求翻译：多层框架为超静定结构，在内力计算之前，要预先估算梁、柱的截面尺寸及结构所采用材料强度等级，以求得框架中各杆的线刚度及其相对线刚度。是什么意思？

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正在翻译，请等待...

The multi-layered frame is the ultra statically determinate structure, before endogenic force computation, must estimate Liang, the column section size and the structure in advance uses the material strength rank, obtains in the frame various poles line rigidity and the relative line rigidity.

Multi-layer framework for statically indeterminate structures, before the internal force calculation, to advance estimate of beam and column sections using material intensity and structure level, to find the stiffness of the frame and its relative stiffness.