Beam

Finite Element Modelling and analysis of rectangular concrete beams reinforced internally with Hybrid Fibre Reinforced Polymer (HFRP) reinforcements under pure torsion is carried out in this study. Different parameters like grade of concrete, beam longitudinal reinforcement ratio and transverse stirrups spicing are considered. The basic strength properties of concrete, steel and HFRP reinforcements are determined experimentally. Experimental torque verses twist relationship is established for various values of torque and twist using elastic, plastic theories of torsion. Finally the ultimate torque is determined using experimentaly for different parameters considered in this study. Based on this study, a good agreement is made between finite element analysis and the experimental behaviour.

It was purposed to understand the dynamic response of beam which are subjected to moving point loads. The finite element method and numerical time integration method (Newmark method) are employed in the vibration analysis. The effect of the speed of the moving load on the dynamic magnification factor which is defined as the ratio of the maximum dynamic displacement at the corresponding node in the time history to the static displacement when the load is at the mid – point of the structure is investigated. The effect of the spring stiffness attached to the frame at the conjunction points of beam and columns are also evaluated. Computer codes written in Matlab are developed to calculate the dynamic responses. Dynamic responses of the engineering structures and critical load velocities can be found with high accuracy by using the finite element method

This paper presents the test results of an experimental study that investigates the
behavior of reinforced concrete (RC) beams strengthened or repaired in flexure by
adding thin lower concrete layer reinforced mainly by Fiber Reinforced polymers
(FRP) bars. A total of seventeen RC beams were constructed and tested under fourpoint
loading. One of these beams was un-strengthened and considered as a reference
beam. Eight beams were strengthened in flexure, and the other eight beams were
loading up to 70% from the ultimate load of reference beam and then repaired using
the same methods provided to the strengthened beams. Five test parameters were
considered in this research; status of beam (strengthened or repaired), type of
reinforcement used (glass FPR, carbon FPR or steel), amount of reinforcing FRP
bars used (2 bars or 4 bars), type of the strengthening technique (reinforcing bars
installed in the adding concrete layer or FRP sheets externally bonded to the soffit of
the adding concrete layer) and type of connection between the adding lower concrete
layer and the original beam (installing dowels bars or not). The test results included
ultimate load, cracking load, the corresponding deflection, the failure modes and
calculated relative ductility and flexure stiffness at un-cracked and cracked stages.
The percentage enhancement in the flexural capacity of the tested beams ranged from
32% to 106% compared with the reference beam. Using FRP bars showed greater
ultimate load and more ductile behavior than using externally FRP sheets. Many
failure modes were observed during testing; FRP rupture, FRP debonding or partial
debonding between the adding concrete layer and the original beam depending on the
method of strengthening or repairing had been applied to the tested beams. The
experimental ultimate strength for all strengthened and repaired beams were
compared with the design provisions provided by ACI 440-2R-08, which showed
reasonable and lightly conservative predictions for all strengthened and repaired
beams

Reinforced concrete jacketing is one of the widely used repairing techniques for beams and columns. The aim of this research is to evaluate the efficiency of using concrete jackets using different reinforcements and thicknesses. The behavior of repaired reinforced concrete defected beams is investigated under flexural effect. The tested beams are preloaded up to 70 and 90% of their ultimate capacity then, repaired using concrete jackets. The main variables are thickness of concrete jacket (3, 5 cm), diameter of reinforcing steel bars (8, 10 mm) and concrete jacket type. The experimental results showed that, repairing using concrete jackets enhances the load capacity up to 378%. Increasing jacket thickness enhances the structural performance of the tested beams and in the same time increases its weight. It also increases the stiffness compared to the control beam and consequently the repaired concrete beams indicated a brittle manner compared to the ductile failure of the control beams.

This paper aims at studying the effect of earthquake loading on the constructional design of a 20-storey reinforced concrete residential building from economical point of view. This type of loading should be taken into considerations now in Iraq especially after the earthquake of 7.3 magnitude that occurred in November 2017 near the city of Halabja by about 31 kilometers. The same reinforced concrete multistory building was designed twice; once with traditional gravity dead and live loading and the second with adding earthquake loading in order to discuss the difference from structural and economical points of view. A commercial package ETABS2018 was used to analyze this 60-meter-high building. The building was analyzed according to the American code ASCE7-10, while it was designed according to ACI 318-14. A huge increase in the steel reinforcement amounts in columns, beams, slabs and shear walls were recorded due to taking the seismic load into considerations. More specifically, the reinforcing steel amounts increased by about 327%, 165%, 40% and 91.3% for columns, beams, slabs and shear walls, respectively. Therefore, cost was raised by about 328%, 165%, 40% and 91.3% for columns, beams, slabs and shear walls, respectively. It is worth to mention here that the maximum increase in main reinforcement of beams was observed on the storey 10. Whereas, in slabs, the maximum increase that was recorded in main steel reinforcement was happened from the storey 8 to the building top. In columns, the main reinforcement increase was seen on the 9 th , 10 th and 11 th storeys. Finally, in shear walls, the main reinforcement increase was seen in the 1 st , 2 nd and 3 rd storey due to effect lateral shear forces.

Reinforced Concrete (RC) jackets are utilised in order to enhance the performance of concrete beam in terms of strength and durability. In the RC structure, the beam is subjected to an uniform and continuous vertical loading with an increase in number of storey, which may lead to partial or total damage in its structure. There are some experimental trials to enhance the beam through RC jackets, but the efficiency or restoration of the retrofitted method still needs to be enhanced. Reconstruction costs are considerably greater than retrofitting costs. In order to overcome the total failure, prompt attention is required. This paper reviews on a variety of refurbishment techniques that demonstrate an improvement in overall load caryying capacity.

The dynamic response of a simply supported beam resting on elastic foundation subjected to a moving uniformly distributed load is investigated in this study. The Winkler foundation model was considered and the analytical solution of the fourth order partial differential equation was obtained using the Fourier Sine Transformation Method. Numerical results were further obtained and presented in plotted curves and tabular forms. The results showed that increase in the dynamic load length, moving at constant speed leads to higher deflections and bending moments of the beam, and decreases with increasing foundation modulus . The results thus underscore the relevance of the method in the dynamic analysis of beams on elastic foundation.

If external loads act far away from the vertical plane of bending, the beam is subjected to twisting about its longitudinal axis, known as torsion, in addition to the shearing force and bending moment. Shear stresses due to torsion create diagonal tension stresses that produce diagonal cracking. If the member is not adequately reinforced for torsion, a sudden brittle failure can occur. Since shear and moment usually develop simultaneously with torsion, a reasonable design should logically account for the interaction of these forces. However, variable cracking, the inelastic behavior of concrete, and the intricate state of stress created by the interaction of shear, moment, and torsion make an exact analysis unfeasible. The current torsion design approach assumes no interaction between flexure, shear and torsion. In the present work performance of reinforced concrete beams with and without steel fibres were studied subjected to pure torsion. The experimental program consists of casting 4 reinforced concrete beams of size 150mm X150 mm and length 2m. One of them was cast without fibres to make a comparative study with the remaining 3 beams; one beam was cast with 0.5% fibre by weight, one beam 1.0% fibre by weight in the rest one beam 1.5% fibre by weight added. The longitudinal reinforcement, spacing of shear stirrups was kept constant. The results concluded that the cracking torsional strength and ultimate torsional strength goes on increasing as the percentage of Steel fiber goes on increasing.

Abstract:-The paper presents a new method to detect damages in beams and assess their location and severity by means of vibration measurements. Typically, changes in natural frequency of beams are relatively small, even for an important reduction of their cross-section; this is one of the major difficulties in locating damages in this way. Our research takes into account the particular manner in which the natural frequencies of the first ten bending modes change due to the occurrence of damage. It is a pattern recognition ...

Reinforced concrete (RC) beams with light transverse reinforcement are vulnerable to shear failure during seismic response. In order to prevent brittle shear failures at beam plastic hinge regions of earthquake-resistant structures, the Turkish Earthquake Code and ACI318 require the use of sufficient transverse reinforcement to resist the total expected shear demand. These codes tend to be excessively conservative and, in some cases, the contribution of the concrete to the shear strength is neglected. The aim of this study is to investigate the contribution of concrete to shear strength of RC beams failing in shear experimentally. The beams were tested under monotonically increasing reversed cyclic loading to determine the concrete contribution to shear strength. It is observed that the concrete contribution to the shear strength at ultimate state ranges from 18% to 69% of the ultimate strength.

This experimental work aims at presenting load-deflection expressions for the concrete beams that reinforced with three different reinforcement ratios of ACI 318-14, which are minimum, maximum and the average of them. Three groups of beams were cast, each group contained three beam specimens. Three types of loading are used, 1-concentrated force, 2-concentrated forces and partial uniformly distributed load. It is also seen that, when reinforcing ratio increases from minimum to maximum, in case of 1-concentrated force, ultimate capacity increases by about 280% and deflection decreases by about 33%, respectively. Whereas, in case of 2-concentrated forces, ultimate capacity increases by about 258% and deflection decreases by about 50%, respectively. Finally, in case of uniformly distributed load, ultimate capacity increases by about 289% and deflection decreases by about 28%, respectively.

This study is devoted to the investigation of the vibration of a cracked cantilever beam under moving mass load. The present formulation contains inertial, centripetal and Coriolis forces that depend on mass and the velocity of the moving load. The existence of crack induces a local flexibility which is a function of the crack depth, thereby changing its vibration behavior and the eigen-values of the system. The response of the system is obtained in terms of Duhamel integral. The differential equation which involves complicated terms on the right side is solved via an iterative procedure. It has been shown that the centripetal and Coriolis forces make an effect to decrease the deformations on the beam since the deformed beam remains concave during the passage of the moving load. It has also been detected that the previous solutions for the case of moving constant force had several mistakes. The results are exemplified for various values of the variables.Straipsnyje nagrinėjami įtrūkusios gembinės sijos, kurią veikia judančios masės apkrova, virpesiai. Šiuo atveju veikia inercinės, įcentrinės ir Koriolio jėgos, kurios priklauso nuo judančios apkrovos masės ir judėjimo greičio. Įtrūkis sukelia vietinį sijos lankstumą, kuris priklauso nuo įtrūkio gylio, tokiu būdu keičia virpesių pobūdį ir sistemos reikšmes. Sistemos atsakas nustatomas taikant Duhamelo integralą. Diferencialinė lygtis, kurios dešinėje pusėje yra sudėtingos sąlygos, sprendžiama taikant iteracijas. Nustatyta, kad įcentrinė ir Koriolio jėgos sumažina sijos deformacijas, nes deformuota sija išlieka išsigaubusi, kai per ją juda masės apkrova. Taip pat nustatyta, kad ankstesniuose sprendimuose judančios nekintamos masės apkrovų atvejais buvo keletas klaidų. Kaip pavyzdžiai pateikiami rezultatai esant skirtingoms kintamųjų reikšmėms.