Study On The Punching Shear Behavior Of FRP Reinforced Concrete Slabs Subjected To Concentric Loading

In the last decades,the durability of reinforced concrete structures has gained much attention in the academic and engineering community.Steel corrosion is the main issue of the durability of RC structures.To resolve this problem,a new kind of bars,fiber reinforced polymer bar,is introduced by engineers to serve as an alternative to steel bars.In this thesis,the punching shear behavior of FRP bar reinforced concrete slabs is investigated.Firstly,the Moment-curvature relationship of FRP flexural members,which considering the tension-stiffening of concrete,is obtained by the finite strip method.Based on this method,a simplified trilinear model for the Momentcurvature relationship is established.Then,a punching shear model for FRP concrete slabs is proposed based on the critical shear crack theory(CSCT).After verification of the proposed model,a parametric analysis on the punching shear strength of FRP concrete slabs is conducted.The following conclusions can be drawn from this investigation:1.study on the bending strength and corresponding failure modes.In this study,the moment-curvature relation of FRP flexural members is obtained by the finite strip method.The tension stiffening of concrete is considered in the modeling.The accuracy of the proposed method is verified by comparing it with existing experiments.The effected of concrete strength and reinforcement ratio on the bending behavior of FRP flexural members are discussed in detail.Based on the numerical results,a simplified trilinear model is proposed.2.study on punching shear strength of FRP reinforced concrete slabs.In this study,the failure modes of FRP reinforced concrete slabs under concentric loads is analyzed and a simplifying assumption for the relationship of the radius and curvature of concrete slabs are proposed.Square slabs with square studs are converted to circular plates with circular studs through virtual work principle and yield line theory.With the help of the moment-curvature relationship of FRP flexural members,the prediction model for the punching strength and critical angle is proposed based on the equilibrium equation of FRP bar concrete slabs.The proposed model is verified by the existing experimental data.3.parameter analysis for the strength and durability of FRP bar concrete slabs.In this study,the effects of concrete strength,column stud size,reinforcement ratio,and the thickness of slab on the punching shear strength and ductility are investigated.Results indicate that with the increase of concrete strength and the column stud size,the nominal stress of concrete slab decreases while the ductility of concrete slabs increases.With the increasing of reinforcement ratio and thickness of slabs,the nominal stress of concrete slabs increases and whereas the ductility decreases.4.assessment of existing models and code formulas for FRP concrete slabs.In this study,the existing experimental data for FRP concrete slabs is collected.A comparison between the calculated values by existing and experimental ones is conducted.Results indicate that the prediction by the ACI 440.1R-06 formula is the most conservative one,while other models are with similar accuracy.The prediction by the proposed model performs the best accuracy and lest deviation.