The only way to expand a standalone device is to first use it to create a concatenated meta.  You can do this by using the "create meta from dev X" command with symconfigure (or you can use Unisphere).  This can be done online.  If you want the device to be a striped meta, you will need to create a concatenated meta first and then convert it to a striped meta. The conversion to striped requires the use of a BCV to preserve the data, allowing the conversion to be performed online.  To convert to striped, you will need to make sure that the additional devices you added to the meta are the exact same size as the meta head (the device being expanded).  You can find more information on this, and the command syntax needed, in the Solutions Enabler Array Controls product guide.  
have a boot lun thats currently 15GB in size that i need to extend.  not familar with the process, found a nice document by Cody Hosterman but it seems only applicable to metas??
expanding tdev on vmax 10k