该建筑为一幢六层现浇钢筋混泥土框架房屋，屋顶有局部突出的楼梯间和水箱间。混泥土强度等级：梁为C20，柱为C25。混凝土密度为2500kg/m3

本题目将对该梁柱结构的框架房屋进行模态分析，求解出该结构的前8阶固有频率及其对应的模态振型。框架的平、剖面见图1，图2。构件尺寸参见表1、表2。

　　其材料为混凝土，相关参数为：杨氏模量C20为2.55e10N/m2 ，C25为2.8e10 N/m

-The building for a six-storey reinforced concrete fr a me houses, the roof has partially prominent between the staircases and water storage tanks. Concrete strength grade: Leung for C20, column C25. Concrete density 2500kg/m3 will be the subject of the fr a mework structure of the column housing modal analysis, solving of the structure before the 8-order natural frequencies and corresponding modal type. Ping fr a mework, profiles are shown in figure 1, Figure 2. Scantlings see Table 1, Table 2. Its materials for concrete, relevant parameters are: Young s modulus C20 for 2.55e10N/m2, C25 for the 2.8e10 N/m