Experimental and numerical investigation of the flexural behavior of CFRP box girders

The advantages of carbon fiber-reinforced plastic (CFRP) box girders include good bending resistance, lightweight and high strength. Therefore, they are widely used in aerospace, rail transit, and other fields. When the CFRP box girder is subjected to bending load, the strength of the initial damage is usually used as the ultimate load. However, after the initial damage of the CFRP box girder, the load will be redistributed and structure still have a higher ultimate load. As the damage accumulates, it eventually leads to complete failure of the structure, which is a progressive damage. It turns out that the composite structure still has bending capacity after the initial damage, but the mechanical response at this stage has not been fully studied. To make full use of the ultimate bearing capacity of the CFRP box girder, this article adopts the theory of progressive damage of a composite material and programs the ABAQUS/Explicit user material subroutine (VUMAT) to analyze CFRP box girder progressive damage. This article also produces CFRP box girder specimens with five typical ply schemes and implements three-point bending tests to verify the bending strength of the CFRP box girder. In addition, this article designs strain measurement and ultrasonic scanning experiments to verify the difference between experiment and simulation. The final result shows that the progressive damage model established in this article is reliable, among the five typical ply schemes, when the 0° ply ratio is 60% and the ±45° ply ratio is 40%, the CFRP box girder has the greatest ultimate load carrying capacity.