browse chinese bbs with urxvt in utf8

for most chinese bbs output gbk encoding,so the urxvt should be told that it is going to treat the stream as gbk,more than that,it should also be told that the input mothod works in a utf8 enviroment,so I start a urxvt to browse bbs like this:

LC_ALL=zh_CN.GBK urxvt -imlocale 'zh_CN.utf8' -fn '10x20,xft:AR PL
New Sung:antialias=false' -e screen

it looks perfect