With the above-mentioned advantages and economics becoming prominent, post-tensioning in buildings is becoming a trend in the region and world over. The economics are being harnessed in each and every possible way by the client and the contractors, by selecting post-tensioning for their projects. Thus, in all, there is a good scope of growth for post-tensioning ahead.
The other is bonded system that consists of3 Types of anchorage systems (3BS13,4BS13, 5BS13) with the multistrand flat ducts.
The C-Post Co., Ltd uses the “ANCHOR post-tensioning system” Developed by Dr. BijanO. Aalami and our company.
The strands are individually gripped in one flat anchor head unit that consists of Block and Guide. The strands are stressed individually by means of mono strand jack and their prestressing forces shall be transmitted by means of a flat type anchorage system. The strands are contained in one flexible flat duct which is made of corrugated galvanized metal. To ensure corrosion protection and to give adequate bond strength, the tendons are filled with suitable cement grout mix after the complete stressing of the strands.
The same anchorage for stressing anchorage can be used as dead-end anchorage in which case the wedges are presented in the anchor head unit by applying nominal force to the strand using the stressing jack.
Alternatively, an onion dead-end anchorage can be used with a simpler solution and more cost-effective. In this case, each strand is formed into an onion shape by means of a special forming jack.
The other civil structure such as bridges, silos, etc. is normally applied by the multi-strand systems. The system is normally adopted for bonded tendons that consist of a bundle of the strand with a nominal diameter of 0.5”(12.7 mm) or 0.6” (15.2 mm). The number of strands per tendon can be from 7 strands up to 19 strands. The tendons are contained in one round duct which is made of corrugated galvanized metal.
A brief overview of post-tensioning has been presented here, followed by its advantages and economics.
Post-tensioning is the technique of pre-loading the concrete in a manner that eliminates, or reduces, the tensile stresses that are induced by the dead and live loads; High-strength steel wires called strands are arranged to pass through the concrete floor. When the concrete has hardened, each set of strands is gripped by means of a hydraulic jack and stretched to a pre-determined force. At this stage the strands are locked in a purpose-made device called an anchorage, which has been cast in the concrete; this induces compressive stress in the concrete. The strand is thereafter held permanently by the anchorage. The non-jacking end of the strand may be bonded in concrete or may be fitted with a similar device on the other end as the case may be. In order to allow the strand to stretch in the hardened concrete under the load applied by the jack, the bond between the concrete and strand is prevented by a tube through which the strands pass. This tube is termed duct or sheathing and is made of galvanized iron. After stressing the duct is filled with grout material. Grout filling of ducts transfers the load to the entire concrete element and ensures corrosion protection.
Post Tensioning offers various advantages, some of which have been listed below:-
• Larger Clear Spans
• Thinner Slabs (Spans of 7mm to 8mm = 210mm thick slab)
• Lighter Structures
• Reduced Cracking
• Reduced Deflection
• Rapid Construction
• Better Water Tightness
• Less Manpower
• Reduced Passive Reinforcement
Conventional reinforced concrete slabs are best suited for spans up to 7m to 8m and also where the spans are uniform and formwork is simple so that farmworkers can work quickly. This is common in simple residential blocks up to three stories. Further, in the driveways often wider spans are required to provide parking access. More columns and thicker slabs are required for conventionally reinforced slabs, and this is where the labor costs come in. As in post-tensioned slabs, the slabs will be thinner, with larger spans and thereby reduced columns and formworks. The works can be carried out faster, and also the slab can be de shuttered quicker than conventional slabs.
The C-Post is one of the leading Thai companies in the design, production, and installation of post-tension slabs. The company is operated by a group of engineers and technicians who have had high knowledge and experience in his business for many years. With continuous technical and service improvements to meet our customer satisfaction. We also would like to make sure that our products and services will optimize your needs.
The C-Post Post-tensioning product is designed and manufactured under the quality program to meet international standards. The products comprise a complete range of post-tensioning components including.
There is 2 system for the Post-tension slab. One is an unbounded system that consists of cast iron (FCD45) anchorage an mono strand with a nominal diameter of 0.5”(12.7mm.) inserted in PE. Duct with grease
ESFPT has been working in Buildings as well as bridge structures and it has been nominated by world-class systems for its applications in the respective fields.
ESFPT has been nominated to adopt a bonded system for post-tensioning by C-Post in the Middle East and other major parts of the world as well.
C – Post is one of the leading companies with its own post-tensioning system. Also apart from the system production, it has its own design and execution divisions as well.
C-Post is also into the post-tensioning works of special structures like silos, tanks, etc. Apart from post-tensioning C-Post is involved in the Pre cast Concrete Wall Panels and Pre cast Concrete Elements. The system supplier’s company profile has been attached for reference.
MEXPRESSA is devoted to the Development and Site implementation of highly technified construction systems for large structures, mainly bridges and buildings. Since 1976 MEXPRESA has been an active partner in the construction of relevant bridges and structures in Mexico and elsewhere; from detailed design through on-site furnishing of purpose materials, equipment, and personnel. ESFPT has been appointed to solely adopt the bridge post-tensioning system of MEXPRESSA.