Concrete Hollow Beams Research Articles

Effect of Laying Service longitudinal and Transverse Openings on Reinforced Concrete Hollow Beam Web under Flexural Loadings

Laying of service pipes such as sewage pipes, electricity pipes, and sometimes water pipes ducts and others had presented some problems especially if it gathered in one place. One of the best solutions to minimize the problems and solve the piping and other services is using longitudinal and transverse opening in beams (BLTO), especially when high strength concrete (HSC) is used. HSC beam that performed experimentally by a researcher and implemented in this study by finite element method. ANSYS software was utilized to prove the experimental results with using the same properties, geometry, materials, and conditions which the comparison included the force-displacement relationship ultimate load capacity, maximum displacement, and crack pattern. The verification process between the experimental program and theoretical one demonstrated that there is a good convergence between the obtained results between the two results. The similarity in the outcomes showed that the matching between the experimental and numerical in force by (99%) and in displacement by (94%). These variances were due to the small difference in the condition of experimental and theoretical side which the numerical considered ideal condition. Also, this study examined the behavior of (RC) beam have longitudinal and transverse opening. The registered failure mode of beam was flexural failure although of presence of shear cracks but the flexural cracks were the controller in the behavior.

Torsional behavior of solid and hollow concrete beams reinforced with inclined spirals

Enhancing the torsional capacity of reinforced concrete (RC) beams while maintaining reasonably economic and efficient cross-sections poses a practical challenge in the design of such elements. Thus, developing and testing economically viable reinforcing techniques for enhancing the torsional capacity of RC beams is a significant aspect. Among these techniques is the continuous spiral reinforcement system that has shown promising results in enhancing the torsional capacity of rectangular RC elements.In this study, the role of continuous rectangular spiral stirrups, as a transverse reinforcement with a controllable pitch (P) and inclination angle (θ), in enhancing the torsional behavior of rectangular solid and hollow RC beams has been investigated experimentally. The applied torque was directed to lock the spirals for all specimens. The experimental program of this investigation included testing of ten specimens of normal strength RC beams; two of which were solid with closed and spiral rectangular stirrups. While the rest of specimens were hollow specimens included one beam reinforced by closed stirrups and seven beams reinforced by rectangular spiral stirrups with different reinforcing ratios. Different variables were considered to develop a wide range of the beams’ reinforcing scenarios. This includes stirrups type (conventional closed stirrups and rectangular spiral stirrups), inclined stirrups ratio, pitch, inclination angle and finally the longitudinal reinforcement ratio. In addition, a three-dimensional finite element model using ANSYS-15.0 was developed to examine the capability of the model to capture the observed torsional behavior of the experimentally tested beams.The obtained results showed that using inclined spiral rectangular stirrups in reinforcing RC solid and hollow beams greatly enhanced the torsional capacity by about 16% and 18%, respectively compared to using the conventional closed stirrups. Moreover, the results showed that using that technique leads to higher twist- angles, more ductile failure and increased strain energy by about 27% and 16% for solid and hollow beams, respectively. Lastly, the comparison between the results obtained from numerical model and experimental results showed good agreement and thus the numerical model can be used to extend the experimental work for investigating different reinforcing schemes.

Experimental Research on Fatigue Behavior of Existing Reinforced Concrete Beams

In order to obtain the law of the fatigue damage development of reinforced concrete hollow beams that has been in service for 24 years, its solid hollow beams were removed and transported to the laboratory for loading test. Two beams were selected for static loading to obtain the ultimate flexural bearing capacity, and three beams were, respectively, subjected to constant-amplitude fatigue loading with different load amplitudes. The static and dynamic behaviors of the beams were monitored in the fatigue test. The fatigue failure of the beams showed that the outermost rebar at the butt weld fractured at first, and the crack width at the fracture position of the steel bar was about 0.3 mm, which was largest in all cracks. After a rebar was broken, midspan deflection and flexibility increased by approximately 20% and 10%, respectively, relative to the initial state. The damage developed rapidly in the following range: (1) the first 10,000 fatigue cycles; (2) after fatigue fracture of the rebar; and in the intermediate stage of fatigue test, the damage development was relatively stable. As the loading amplitude increased, the stiffness degradation and the cumulative damage that occured under the same loading cycle were more significant.

Experimental research on torsional strength of synthetic/steel fiber-reinforced hollow concrete beam

Past research has used synthetic fiber (SY.F) and steel fiber (ST.F) for decades to advance concrete mechanical characteristics, including shear, tensile, and flexural strengths. Nevertheless, there is limited information concerning the torsional concrete reinforced with SY.F and ST.F performance. This research aims to explore the torsional performance of hollow reinforcement concrete beams reinforced with various fiber types. The fiber content of 1% with three different lengths of SY.F, 19, 38, and 57 mm, along with 13 mm of ST.F, was used. Two specimens were cast with normal concrete without using fibers as control beams and four hollow beams with ST.F and SY.F. To use a pure torsional load on the tested samples, an innovative test method was employed. The twisting angle of tested beams was calculated at each interval of the load as well as the first crack load and failure load. Outcomes illustrated that the utilizing of SY.F and ST.F in the reinforced concrete beams (RCB) enhanced the overall performance under torsional load compared to the control beam behaviors. This enhancement in the performance was relative to the fiber type and length. For the first cracking load, the tested beams reinforced with the ST.F and SY.F of 19 and 37 mm lengths showed approximately the same value. Also, the beam reinforced with the SY.F length of 55 mm exhibited the highest first cracking load value, among other tested beams. As the fiber length increases of SY.F, the ultimate load capacity was raised by 4.7, 9.4, and 21.9% for beams cast with 19, 37, and 55 mm fiber length, respectively. For the ST.F reinforcement concrete beam, the ultimate load capacity was raised by 5.5%. Therefore, due to the significant impact of SY.F on the torsional performance, it is recommended using SY.F with normal concrete.

The Development of Finite Element Model to Investigate the Structural Performance of Reinforced Concrete Hollow Beams

The self-weight of a reinforced concrete beam contributes to the permanent loads of a structure. This can be reduced by creating a longitudinal void along the beam so that it will not affect the performance of the beam. In addition, this process can reduce the amount of building cost. Therefore, a finite element model was developed in this study with the aid of a computer program, Ansys, to investigate the behavior of the hollow beam. The model was tested for reliability by comparing the predicted results with those obtained from the experiment in terms of the load-displacement responses, mechanical properties, and parametric responses. The result showed that the reliability of the model was questionable. The main cause of the non-reliability was the inaccurate prediction of the beam deflection by the model. The poor prediction of beam deflection led to significant variations of relevant mechanical properties including stiffness, deflection, and ductility. For beam deflection, only 1/3 of the specimens were correctly predicted with a reliability of 36% while the strength properties were discovered to have higher values as observed in the yield and the ultimate strengths with 73% and 64% respectively. However, both the model and experimental results showed the hollow beam was relatively effective when the diameter of the longitudinal void was 1/3 times the beam width and placed at the neutral axis. For the evaluation to improve the reliability, some revision including the properties of the materials, boundary conditions of the beam support, bonding conditions between different materials, and meshing shape and size suppose to be applied to the model.

Material nonlinear finite element analysis of hybrid hollow concrete beams encasing steel sections

Steel-concrete composite precast frames reduce construction times with improved productivity and quality compared to conventional frames, and they can be assembled as rapidly as steel frames. However, composite frames can be heavy, complicating the overall erection progress. In this study, hollow composite precast beams, which weigh about 15% less than steel-concrete composite frames, preserve the merits of solid concrete beams, including reduced floor depth, and eliminate the fireproofing necessary for all-steel sections. A numerical investigation of the flexural strength of hollow concrete beams encasing steel sections was conducted using nonlinear finite element analysis (FEA) considering concrete damaged plasticity (CDP). Modeling showed no significant differences in flexural capacity between hollow and solid composite concrete beams. The numerical models with FEA parameters of dilation angle, eccentricity, fb0/fc0, Kc, and viscosity were calibrated for hollow composite beams using test data. The flexural strength of composite beams was evaluated based on embedded and tie models representing interfaces between the concrete and steel sections and concrete and rebar, respectively. Various numerical parameters, including rate of strain increase, were analyzed to investigate the structural behavior and degradation trends of hollow concrete beams encasing wide-flange steel sections.

Experimental investigation for structural behaviour of self-compacting reinforced concrete hollow beams with in-place circular openings strengthened with CFRP laminates

This study aims to experimentally examine the structural behavior of self-compacting concrete hollow beams containing in-place circular openings in various positions. The studied parameters were the number and positions of openings that are strengthened or not strengthened by CFRP with multiple schemes. For this, seven reinforced self-compacting concrete hollow beams of identical properties were tested under two concentrated and symmetrical loading. The experimental work included two groups of beams in addition to one control beam (beam without opening). The first group comprised three beams with an opening (s) in the front and rear of the web, while the second group contained three beams with an opening (s) in an identical position of the first group, strengthened by CFRP laminates. Results revealed that all reinforced concrete specimens with openings suffered from higher deflection owing to the reduction in their stiffness. Moreover, decreases in the ultimate failure loads were noticed for the first group ranged from 9.5% to 16%. In contrast, the reduction ratios for the second group of beams were with lower ranges. Regarding the first group of beams, the values of the ductility indices were less than two when compared with the control beam. On the other hand, higher values of the ductility indices were recorded for the beams in the second group compared with the unstrengthened beams in the first group.

Experimental Study on the Torsional Behaviour of Prestressed HSC Hollow Beams

This article describes an experimental program developed to study the influence of longitudinal prestress on the behaviour of high-strength concrete hollow beams under pure torsion. The pre-cracking, the post-cracking and the ultimate behaviour are analysed. Three tests were carried out on large hollow high-strength concrete beams with similar concrete strength. The variable studied was the level of longitudinal uniform prestress. Some important conclusions on different aspects of the beams’ behaviour are presented. These conclusions, considered important for the design of box bridges, include the influence of the level of prestress in the cracking and ultimate behaviour.

Experimental investigation of the structural behaviours of self-compacted reinforced concrete hollow beams with in-place circular openings

This paper aimed to experimentally investigate the structural conduct of self-compacted concrete hollow beams with various in-place openings. For this purpose, ten reinforced concrete hollow beams were tested under two concentrated and symmetrical loadings. The primary parameter in this study was the location of the openings, and specimens were divided into two groups in addition to the control beam: group one included six beams with openings in front or front and rear of the web, while the second group contained three beams with an opening in the bottom flange of the beam. The results showed that all reinforced concrete specimens suffered from higher deflection and stiffness reductions. The load-carrying capacity was decreased in ranges between 5.2% and 16 % for group one and 5.5 % to 9 % for group two compared to the control beam. A reduction was also observed in the ductility index values, ranging from 2.8 to 1.5 compared to the control beam.

Experimental Study on Flexural Behaviour of Reinforced Foamed Concrete Square Hollow Beam

Nowadays construction industry continuously looking for new, better and efficient construction material and method due to environmental impact. This research reported the effect of reinforced foamed concrete square hollow beam in order to reduce the effect of the application of concrete materials. Foamed concrete with density of 1600kg/m³ is now widely used as a structural component like slab and wall due to it lighter than the normal concrete. Meantime, it helps in saving cost and reduce the use of formwork. The hollow section also can reduce the dead loads which contribute to seismic effect in high rise buildings. In addition, the Processed Spent Bleaching Earth (PSBE) is an industry waste which possess a good pozzolanic reaction is used as partial cement replacement in order to make it more environmentally friendly. The experimental program consists of casting and testing of foamed concrete beams of size 150 x 200 x 1500 mm with and without square hollow section. To study the flexural behaviour, all beams are tested after 28 days of curing subjected to four-points bending test in order to analyse the effect of the reinforcement of hollow section on the strength, deflection and mode of failure of foamed concrete beam. The performance of reinforced foamed concrete hollow square beam (RHB) under flexural shows better when compared with conventional solid beam (CSB) and hollow square beam without reinforcement (HB). The RHB exhibited greater strength with lesser deflection and cracking.

Fatigue Characteristics of Prestressed Concrete Beam under Freezing and Thawing Cycles

In order to reveal the influence of freezing and thawing on fatigue properties of the prestressed concrete beam, a kind of novel freeze‐thaw test method for large concrete structure components was proposed, and the freeze‐thaw experiments and fatigue failure test of prestressed concrete hollow beams were performed in this paper. Firstly, the compressive strength and dynamic elastic modulus of standard specimens subjected to different numbers of freeze‐thaw cycles (0, 50, 75, and 100) were determined. Then, the static and dynamic experiments were performed for prestressed concrete beams under different freeze‐thaw cycles. Depending on the static failure test results, the fatigue load for the prestressed concrete beam model was carried out, the fatigue tests for prestressed concrete beam under freezing and thawing cycles were done, and the influence of fatigue loading times on dynamic and static characteristics of prestressed concrete beam was also studied. Finally, the relation between fatigue characteristics and numbers of freeze‐thaw cycles was established, and the fatigue life prediction formulas of prestressed concrete beams under freeze‐thaw cycles were developed. The research shows that the freezing and thawing cycles had obvious influence on fatigue life, and the freezing and thawing cycles should be taken into account for life prediction and quality evaluation of prestressed concrete beams.

Flexural response of hollow high strength concrete beams considering different size reductions

In this work, 14 reinforced concrete solid and hollow beams were tested under four-point bending test to evaluate the flexural behavior of hollow concrete beams. The experimental program focused on two main variables which are the size reduction percentage and the inclusion of steel fiber. In addition, the longitudinal reinforcement ratio and the presence of lateral stirrups were also within the investigated parameters. Four solid beams in addition to 10 hollow beams with central square holes with side lengths of 60, 80, and 100 mm were fabricated to evaluate the test parameters. These beams were either reinforced with 1% steel fiber or contain no fiber. The flexural performance of the beams was evaluated using the load–deflection behavior, flexural ductility, stiffness and toughness. In addition to the experimental work, analytical formulas were introduced to evaluate the cracking and peak loads of the hollow beams. The test results showed that ductility of hollow beams with size reductions of 16% and 28.4% was higher than that of the reference solid beam, while the ductility of the hollow beam with 44.4% size reduction was quite comparable to that of the solid beam. Moreover, the toughness values of the hollow beams were higher by 19 to 37% than that of the reference solid beam. Based on the obtained results, it can be concluded that hollow reinforced concrete beams with 1.0% steel fiber and with size reduction up to 44.4% can replace solid beams without suffering significant reductions in strength, ductility and toughness.

Experimental investigation on flexural behaviour of RC hollow beams

Abstract This investigation examines the Flexural behaviour of reinforced concrete hollow beams under a gradually applied two-point load. The deflection at the ultimate stage is experimentally examined and compared with RC hollow beams. And we are concentrating material optimization by introduction of hollow portion using PVC pipe and GI pipe at tension zone in RC control beams. This experimental investigation includes casting and testing of five reinforced concrete beams having a size of 1200 × 150 × 200 mm with and without hollow portion at tension zone. The behaviour of the beam is with respect to first crack load, ultimate loads, load-deflection behaviour and crack pattern.

Strength of Reinforced Reactive Powder Concrete Hollow Beams

The main objective of this research is to investigate the structural behavior and strength of reinforced reactive powder concrete beams with a hollow section subjected under two point concentrated loading. The experimental work consist of ten beams with dimensions (150mm width×200mm height×1000 mm length), eight of them are hollow beams and two solid beams were cast and tested up to failure. The major parameters adopted in the current research includes the hollowness ratio (10% and15%), hollow location (at top or at bottom), and hollow shape (circle or square). The amount of longitudinal and transverse reinforcement, concrete strength and the other parameters were kept constant for all the specimens. The comparisons between all specimens (hollow and solid) are based on the load carrying capacity, deflection, crack pattern and mode of failures. Results showed that the strength capacity of hollow beam when the hollow lies in the bottom is much higher than for top hollow, and the square hollow will lead to more decrease in the beam strength compared with the circular hollow and this is more evident when the hollowness ratio increases from (10% to 15%).

Experimental Investigation on the Effect of Steel Fibers on the Flexural Behavior and Ductility of High‐Strength Concrete Hollow Beams

In this study, an experimental work was directed toward comparing the flexural behavior of solid and hollow steel fiber‐reinforced concrete beams. For this purpose, eight square cross‐sectional beam specimens, four solid and four hollow, were prepared. One concrete mixture with four different steel fiber contents of 0, 0.5, 1.0, and 1.5% were used. The side length of the central square hole was 80 mm, whereas the cross‐sectional side length was 150 mm. All beams were tested under four‐point monotonic loading until failure. In addition to the solid and hollow beams, cylinders were cast to evaluate the compressive strength, splitting tensile strength, and modulus of elasticity, whereas prisms were used to conduct the fracture test. The test results showed that all fibrous beams failed in flexure, whereas those without fiber exhibited flexural‐shear failure. In general, the flexural behavior of fibrous‐beams was superior to that of beams without fiber. The hollow beams with fiber contents of 0, 0.5, and 1.0% were observed to withstand lower loads at cracking, yielding, and peak stages compared with their corresponding solid beams; this was not the case for the 1.5% fiber hollow beam, which exhibited a higher peak load than its corresponding solid beam. Although all eight beams exhibited ductility indices higher than 3.7, hollow beams exhibited better ductility than solid beams, showing higher ductility index values.

Experimental Study on Flexural Behavior of Reinforced Solid and Hollow Concrete Beams

The incessant uptick in the prices of steel reinforcement and cement steer to the dredging up ways to minimize the weight of concrete. This directly reflects on the total outlay for the construction project. In addition to this, anthropogenic CO2 generatedduring cement and steel production leads to disturbance to landscape, dust and noise and other significant environmental problems. In reinforced concrete beams, strength of concrete lying in and near neutral axis is not fully utilized and hence thisconcrete can be supplanted with any light weight material. The idea of providing hollow section to the beam by incorporatingPVC pipe in order to reduce the weight of the structure is one of the solutions for light weight beam structure. To check thesuitability of such beam structures, an experimental testing was conducted to identify the flexural strength, deflection profile andcrack pattern of the solid and hollow beam samples. For this, 6 beams each with dimension (200mm*300*2300) mm were takenwith 2 beam samples being solid whereas remaining beams with longitudinal circular hollow section below neutral axis at calculated depth.M30 Grade of concrete was used. The beam samples were finally tested under gradually increasing two pointsloading and Linear Variable Displacement Transducer (LVDT) was used to measure the deflection produced.

Effect of an Opening on Reinforced Concrete Hollow Beam Web Under Torsional, Flexural, and Cyclic Loadings

HOLLOW SECTIONS HAVE BEEN INCREASINGLY APPLIED IN THE CONSTRUCTION OF BUILDINGS, BRIDGES, OFFSHORE STRUCTURES, AND TOWERS FOR PASSING ELECTRICAL AND MECHANICAL PIPES OR OTHER UTILITIES. ONE OF THE WEAKNESSES OF HOLLOW SECTIONS IS UNDER TORSION FORCE CAUSED BY EXTERNAL FORCE WHICH IS RARELY INVESTIGATED. IN PARTICULAR, THE BEHAVIOR OF HOLLOW SECTIONS WITH HIGH-STRENGTH CONCRETE (HSC) AND ULTRA-HIGH PERFORMANCE CONCRETE (UHPC) REMAINS POORLY STUDIED. THIS STUDY AIMS TO EXAMINE THE BEHAVIOR OF A REINFORCED CONCRETE HOLLOW BEAM WITH OPENING AND COMPARE IT WITH A HOLLOW BEAM WITHOUT OPENING. THE HOLLOW BEAM WITH AN OPENING IS MODELED USING THE FINITE ELEMENT METHOD AND ANALYZED UNDER TORSION, FLEXURAL, AND CYCLIC LOADING FOR TWO DIFFERENT HSC AND UHPC MATERIALS. THE EFFECT OF THE OPENING SECTION SIZE ON THE BEHAVIOR OF HOLLOW BEAM IS ALSO EVALUATED. RESULTS SHOWED THAT THE OPENINGS CREATED IN THE WEB OF HOLLOW BEAMS LED TO A DECREASE IN THE CAPACITY OF THE BEAMS ALTHOUGH THE HOLLOW BEAM WITH SMALL OPENING CAN CARRY ALMOST THE SAME LOAD AS THAT OF HOLLOW BEAM WITHOUT AN OPENING. THE RESULT ALSO INDICATED THAT THE CAPACITY OF UHPC BEAMS FOR TWISTING IS TWICE THAT OF HSC BEAMS.

Effect of Transverse Internal Ribs on Shear Strength Evaluation of Hollow RC Beams

This paper is devoted to investigate experimentally and theoretically the structural behavior of reinforced concrete hollow beams which have internal transverse ribs under effect of shear. The number of the internal ribs is the major variable adopted in this research, while, the other variables are kept constant for all tested specimens. The experimental part includes poured and test of four (200x300x1200mm) beam specimens, three of these specimens were hollow with different locations of internal ribs and one of them was solid. The experimental results indicated that the shear strength are increased (33%) to (60%) for beams containing internal ribs in comparison with reference beam. Also, the change of beam state from hollow section to solid section led to increase the capacity for about (100%). In order to study more thoroughly the performance of tested beams, a nonlinear analysis using ANSYS-11 finite element program is used. The analytical results indicated that the load-deflection response, ultimate loads, and crack pattern are in good agreement with the experimental results.
 

Ultimate Strength OFR.C Hollow Beams having Hole above and below the Neutral Axis

To study the behavior and ultimate strength of reinforced concrete hollow beams, seven reinforced concrete beams were cast and tested by applying gradually increased two point loads. Out of these seven beams one beam was solid beamtested for the purpose of comparison. Six beams were hollow beams which had a longitudinal circular hole either above or below the neutral axis. It was found that, though all the beams had the same type of reinforcements, the strength and behavior of the beams were different in relation to the beam deflection, crack pattern, crack width, ultimate load carrying capacity and failure mode of the beam. The size of the hole and position of the hole were varied in these beams. It was found that the size of hole is the most important parameter that affects the beam behavior. Finally, theoretical analysis has been made for all the tested R.C. hollow beams to estimate the ultimate load carrying capacity of such beams.

Analisis Lentur Balok Penampang T Berlubang Memanjang Menggunakan Metode Elemen Hingga Non-linier

Numerical analysis is a time-, cost- and equipment-effective method to study the behavior of structures. ATENA is one of the available software-based on finite element method. Hollow cross section is one way to reduce the weight of concrete beam. The effect of holes on beam may reduce the bending resistance. The hollow beam was numerically modeled which and subsequently analyzed using the ATENA v.2.10 software. Material parameters being used as input data was obtained from laboratory tests, assuming that steel-concrete bond was prefect, and and the steel reinforcement was modeled as discrete. The results of numerical analysis of the ATENA were then compared with experimental test results on the flexural behavior and serviceability limit state of reinforced concrete hollow beams lengthwise (Amir, 2010), then study the variation of quality parameters of concrete and the hole size variations. The results shows that the collapse load of hollow beam reached only 96.71% and deflection reached 135.96%. Stiffness of hollow concrete beam was also showed a higher stiffness of the experiment. The crack pattern is flexural fracture and very much agree with that of the experiments. Test parameters of concrete quality variations as well as the hole size variation showed higher concrete quality/size of the hole will reduce the ductility of beam.