| The application of Fiber-Reinforced Polymer(FRP)in the civil engineering industry is due to their superior advantages such as high tensile strength-to-weight ratio,corrosion resistance,ease of handling and construction,and the wide range of working temperatures.These FRP composites have a linear elastic stress-strain response with brittle rupture failure at a small rupture stain(typically around or less than 1.5% for CFRP,around or less than 2.5%for GFRP around or less than 3% for AFRP).For years Engineers and researchers have been studying ways to retrofit or strengthen existing deficient RC columns to meet new code requirements,especially in earthquake-prone areas.This has often been achieved through the use of FRP jackets as an external means to strengthen the shear or flexural performance of existing RC columns.It has well been established that the compressive response of confined concrete greatly depends on the mechanical properties of the confining material.Generally,a confining material with a large hoop strain is generally beneficial as it leads to more ductile behavior and greater energy absorption with the same degree of strength enhancement.In addition,to the confining material(external/Internal Confinement),numerous other variables affect the behavior of confined concrete such as,unconfined concrete strength,type of concrete,and shape of cross-section among others.There has been numerous study on the stress-strain model proposed to predict the response of steel-confined concrete.Despite the advantages of steel,its high weight and difficulty in installation and proneness to corrosion if not properly protected,many other alternative materials with lightweight,time-efficient installation,and better installation,and better corrosion resistance have been introduced and successfully applied in the industry over the last three decades.This thesis is concerned with the the application and behavior of Steel-basalt fiber hybrid stirrups(SBFHS)and its behavior as internal confining material in small scale cylindrical concrete specimens as a potential innovative hybrid spiral reinforcement.A systematic study of the proposed stress-strain model were presented in this thesis.It is composed of 4 parts;(1)Firstly,the existing literature study on FRP and its various forms and mechanical properties was discussed.The various suitable fields or industry that the FRPs could be applied to was also mentioned.A brief peek in to the development of Hybrid Reinforcement over the years specifically in terms of Hybrid FRP sheets,Hybrid FRP bars and Steel-SFRP composite was also looked at.Existing steel confined concrete stress-strain models and FRP confined stress strain models was studied in how these models predict the compressive response behavior of concrete due to the confining material.In comparison to the constant confining pressure of steel after yielding,FRPs provide an increasing confining pressure which is directly associated with the dilation of concrete core untill failure;(2)Secondly,the experimental study on SBFHS confined concrete cylinders subjected to monotonic axial compression is discussed,particurlarly the test specimen details,tested parameters and the test setup and Instrumentation was outlined;(3)Thirdly,this thesis looked into the analysis of experimental results against the proposed Stress-Strain Model.Results from the experimental study showed that the confinement strength of concrete by SBFHS increased with the decrease in spacing of stirrups.The proposed model performed better in predicting the critical and ultimate stress-strain points of SBFHS when compared to other models;(4)The final part was the parametric study of the proposed model where certain discrepancies and adequacy about the model was revealed which need to be improved in future studies. |
PDF Full Text Request