ʻOiai he ʻano "C" lāua ʻelua, ʻokoʻa nā kikoʻī cross-section a me nā ikaika hoʻolālā, e pili pono ana i kā lākou haʻahaʻa haʻahaʻa a me nā scopes noi.
ʻO ka ʻāpana keʻa o C Channel he ahale hoʻohui hui wela. ʻO kāna pūnaewele (ʻo ka ʻaoʻao kū o ka "C") he mānoanoa (maʻamau 6mm - 16mm), a ʻo nā flanges (nā ʻaoʻao ʻelua ʻaoʻao) he ākea a loaʻa kahi pali (no ka hoʻomaʻamaʻa ʻana i ka hana ʻōwili wela). Hoʻolālā kēia hoʻolālā i ka ʻāpana keʻa i ke kūpaʻa kūlou ikaika a me ka rigidity torsional. No ka laʻana, he 10# C Channel (me ke kiʻekiʻe o 100mm) he 5.3mm ka mānoanoa pūnaewele a me ka laulā flange o 48mm, hiki ke maʻalahi i ke kaumaha o nā papahele a i ʻole nā paia i ka hale nui.
ʻO C Purlin, ma ka ʻaoʻao ʻē aʻe, ua hoʻokumu ʻia e ka piko anuanu o nā papa kila lahilahi. ʻOi aku ka "slim" o kāna ʻāpana keʻa: ʻo ka mānoanoa pūnaewele he 1.5mm - 4mm wale nō, a he haiki nā flanges a loaʻa pinepine nā ʻāpana liʻiliʻi (i kapa ʻia ʻo "reinforcing ribs") ma nā ʻaoʻao. Hoʻolālā ʻia kēia mau iwi ʻaoʻao e hoʻomaikaʻi i ke kūpaʻa kūloko o nā flanges lahilahi a pale i ka deformation ma lalo o nā haʻahaʻa liʻiliʻi. Eia nō naʻe, ma muli o ka mea lahilahi, nāwaliwali ke kūpaʻa torsional holoʻokoʻa o C Purlin. No ka laʻana, he C160×60×20×2.5 C Purlin (ke kiʻekiʻe × flange width × pūnaewele kiʻekiʻe × mānoanoa) he 5.5kg wale nō ka mānoanoa, ʻoi aku ka māmā ma mua o ka 10# C Channel (ma kahi o 12.7kg no ka mika).