back
Multistrand Post-tensioning:
With tendon Capacities up to
Monostrand Post-tensioning can be used in almost every work related with post-tensioning
- Slabs on ground
- High rise slabs
- Water tanks and silos
- Tie backs
- Structural Repair
PDF brochure to download:
We use DEL technology:
|
Multistrand Post-tensioning
The DEL Post-tensioning Systems are the result of a constant, ongoing evolution in Materials, Equipment and Techniques, focusing in field installation simplicity, while assuming the necessary requirements of quality, reliability, safety, serviceability, practicability and durability of structures in which they may be used, otherwise stated in the main international post-tensioning standards.
After 20 years of designing, testing, manufacturing and installing, originally in Mexico, then elsewhere, DEL Post-tensioning products, as well as theri related Construction Systems have won a deserved reputation for service and dependability.
Applications
- Beams, Columns and Slabs. To resist bending moments and shear forces.
- Beams, Columns and Slabs. To resist bending moments and shear forces.
- Cantilever Bridges. To prevent deformations on the done segment and to resist bending moments and shear forces.
- Incrementally Launched Bridges. To join segments and resist bending moments and shear forces during launching.
- For Precast Segmental Bridges. To join segments and resist bending moments and shear forces.
- Stay & Suspension Cables for bridges and other structures. To carry the weight of the superstructure and resist bending moments and shear forces.
- Ground Anchors. For stabilization of excavations.
- Tanks, towers and silos. To resist internal pressure and avoid fissures.
- Lifting, lowering, pushing, pulling, pile driving and pipe jacking.
- Unification of two or more parties.
Advantages
- Stress forces up to 1200 Mtons.
- Jacks available for the most common tendon compositions.
- Jack with frontal or rear, simultaneous, automatic gripping with hydraulic wedge setting.
- Strand stressing tails shorter than 35cm.
- Quick stressing operations: one 12 strand tendon in less than 5 minutes.
- Light, small, handy and durable equipment.
Materials
Anchorages
- AS Active, Standard
Active or Stressing anchorages are those located at the stressing ends of tendons. AS anchorages are supplied including wedges, wedge & bearing plates, transition and grout port. Grout caps, when and as required. Design may specify active anchorages on both ends of a P.T. tendon even though stressing is carried out at one only. For wedge seating loss recuperation, shims can be placed between wedge plate and bearing plate, through a lift-off. - AE Active for External Post-tensioning
Adjustable an esay to install and remove, AE anchorages have been specially developed to withstand the dynamic actions ocurring at the ends of external tendons, and to ensure a correct grouting or filling of protectio pipes. They are supplied complete with wedges, threaded wedge plate & nut, capsule, bearing plate, form tube, strand concentrator and grout vent. Where adjusting is not required, shims are provided instead of nut.
For Multistrand Ground Anchors, AE type anchorages adapting to Design’s needs are used at the stressing end. - AR Active,Adjustable
For tension adjustment after lock-off.They are supplied complete as for AS type, including adjusting nut. - PA Passive, Bonding
Passive or Fixed Anchorages are those used at the non stressing ends, for which room must be provided in the Design. Supply includes base, bearing and head retention plates, and transition. They may be substituted by AS anchorages with a wedge isolation box. - PC Passive with Swage Heads
Same as PA when room for bond length is not available. Supply includes base, bearing and head retention plates, and transition. They may be susbstituted by AS anchorages with a wedge isolation box. - AF Active for Flat tendons
They are typically used in bridge or building slabs and tank walls, when concrete cover is a must for corrosion protection. Stressing is done strand by strand with standard Monostrand Jacks. Available in sizes up to 4 strands, they are supplied with wedges, wedge/bearing plate, transition and grout port. Pocket formers and grout caps, whether and as required.
Couplers
- F Fixed.
Used for prestressed concrete elements’ post-tensioned connection. Also called Continuity Anchorages - M Mobile
For multistrand cable extension. Used mostly in repair jobs for big size cables. They are supplied complete with strand concentrators & deviators, single couplers, shell and grout ports.
Sheaths
DEL corrugated steel and plastic, flat and circular sheaths are supplied at client’s convenience, as per current quality standards. Supply includes grout vents to be placed at selected points.
There is a sheath size for every anchorage size & type as shown in table.
For steel galvanized or bright circular sheaths machines are available. This is a recommended option for remote sites. See equipment pages for details.
Equpiment
Jacks:
- E jacks
DEL Multistrand Pumping Units include all the hydraulic control devices for the operation. They have been ergonomically designed for heavy duty and low maintenance. Electrical or gas power, optionally. Two circuit, for Stressing and Retraction. They work at mid-high oil pressure for lowest maintenance, in accordance with their corresponding E jacks.
- T jacks
Three circuit, for Stressing, Retraction and Wedge Seating, they feature 2 gauges for superior control. Used with T jacks.
see more details
Pumping Units:
DEL Multistrand Pumping Units include all the hydraulic control devices for the operation. They have been ergonomically designed for heavy duty and low maintenance. Electrical or gas power, optionally.
- T Pumps
Three circuit, for Stressing, Retraction and Wedge Seating, they feature 2 gauges for superior control. Used with T jacks. - E Pumps
Two circuit, for Stressing and Retraction. They work at mid-high oil pressure for lowest maintenance, in accordance with their corresponding E jacks.
Grouting Machine DEL
Grouting Machine:
The mixture of cement, water and admixtures must be done under a strict mixing time and velocity control and must not contain lumps nor any air bubbles during injection into the ducts.
DEL grouting machines include the mixing and injecting operation in a single piece of equipment, easily handled, with pressures of up to 25 bar, without the presence of air bubbles, using any type of cements and admixtures.
Strand Pushing Machine:
Used to place the strands inside the ducts when manual placement is difficult. Hydraulic-action DEL pushing machines have been sucessfully used in cables more than 100 meters long in all diameters and types of curvatures.
1. Strand Pushing Machine 2. Sheath fabricating Machine
Sheath fabricating Machine:
They work with bare or galvanized steel sheets and are able to fabricate sheaths up to 200 mm inner diameter at the highest speed.
They are supplied complete with deformation tools, feeding reel and cutting device.
Monostrand Post-tensioning
Comparison between reinforced concrete slabs and DEL monostrand postensioning system
The prestresed concrete optimizes the basic materials characteristics for building any kind of structure. MEXPRESA has the most efficient and advanced procedure and techniques for structural analisis so the design results are always optimal.
To understand the difference between the two procedures (reinforced and postensioned concrete slabs)
Characteristics of the reinforced concrete slabs
- Less space between columns
- Need of beams
- Higher buildings
DEL monostrand postensioning system
- More space between columns that means comfort and better use of areas.
- No need of beams, which means an even surface and easier construction.
- Lower buildings
MEXPRESA offers the following services:
- Structural Design
- Monostrand Post-tensioning
- A great variety of concrete forms.
