Experimental Study On Tensile Character And Failure Mechanism Of GFRP Rebar

Geotechnical anchorage is an important branch in geotechnical engineering field, anchoring technology can sufficiently increase strength and stability of rock and soil bulk, reduce size of structure, lighten its self-weight, economize notably engineering material, control effectively deformation of rock and soil bulk, anchorage technology has been an effective method for increasing stability of geotechnical engineering and solving complicated rock and soil engineering problem. Rebar as a main supporting form of understructure and rock slope will yield very important effect for maintenance of the stability of engineering structure. With the continuation and development of anchorage technology, steel rebar has been widely applied in engineering project, such as slope,trench,tunnel,understructure,dam,airport,harbor,bridge abutment and so on, and its applying range is increasing year by year.However, engineering experience indicating: traditional steel rebar has some prominent defect in the applying of anchor engineering, such as: low corrosion resistance,high self-weight,difficult to transport and assemble and al et. The defect of steel rebar restricts its application, especially the corrosion, not only influence the durability of structure, but also lead to heavy engineering accident under dangerous situations.The glass fiber reinforced Polymer (GFRP) rebar is a new kind of material formed with resin and glass fiber compound, with good character of high tensile strength, excellent corrosion resistance, low specific weight and similar coefficient of thermal expansion to concrete, the tendency of GFRP instead of steel for geotechnical engineering is increasing year by year. Using GFRP rebar instead of steel rebar for engineering reinforcement can overcome the deficiency of steel rebar in some degree, and tap more application prospect for the development of anchor technology.Nowadays, research and application of GFRP rebar are relatively deficient in home and abroad, it is almost void on design theory and production, for applying widely in anchor engineering field, this text principally carried on two aspects of test based on the project of Guangdong communication scientific research (name of the project: experimental investigation of GFRP rebar for high slope reinforcement; serial number:2004-17), in one aspect, pull-out tests of GFRP rebar are carried out using screw coupling semi-mould steel jig designed by ourselves, with the aim of obtaining pull-out strength character of GFRP rebar and discussing the reasonableness of test method, in another aspect, laboratory pull-out test model are designed and simulated, parallel destructive test of two specimens have been conducted for three times, with the aim of sufficiently arguing probable destructive form and mechanism of GFRP screw rebar structure, according to the test phenomenon and result of the analyzed test data, a serial of conclusions are gained, and the main research achievement are as follows:(1) According to the test result of 91 specimens divided into three batches, a simple easily controlled tensile test method for directly determining GFRP bar's tensile strength is put forward, the failure forms for GFRP bar with different sections and the reasonable morphological character of stress-strain cure of GFRP bar in the tensile process are presented, we put forward a reasonable tensile test method for GFRP bar and recommend using the method associating electronic extensometer, then the relationship of GFRP rebar's tensile strength varying with its physical dimension and intrinsic cause of its tensile strength's discreteness is analyzed.(2) Laboratory pull-out model tests are designed, according to the test phenomenon and result of the analyzed test data, rationality of GFRP rebar pull-out test model are affirmed, the relationship of mortar bulk strength against rebar's stress transfer depth is explained, and the trend of peak value character of GFRP screw rebar's shearing stress varying with adding of load are presented, combing stress distribution characteristics of mortar bulk, probable destructive form and mechanism of GFRP screw rebar structure have been sufficiently argued.