The word "栏杆" is formed by combining the characters "栏" and "杆". "栏" consists of the semantic radical "木" (wood) and the phonetic component "兰" (lán), conveying the idea of a wooden barrier. "杆" similarly uses "木" as the radical and "干" (gān) as the phonetic component, referring to a wooden pole. Together, they create a compound word where both characters contribute meanings related to wooden structures, specifically denoting a railing or balustrade.