SERVICES OVERVIEW
Post-Tensioning In Building Structures
Post-tensioning is a method of reinforcing concrete or other construction materials with high-strength steel strands/wires/cables generally known as tendons, applications include office and apartment buildings, parking structures, slabs-on-ground, bridges, sports stadiums, rock and soil anchors, and water-tanks. The advantages of post-tensioning brings to a structure include large span, column free floor spaces and also reduces the amount of conventional reinforcement and concrete required thus delivering a more adoptable and environmentally friendly solution.
History
In 1872, P.H.Jackson (Billington, 2004), a Northern California Engineer, obtained a patent for post-tensioning.
In 1888 by C.W.doehring, who obtained a patent in Germany for pre-stressing slabs with metal wires/cables.
In 1940 Egene freyssinet introduced the system comprised of conical wedge anchors for 12 wire tendons.
In 1950s the post-tensioning is introduced in building structures in India.
In 1963, by T.Y.Lin come up with the load balancing which is a basics form of load balancing allows the engineer to view the effects of post-tensioning as a reduction in the desigh dead load applied to slab. As explained below
Why Post-Tensioning ?
Post-tensioning is the slab reinforcement process of choice for slab-on-ground, elevated slab applications and many more. This engineered solution creates cast-in-place, pre-stressed concrete by reinforcing the foundation after the concrete has been placed.
In post-tension construction, tendons are placed prior to concrete placement, and once the concrete reaches a specific initial compressive strength, the tendons are stressed to a specified force and anchored.
Post-Tensioning enhances concrete strength under both compressive and tensile stresses.
Post-tensioning external compressive force makes the concrete more resistant to the tensile stresses that would otherwise cause a foundation to pull apart and crack.
Post-tensioning offers number of advantages.
- Greater flexibility of design,
- Lower lifetime cost of the structure.
- Adaptability to most soil conditions.
- Reinforcement for a variety of applications.
- LEED points for green building initiatives.
Reinforced Concrete vs. Pre-stressed Concrete
Floor System and Suitable Arrangement for Slab
| Floor System | Span Range |
|---|---|
| Flate Plate | 7-10 MTR |
| Flat Slab With Drops | 8-12 MTR |
| Beam Slab | 8-16 MTR |
| Beam Waffle Slab | 10-20 MTR |
Why MPTS SYSTEM Post Tension?
What sets mpts Post-Tension apart from other mpts specialists are our breadth and scope of services, our commitment to excellence, and our strong, national presence.
MPTS Post-Tension is:
- The only national post-tension specialist with locations placed strategically across Amman-Jordan to ensure a secure supply of product for our customers.
- The largest provider of bonded post-tension materials in Amman, with the post-tension service expertise to match.
- A trusted resource for all kinds of post-tensioning services, including supply, design and even installation in select markets.
- An expert in foundation engineering, with registered professional engineers that can optimize foundation design to make the most efficient use of resources.
- mpts Amman leader in quality, on-time delivery and competitive pricing.
- Committed to excellence, with job site technicians that are highly trained and experienced in the placement and support services of post-tensioning materials.
Our Safety Commitment:
- At mpts Post-Tension, safety is always our top priority. Our safety program teams up employees to create accountability partnerships that promote safety awareness and prioritize safety procedures.
- mpts Post-Tension rewards teams that meet safety standards through a safety incentive program, and our in-house safety director is charged with monitoring the safety of each facility and job site…
Experience the MPTS Post-Tension Difference:
- Through innovative engineering, a flexible approach tailored to meeting our clients’ needs, and a commitment to providing the highest quality materials and services in the industry, MPTS Post-Tension has earned its status as the post-tension supplier of choice for builders across Jordan.
Post tensioning permits longer span than conventional reinforced concrete Large column free floor areas provide flexibility for internal planning and space utilization.
Two-way post tensioning flat slabs dispense with the requirement for drop beams, providing enhanced flexibility for space partitioning and for the placing of service networks. (HVAC, electrical, sanitary etc..)
The design of post tensioned flat slabs can cope with irregular grids and curved floor plates. Tendons can easily be profiled horizontally to suit any layout geometry or to allow for openings in slabs. 
Pre stressing with appropriate tendon profiling and resultant load balancing effects enables reduced slab thickness. Maximum ceiling services are available for horizontal services. 
The simple concept of post tensioned slabs has a reduced amount of ordinary reinforcement and flexibility in the positioning of openings and inserts for services.
Little coordination is required between designers for this purpose, and late modifications can be implemented without detriment to the initial structural and architectural design. 
By varying the amount of balanced post tensioning force, the designer is able to control deflection under service loads.
The concerns about the demolition or alterations of post tensioned slabs have been dispelled in recent years. Knockout zones can be easily identified for future service penetrations. Tried and tested methods are available to enable large openings to be formed subsequently in as built slab conditions, particularly for bonded slabs.
Due to minimal need for drop beams and the reduced slab thickness, minimum storey height is achieved, leading to a lower overall building height.
In situations where the height of the building is limited, the reduced storey height can allow for additional floors to be constructed within the building envelope. The reduced façade area, as well as the vertical runs of mechanical and electrical systems sees cost benefits.
Post tensioned floors being in compression, allow for easier control of cracking. If appropriate design criteria are applied, crack-free construction can be achieved. This is often exploited in car parks with concrete surfaces exposed to an aggressive environment. With reduced cracking and better water tightened the durability of the structure is improved.
Types of Post Tensioning
Bounded Post-tensioning
Bonded post-tensioned concrete is a method of applying compression after pouring concrete and during the curing process (in situ). The concrete is cast around a plastic/steel/aluminum circular/flat duct. A group of tendons/wires/cables are fished through the duct circular/flat and the concrete is poured, Once the concrete has hardened, the tendons are tensioned by hydraulic jacks that react (push) against the concrete member itself. When the tendons have stressed sufficiently, according to the design specifications, they are wedged in position and maintain tension after the jacks is removed; transferring pressure to the concrete, then duct is grouted to protect the tendons from corrosion.
Advantage of Bounded Post-tensioning System
- Large reduction in conventional reinforcement.
- Tendons cannot distress in accidents.
- Tendons can be easily ‘introduced’ allowing a more efficient design approach.
- Bond generated b/w the strand and concrete leads higher ultimate stress.
- No issues with maintaining the integrity of the anchor/dead end.
Advantage of Un-Bounded Post-tensioning System
- Reduces friction losses
- Grouting not required
- Smaller diameter
- Provides greater lever arm
- Simplifies prefabrications of tendons
- Faster Construction
Disadvantages of Un-bonded over Bonded Post-tensioning system:
“Cable can de-stress itself and burst out of the slab if damaged (such as during repair on the slab)”
Components Of Post-Tensioning
Bonded System
Un-Bonded
Applications of Post-tensioning system in building construction:
- Flat slab
- Beam and slab
- Podium slabs in low rise building
- Transfer plates
- Raft foundation
- Ground support slab in industrial areas
- Restore geometry in seismic frames
Factors Affecting the Cost of Post-tensioning
- Tendon Lengths
- Tendon Arrangement
- Structural System
- Treatment of Construction Joints
- Main Contractor
- Site Access
SLAB SYSTEM
The three most common floor systems used for building structures such as offices, shopping centers and carparks are the flat plate, flat slab and banded slab. For high rise construction a fourth system is widely used which consists of band beams at relatively close spacing spanning from the building perimeter to the service core.
Although economy of each of these depend primarily on the span and applied load, it is generally true to say that a band beam scheme is cheaper than a flat slab which in turn is cheaper than a flat plate.
Flat Plate
This system is commonly used in Sydney for high rise residential construction where the span is usually 7 to 8 metres, most attractive feature of this floor system is its flush soffit which requires simple formwork and greatly simplifies construction. The depth of a flat plate is often dictated by shear requirements. Thinner slabs or longer spans can be constructed if column capitals or shear heads are employed. Used Where spans are similar both directions
| Economic Span Range | 7.0 to 9.0 m |
| Imposed Loads up to | 7.5 kPa |
Flat Slab
The economical span range over a flat plate is increase by the addition of drop panels. The drop panels increase the flexural stiffness of the floor as well as improving its punching shear strength.
This system provides the thinnest floors and can lead to height reductions and substantial savings in facade costs.
| Used | Where spans are similar both directions |
| Economic Span Range | Up to 13.0 m |
| Imposed Loads | Up to 10.0 kPa |
Banded Slab
This system is used for structures where spans in one direction are predominant. The sides of the band can be either square, or tapered for a more attractive result. The band beam has a relatively wide, shallow cross section which reduces the overall depth of the floor while permitting longer spans. This concrete section simplifies the formwork and permits services to easily pass under the beams. The post-tensioned tendons are not interwoven leading to fast installation and decreased cycle time.
| Used | Span predominant in one direction |
| Economic Span Range | Band Beam: 8.0 to 15.0 m Slab: 6.0 to 10.0 m |
| Imposed Loads | Up to 15.0 kPa |
High Rise Banded Slab
This system has gained favour over the past 10 to 15 years for high rise construction and consists of band beams at relatively close centres spanning between a perimeter beam and the service core. The system suits system formwork due to the amount of re-use in high rise construction.
Services may either pass under the shallow bands or, alternatively, pass under service ‘notches’ in the band soffit. For clear slab spans in excess of 4.5m the use of post-tensioning is economical perpendicular to the bands and assist in reducing the weight of slab carried by the bands.
| Used | Long span high rise construction |
| Economic Span Range | Band Beam: 9.0 to 15.0 m Imposed |
| Loads | Up to 7.5 kPa |
GROUND ANCHORS
Structural Systems for Ground Anchors have been practiced worldwide, Ground Anchors comprised of wires, strands or bars can be installed into rock/soil and secured by injecting with cement grout. Standard Structural Systems Ground Anchors can provide an ultimate load of between 350kN and 22500kN depending on the configuration.
Common Types
- straight shaft gravity-grouted ground anchors (Type A);
- straight shaft pressure-grouted ground anchors (Type B);
- Post-grouted ground anchors (Type C).
- Under-reamed anchor (Type D).
Applications of Structural Systems Ground Anchors include:
- retaining structure tie backs
- Resistance of uplift forces
- Slope stabilization
- Underground structures
- Dam stabilization
- Tension foundations
- Soil nailing bar anchors
MULTI STAND SYSTEM
The multi strand/tendons system is used in bridge and transportation structures, bonded multi strand post-tensioning systems have also been successfully applied to commercial building construction, office buildings, condominiums, hotels, parking structures, slab-on-ground foundations, ground anchors, storage tanks, stadiums, silos, and bridges.
The systems are normally adopted for bonded tendons. The tendons consist of a bundle of strand with a nominal diameter of 0.5″ (12.7 mm.) or 0.6″ (15.2 mm.).
When bonded multi strand post-tensioning systems are used for large structural members, such as beams and transfer girders, design advantages include increased span lengths and load-carrying capacity and reduced deflection. Additionally, because the strands are stressed simultaneously, less labor is required resulting in cost savings.
The strands are individually gripped in one anchor head unit and transmit their pre-stressing force by means of anchor plate casting unit. For each anchor size, special spiral reinforcement is provided at the anchor plate casting to give adequate splitting reinforcement for bustling stresses developed at the anchorage zone.
The strands in tendon are stressed simultaneously by means of a multi strand stressing jack from capacity 1,100 KN up to 5,000 KN. The strands can also be stressed individually by means of mono jack.
RAFT & TRANSFER SLAB
Raft foundation is same to that of a floor slab turned upside-down. The distributed ground or soil pressure acts at the bottom surface and is held in equilibrium by the downward acting concentrated forces from columns and walls. The tendons are arranged as in an elevated slab, but with an inverted layout such that the low points are under the columns and walls, and the high points are in the spans.
In setting the slab depth, primary consideration is given to shear resistance and allowable soil pressure. Common L/h values range from 10 to 12, depending upon the modulus of sub grade reaction, the load magnitude and arrangement, the concrete strength, the level of stress, and the allowable differential deformation. Check of the punching shear resistance is generally performed. If the resistance is insufficient, the slab thickness can be increased overall, or just thickened under the columns.
To improve the tendons contribution for shear resistance and local flexural effects in the columns region, most of the tendons in each direction should be located in the column strips.
Raft thickness and pre-stressing requirements selection criteria as follows:
In buildings there are requirements of transfer slabs needed to transfer, at a certain level, some of the vertical loads to other alignments in order to obtain bigger spans at the lower levels, a more cost-effective structure, with smaller column or wall spacing can be envisaged for the upper floors, while at the lower levels, in particular at the ground level, bigger inter-column distances can be adopted, this is generally used at hotels for lobbies or where there is requirement of open space.
In order to transmit the high concentrated forces from the columns or wall, that have no continuity to the foundations, the transfer structures require, design dependant not only on the flexural behavior but, is considerably influenced by shear or punching resistance.
Due to the considerably high forces involved, the transition structure usually requires large depths and great amounts of reinforcement, in this case Post-tensioning is used, in these cases, a very cost-saving way to reduce both depth and reinforcement content & also provides a positive measure against early age shrinkage cracking in concrete.
SERVICES OVERVIEW
Post-Tensioning In Building Structures
Post-tensioning is a method of reinforcing concrete or other construction materials with high-strength steel strands/wires/cables generally known as tendons, applications include office and apartment buildings, parking structures, slabs-on-ground, bridges, sports stadiums, rock and soil anchors, and water-tanks. The advantages of post-tensioning brings to a structure include large span, column free floor spaces and also reduces the amount of conventional reinforcement and concrete required thus delivering a more adoptable and environmentally friendly solution.
History
n 1872, P.H.Jackson (Billington, 2004), a Northern California Engineer, obtained a patent for post-tensioning. In 1888 by C.W.doehring, who obtained a patent in Germany for pre-stressing slabs with metal wires/cables. In 1940 Egene freyssinet introduced the system comprised of conical wedge anchors for 12 wire tendons. In 1950s the post-tensioning is introduced in building structures in India. In 1963, by T.Y.Lin come up with the load balancing which is a basics form of load balancing allows the engineer to view the effects of post-tensioning as a reduction in the desigh dead load applied to slab. As explained below
Why Post-Tensioning ?
Post-tensioning is the slab reinforcement process of choice for slab-on-ground, elevated slab applications and many more. This engineered solution creates cast-in-place, pre-stressed concrete by reinforcing the foundation after the concrete has been placed. In post-tension construction, tendons are placed prior to concrete placement, and once the concrete reaches a specific initial compressive strength, the tendons are stressed to a specified force and anchored.Post-Tensioning enhances concrete strength under both compressive and tensile stresses. Post-tensioning external compressive force makes the concrete more resistant to the tensile stresses that would otherwise cause a foundation to pull apart and crack.Post-tensioning offers number of advantages.
- Greater flexibility of design,
- Lower lifetime cost of the structure.
- Adaptability to most soil conditions.
- Reinforcement for a variety of applications.
- LEED points for green building initiatives.
Reinforced Concrete vs. Pre-stressed Concrete
Why MPTS Post Tension ?
What sets MPTS Post-Tension apart from other PT specialists are our breadth and scope of services, our commitment to excellence, and our strong, national presence. MPTS Post-Tension is:- The only national post-tension specialist with locations placed strategically across the Amman Jordan to ensure a secure supply of product for our customers.
- The largest provider of bonded post-tension materials in Amman, with the post-tension service expertise to match.
- A trusted resource for all kinds of post-tensioning services, including supply, design and even installation in select markets.
- An expert in foundation engineering, with registered professional engineers that can optimize foundation design to make the most efficient use of resources.
- Amman Jordan leader in quality, on-time delivery and competitive pricing.
- Committed to excellence, with jobsite technicians that are highly trained and experienced in the placement and support services of post-tensioning materials.
- At MPTS Post-Tension, safety is always our top priority. Our safety program teams up employees to create accountability partnerships that promote safety awareness and prioritize safety procedures.
- MPTS Post-Tension rewards teams that meet safety standards through a safety incentive program, and our in-house safety director is charged with monitoring the safety of each facility and job site...
- Through innovative engineering, a flexible approach tailored to meeting our clients' needs, and a commitment to providing the highest quality materials and services in the industry, MPTS Post-Tension has earned its status as the post-tension supplier of choice for builders across AMMAN Jordan.
Types of Post Tensioning
Bounded Post-tensioning
Bonded post-tensioned concrete is a method of applying compression after pouring concrete and during the curing process (in situ). The concrete is cast around a plastic/steel/aluminum circular/flat duct. A group of tendons/wires/cables are fished through the duct circular/flat and the concrete is poured, Once the concrete has hardened, the tendons are tensioned by hydraulic jacks that react (push) against the concrete member itself. When the tendons have stressed sufficiently, according to the design specifications, they are wedged in position and maintain tension after the jacks is removed; transferring pressure to the concrete, then duct is grouted to protect the tendons from corrosion.
SLAB BONDED POST-TENSIONING SYSTEM WITH FLAT DUCT (LIVE END SHOWING)
Advantage of Bounded Post-tensioning System
- Large reduction in conventional reinforcement.
- Tendons cannot distress in accidents.
- Tendons can be easily 'introduced' allowing a more efficient design approach.
- Bond generated b/w the strand and concrete leads higher ultimate stress.
- No issues with maintaining the integrity of the anchor/dead end.
Components Of Post-Tensioning
Bonded System
Applications of Post-tensioning system in building construction:
- Flat slab
- Beam and slab
- Podium slabs in low rise building
- Transfer plates
- Raft foundation
- Ground support slab in industrial areas
- Restore geometry in seismic frames
Factors Affecting the Cost of Post-tensioning
- Tendon Lengths
- Tendon Arrangement
- Structural System
- Treatment of Construction Joints
- Main Contractor
- Site Access
SLAB SYSTEM
The three most common floor systems used for building structures such as offices, shopping centers and carparks are the flat plate, flat slab and banded slab. For high rise construction a fourth system is widely used which consists of band beams at relatively close spacing spanning from the building perimeter to the service core.Although economy of each of these depend primarily on the span and applied load, it is generally true to say that a band beam scheme is cheaper than a flat slab which in turn is cheaper than a flat plate.
Flat Plate
This system is commonly used in Sydney for high rise residential construction where the span is usually 7 to 8 metres, most attractive feature of this floor system is its flush soffit which requires simple formwork and greatly simplifies construction. The depth of a flat plate is often dictated by shear requirements. Thinner slabs or longer spans can be constructed if column capitals or shear heads are employed. Used Where spans are similar both directions.
Flat Slab
The economical span range over a flat plate is increase by the addition of drop panels. The drop panels increase the flexural stiffness of the floor as well as improving its punching shear strength.
This system provides the thinnest floors and can lead to height reductions and substantial savings in facade costs.
Banded Slab
This system is used for structures where spans in one direction are predominant. The sides of the band can be either square, or tapered for a more attractive result. The band beam has a relatively wide, shallow cross section which reduces the overall depth of the floor while permitting longer spans. This concrete section simplifies the formwork and permits services to easily pass under the beams. The post-tensioned tendons are not interwoven leading to fast installation and decreased cycle time.
High Rise Banded Slab
This system has gained favour over the past 10 to 15 years for high rise construction and consists of band beams at relatively close centres spanning between a perimeter beam and the service core. The system suits system formwork due to the amount of re-use in high rise construction.
Services may either pass under the shallow bands or, alternatively, pass under service 'notches' in the band soffit. For clear slab spans in excess of 4.5m the use of post-tensioning is economical perpendicular to the bands and assist in reducing the weight of slab carried by the bands. GROUND ANCHORS
Structural Systems for Ground Anchors have been practiced worldwide, Ground Anchors comprised of wires, strands or bars can be installed into rock/soil and secured by injecting with cement grout. Standard Structural Systems Ground Anchors can provide an ultimate load of between 350kN and 22500kN depending on the configuration.
Common Types:
- straight shaft gravity-grouted ground anchors (Type A);
- straight shaft pressure-grouted ground anchors (Type B);
- Post-grouted ground anchors (Type C).
- Under-reamed anchor (Type D).
Applications of Structural Systems Ground Anchors include:
- retaining structure tie backs
- Resistance of uplift forces
- Slope stabilization
- Underground structures
- Dam stabilization
- Tension foundations
- Soil nailing bar anchors
MULTI STRAND SYSTEM
The multi strand/tendons system is used in bridge and transportation structures, bonded multi strand post-tensioning systems have also been successfully applied to commercial building construction, office buildings, condominiums, hotels, parking structures, slab-on-ground foundations, ground anchors, storage tanks, stadiums, silos, and bridges.
The systems are normally adopted for bonded tendons. The tendons consist of a bundle of strand with a nominal diameter of 0.5″ (12.7 mm.) or 0.6″ (15.2 mm.).
When bonded multi strand post-tensioning systems are used for large structural members, such as beams and transfer girders, design advantages include increased span lengths and load-carrying capacity and reduced deflection. Additionally, because the strands are stressed simultaneously, less labor is required resulting in cost savings.
The strands are individually gripped in one anchor head unit and transmit their pre-stressing force by means of anchor plate casting unit. For each anchor size, special spiral reinforcement is provided at the anchor plate casting to give adequate splitting reinforcement for bustling stresses developed at the anchorage zone.
The strands in tendon are stressed simultaneously by means of a multi strand stressing jack from capacity 1,100 KN up to 5,000 KN. The strands can also be stressed individually by means of mono jack.
RAFT & TRANSFER SLAB
