Dynamic fracture process of T-shaped beam-column specimens with prefabricated cracks under offset impact

Abstract

Using the digital dynamic caustics experimental system and numerical simulation software, the drop hammer impact tests of T beam-column specimens with different locations of precast cracks were carried out, and the change rules of the track, velocity, dynamic stress intensity factor, and the distribution law of stress field were obtained under dynamic pressure. The results show that under the action of the reflected tensile wave, the beam-column joint is most vulnerable to damage due to the stress concentration at the beam-column joint. Because of the interaction between the two precast beams with more free cracks, it is easier to form cracks between the two precast beams. The maximum value of crack propagation velocity was about 300 m / s, showing the change law of rapid increased at first and then decreased vibration. The stress intensity factor was between 1.7 MPa·m1/2 and 1.8 MPa·m1/2, the specimen with two prefabricated cracks was easier to form stress concentration at the intersection of beam and column, and the effect of stress wave is stronger. Taking the neutral axial symmetry of the beam as the symmetry center, the strain amplitude is approximately equal and the force is opposite. Due to the attenuation of the stress wave, the strain on the upper and lower sides of the beam decreases gradually with the increase of the distance from the impact loading position. Numerical simulation software was used to verify the experimental results, and MAXS failure judgment was added to calculate the strain change in the fracture process.