pkpm系数(PKPM coefficient) 1. Determination of seismic grade: According to the difference of the intensity, structure type and the height of the building, the seismic grade of the project is determined by items: "" or "high regulation". But we should pay attention to the following points: (1) the above seismic grade is a "C" type building, and if it is a "," "B", "Ding" type of building, it is necessary to adjust the seismic grade according to the standard requirements. (2) close to or equal to the height of the boundary, should bined with the degree of housing irregularity and site, foundation conditions, carefully determine the seismic grade. (3) when the conversion layer, =3 and above, the column and shear wall at the bottom of the shear wall should be strengthened according to "regulation" grade "or" high regulation check increase the seismic grade level, is a can not adjust. (4) the seismic grade of short leg shear wall structure should also be improved according to the seismic grade of "anti code " or "high regulation" .. But pay attention to the multi short pier shear wall structure can be improved. (5) Note: steel structure, masonry seismic grade no node. When calculating the optional "5", without considering the seismic fortification measures. 2, the choice of vibration bination number: In the calculation of seismic force, the number of vibration modes should be determined by the number of vibration modes required to reach more than 90% of the total mass. But we should pay attention to the following points: (1) the number of vibration modes can not exceed the total number of vibration modes of the structure. Because there are only three effective degrees of freedom on one floor, there are 3 optional modes at one floor. If the number of selected modes is more than the total number of vibration modes, the calculation of seismic force will be abnormal. (2) the structure of the coupling calculation of the selected mode number
