cat file.txt | awk -v RS="your_tag" '{ print $0 > "structure" NR }'
this tend to create empty files / useless files after the final tag, so remove them as below
$5==0 $5 is file size column, 0 is to empty sometime it may be 2,3 kb, add file size accrodingly
ls -ltr structure* | awk '{if($5==0) system("rm "$9)}'