Structural steel sections include angles, I-beams, channels, tees, bars, flats/plates/sheets, and tubes. Rivets are permanent cylindrical fasteners with heads on one end and tails on the other. Riveted joints include lap joints where members overlap and butt joints where ends meet directly. Welded joints include butt welds where ends meet and lap welds where materials overlap. Tension members experience axial pulling forces like wires and cables. Compression members experience pushing forces and include struts like columns. Roof trusses use economical materials and come in designs like fink, fan, Howe, Pratt, and north light trusses. Beams support heavy loads