Experimental Research And Analysis On The Concrete Beams With Embedded Steel Bars Under Fatigue Load

The technology of embedded steel bars is a new post-anchorage technology based on concrete structure, which has been widely used in structural reinforcement. This paper has produced seven reinforced concrete beams using the technique of embedded steel bars, doing the static load test and fatigue test to explore the force performance of different length of embedded steel bars beams. Conclusions of this study are as follows:Static test results show that, with the increase of the length of embedded steel bars, the untimate load of the beams is greater, and increase the length of embedded steel bars can effectively improve the ultimate bearing capacity of the beam. The limit deformation of the beam increases with the length of embedded steel bars becoming bigger. under the three static loads test, the average strain of steel and concrete accord with flat section assumption. The stress of embedded steel bar increases as the measuring point to the end of the distance increases under the same load,this suggest the stress of embedded steel bar ends undertaken smaller, the greater the distance from the tip, the greater of the stress borne by steel. To give full play to the strength of steel, the beam should be implanted in a certain depth, this paper suggests the depth of embedded steel bars should reach 25d(d for the diameter of embedded steel bars).Fatigue test results show that, three fatigue test beams have emerged more cracks when it comes to 0 times static load test, the main crack location appear in the concrete joints and in the middle of the beam. The crack basically a homogeneous before 500,000 times, the loading process going from 500,000 times to 2 million times, cracks have some development, but the development is not obvious, there is no new cracks appear. The flat section assumption can be used not only under static loads but also under fatigue loads. Increased the length of embedded steel bars can help to improve the fatigue performance of the beam; For beams, increased the length of embedded steel bars can reduce the fatigue deformation of beams in a certain extent; With the increase of length of embedded steel bars, the degradation rate of concrete beam stiffness is significantly smaller, the stiffness of the shortest length being the biggest drop, thus increasing length of embedded steel bars can effectively improve the stiffness degradation performance of the beam.