| Steel anchors are being used in a wide range of ground or rock conditions. They can improve the strength and reliability of ground, reduce the dimension of structures and lighten their weight. So they can save the materials in engineering. With increased experience and improved anchoring techniques, steel anchors has become a common practice in almost every aspect of civil engineering such as slopes, foundations, mines, tunnels, underground excavations, concrete dams, airports, aerodrome, ports, retaining wall, bridge abutments, rehabilitation of existing concrete structures and so on.With the engineering applications, it has been shown that there exist some problems in steel anchors such as corrosion of steel tendon, requirements for corrosion protection, heavy weight, difficulty in transportation and installation. These disadvantages of steel anchors restrict their applications i?a certain extent. Above all, the corrosion of steel anchors not only affects the durability of steel anchors, but may result in serious accidents. Fiber reinforced plastic (FRP) rebar is a new composite material. It is composed of fiber filaments and a resin matrix. The fiber of high tensile strength and high modulus of elasticity is used as reinforcing material. The synthetic resin is used as matrix material and is mixed with adequate auxiliaries. The fiber reinforced plastic rebar is manufactured using a pultrusion method and necessary surface process. It offers significant advantages over conventional reinforcing steel bars, namely, high tensile strength to weight ratio, excellent chemical resistance, strong designability, high fatigue strength and electro-magnetic neutrality. So the fiber reinforced plastic bar anchors can make the anchoring techniques have a more wide range of rock engineering applications.However, few investigations and field applications are availablerecently. In our country, theory analysis has just begun, no information is available for the field applications, and the design theories have hardly been formed. According to the available investigations at home and abroad, main problems should be attached importantce to, namely, the study of the properties of FRP bar anchorage system bearing load is rarely made, the behavior of bond between FRP rebar and concrete/cement grout is scarcely investigated, the calculating method of applied tensile load about FRP anchor, which takes into account the effect among FRP rebar members, and the properties of bond materials(such as cement grout) and rock , has not yet been attached importance to.In order to make the FRP rebars anchors widely applied in anchoring engineering, with the help of the Physical Science Fund of our country(the title of the item: Research into the anchoring mechanisms of FRP anchors, No.50079028) and The Preeminent Youth Fund of Henan province, based on experiments and theory analysis, the study of the mechanical properties of FRP tendon anchors is made. The main achievements of this dissertation are as follows: ~l.The test methods of the behavior of the bond of FRP rebars to concrete, the bond mechanisms and influential factors are discussed. According to the mechanism of force transference between FRP bars and concrete, this dissertation discusses the relationship among bond stress, the stress of FRP bar and embedment length. The basic equations for the bond calculation of FRP reinforced concrete are established.2.Based on the summary of the existent constitutive models for bond slip relation between FRP and concrete at home and abroad, the smooth curve model for bond and slip relation is presented. The model based on the three key points on the bond-slip curve is explicit in physical conception and smoothly sequent and fit the test results.3.The bond layer between the tendon and the fixed anchor length issimplified into the bond interface. On the basis of the constitutive models for bond slip relation between the tendon... |
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