Calculation methods for overturning moment carried by member
Based on the equilibrium equations of moments for all the vertical members of a story,the formula of overturning moment carried by frame parts in Code for seismic design of building(the seismic code'formula for short)was deduced.An interpretation of the seismic code'formula was presented,and the seismic code'formula was extended to suit a structure with inclined members and a structure with pitched roofs/floors.For a structure with inclined members,the shears of the seismic code'formula were modified as the horizontal component forces of inclined members;for a structure with pitched floors/roofs,the story heights of the seismic code'formula were the differences of the heights of the resultants of the lateral loads at adjacent floors.The concept of overturning moment carried by frame parts determined directly by the axial forces of the columns(the axial force method for short)in the literature was different from the concept of the seismic code'formula,and the flaw of the axis for moment about which was determined by the usual method in the axial force method was pointed out by an example.A numerical example of a 6-story frame-shearwall structure with inclined members,pitched floor and pitched roof illustrated the application of the seismic code'formula,and interpretated the reason of the different results that the axis for calculating moment by the axial force method was different from the implicit axis by the seismic code'formula.