Fatigue Life Of Concrete Beams Research Articles

Characterizing fatigue damage behaviors of concrete beam specimens in varying amplitude load

In this paper, the random and nonlinear mechanical characteristics of the composition distribution of concrete in each phase are investigated to solve the difficulty of fatigue damage test of concrete beam specimens under variable amplitude loading. A three-dimensional (3D) concrete composite random aggregate meso-model of concrete beam specimens is built with Digimat as a composite modeling tool. Subsequently, the bending-tensile strength and fatigue life of the model under four-point bending loading is analyzed and calculated using Abaqus finite element analysis model based on the concrete elastic-plastic damage criterion. The mechanical behaviors of concrete materials under static load failure, multistage fatigue loading, and random fatigue loading are studied. Finally, compared with the test results, the following conclusions are obtained. The random aggregate model and elastoplastic damage mechanics model of concrete composite constructed by concrete in Abaqus and Digimat can better describe the geometric and distribution characteristics of composite structure and aggregate in concrete beams and the mechanical behavior of fatigue and static load failure. The difference is 4.08 % with the experimental results, which verifies the validity and reliability of the numerical simulation model, and the fatigue life of concrete beams under random loading Sra and Srb is 1622 and 164 times, respectively. The research results have certain guiding significance and reference value for accurate calculation of bending and tensile strength of concrete beams under specified raw material and mix ratio and prediction of fatigue damage cracking in airport cement concrete pavement structure.

Shear fatigue behavior of reinforced concrete beams produced with manufactured sand as alternatives for natural sand

Compared to natural sand, manufactured sand (M-Sand) has significant differences in terms of stone powder content, particle size distribution, and particle shape. The fatigue performance of M-Sand concrete structures is a crucial problem for the application of M-Sand in significant engineering structures. In this study, four different types of fine aggregates were selected to investigate the shear fatigue behavior of reinforced concrete (RC) beams by considering the influence of the maximum load level. Next, the performance indexes of the fatigue life of M-Sand concrete beams were evaluated. The results showed that the fatigue failure processes of concrete beams produced with different sand types were similar. The fatigue life of concrete beams was found to be related to the stress or load range. At the same maximum load level, the methylene blue (MB) value is a critical index that influenced the fatigue life of concrete beams containing M-Sand. Moreover, the fatigue life showed a linear logarithmic relationship with the average permanent deflection of Stage II. The total dissipation energies of the concrete beams in Stage II were different for the various fine aggregates. Generally, the higher the total dissipation energy, the longer the fatigue life of the concrete beam. The average dissipation energy in Stage II can be used as a characteristic index for evaluating the fatigue performance of concrete beams produced with different types of fine aggregates. • Shear fatigue behaviors of sixteen reinforced concrete beams containing manufactured sand were innovative analyzed. • Three different types of manufactured as well as natural sand were used in experimentally program. • The fatigue life of manufactured sand concrete beams was found to be related to the stress or load range. • The magnitude of the dissipation energy together with permanent deflection could indicate the fatigue life of concrete beams.

Experimental study on deflection of partially prestressed concrete beams at different corrosion rates under fatigue load

This paper studies the deflection under fatigue load failure and the corrosion fatigue life of partially prestressed concrete beams through the static test and fatigue test of 6 different corrosion rates of partially prestressed concrete beams. The experimental results show that: 1) The corrosion inserts a great influence on the fatigue failure of concrete beams; the fatigue failure of reinforced concrete beams at a low corrosion rate is mainly caused by fatigue fracture of tensile rebars; and when the corrosion rate is high, the failure mode of concrete beams evolves into the cracking and final crushing of reinforced concrete in compressive zone. 2) As the corrosion rate increases, the fatigue life of concrete beams decreases significantly, which affects the fatigue performance of concrete beams. (3) With the increase of fatigue load, the development of mid-span deflection of the test beams shows an obvious rule of three stages: the deflection grows faster at the initial stage, and slower at the medium stage.

Flexural Fatigue Behavior and Performance Characteristics of Polyacrylonitrile Fiber Reinforced Concrete

This paper presents the results of an experimental investigation to determine the flexural fatigue strength and fatigue life of concrete beams reinforced with monofilament polyacrylonitrile fibers (PAN fiber for short). The performance of fresh concrete and the elastic and mechanical properties of hardened concrete are compared by samples with and without fibers. The toughness calculated according to both ASTM and JCI methods increased with the addition of fibers. The toughness indexes I5 was 3.8-4.2 times，I10 was 5.8—6.8 times that of the plain concrete. The equivalent strength was 0.63-0.87 MPa for PAN fiber reinforced concrete. When compared to plain concrete, the endurance limit of concrete beams only reinforced with PAN fiber is increased by 12 percent.