A strut member to be secured to the floor structure includes a top skirt-contacting portion for the aerodynamic skirt panel to be secured thereto, a lower skirt-contacting portion for the aerodynamic skirt panel to be secured thereto distant from the top skirt-contact portion, and a strut portion connecting the top skirt-contact portion to the lower skirt-contacting portion. The strut member provides a clearance in which the skirt panel is free of contact with the strut member between the top skirt-contact portion and the lower skirt-contacting portion. The strut portion is configured to resiliently buckle between a buckled position upon the skirt panel undergoing a force exceeding a threshold value toward the strut member and an original position when no force is applied and when the skirt panel is undergoing a force that is less than the threshold value.