Unbonded prestressed tendons
1 scope
This technology is applicable to 8 degrees
in Beijing area of post-tensioned Unbonded prestressed concrete structures for
earthquake.
2 construction preparation
2.1 materials and equipment
2.1.1 production of Unbonded-wire and
should be in line with national standards of the prestressed concrete steel
wire strand (GB5223
185), of the prestressed concrete steel
strands (GB5224-85) requirements.
2.1.2 the coating layer of Unbonded Tendons
"special construction of oil", its performance, product quality
indicators should conform to the standard Bureau of Hunan province on June 6,
1983, on July 1, 1983 the pilot "condition of Unbonded prestressed tendons
with antirust grease lubrication technology" requirements.
2.1.3 Unbonded Tendons using low density
polyethylene coating material (190 ℃ temperature,
melting index for the 1.5~5 range).
2.1.4 has been completed the Unbonded
Tendons quality requirements should conform to the Beijing standard of the
Unbonded prestressed concrete structure system (BUPC) design and construction
rules (draft) (DBJ01-7-90) in chapter II of part two 2nd. 2.5 requirement (see
table 4-44). Unbonded steel wire, steel wire, dog leg is not allowed, see dog
leg cut off. Wires should be long, no joints.
2.1.5 of Unbonded prestressed concrete
structure with influenza a, b-type anchorage system structure, technical
requirements, must comply with DBJ01-7-90 requirements proposed in chapter III
of part two.
Construction of anchorage system as shown
in figure a, and b 4-52~4-57.
Influenza a and b-type anchorage
performance and condition is shown in table 4-45.
Usually steel wire beams is equipped with
type a or b, strand was equipped with b-type.
2.1.6 supporting the tensioning device have
an oil pump jacks, the technical properties as shown in table 4-46. Machine has
a voltage divider (both hydraulic and springs), tension rods, anchor, etc.
2.2 operating conditions
2.2.1 tensioned concrete strength to meet the
design requirements, General design strength of not less than 70%, a test
report form.
2.2.2 Unbonded tendon compound and steel
processing to complete.
2.2.3 anchor has inspection and acceptance.
2.2.4 tensioning equipment has been
certified equipment is ready.
2.2.5 stretching parts of the scaffold and
fence installation has been completed and inspected in accordance with
operational requirements.
2.2.6 design made to Unbonded tendon
tension, tension, elongation value, Unbonded tendons of laying and operation,
to technical quality standards of disclosure.
3 operational processes
3.1 process:
Construction preparation of beams and
formwork pitched →
→ non-prestressed rebar placement, lashing →
Ends of Unbonded prestressed tendons
placement, node installation on non-prestressed rebar placement, lashing → →
Unbonded prestressed arch, lashing → hidden test
collection of → concrete pouring and tamping →
Concrete curing → → tension ends
3.2 check patch no bond reinforced: no bond
reinforced entry Hou, should timely verification reinforced of specifications,
and size and number, by root check reinforced of outside package layer quality
and the end Department accessories, on distribution has methyl anchor wire
beam, should seriously check anchor Cup both inside and outside thread, and
heading head shape size, and leak heading phenomenon,, and will positioning Rod
twist into anchor Cup within, twist into depth see table 4-47. After checking
correct can be classified and piled up. Coating damage of Unbonded tendons,
with plastic repair.
3.3 mode reserved hole location: Zhang
Laduan die outside, according to construction plans by Unbonded elastic wire,
numbering, and drilling. Equipped with a anchor bar diameter for PHI 40,
equipped with anchor bars b hole diameter for PHI 30.
3.4 installation of bearing plate: plate is
set for Unbonded Tendons Zhang Laduan, installation should prevent tension due
to bearing plate face tilted cylinder and plate perpendicular to each other and
affect the normal tension. Vertical deviation of bearing plate as described in
section 4.3.
Shop 3.5, the Unbonded Tendons: Unbonded
Tendons usually configured with one-way and two-way curved configuration in two
ways. Placement should be noted:
3.5.1 for assurance of Unbonded curve rise
requirements, Unbonded Tendons sing with non-prestressed reinforcement
configuration in the same direction at the same horizontal location (and
support).
3.5.2 before placement, iron stool should
be established to control the curvature of Unbonded tendons, generally every 2m
a horse stool, stool height determined in accordance with design requirements.
No horse in stool, direct lashing at the end of the muscles.
3.5.3 two-way curved configuration, you should
also pay attention to the placement of the reinforcement sequence. Due to the
reinforcement of the ups and downs of different heights, there will be two
alternating pressure to the reinforcement. To avoid laying wear bars, must be
made before construction of manual or computerized sequencing. Sequencing is
the elevation at the intersection of Unbonded tendons (from the height of the
plate from the end of the Unbonded Tendons epithelial) marked, taken on the
intersection of the two elevations, a reinforced point in one direction Jun Gao
respectively when the elevation is below instead intersects the tendons, this
bar can be placed. According to this pattern to find placement order. In this
order, finished tied at the end of non-prestressed reinforcement bars, putting
the Unbonded tendons in your template.
3.5.4 the Unbonded Tendons below should be
laid in raceways, avoid down Unbonded tendon tension force, resulting in under
the wire and tube bending and breaking of concrete.
3.6 end of node installation:
3.6.1 swine anchorage system of
tension-side installation: gently into the bearing plates reserved for plastic
protective sleeve hole to prevent pouring concrete, cement slurry into the
socket screw, and tension. And according to design requirements, determine the
embedded depth of anchor glass. In order to ensure its correct position can be
achieved by positioning the connecting rod. Position the connecting rod length
is 160mm, with two end threads will be screwed into the socket at one end (its
provisions into lengths as shown in table 4-47), pushing inside the wire
heading, at the other end fixed in end mode. By measuring the positioning Rod
dew in mode to check the size of anchor Cup embedded depth. In the process of
locating operations, embedded depth of anchor Cup to be checked one by one,
checking, and strictly control the positioning Rod exposed. Exposed dimension
tolerances of the connecting rod as shown in table 4-47, exposure size
calculated figure 4-58.
Lr=A-B-ΔL+30-C
Lr-connecting rod in an exposed-end model
external dimensions (mm);
A--connecting rod length;
B-the fixed length of the connecting rod is
screwed into the socket:
Δ calculated after L-a Unbonded tendon tensioning elongation value
(mm);
C-side template thickness (mm).
3.6.2 swine anchorage system installed on
the fixed side: according to the design requirements of the elevation, will end
seven-hole anchor plates held together by wire prestressed tendons or muscles
attached and in its configuration with spiral reinforcement to enhance local
bearing strength of concrete. Heading should be flush with the anchor plate
snaps, wire, does not allow random phenomena.
3.6.3-anchorage system installed on the
tension side: when installing, the Unbonded Tendons from the bearing plate
reserve holes out, its perpendicular to the bearing plate sections with a wire
tie, beams exposed length inside of the end die straight section length see
table 4-47. When installing recessed concrete with tensioned anchorage side,
the plastic surface oiled to prevent bonding. While prior to pouring concrete,
outsourcing will be provided on the inner surface of the bearing plate of
prestressed tendons around the pipe along the cut, tension and then remove it.
3.6.4-anchorage system-end of installation:
fixed according to the design in the template, and configuration with spiral
reinforcement. Fixed by steel wire end need to be disseminated, steel arch
Board header.
3.7 fastening: check the protective plastic
sleeve without damage. Soft plastic and tie both ends to the protective sleeve
on the Unbonded tendons, and elevation according to the design of Unbonded tied
to end non-prestressed reinforcement or additional muscles, when binding,
Unbonded Tendons should be protected with the socket overlapped, and perpendicular
to the plate, in order to facilitate smooth pulled out of the socket when the
tension plate end.
3.8 arch: after you tie the non-prestressed
reinforcement, construction drawing design of Unbonded prestressed tendons in
number position, Unbonded, reinforced curved high point horse bench locations
are secured. Reinforced arch quality requirements as detailed in table 4-47.
3.9 concrete pouring and tamping:
3.9.1 the Unbonded Tendons assemblies after
the placement is completed, by the construction unit, quality inspection
departments, in conjunction with the joint hidden design unit test charge,
confirmed only after pouring concrete.
3.9.2 concrete pouring, forbidden step
stool and prevent touching stroke, sure Unbonded beams and anchor location accurately.
3.9.3 Zhang Laduan and end serious
vibration should be concrete, no leakage, and avoid the voids, its density, and
is strictly prohibited to touch the tension-side plastic sleeve, avoiding
impact tensioning sleeve off violations.
3.10 alpha anchor tensioning process:
3.10.1 construction preparation: tension to
remove location link, end templates, cleaning, scaffolding and a protective
barrier.
3.10.2 equipment installation: the tension
rod is screwed into the socket, installing Jack, tension lever lock nut (must
buckle). Jack installation location should be on the same axis with Unbonded
tendons, and perpendicular to the plate. Does not meet requirements, available
pads adjust pad on the end surface of the support frame.
3.10.3 tension: switch on pump, pressure.
When the hydraulic expression to 5MPa, stopped pressured, adjust the fuel tank
position, continued to pressure until the desired tension value is reached,
turn off the pump power, stop giving oil pressure. And then anchor glass
cleaner for cleaning outside, screw on the nuts, connect pump again, and pull
to tension, tighten the nut.
Electric oil pump under pressure, to
control the speed, to control the hydraulic oil time cannot be less than
0.5min.
Tensioning process, when the fracture
occurs when individual wires, can reduce tension. But the number of faults
should not exceed 2% of the same total number of prestressed tendons,
multi-span continuous two-way slabs, calculate the same section by each.
3.10.4 measuring record: in order to check
the pre value during stretching process, should be graded a random record
Unbonded tendon extension value. Normally each takes oil pressure reading to
10MPa multiple is appropriate.
Start to tension, Unbonded Tendons placed
in plastic sleeve is free, to use a certain tension tightening, so it is
difficult to measure the tension of the starting point, that is, of zeros of
Unbonded prestressed tendons stress, which in theory is to measure muscle
elongation value of tag.
0 points of determine method is: will Jack
pressure to 10MPa, in Jack Shang note mark, as measurement no bond reinforced
elongation value of starting points, see Figure 4-59 in the a, points, then
gradually increased pressure to 20MPa, until reached requirements of last
pressure value, and group records each level pressure Hou reinforced of
elongation value, can obtained Figure 4-59 in the b, and c, and d points. In
the elastic range, elongation proportional to the stress, so that the points in
Figure 4-59 in a straight line and extend the horizontal axis in O1, O1 is ask
zero, unbounded bundles total elongation values should be δ L1+ δ L2.
Elongation value is 10% when the measured
value of extension of the calculation above, should be studied.
Elongation elongation when the value 10%
value is greater than the calculated measured, should stop the tension, check
that the meter is in error and, if necessary, it should check and calibration.
When the observed elongation elongation
values less than the calculated 10%, should identify the reasons may continue
to pressure relax or Unbonded beams, a second tensioning, but neither tensile
stress over Unbonded tendon tensile strength of standard 75%.
3.10.5 anchorage and dismantling equipment:
tighten the nuts, but gradually oil, relaxing the Unbonded tendons and remove
Jack. Oil should slow in operation, shut off power, after moving the position
of valve oil return to, and then oil the piston back, dismantle the jacks.
Socket submerged errors causing tension to
meet the design requirements, glass exposed face is too long (greater than
50mm) or too short (less than 20mm), add nuts or socket connections should be
taken to anchorage.
3.11-anchor tensioning process:
3.11.1 construction preparation: before
tensioning plate surface should be cleaned, stripped of the exposed strands
(wires) outsourcing of plastic casing, check them one by one to anchor, no
rusted anchor. And one by one, measure the length of exposure of the Unbonded
tendons, recorded as the original length before tensioning.
3.11.2 tension: switch on pump, pressure,
when the pressure reaches 2.5MPa, stopped pressured. Adjust Jack's position,
and continued to pressure the tension until it meets the design requirements.
When Jin trip meets no tensioning required extension value, stretching to stop
in the Middle, as a temporary anchor, back Jack tour, and then a second
tensioning. Both the tension and stretching speeds to be consistent on both
ends, the pressure difference should not exceed 10MPa.
3.11.3 pushing and removal of equipment:
there are two ways, automatic hydraulic pressure and spring pressure. Hydraulic
pressure is used to manually pump top pressure pressure. When stretching to
control stress, stopped pressured, under the required pressure, using hand
pressure pump top pressure, pressure 30MPa, pushing and Jack slowly back to
oil, finally dismantled tensioning devices. By spring pressure, when tensioned
control stress, you can return, due by spring pressure is anchored, anchor
neck-in large secondary tension should be taken. The second tension, you must
remove the top pressure equipment, put on the supporting frame, Jack supports
on the members. Tension jacks and anchorage must be kept on the same axis,
pressure should be the design stress values. Using open type gaskets, pad in
Anchorage and bearing plate gaps.
3.11.4 measurement records: tensioned
Unbonded Tendons exposed length measurement again after subtracting measures
before measuring the length of income the difference between the actual
elongation values for which calculation length, its deviation is +10% or 5%.
3.12 anchorage zone of protection must be
adequate rust protection and fire safety measures to prevent moisture to enter,
rusted anchors or prestressed reinforcement.
There are two common approaches:
3.12.1 enclosed reinforced concrete ring
beam outside anchorage. Anchorage for influenza a, should oil the gun through
the socket within the ducts to the protective plastic sleeve and enough
lubrication antirust grease fill (grease ducts out from another), to
outsourcing of reinforced concrete. B type anchor, it should first be exposed
the Unbonded Tendons cut, leaving only 20cm, and then spread its bending and
pouring concrete.
3.12.2 anchor embedded in concrete
structure in advance until after tensioning, cutting away the excess of
Unbonded tendons (to abrasive saws, not arc or oxy-acetylene flame), epoxy
mortar used up.
3.13 Unbonded Tendons-tension after the
prestressing form should be filled in, operation signatures for future
reference. Archive: high strength steel wire or steel stranded wire, anchor
clamps factory certificate and retest report of mechanical properties of steel;
Unbonded prestressed reinforcement and anchoring clamp certificates; supporting
sensors, pump Jack calibration test; tensioning elongation of Unbonded records.
4 quality criteria
4.1 project:
4.1.1 production of Unbonded steel wire and
strand to be in line with national standards of the steel wire for prestressed
concrete
(GB5223-85) and of the prestressed concrete
steel strands (GB5224-85) requirements.
Inspection method: quality inspection
certificate and test report.
4.1.2 the Unbonded Tendons coating, coating
material shall conform to the provisions of the relevant standards of quality.
Inspection method: quality inspection
certificate.
4.1.3 use of Unbonded prestressed BUPC
swine anchor system, b-type anchorage quality shall conform to (DBJ01-7-90) the
relevant provisions of chapter III of part two. See 4-45.
Check amount: according to construction
specifications Chapter Sixth 6th. Article 2.12 extract specimens.
Inspection method: check the anchor factory
certification and inspection, hardness inspection, static load anchoring tests
report.
4.1.4 the strength of concrete provisions
must comply with the design requirements and specifications.
Inspection method: check the same condition
curing concrete block pressure test report.
4.1.5 anchoring phases stretching tendons
neck-in end, swine anchorage is not more than 1mm type b, anchorage is not more
than 5mm.
Inspection method: examination of
prestressing records.
4.1.6 heading strength shall not be less
than steel standard steel strength of 98%, its dimensions and appearance
quality meet the requirements.
Inspection method: check the heading test
reports.
4.2 Basic project:
4.2.1 each beam of Unbonded prestressing
anchorage actual prestressed value with design value is the relative tolerance
to ± 5%.
Inspection method: examination of
prestressing records.
4.2.2 broken wire and slide number should
be no more than one section of wire 2% of the total number of roots.
Check amount: total inspection.
Inspection method: comprehensive
observation or examination of prestressing records.
4.3 allowable deviation shall conform to
the requirements in table 4-47.
Unbonded Tendons end node installation and
beam deviation table 4-47
Tolerance (mm) method
End-node plate vertical deviation of ± 3
Screwed into the socket length
Anchoring-link
Show template dimensions not less than 20
+10
-5
Measurement
Unbonded Tendons-tension-side exposure of
dimensions not less than 600
Bar in tension-side template vertical plate
on the inside of the curve length of the straight section not less than 300
Spacing
Unbonded tendon control point rise errors
Standard deviation of 20
± 5
± 30 Visual horizontal even vertical
Entrance of Unbonded size detail
A not less than 75
B not less than 300
Measurement
finished product protection
5.1 the Unbonded Tendons shall be
classified according to different specifications into bundles, reels listed
stacked neatly. When air storage, need to cover ponchos, the following should
be added to wood to prevent anchorages and corrosion of Unbonded tendons, no
crash crushes stacked finished products, avoid damage to the plastic sleeve and
anchor, the anchor fixtures used for tensioning required coated oil in indoor
storage, to prevent rusting.
5.2 the Unbonded Tendons during transport
should travel light light discharge, no fall flip and sharp surface damage of
Unbonded tendons and accessories. Slings wire rope required plastic pipe, to
avoid damage when handling the Unbonded Tendons plastic sleeve, if shall
promptly plastic repair of damage, its winding rubber lap length 1/3 width.
6 quality problems to be noticed
6.1 Unbonded prestressed steel wire, steel
wire, dog leg is not allowed, see dog leg cut off. Each wire, steel wire should
be long, no joints.
6.2 the Unbonded Tendons selection, the
muscle length is less than 24m, and generally choose wire harness is greater
than 24rn, with an optional strand.
6.3 the Unbonded Tendons the design stress
σ con control for Prestressed reinforcement tensile strength of standard 70%
and, if necessary, can be increased to 75%. In order to reduce the relaxation
effects of prestressed reinforcement and construction method of hyper-tension
method can be used, but the maximum tensile force shall not exceed the standard
tensile strength of Unbonded Tendons 75%. Tensioning method usually uses a
hyper-tension, or 0 10% σ
→ con, or secondary, σ 0 → 100% con is relaxed to 0, plate pressed again after pulling 0 100% σ → con
(Con for design stress σ).
6.4 Unbonded curve when you configure both
ends or longer than 24m tension method, stretching speed two devices should be
consistent.
6.5 Unbonded tendon tension should be
carried out according to the design requirements, such as when there is no
special requirement, followed by stretching.
6.6 in order to avoid large-span
prestressed cast beam top during an additional bending moment bearing and the
column constraints impact beam bearing sliding hinged steel bearing can be
used, as described in Figure 4-60, after treating the tendons and, buried parts
of bearing and beam welding with concrete pouring qi.
Figure 41-steel bracket, 2-column
7 quality records
This standard shall meet the following
quality records:
7.1 the strength of concrete test piece
test report form.
7.2 Unbonded PC wire and strand the quality
certificate.
7.3 mechanical properties of PC steel wire
and strand test report form.
7.4 non-bond prestressed anchor certificate
and inspection records.
7.5 heading test reports.
7.6 tensioning equipment calibration
record.
7.7 for Unbonded Tendons laying hidden
inspection records.
7.8 record Unbonded prestressing.
7.9-end strength of concrete test piece
test report form.
7.10-side concrete cement factory
certificate.
7.11 the design requirements of other
technical information.
Because of the war, many people become homeless. I can't do it well. Please help me.my PayPal is xhhnet@163.com.
No comments:
Post a Comment