@phdthesis{oai:muroran-it.repo.nii.ac.jp:00005092,
 author = {ABDEL AZIZ Mohamed Ali Ibrahim Abdel Aziz, and アブドル アジズ モハメド アリ イブラヒム アブドル アジズ,},
 month = {2016-02-15},
 note = {application/pdf, Nowadays, Fiber Reinforced Polymer (FRP) sheet bonding method has been rapidly introduced for reinforcing and/or retrofitting of the existing Reinforced Concrete (RC) structures. Due to bonding normal FRP sheet onto the tension-side surface of the RC members, the effects due to bonding the FRP sheet can be expected after rebar yielding. However, cracking and rebar yielding loads cannot be much improved. Recently, in order to increase not only the ultimate load-carrying capacity of the RC members but also cracking and rebar yielding loads, pre-tensioned FRP sheet bonding method has been developed. In the previous studies, metal system was applied as anchoring devices of the sheet. Even though the premature failure at the ends of the sheet can be prevented by applying the metallic anchoring system, the installation of the system into RC members is not easy task because of its heavy weight. Also, stainless steel must be used to be anti-corrosive when FRP sheet is applied. Then, in order to easily apply the pre-tensioned FRP sheet bonding method for reinforcing RC members, the anchoring system should be simplified without any dropping of anchoring performance. From this point of view, here, a flexural reinforcing method using pre-tensioned AFRP sheet without metallic device was proposed. In this method, to distribute the concentrated anchoring stresses of pre-tensioned AFRP sheet, the base cross-directional non-pre-tensioned AFRP sheet was bonded to the concrete surface around the anchoring area. In addition, to decrease gradients of bonding stresses near the anchoring area, a strain relaxation polymer (with low young’s modulus) was used as a bonding material. The applicability of the method was discussed by conducting four-point loading test of the flexural reinforced RC beams with pre-tensioned AFRP sheet and comparing the experimental results with the numerical ones. The analytical portion of the research is employed to describe the flexural behavior of the all tested beams. A multi-section method was applied to analytically estimate the load-displacement relation and the axial strain distribution of AFRP sheet used for flexural reinforcing each RC beam. This research is divided into three studies as follows; (1) Strengthening Study of RC beams; this study examined the behavior of flexural pre-tensioned AFRP strengthening systems without anchoring device, hence investigate the effectiveness and feasibility of a proposed anchoring method. The variables used in the experimental program included the pre-tension force ratio introduced to the AFRP sheet (0, 20, and 40%) and the main reinforcement steel ratio (0.79 and 1.24%). From this study, the results show that the proposed anchoring method is effective and feasible because the load-carrying capacity increased considerably. A good agreement between experimental and analytical methods was achieved up to ultimate state with somewhat a perfect bonding between the AFRP sheet and concrete surface. (2) Strengthening Study of pre-cracked RC beams; this study investigated the load-carrying behavior of pre-cracked RC beams strengthened with pre-tensioned sheet compared to non-pre-cracked ones. Pre-tension force ratio introduced to the AFRP sheet (0 and 40%) and level of prior loading (Level 1 is up to main rebar yielding; Level 2 is up to average point between main rebar yielding and ultimate load) were taken as variables. From this study, it is observed that due to introducing pre-tension force into the sheet, flexural capacity and durability of the pre-cracked RC beams can be improved and the width of cracks can be decreased. This implies that a new anchoring method is effective and feasible. Numerical results can better match the experimental results for non-pre-cracked beams but not for pre-cracked beams subjected to high prior loading because the existing cracks and the stiffness of putty used for flattening the bonding surface were not considered in numerical analysis. (3) Repair Study of pre-cracked RC beams; this study examined the effectiveness of pre-tensioned AFRP systems to restore capacity of repaired pre-cracked RC beams reinforced with pre-tensioned sheet. Pre-tension force ratio introduced to the AFRP sheet (0 and 40%), with/without existing cracks and with/without repairing the cracks by injection epoxy resin were taken as variables. From this study, it can be concluded that : 1) flexural load-carrying capacity of the pre-cracked RC beams can be significantly improved by bonding the pre-tensioned AFRP sheet onto the tension-side surface;2) by repairing the existing cracks, the sheet rupture can be prevented because the opening of cracks and also large strains occurring in the sheet due to the opening can be rationally restrained; and 3) numerical results can better match the experimental results for non-pre-cracked beams but not for pre-cracked ones.},
 school = {室蘭工業大学, Muroran Institute of Technology},
 title = {Experimental study on development of strengthening method for RC beams reinforced with pre-tensioned AFRP sheet},
 year = {}
}