Table 7: Modal analysis results of the column.

Six factors and five levels The top to the first rib plates The first to the second rib plates The remaining distance between rib plates The roof column width The column plates thickness The rib plates thickness Natural frequency 1 800 800 925 1050 135 45 17.953 2 900 800 1150 1100 150 55 18.016 3 1000 800 1075 900 143 40 18.063 4 1100 800 850 1000 120 50 17.906 5 1200 800 1000 950 127 60 17.859 6 800 900 1000 1000 143 55 17.965 7 900 900 925 950 120 40 17.903 8 1000 900 1150 1050 127 50 17.960 9 1100 900 1075 1100 135 60 17.921 10 1200 900 850 900 150 45 18.072 11 800 1000 850 1100 127 40 17.773 12 900 1000 1000 900 135 50 17.779 13 1000 1000 925 1000 150 60 17.842 14 1100 1000 1150 950 143 45 17.859 15 1200 1000 1075 1050 120 55 17.799 16 800 1100 1075 950 150 50 17.768 17 900 1100 850 1050 143 60 17.778 18 1000 1100 1000 1100 120 45 17.772 19 1100 1100 925 900 127 55 17.785 20 1200 1100 1150 1000 135 40 16.739 21 800 1200 1150 900 120 60 17.656 22 900 1200 1075 1000 127 45 17.833 23 1000 1200 850 950 135 55 17.766 24 1100 1200 1000 1050 143 40 17.941 25 1200 1200 925 1100 150 50 17.937