Why do the analysis results for all members in the model have positive values?
The modal response (nodal deflections, member forces, reactions) determined from a response spectra analysis have signs associated with them. However, once the analysis results are determined by combining the modal results using either the SRSS or CQC method, each response has only a positive value. Because the sign of the result is important for member design, there is an option in the RAM Frame (General > Criteria) to consider the sign in the results. When this option is selected, the sign of the analysis result will match the sign from the predominant modal result. You should not design continuous footings, gusset plate connections, or other elements based on the forces from multiple members using dynamic results unless the sign of the analysis result has been considered.
