In ETABS 9, it was possible (although not easy) to import a model to SAP. ETABS 2013 does not yet offer this capability directly, but CSI is developing an ETABS-SAP translator. They graciously shared a beta version with me, and I offer it to you in the same spirit.
To use the tool, download both files and place them in the same folder, then run “ConnectSAPandETABS.exe”
The translator is currently able to export model geometry and section properties to SAP 15, but not frame assignments (!) nor loadings. CSI will hopefully release an updated version of this tool soon.