MAT-722: EFFECT OF FIBER ORIENTATION ON THE BEHAVIOR OF CFRP CONFINED CONCRETE CYLINDERS

This paper presents the results of an ongoing experimental investigation examining the effect of fiber orientation and stacking sequence on the behavior of FRP-confined concrete. As part of the experimental study, 100 mm x 200 mm concrete cylinders were jacketed with carbon fiber reinforced polymer (CFRP) sheets and tested under pure axial compressive loading. The specimens were confined using various CFRP stacking sequences, with fibers oriented at 0⁰, 90⁰, and ±45⁰. Furthermore, within each stacking sequence, the numbers of layers was varied from 4 to 8 to examine the effect of number of plies on the behavior of the FRP-confined concrete cylinders. In addition, the research program included a companion set of CFRP coupons made from CFRP laminates having the same properties as the CFRP jackets used in the cylinder series. The preliminary results show that parameters such as fiber orientation, stacking sequence, and number of confinement layers have a direct impact on the strength, ductility and stress-strain behavior of CFRP confined concrete

Structural behaviour of steel fibre reinforced concrete members

A series of full-scale axial compression tests was conducted on RC and SFRC columns. The specimens, which were detailed with varying amounts of transverse reinforcement, were cast using a self-consolidating concrete (SCC) mix that contained various quantities of fibres. The results demonstrate that the addition of fibres leads to improvements in load carrying capacity and post-peak response. The results also show that the addition of steel fibres can partially substitute for the transverse reinforcement in RC columns, thereby improving constructability while achieving significant confinement. Analytical models for the prediction of the load-strain response of SFRC columns are presented and validated with the experimental results. The tensile behaviour of SFRC members reinforced with a single reinforcing bar was also studied. The results indicate that the addition of fibres leads to improvements in tension stiffening and crack control. A procedure for predicting the response of tension members, accounting for the presence of fibres, is presented. Experimental investigations were carried out on a series of RC and SFRC beams. The effects of steel fibres on shear capacity, failure mechanism and crack control are studied. The results show that the addition of steel fibres leads to improvements in load carrying capacity and can lead to a more ductile failure. A simple procedure that can be used to predict the ultimate shear capacity of SFRC beams is introduced and validated using results from other researchers.Une série d'essais a été réalisée sur des poteaux de taille réelle soumis à des charges axiales. Les échantillons, qui avaient des quantités variables d'armature transversale, ont été construits en utilisant un béton auto-plaçant qui contenait une quantité variable de fibres métalliques. Les résultants de cette étude expérimentale démontrent que la présence des fibres influence positivement la capacité portante des poteaux. De plus, les résultats montrent que l'utilisation d'un béton renforcé de fibres métalliques (BFM) peut s'avérer une solution appropriée pour assurer une ductilité adéquate aux poteaux. L'auteur propose des modèles analytiques pour prédire le comportement de poteaux chargés uniaxialement. Le comportement sous tension d'éléments en BFM armés d'une seule barre a été étudié. Les résultats montrent que la présence de fibres améliore la résistance en tension. Une procédure pour la prédiction de la réponse des éléments soumis sous tension, prenant en compte la présence de fibres métalliques, est présentée. Des recherches expérimentales furent entreprises afin d'étudier le comportement de poutres sans étriers. L'influence de la présence de fibres sur le développement de fissures ainsi que les mécanismes de ductilité et de rupture est discutée. Les résultats montrent que l'ajout de fibres améliore la capacité portante et la ductilité des poutres. Une procédure est suggérée afin de déterminer la capacité portante de poutres construits avec BFM

Behaviour of slender concrete shear walls with high-strength reinforcement under reversed cyclic loading.

Research on seismic behaviour of shear walls with high-strength steel is limited. A combined experimental and analytical investigation was conducted to assess seismic behaviour of flexure-dominant shear walls. A large-scale concrete shear wall with Grade 690 MPa (ASTM A1035) reinforcement and 84 MPa concrete was tested under simulated seismic loading. The wall was a -scale of a 6-storey shear wall, with 4.53 m height and 1.45 m length. It sustained a lateral drift of 1.8% prior to developing failure due to the rupturing of longitudinal reinforcement. This is 35% less than the drift capacity of a companion wall reinforced with 400 MPa reinforcement tested earlier. VecTor2 software was used to conduct an analytical parametric study to expand the experimental findings. The results indicate that the reinforcement grade has a significant impact on strength, ductility and hysteretic behaviour of shear walls.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Seismic performance of concrete walls reinforced by high-strength bars: cyclic loading test and numerical simulation

This study examines the influence of cross-section shape on the seismic behaviour of high-strength steel reinforced concrete shear walls (HSS-RC) designed with Grade HRB 600 MPa reinforcement. As part of the study, two flexure-dominant walls with rectangular and T-shaped cross-sections, are tested under reversed cyclic loading. Seismic performance is evaluated by studying the failure characteristics, hysteretic curves, energy dissipation, ductility and reinforcing bar strains in the two walls. As part of the numerical study, two-dimensional (2D) and three-dimensional (3D) finite element modelling (FEM) are used to predict the seismic response of the rectangular and T-shaped walls, respectively. The test results show that compared to the rectangular wall, the flange in the T-shaped HSS-RC wall increased strength, energy dissipation and stiffness, but decreased ductility. The analytical hysteretic curves calculated using 2D and 3D FEM analyses show good agreement with the experimental test results.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Blast Behavior of Columns Built with High-Strength Concrete and Grade 690 MPa High-Strength Reinforcement

As part of this study a series of columns built with high-strength concrete (HSC) and Grade 690 MPa high-strength reinforcement are tested under blast loads using a shock-tube. The performance of the columns is compared to a set of columns specimens built with Grade 400 MPa reinforcement. In addition to the effects of concrete and steel type, the effects of longitudinal steel ratio and seismic detailing are also investigated. The results show that concrete strength has limited effects on blast behavior. Conversely, use of high-strength bars significantly enhances column blast performance by reducing displacements and increasing blast resistance, with an ability to reduce reinforcement. The results further demonstrate that increasing the longitudinal steel ratio and seismic detailing improve the blast behavior of columns built with conventional and high-strength bars. As part of the analytical study the blast response of the columns is predicted using SDOF analysis and finite element modelling.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author