双层弦网与跨层腹杆

提示词

按已给节点和杆件分清上弦网、下弦网及跨层腹杆，每根腹杆接回其真实两端节点；保留层间深度和杆间空隙，不把两层压成单层网纹。

Distinguish the supplied upper and lower chord grids and interlayer web members, connecting each web to its actual endpoint nodes. Retain layer depth and open gaps between members rather than flattening both grids into one mesh pattern.