AMSYSCO Post Tension Blog

Updated PTI Specification Requiring Encapsulated Tendons

admin — Thu, 19 Jan 2012 20:45:35 +0000

The following is a press release from the Post-Tensioning Institute which requires the use of Encapsulated Tendons for all unbonded PT buildings subject to ACI-318.

Release:

NEW PTI SPECIFICATION UPDATE REQUIRES THE USE OF ENCAPSULATED TENDONS

FARMINGTON HILLS, MI (January 16, 2012) – The Post-Tensioning Institute (PTI) has announced a new specification update approved by the PTI Board of Directors and the Technical Advisory Board. Addendum #3 to PTI M10.2-00 Specification for Unbonded Single Strand Tendons requires the following:

All unbonded single strand post-tensioning tendons used for structures designed in accordance with the Building Code Requirements for Structural Concrete (ACI 318) must be encapsulated. The encapsulation of the tendons shall be in accordance with the material requirements for aggressive environments in the PTI Specification for Unbonded Single Strand Tendons (PTI M10.2-00).

The intent is to augment the durability of the post-tensioning systems used for all applications governed by ACI 318. Encapsulated systems provide additional protection of the prestressing steel regardless of location of the structure or exposure to moisture intrusion from any source.

Addendum #3 to PTI M10.2-00 Specification for Unbonded Single Strand Tendons is available for free download on PTI’s website at http://post-tensioning.org/Uploads/Addendum3.pdf .

Source: http://www.post-tensioning.org/press_releases_details.php?id=21

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Missed Stressing Operation

nkhosa — Sun, 18 Dec 2011 17:00:51 +0000

Q: What happens if you forgot to stress an unbonded post-tensioning tendon at the construction joint and have already poured the subsequent pour?

A: The most preferred option is to stress the tendon in the subsequent pour. However, the following items should be factored in:

a) The 7% Elongation Range must be revised.

Since you have a longer pull, the elongation calculation needs to be revised also. This should be noted in the elongation records from the PTI-Certified Inspector. A thumb-rule is to just add Min1+Min2 and Max1+Max2 together. For example,

First pull of 50′ would be Min1 = 3.72″ and Max1 = 4.28″
Second pull of 100′ would be Min1 = 7.44″ and Max1 = 8.56″
New elongation range for 150′ pull would be Min1 = 3.72″ + 7.44″ = 11.16″ and Max1 = 12.84″.
The new range is an close approximation. A more accurate range can be calculated with PT software. This is especially important for very long pulls.

b) The force in the tendon will likely be less.

Since the stressed tendon length is now longer, your angular and wobble friction have likely increased somewhat due to the increased number of spans. In other words, the final average force will drop in both pours for that particular tendon.

Previously, the 50′ pull may provide 27.5 kips of force in Pour #1.
Previously, the 100′ pull may provide 27.3 kips of force in Pour #2.
Now, the 150′ pull may provide only 26.9 kips of force in Pours #1 and #2.

c) The intermediate anchor has been abandoned.

The force within the 150′ tendon will be transmitted uniformly through the construction joint. Conversely, the 50′ tendon transmits force only within Pour #1 and the 100′ tendon transmits force only within Pour #2 (i.e. the construction joint “locks-off” the force within each pour). This is important should be there be any repair/renovation conducted in the future.

- Neel Khosa, Vice President, AMSYSCO

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Scholarship for College Students – Post Tensioned Concrete

admin — Thu, 10 Nov 2011 15:38:57 +0000

PTI AMSYSCO Scholarship Program

The new PTI AMSYSCO Scholarship program has been recently established by AMSYSCO, Inc. to commemorate the company’s 30 years in the post-tensioning industry. In announcing this new scholarship program, AMSYSCO owner, Rattan Khosa said

“Last week AMSYSCO completed 30 years in business. Only in this great country America, one can come with just $8 and later start a business in a basement. Over the years, I have been returning to the community, part of what I make every year, through my private foundation named after my parents. I thought it was time that I did something for the post tensioning. It will be great to award scholarships through PTI.”

The AMSYSCO Scholarship will provide two engineering students with $2,500 each for the Winter/Spring 2012 school term.

The student must attend an U.S. engineering undergraduate or graduate program with preference given to those attending the University of Maryland, and the University of Illinois at Urbana, IL.
The student is required to be in good standing academically and must be pursuing a civil and/or structural engineering degree.
Preference will also be given to students studying and/or researching in the field of post-tensioned concrete.

Award recipients will be selected and announced March 30, 2012. In addition, the award recipient will be honored at an awards ceremony that will be held in conjunction with the Post-Tensioning Institute’s 2012 Annual Technical Conference.

The student will be invited to attend the conference and awards presentation at PTI expense. Please refer to information below to apply:

These forms are also available in Microsoft Word file format. Contact PTI and request the 2012 PTI AMSYSCO Scholarship package

Application deadline: February 29, 2012

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The content of this post is provided from the Post-Tensioning Institute. The scholarship selection process will be managed by the Post-Tensioning Institute.

http://post-tensioning.org/student_competitions.php

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Pictures of our 30th Anniversary Employee Party

admin — Fri, 21 Oct 2011 23:11:30 +0000

AMSYSCO celebrated it’s 30th anniversary in business with some food and cake. Enjoy some of the green-themed pictures.

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Job Opening – Plant Supervisor

admin — Fri, 07 Oct 2011 14:59:08 +0000

Plant Supervisor

AMSYSCO, Inc., 1200 Windham Parkway, Romeoville, IL 60446

Job Description

AMSYSCO is the largest supplier of the post-tensioning steel tendons on commercial structures in the Midwest. The company has an immediate opening and is seeking a highly-motivated Plant Supervisor to run the manufacturing plant in Romeoville, IL. The individual will plan and direct personnel and oversee the daily product, manpower and manufacturing operations.

Fax one-page resume and cover letter to 630-296-8380 or email to info@amsyscoinc.com. Salary range will depend on work experience. Past experience with post-tensioning is not required.

Desired Skills & Experience

Main responsibilities include:

- Scheduling of plant production and shipments

- Inventory control.

- Quality control.

- Plant certification program.

- Maintenance, servicing and calibration of equipment.

- Supervision of plant workers.

- Ensure safe work environment.

- Travel to jobsites.

Individual is required to have:

- Computer skills (MS-Word, Excel, Outlook).

- Customer service skills (English required, Spanish optional).

- Manufacturing-related degree (Minimum of community or technical college).

- Mechanical aptitude with hands-on attitude.

- Valid U.S. driver’s license.

- Valid employment documents to work in U.S.

Company Description

AMSYSCO, Inc. has been serving the needs of construction contractors and structural engineers since 1981. During this time, we have transformed from a small player to a leading unbonded post-tensioning supplier.

AMSYSCO’s state-of-the-art manufacturing facilities are unrivaled. The entire procurement, manufacturing and testing processes of AMSYSCO’s distinctive GREEN PT System is produced under the Post-Tensioning Institute’s rigorous plant certification program for Unbonded Tendons.

We offer a complete package for extruding the plastic sheathing onto the steel strand, cutting PT tendons and installing anchorage devices. Our plant can service the entire nation and abroad.

Additional Information


Type:: Full-time
Experience:: Entry level
Functions:: Production, Distribution, Manufacturing
Industries:: Construction, Building Materials, Business Supplies and Equipment

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Detensioning Unbonded Post-Tension Tendons

admin — Thu, 28 Jul 2011 15:31:33 +0000

On rare occasions, the ironworker/installer will need to detension an already-stressed post tensioning tendon. The reason may be due to a repair procedure or re-stressing due to out-of-range elongation readings.

Recommendations:

During the detensioning process, the post-tensioning tendon will have to be “over-stressed.” The PTI Field Manual recommends that the hydraulic jack and pump gauge pressure should not be taken more than 5% over the normal stressing gauge pressure (at 33 kips of 0.5″ tendon).
The jack should be opened at least 4 inches so that it does not get “hung up” in case the wedges fail.
The detensioning procedure be performed shortly after the normal stressing operation. Over time, the wedges deformed inside the anchor cavity and form a “lock” with the strand and anchor. (Refer to the PTI Field Manual 3rd Edition section 10.9).

The pictures below show an example of how to detension the tendons with a Detensioning Tool.

Place detensioning tool level with anchor cavity and strand. Secure hydraulic jack behind detensioning tool.

Extend Hydraulic Jack to unseat wedges. This follows the normal stressing procedure. Hold gauge pressure at 5% overstress.

Use pliers (and magnet) to take wedges out of anchor cavity. Do not use your fingers.

Failure to use the proper parts or equipment could result in damaging the anchor, strand, equipment or harming the operator/by-standers. This procedure should be carried out by a Post-Tensioning Institute Certified Ironworker (level 2). This post is not a complete procedure for detensioning PT tendons. Proper jobsite precautions should be taken to restrict personnel during stressing and detensioning processes.

- Neel Khosa, Vice President, AMSYSCO

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4 Questions to ask your Unbonded Post-Tension Supplier

nkhosa — Sat, 02 Jul 2011 19:50:55 +0000

Hiring a quality Unbonded Post-Tension Supplier can be the difference between a smooth construction project and a problematic situation. The Post-Tension (PT) supplier will play a key role in your reinforced concrete project. Therefore, general contractors and concrete contractors need to choose wisely.

Traditionally, the Post-Tension Supplier is awarded their contract after other subcontractors in larger trades have been selected. Finding the right PT supplier to work with is essential to completing your concrete construction project on time and within budget.

Aside from checking whether the project has been bid per specifications, the following are some questions to ask PT suppliers before awarding the job:

What is your proposed pour sequence?

Unless the construction joints and pour numbers have been referenced on the structural drawings, a PT supplier will have to assume a pour sequence for bidding purposes. If you and your PT supplier had different pour sequences in mind, then time may be wasted in the shop drawing stage. It’s best to be on the same page prior to the contract award.

How many trucks (or deliveries) have you included in your proposal?

If your construction site has limited lay-down areas, then you may not want full truck-load deliveries from your PT Supplier. Your PT Supplier should provide the construction materials per your schedule, but it’s always good idea to let them know the plan.

What previous PT projects have has the PT Supplier worked on that are similar to this project?

Whereas having the lowest price is important during bidding, but hiring a Post-Tensioning Supplier with the right expertise could help you avoid losing money during construction. There may be unique challenges in your construction project that need to be overcome in a timely and cost-effective manner. As with other construction trades, experience matters.

How many sets of stressing equipment will you provide and for how long?

Most PT specifications require at least 2 sets of stressing equipment at the construction site. If one set goes down, then having a backup set can help maintain the schedule. For larger projects with multiple crews, a contractor may require more than 2 sets. As with other rented equipment, the rental period may vary depending on the duration of the project.

- Neel Khosa, Vice President, AMSYSCO
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The importance of clean anchor cavities

nkhosa — Wed, 22 Jun 2011 16:26:20 +0000

Having clean anchor cavities is one of the most important part of getting proper elongations of unbonded post-tensioning tendons.

Post-Tension Stressing Tails - side

Post-Tension Tendon Stressing Tails

Since construction is not the cleanest of jobs, there may be debris inside the PT anchor cavity. A major cause of under-elongations and/or strand-slippage is due to having debris (concrete, dirt, mud, etc.) inside the PT anchor cavity. The debris doesn’t allow the wedges to seat properly (the wedges are inside the anchor cavity and hold the strand in place after the stressing operation). If enough tendons have under-elongations, then the structure may not have enough force within the concrete member. Therefore, it is important to have clean anchor cavities prior to stressing operations.

Post-Tension Anchor Cavity

Post-Tension Anchor Cavity - closeup

In order to clean the post-tension anchor cavities prior to stressing (and installation of wedges), we recommend spraying WD-40, or approved equal, into the anchor. This non-corrosive chemical should dislodge any loose debris. Afterwards, the strand and anchor cavities should be cleaned prior to the installation of the wedges and the stressing operations. (Note: The WD-40 should be compatible with the post-tension grouting used to fill the anchor cavity. The anchor cavity must be clean in order for the grout to bond properly.)

- Neel Khosa, Vice President, AMSYSCO

Pictures taken by AMSYSCO on the 31st Street Marina Harbor project. Structural Engineer: Desman Associates. General and Concrete Contractor: McHugh Construction.

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PTI Certified Plant – AMSYSCO 2011

admin — Sat, 18 Jun 2011 17:50:22 +0000

AMSYSCO, Inc. passed its first unannounced Plant Inspection in the 2011 calender. The certification program is overseen by the Post-Tensioning Institute.

“Certification of Plants Producing Unbonded Single Strand Tendons—Launched in 1989, the first program, Unbonded Single Strand Tendon Fabrication Facilities, is for facilities that fabricate unbonded single strand tendons. Since its inception, participation in the program has grown steadily. Fifty-five plants are certified, which represents approximately 95% of the industry’s production. In 2007, PTI added provisions to permit certification of mobile fabricating facilities in addition to fixed plants.”

(Source: http://www.post-tensioning.org/certification_program.php)

Related Links: AMSYSCO Certified Plant for past year’s certificates (1989-2009)

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Video : Stressing Unbonded Post Tension Tendon

admin — Thu, 16 Jun 2011 23:31:35 +0000

This short video show the stressing an unbonded post-tensioning tendon with a hydraulic jack (8-inch stroke). This tendon was roughly 130 feet long so it required two strokes. The elongation for a 100-foot-long tendon is roughly 8 inches. Refer to the Post-Tensioning Institute’s “Field Procedures Manual for Unbonded Single-Strand Tendons” Chapter 6 for additional information.

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