Dear Vishal,
Regarding your first query
No the cumulative mass participation of all the modes considered in analysis should be more than 90%.
As you achieved more than 90% mass participation in both X and Z directions, the directions in which you have applied seismic response spectrum load. So, you can go with that. There are some specifications in the respective code for load in Y directions for structures having very high seismic weight or irregularity. On the other hand, if you want to include the effect of the modes not considered in the analysis, you can for MISSING MASS. There are various threads available in the forum on that.
For last query, you may be not scrolling down to load number 2 results in the output. As you have load 1 in X-direction and load 2 in Z-direction. The base shear in Z will be reported in the results of load 2.
Regards
Kaushal Aggarwal
Regarding your first query
No the cumulative mass participation of all the modes considered in analysis should be more than 90%.
As you achieved more than 90% mass participation in both X and Z directions, the directions in which you have applied seismic response spectrum load. So, you can go with that. There are some specifications in the respective code for load in Y directions for structures having very high seismic weight or irregularity. On the other hand, if you want to include the effect of the modes not considered in the analysis, you can for MISSING MASS. There are various threads available in the forum on that.
For last query, you may be not scrolling down to load number 2 results in the output. As you have load 1 in X-direction and load 2 in Z-direction. The base shear in Z will be reported in the results of load 2.
Regards
Kaushal Aggarwal