an effective method for restoring the original structure and stiffness if sufficient repairing procedures are followed. A low viscosity epoxy is preferred as it can penetrate easily into the crack depth and restore strength. On the other hand, beams with smaller depth had a higher percentage of improvement, and the number of drilled holes for injection directly affects the results, fewer holes better the strength improvement.

Flexural Strengthening of Normal Strength Plain Concrete Beams using Ultra-High Performance Fiber Reinforced Concrete Strips

In recent years, the strengthening of reinforced concrete elements in existing structures has become a very important interest topic because of the demand for development structures and extending their service life. Since the ultra-high-performance fiber-reinforced concrete properties in terms of durability and strength are fully exploited, it became early in the rehabilitation and strengthening field. This paper highlights the flexural behavior of small-scale plain normal strength concrete beam strengthened in flexure by ultra-high performance fiber reinforced concrete strips at the tensile surface by adhesive epoxy material to evaluate and quantify the effect on strength in flexure. Experimental results indicated that the ultra-high performance fiber reinforced concrete strengthening strips enhanced the flexural capacity and stiffness of the normal strength concrete substrate by 369%, 364%, and 168% at crack load and 364%, 232%, and 127% at ultimate load for concrete grades 20.8, 32.6 and 43.3 MPa respectively, delayed the crack development corresponding to apply load more than 0.37, 0.97 and 1.25 kN for strips thickness 10, 15 and 20 mm respectively in all grades of concrete beam and improved beams' ductility behavior. The main important point that affects the performance of flexural strengthening concrete beams using adhesive material is the quality of the interfacial transition bonded zone of the composite system produced between the strengthening material and the existing concrete substrate.

Effects of the Concrete Strength and FRP Reinforcement Type on the Non-Linear Behavior of Concrete Deep Beams

To provide sustainable reinforced concrete deep beams, the replacement of steel rebars by FRP rebars with high-chemical resistance is proposed by researchers. However, the effects of the concrete strength, top and web longitudinal reinforcements, and types of FRP flexural rebars on the non-linear performance of concrete deep beams have rarely been evaluated. This study numerically assessed the effects of the top and web longitudinal reinforcements and concrete strength on the non-linear behaviour of GFRP- and CFRP-strengthened concrete deep beams with various shear span-to-overall depth (a/h) ratios. As per the results, the highest tensile stress was obtained for the steel reinforcement, and the tensile stress in the CFRP reinforcement was more than that of the GFRP reinforcement under the failure load. Meanwhile, the results of high- and normal-strength concrete deep beams with the web reinforcement (16.4%) were lower than those without the web reinforcement (22.3%). Therefore, the web reinforcement moderately compensated for the low strength of normal concrete and the absence of the top longitudinal rebar to reinforce concrete deep beams in carrying the ultimate load. Furthermore, the participation of the GFRP reinforcement with the high-strength concrete was more than that with the normal-strength concrete in carrying a higher amount of loading.

Impact resistance of porosity-free fiber-reinforced concrete (PFFRC) beams under low-velocity impact loading

Ultrahigh-performance fiber-reinforced concrete (UHPFRC) is an advanced cement-based composite material. Its ultrahigh compressive strength and high ductility can enable the downsizing of structural members, with special application to high-rise buildings. These excellent mechanical properties also allow its application in protective structures to resist high-speed penetration, low-velocity impact, and blast loading. UHPFRC with a compressive strength of approximately 150–200 MPa has traditionally been used to investigate the impact resistance of structural members under low-velocity impact loading. Recently, however, porosity-free concrete of the 400 MPa class of compressive strength has been developed. In this paper, to investigate the effects of the concrete strength and the steel fiber volume fraction on the impact resistance of porosity-free fiber-reinforced concrete (PFFRC) members, static and drop-weight impact loading tests were conducted on PFFRC beams by varying the volume fraction of steel fiber from 1 to 3.5%. As reference beams, 90 MPa high-strength fiber-reinforced concrete (HSFRC) beams with a 2% fiber volume fraction and normal-strength concrete (NSC) beams without stirrups and steel fibers were also tested. The results obtained from this study were as follows: (1) the static load-carrying capacity of a PFFRC beam can be enhanced by more than two and three times that of an NSC beam by adding 1 and 3.5% volume fractions of steel fiber, respectively; (2) a PFFRC beam with 3.5% fiber had the greatest impact resistance of all the beams considered in this study, and the beam with 2% fiber volume had the second-greatest performance, but the difference was small; (3) even though an HSFRC beam with 2% fiber had a smaller static load-carrying capacity than a PFFRC beam with 1% fiber, the former exhibited a slightly greater impact resistance than the latter because the bridging effect of the steel fibers has a greater influence under impact loading than under static loading.

A Comparative Investigation on Normal and High Strength Concrete Beams under Torsion

In this study, an experimental investigation was done to study the behaviour of Normal Strength Concrete (NSC) and High Strength Concrete (HSC) Plain beams under torsion with the concrete mix of M40 and M100. No mineral admixtures are used to obtain the required strength of concrete. Eight NSC beams and eight HSC beams whose width was varying with 75 mm, 100 mm, and 150 mm; depth varying as 75 mm, 100 mm, 150 mm and 200 mm; and span of the beams varying 600 mm, 800 mm and 1200 mm were casted and cured to stud the effect of torsion. The principle aim of this study was to understand the torsional behaviour of the NSC and HSC beams for rotation, cracking, size effect and torsional strength. A standard torsional loading method was used for conducting the testing of beams. The results obtained were compared with different theories and code equations. It was observed that the torsional strength of the beam increases with the increase in strength of concrete. HSC beams have higher torsional strength than the NSC beams which has the same amount of reinforcement.