Static Analysis of Reinforced Concrete Pipe Strengthened with GFRP Laminates
This paper presents a study of reinforced concrete pipe with the application of continuous glass fiber reinforced polymer sheet (GFRP). The pipe material is considered to be composed of reinforced concrete and the pipe is strengthen by using glass fiber reinforced polymer sheet. The reinforced concrete pipe is analyzed with different layers of externally applied GFRP sheet. Analysis is carried out in commercially available ANSYS software. A finite element model is developed for the pipe wherein the material properties as mentioned are used. The solid 186 layered structural solid element has been used for discretization of the model. Two sets of GFRP sheets (4 layer & 8 Layer) were considered for the analysis. Results obtained were compared with the controlled pipe made up of reinforced concrete. Results are presented for simply supported boundary conditions for the pipe. The deformation and stress distribution across the pipe has also been analyzed
Size Effect of Axial Compressive Strength of CFRP Confined Concrete Cylinders
The main objective of this investigation is to study size effect on compressive strength of CFRP confined concrete cylinders subjected to axial compressive loading. In total 24 concrete cylinders with different sizes were tested, small specimens with a diameter of 100 mm and a height of 200 mm, medium specimens with a diameter of 200 mm and a height of 400 mm, and big specimens with a diameter of 300 mm and a height of 600 mm. The lateral confining pressure of each specimen is the same and from that hypothesis the small specimens were confined with one layer of CFRP, medium and big specimens were performed by two and three layers of CFRP respectively. Test results indicate a significant enhancement in compressive strength for all confined specimens, and moreover, the compressive strengths of small and medium specimens are almost the same while a bit lower for big specimens. These results permit to conclude that there is no size effect on compressive strength of confined specimens regardless of cylinder dimension.
RETROFITTING RC CIRCULAR COLUMNS USING CFRP SHEETS AS CONFINEMENT
Reinforced concrete is used in common infrastructures. In the design process, deformed steel bars are used to compliment with the properties of concrete. These steel bars are used as lateral and longitudinal reinforcement to prevent shear and tensile failure. But due to overloading and updates on seismic codes in columns or bridge piers, retrofitting becomes dominant in order to improve the compressive strength and ductility of reinforced concrete columns. One way of retrofitting existing column structure is the application of Carbon Fiber-Reinforced Polymer (CFRP) Sheets to be wrapped around the circumference of circular column. The retrofitting method will result to an increase in compressive strength and ductility. This strength and ductility enhancement is done by the confinement effect of the CFRP sheets and the contribution of steel ties present on the existing column in resisting lateral expansion. From references, the interrelationships of the confinement effect done by the newly applied CFRP sheets and existing steel ties present in concrete columns are complex. Further experimental data should be made in order to study the effects of both materials when used as confinement in retrofitting structures. The study dealt with experiments on retrofitting designed concrete cylinders of size 180mm diameter x500mm height by wrapping around CFRP of 75mm-strips, one-ply, two-ply with varying amount of steel bars present. A total of 94 concrete cylinders were made and retrofitted from materials available in local conditions. With these data, analysis on the strength enhancement and common modes of failure will be investigated. The goal of the research is in conjunction with the current problems on strengthening existing structures on how structural designers and constructors efficiently and effectively use CFRP.