## 5 Discussion and Conclusions  
This study discussed the use of FRP for strengthening non-seismic RC interior beam-column joints (BCJs) in shear, which constitute the essential components of the present RC building. In addition, the efficiency of the FRP materials in strengthening non-seismic interior beam-column connections was greatly established. However, an accurate and straightforward equation is still required to estimate an increase in the shear strength of the deficient interior beam-column joints due to FRP strengthening. A literature review was carried out to identify significant parameters that affect the externally bound FRP system's mechanical behavior. The research focused directly or indirectly on the parameters that impact the mechanical characteristics of the externally bonded systems of FRP. In addition, the available analytical models were critically evaluated and discussed. The procedure outlined by [19; 20] for corner and external beam-column joints was followed. A reliable and straightforward analytical model was outlined in compliance with the available updated test data. The predicted results of the suggested model were compared and verified with the experimental test database. The model was based on the primary approach to principal tensile stress. The debonding phenomenon was considered in the expression for the effective FRP strain and was calibrated on experimental tests. An illustrative example of utilizing the suggested model for calculating the shear strength of the FRP-strengthened interior deficient BCJ is given in Appendix A. The use of the proposed equation to calculate the number of fibers required to fulfill the deficiency in shear strength of the beam-column joint due to the absence of seismic reinforcement is also explained. The suggested formulation is compatible with experimental results in terms of the mean effective stress. The derived equation permits the FRP strain limited to 0.4% to be exceeded, as usually anticipated in the guidelines of the existing building design. The suggested design method was calibrated by experimental test results of interior beam-column joints with geometric attributes and mechanical parameters characteristic of RC structures exposed to large earthquakes. It enables to determine the shear strength of the non-seismic interior beam-column joints reinforced with various types of fiber (CFRPs and GFRPs), various fiber reinforcement arrangements on the joint panel with a flexible amount of fiber, layer numbers, side numbers, the fiber inclination (or multiple inclined fibers), continuous strips and sheets, damaged and lightly repaired joints with FRP system, and the effect of the various types of anchorage systems to enhance the effectiveness of the fiber in strengthening. The following conclusions can be drawn:  
* The available experimental tests related to deficient interior RC beam-column joints were explored, out of which 17 specimens were applicable to be used. * The corner and exterior joints-oriented method outlined by [20], later refined by [19], was extended to formulate a simple analytical model for non-seismic RC interior beam-column joints. * A reliable equation for effective FRP strain was derived. The equation was calibrated and verified by using the available experimental test data. The FRP strain showed a maximum dependency on the joint parameters of which the equation was formed. The regression coefficient (R2) was 0.80, showing a better relationship between the considered parameters and the FRP strain. * The proposed equation was very efficient in predicting the FRP's contribution to the joint's shear strength. The difference in the average ratio of the experimental and shear strength of the joint calculated with the suggested method was less than 1% for principal compressive stress in each direction. * Enhancement in the shear strength of the joint due to FRP was predicted very well compared to that of the experimental results of the same specimen.