While breaking out concrete we damaged one wire (not cut just damaged)of a 7 wire strand. The strand itself belongs with a 4 strand bonded (grouted)tendon. So in effect we have damaged 50% of the prestressing steel area of 1/28 of the tendon. The Engineering Consultant now suggests that this a huge error that is almost insurmountable. Does anyone have reference to an engineering code which would allow a reduction in prestressing area due to such site difficulties.
Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Damaged Prestress Wire
- Thread starter Zambo
- Start date
To add to HENRI2's reply:
ACI 318 2002 states:
18.20.4 — Total loss of prestress due to unreplaced
broken prestressing steel shall not exceed 2 percent of
total prestress.
Commentary states:
R18.20.4 — This provision applies to all prestressed concrete members. For cast-in-place post-tensioned slab systems, a member should be that portion considered as an
element in the design, such as the joist and effective slab
width in one-way joist systems, or the column strip or middle strip in two-way flat plate systems.
I have used the "2% rule" many times - sometimes a wire or two, or even a full strand may break during stressing at original construction. And during the life of the building the 'concrete coring machine' is always there to ruin your day.
I just looked at a project 2 days ago where an electrical contractor chased the underside of an existing precast/pretensioned slab panel and sawed/cut through all 7 x 1/2" strands, at MIDSPAN. Needless to say this is getting repaired with some significant $$$ being spent.
ACI 318 2002 states:
18.20.4 — Total loss of prestress due to unreplaced
broken prestressing steel shall not exceed 2 percent of
total prestress.
Commentary states:
R18.20.4 — This provision applies to all prestressed concrete members. For cast-in-place post-tensioned slab systems, a member should be that portion considered as an
element in the design, such as the joist and effective slab
width in one-way joist systems, or the column strip or middle strip in two-way flat plate systems.
I have used the "2% rule" many times - sometimes a wire or two, or even a full strand may break during stressing at original construction. And during the life of the building the 'concrete coring machine' is always there to ruin your day.
I just looked at a project 2 days ago where an electrical contractor chased the underside of an existing precast/pretensioned slab panel and sawed/cut through all 7 x 1/2" strands, at MIDSPAN. Needless to say this is getting repaired with some significant $$$ being spent.
- Status
Similar threads
- Locked
- Question
- Locked
- Question
- Locked
- Question
