## 1 Introduction  
The use of high-strength materials permits the structural reinforced concrete (RC) elements to have smaller and lighter members through the enhancement of their capacities. In particular, the fiber reinforced polymer (FRP) bar possesses non-electrochemical corrosion performance and a higher strength-weight ratio when compared with the common properties of conventional steel bars [1; 2; 3; 4]. As a result, a large part of the building and infra structures are displaying considerable interest in practical applications of high-strength FRP bars as an alternative for the conventional mild steel bar used for longitudinal reinforcement of flexural members [1; 2; 3; 4]. Meanwhile, use of FRP bars as a longitudinal reinforcement of flexural members requires several precautions for the reduced bond capacity with surrounding concrete and brittle fracture potential of the bars at the large deformation of the members. The reduced bond capacity of FRP bars can require a longer anchorage length to prevent the splitting failure and/or pull-out failure of the longitudinal reinforcement in RC members. However, there are very limited available test data and reports on the effect of the poor anchorage on the flexural strength and ductility of concrete members. For reinforced concrete members subjected to flexure, the resultant compressive forces are mostly resisted by concrete whereas the resultant tensile forces are transferred to a support through the longitudinal reinforcing bars in tension. Thus, the bond resistance capacity of longitudinal reinforcing bars significantly influences their anchorage length within the support [2; 4; 5; 6] to resist the applied tensile forces. ACI 318-14 provisions [5] specify the required anchorage length of the conventional mild longitudinal reinforcement as a basic function of the compressive strength of concrete, and the yield strength and diameter of the bar on the basis of regression analysis using comprehensive databanks, including pull-out bond tests. Thus, the ACI 318-14 provision provides no details for the anchorage length of FRP bars. The ACI 440.1R-15 guideline [6] specifies the required anchorage length of the FRP bar as a function of the area, tensile strength, and diameter of the bar, and the bond capacity with the surrounding concrete in accordance to the approach that was employed in the ACI 318-14 provision to determine the anchorage length of conventional steel bars. The required anchorage length of FRP bars in beams calculated using the design equations of the ACI 440.1R-15 is commonly shorter than that of the conventional steel bars determined using the ACI 318-14 equations, although the FRP bars potentially possesses a lower bond capacity when compared with the deformed steel bars. This implies that the reliability of the code equations needs to be further examined for flexural members that have insufficient space for anchorage of longitudinal reinforcement, such as exterior beam-column connections. Recently, there is increasing attention [1; 2; 3; 4; 7; 8] on the development of glass fiber reinforced polymer (GFRP) bars with good bond capacity on the grounds of high-tensile strength and economic efficiency. [PERSON] [3] revealed that the flexural behavior of beams reinforced with the GFRP bar was typically governed by the excessive deflection and crack propagation under the service load, rather than the flexural moment capacity, because of the low modulus of elasticity and poor bond capacity of GFRP bars. [PERSON] et al. [7] reported that the ductility of beams with GFRP bars does not satisfy the minimum requirement recommended by CSA-S6-00 [9]. In addition, [PERSON] [3] and [PERSON] et al. [8] showed that beams with GFRP bars have a lower shear transfer capacity of concrete than the predictions obtained from the design equations of ACI 318-14 because of the reduced dowel actions of the GFRP bars used for longitudinal reinforcements.