A further typical concrete structure is illustrated in FIG 10 at 28 having {TAIL ~ buttresses} 29 {HEAD ~ each} with ducts 30 
A further typical concrete structure is illustrated in FIG 10 at 28 having { TAIL ~ buttresses } 29 { HEAD ~ each } with ducts 30
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH