Experimental Study On The Behaviors Of HDFRC Under Tension-compression Fatigue Loading

Concrete is the most widely used building material in the world.It has many advantages such as wide source,low cost and simple manufacture,etc.so it is still at the leading position in the engineering application nowadays.However,the traditional four-component concrete is a brittle material,the poor deformation capacity leading to the structure of the early deterioration reduced its engineering life.High ductile fiber reinforced concrete(HDFRC)is a kind of new concrete material with good mechanical properties and good durability.It has added fibrous components on the basis of the original high ductile concrete,and has successfully improved the ductility and toughness of concrete.In this experiment,the compressive strength,flexural strength and tensile strength of HDFRC materials at room temperature were tested and,according to its tensile strength,the tensile-compressive fatigue properties of the HDFRC materials were tested then.Those basic mechanical properties of HDFRC materials above were analyzed respectively.so as the durability under the constant amplitude load.The most important feature of HDFRC is that it has tensile strain-hardening characteristics and multi-microcrack energy dissipation capacity when tensioned.The two kinds of specimens have reached more than 1.4% tensile strain.Its tensile strength is about 1.6 times of that of ordinary concrete.The flexural strength of HDFRC is about 4 times of its tensile strength,far exceeding the ordinary concretethe 4 times of its tensile strength,and the maximum strain value can be measured up to 4.5%;The compressive strength grade of HDFRC is equivalent to C70,its Compressive strain is more than 1%.The HDFRC exhibits good durability in the tensile compressive fatigue load at constant amplitude.A total of 54 specimens were prepared and tested at the age of 120 days.The damage process and failure modes were carried out under different stress levels(0.7,0.8,0.9)at different frequencies(10Hz,20 Hz,30Hz).The experimental results show that the fatigue failure ofHDFRC conform to the Weibull two parameter distribution and gives the corresponding p-S-N equation.The results of this study can provide the basis for the analysis of seismic design of concrete structure,and so as the analysis of the vibration of road and bridge.At the same time,this can be used as the reference to evaluate the anti-fatigue ability of HDFRC.