Multi strand system.avi

The systems are commonly used in bridge construction as well as other civil Engineering structures such as Silo, Water tank etc. The systems are normally adopted for bonded tendons. The tendons consist of a bundle of strand with a nominal diameter of 0.5" (12.7 mm.) or 0.6" (15.2 mm.). The number of strands per tendon can be from 4 strands up to 31 strands of diameter 0.5" or 22 strands of diameter 0.6". The strands in the tendons are contained in one round duct which is made of corrugated galvanized or non-galvanized metal.

The strands are individually gripped in one anchor head unit and transmits their prestressing force by means of anchor plate casting unit type M. For each anchor size a special spiral reinforcement is provided at the anchor plate casting to give adequate splitting reinforcement for burstling stresses developed at the anchorage zone. The strands in tendon are stressed simultaneously by means of a multi strand stressing jack from capacity 1,100 KN up to 5,000 KN. In case of small size tendon unit such as type M405 the strands can also be stressed individually by means of mono jack.

To ensure corrosion protection and to give adequate bond strength, the tendons are filled with suitable cement grout mix after complete stressing of the strands. http://emiratesposttension.com/multi_...