Application of External Prestressing of Bridges in Germany
Holger S. Svensson
Appears on pages(s):
bridges (structures); concrete construction; corrosion; economics; grouting; history; limit design method; post-tensioning; prestressed concrete; prestressing; strains; structural design; unbonded prestressing; Design
The main advantage of external prestressing is that it facilitates the placement and vibration of the web concrete and thus permits thinner webs. The main disadvantages of unbonded external prestressing are its reduced ultimate capacity and lack of contribution to crack control. The cost of bridges built with unbonded external tendons in Germany is currently higher than for those with bonded internal tendons, mainly because of code requirements for minimum web thickness and crack control, and higher costs for the external unbonded tendons. External prestressing has only limited application in Germany. For new concrete bridges, it has been used a few times since the 1950s for tendons bonded to the webs. The first experimental new bridge with unbonded external tendons in Germany is currently under construction. Special applications of external tendons are for incrementally launched bridges, the rehabilitation of bridges, and as longitudinal force couplers. In the future, unbonded external tendons will probably be used mainly for the rehabilitation of existing bridges in Germany.