A joint structure includes a first floorboard and a second floorboard. The first floorboard and the second floorboard each includes: a top surface; a bottom surface; a first side surface; a second side surface; a third side surface; a fourth side surface; a first beveled tenon, the first beveled tenon including a first tenon face facing upwards; a first beveled mortise, the first beveled mortise including a first mortise face facing upwards; a second beveled tenon, the second beveled tenon including a second tenon face facing downwards; and a second beveled mortise, the second beveled mortise including a second mortise face facing downwards. The top surface is disposed substantially parallel to the bottom surface. The first side surface, the second side surface, the third side surface, and the fourth side surface are disposed substantially perpendicular to the bottom surface.