Suspender and tie bar cable system
- 产品详情
Suspender and tie bar cable system
The suspender cables mainly include parallel steel wire cables and steel strand cables, which are mainly used in cable-stayed bridges, arch bridges, suspension bridges and other bridge structures.
Parallel steel wire cable is a kind of combined system of hot extrusion HDPE high strength steel wire and cold casting heading anchor, which is composed of internal and external dampers, waterproof cover, anchor head protection cover and other accessories. The products comply with GB / T 18365-2001 "technical conditions for hot extruded polyethylene high strength steel wire cables for cable stayed bridges" and JT / T 775-2016 "parallel steel wire cables for long span cable stayed bridges".
Extrusion anchorage steel strand cable is a combination system of steel strand cable body and whole bundle extrusion tracing head. It has the characteristics of reliable anchorage, good fatigue resistance, fully sealed structure and compact structure. It is suitable for new arch bridge suspension bridge or old bridge cable replacement. The product complies with JT / T 850-2013 "extruded anchorage steel strand cable".
Qsmxg tie bar anchorage system is a new type of steel strand tie bar anchorage system. It adopts all anticorrosive structure and is equipped with high reliable anchoring performance under low stress state.
● QSM suspender cable system
System introduction
The suspender system is a new type of suspender anchorage system developed on the basis of the original suspender. It covers a number of new technologies and new structures, such as new low stress anti-corrosion cable body, epoxy coated high-corrosion steel wire, epoxy coated steel strand, new waterproof sealing device and ball hinge device, which can solve the problem of short-time cracking of HDPE casing, water inflow at the lower end, and inadaptability of short suspender to deformation In order to improve the safety and durability of the boom. The suspender cable mainly includes: cold casting heading anchor steel wire cable, GJ type steel strand whole bundle extrusion cable.
QSM arch bridge suspender cable system mainly includes the following basic contents:
● cable body ● anchoring device ● damping device ● anti-corrosion device ● monitoring system
Boom form
At present, our company's suspender has the following three forms
（1） Cold casting heading anchor steel cable
1. Main technical performance indexes
① The static load performance meets the requirements of GB / T 14370-2015 anchorage, fixture and connector for prestressed tendons: the anchorage efficiency coefficient η a ≥ 95%, ξ APU ≥ 2%.
② The fatigue performance meets the requirements of GB / T 18365-2001 "technical conditions for hot extruded polyethylene high strength steel wire cables for cable stayed bridges". It can pass 2 million fatigue tests of 0.4 σ B stress upper limit and 0.28 σ B stress lower limit, and the total number of broken wires is less than 5%.
③ The HDPE performance of cable body meets the requirements of GB / T 18365-2001 "technical conditions for hot extruded polyethylene high strength steel wire cables for cable stayed bridges" and CJ / T 297-2016 "high density polyethylene sheathing materials for bridge cables".
④ Properties of high strength steel wire: tensile strength ≥ 1670mpa, other properties shall not be lower than the requirements specified in GB / T 17101-2008 hot dip galvanized steel wire for bridge cables.
⑤ Elastic modulus of cable: e ≥ 1.9 × 105Mpa.
⑥ Waterproof performance: fully sealed waterproof structure.
⑦ The static stress release coefficient of HDPE is k > 0.3;
⑧ The maximum allowable rotation of spherical bearing: a = ± 4 °.
2. Design and selection suggestions
In order to ensure the safety of the structure, it is suggested that the safety factor of the suspender be greater than 2.5 ~ 3. If the safety factor is too large, the cable body will not be straightened. It is suggested that the actual stress of the cable should not be less than 20% of the nominal breaking force of the cable body to ensure that the cable body does not bend.
In structural design, the position of the shortest rod should be reasonably arranged, and the free length of the shortest suspender (excluding anchorage at both ends) should not be less than 2m.
In order to ensure the waterproof of the lower end, the lower cable conduit must be extended 100-150 mm out of the bridge deck structure.
In order to facilitate cable replacement, double suspender structure is recommended if the structure allows.
3. Structure and parameters of hanger cold casting anchorage
Cold cast heading anchor (cold cast anchor) is usually used as the anchor head of parallel steel wire cable. Its main structure includes: cover plate, nut, anchor cup, restraint ring, filling material, sealing device, etc.
The steel wire with diameter of φ 7 or steel wire with diameter of φ 5 should be used preferentially for parallel steel wire stay cables of cable-stayed bridge.
4. Cable body composition
The cable body is composed of high strength steel wire, anti-corrosion grease, winding tape, inner PE and outer PE.
（2） Extrusion anchorage steel strand cable
The extruded anchor steel strand cable includes fixed end and tension end, with reliable anchorage, convenient tension and adjustment, compact anchor head structure, good fatigue and anti-corrosion performance. It is suitable for new arch bridge suspension bridge or old bridge cable replacement. The product complies with the standard of JT / T 850-2013.
1. Main features
① The two ends of the steel strand are extruded and anchored, and the stress of each strand is isolated from each other. The steel strand is difficult to fall off. Its static load is safe and reliable, and its fatigue performance is good.
After the two ends of the steel strand are squeezed into the anchorage sleeve, the holding force of the anchor head to the steel strand will not change again, and the retraction is very small during the tension, and the steel strand will not slip off under the condition of low stress or even negative stress. The bending angle of the steel strand entering into the anchor head is very small and almost free from bending stress. The whole bundle of isolated extrusion anchor of steel strand is mainly anchored by friction force, so its fatigue performance is very good.
② The structure of anchor head is compact, which is conducive to the optimization and beauty of the overall structure.
In the case of the same stress level, the external dimension of the extrusion anchor head is much smaller than that of the cold cast anchor, hot cast anchor and clip anchor, which can reduce the size of the embedded pipe, and facilitate the connection of steel tie rod, fork lug and other structures, which brings great convenience for the installation and replacement of the bridge. Moreover, the steel strand (1860MPa) with higher strength than steel wire (1670mpa) is adopted. Under the same design stress, the total cross-sectional area and total weight of cable can be reduced a lot, which makes transportation more economical and convenient.
③ The anchor head adopts fully sealed structure with good anticorrosion and protection performance.
After the anchor head is extruded, there is a sealing cover plate at the front end of the anchor head, and the PE part of the cable is sealed by the sealing cylinder and sealing device at the rear. Then, the elastic wrapping material is poured into the anchorage cavity for anti-corrosion, and the steel strand is completely and permanently isolated from the outside air and water vapor. After construction, the anchor head is coated with special anti-corrosion grease, which requires that the external surface is completely covered, and then the protective cover is installed. Because of the multi-layer protection, its permanent protection performance is quite reliable. Extrusion anchorage and its cable production, processing, assembly are completed in the factory, in the form of finished cable sent to the construction site, its quality is guaranteed.
2. Main performance indexes
① The static load performance meets the requirements of GB / T 14370-2015 anchorage, fixture and connector for prestressed tendons: the anchorage efficiency coefficient η a ≥ 95%, ξ APU ≥ 2%.
② The fatigue performance meets the requirements of pti-2003 regulations for design, testing and installation of stay cables. It can pass the fatigue test of 200 MPa and 0.45 σ B stress limit for 2 million times, and the broken wire rate is less than 2%.
③ It can meet the requirements of DG / T j08-019-2005 technical specification for application of cables for building structures: it can pass 2 million times of fatigue test with stress amplitude of 250Mpa and 0.45 σ B upper limit stress, and the wire breaking rate is less than 2%.
④ The HDPE performance of cable body meets the requirements of CJ / T 297-2016 "high density polyethylene sheath material for bridge cables".
⑤ Performance of steel strand: tensile strength ≥ 1860MPa, other properties shall not be lower than the requirements specified in GB / T 5224-2014 steel strand for prestressed concrete.
⑥ Elastic modulus of cable: e ≥ 1.8 × 105Mpa.
⑦ Waterproof performance: fully sealed waterproof structure.
3. Parameters of steel strand extrusion cable anchorage
QSM extruded cable anchorage (fixed end) type A
QSM extruded cable anchorage (tension end) type B
QSM fork lug type extruded cable anchorage type C
Suggestions on design and selection
1. The free section length of the shortest cable should not be less than 2m;
2. In order to ensure the safety of the structure, it is suggested that the safety factor of stay cables η ≥ 2.5 ~ 3;
3. In order to ensure the waterproof and rust proof of the anchor end of the cable, the lower embedded pipe must be extended out of the bridge deck structure for 100-150 mm when it is used for the suspender;
4. Apply anti-corrosion grease on the outer surface of anchor heads at both ends before sealing;
5. Screw in position of nut: the installation position of nut is recommended to be set in the middle of effective thread section of anchor cup, and it is forbidden to screw in the part with internal thread.
4. Steel strand extrusion cable body
Note: the steel strand in the finished cable can be smooth, galvanized, epoxy sprayed or epoxy filled.
● tie bar
Qsmxg tie bar anchorage system is a new type of steel strand tie bar anchorage system. It adopts all anticorrosive structure and is equipped with high reliable anchoring performance under low stress state.
The characteristics of tie bars are as follows:
1. The strength of steel strand tie rod is high and the stress loss is small;
2. The cable body adopts finished steel strand cable, which is compact in structure and convenient in design;
3. Convenient construction, simple operation and easy quality control;
4. It has multi-layer protection and excellent anti-corrosion performance。
Structural drawing of qsmxgk replaceable cable type steel strand tie bar
Structural drawing of qsmxgy permanent anchoring steel strand tie bar
Precautions for use of tie bar:
1. In order to ensure the waterproof performance of the tie rod, the embedded pipe of the suspender shall extend above the top of the tie bar box at the place where the suspender passes through the tie bar box, and reliable waterproof measures shall be taken for the suspender to prevent water from entering into the tie rod box along the suspender;
2. In order to ensure the overall anti-corrosion of the structure, the embedded pipe should extend 150 ~ 200 mm out of the arch seat structure;
3. The adjusting nut of tie rod is installed in the middle of support barrel or anchor cup.
Supporting frame structure and parameters:
In the free section of the tie bar, the supporting frame should be used to support the cable body to protect and reduce the friction loss during tension. The supporting frame is a standard type of combined support frame, which can be set in multiple layers. The structure, installation and parameters of the support frame are shown in the following table.
Structural drawing of steel strand tie bar supporting frame
Installation diagram of steel strand tie rod support frame
Installation diagram of tie bar support frame in multi-layer setting
Construction technology
1. If both ends of suspender cable are nut type, tension construction can be carried out as shown in the figure below after installation.
2. If one end of the suspender cable is nut type and the other end is fork lug type, it is recommended to install the fork lug at the upper end to facilitate the tensioning operation at the lower end. After installation, the tension construction can be carried out according to the above figure.
3. If both ends of suspender cable are fork lug type (as shown in the figure below) and adjustment device is required, special tooling equipment shall be used for tension after the suspender is installed.
Note: the parameters are shown in the "QSM fork lug type extrusion cable anchorage C type parameter table", and the specification and form of the regulating device are actually designed according to the design requirements.
Construction precautions
1. According to the type and specific situation of the cable, prepare the required relevant accessories and auxiliary construction equipment (such as tensioning machines and tools).
During lifting, the cable must be stable to avoid accident.
3. The anchor plate should be vertical to the extension direction of the cable when it is installed, and shall not be inclined.
4. Clean up the construction site, and clean up the support duct and surrounding.
5. The anchor head shall be kept clean and free from corrosion, and the anchorage shall not be damaged by bumping and knocking, and the surface shall not be attached with other substances affecting the tension construction and anchoring.
6. Enough installation and tensioning space shall be ensured, and the cable body shall not be damaged during installation.
7. The cutting length must be accurately calculated, and the adjustment range required for the reserved tension should be calculated to avoid the cable being too long or too short to meet the use requirements.
8. The surface of free section cable body shall not be damaged. If there is any damage, it must be repaired in time.
9. After tensioning, the anchor head shall be kept clean, and anti-corrosion grease shall be poured or applied, and anti-corrosion protection shall be done.