Try This
<br />
StrContent &= "<tr><td align="center" class="LineLightAPP" with="20%"><input type='checkbox' Name='chk'" & Convert.ToString(T) & "ID='RR'" & Convert.ToString(T) & "runat="'server'" onclick='javascript:CalcTotTickets(this);' title='T' " & T & " />" & DtTable.Rows(T).Item("ROOM_NAME").ToString & "</td></tr>"<br />
Now you can access each checkbox separately.