In areas The selection was based on STRUCTURAL’s years of experience and knowledge of post-tensioning repair procedures as a specialty contractor. I was involved in the rehabilitation of a large, unbonded, post-tensioned parking structure where the slab tendons were de-stressed, removed and replaced. he use of unbonded post-tensioned (PT) reinforcement in concrete parking ramp structures has been popular for many decades. Post-tensioned parking garages can be either stand-alone structures or one or more floors in an office or residential building. At Schaefer, we believe there is no one-size-fits-all solution for parking structure construction. An unbonded post-tensioned system includes several key components (Figure 2): ... Understanding the technical challenges of repairing post-tensioned cables and the safety issues relating to the structure, the patrons, and the workers when highly tensioned cables are repaired, the owner selected STRUCTURAL to perform the work. The post-tensioned structure was completed in association with Perkins + Will (Design Architect), WMA (Engineers), V3 (Civil Engineer), and Power Construction (General Contractor). The tees and cast in place concrete deck slabs were post-tensioned. The 18-story buildings undergr’ ound, two-level, parking garage structure was in need of repair to restore its structural integrity, protect the Also, special sleeves for future tendon installation and racks for supporting the rolls of tendons while awaiting ramp forming were used. The aging structure showed significant signs of structural degradation as well as the need for architectural improvements. Post-tensioning is the system of choice for parking structures since it allows a high degree of flexibility in the column lay-out, span lengths and ramp configurations. The foundation used poured in place caissons to hardpan. Using rebar for shrinkage and temperature reinforcement in parking garage slabs. Corrosion can occur in grouted and ungrouted post-tension structures leaading to post-tension cable repair, in the presence of moisture and air in voids along the cable tendon. Today post-tensioning is becoming increasingly popular for many different use categories including parking structures, high-rise office and residential, hospitality, and podium slabs for mixed-use projects. Keep in mind, every situation/structure is different. Construction from the 1970s tends to be particularly “light,” with design engineers saving every foot of rebar and pound of concrete possible, making for underbuilt structures by today’s standards. Post-tensioning is the system of choice for parking structures since it allows a high degree of flexibility in the column layout, span lengths and ramp configurations. These tendons, with a typical strength of 270 ksi (1860 MPa), are also greased and sheathed. This paper discusses the former type and presents a brief survey the state-of-the-art of the design and construction of double-tee precast-prestressed and post-tensioned concrete parking structures … The structure is made of precast concrete columns and tee beams. Post-Tensioned concrete parking structures have lower life-cycle costs compared to alternative system due to the lack of maintenance on joint repair. PTI has an active presence on social media and regularly updates its followers on everything new at PTI via the following platforms: PTI is recognized as the world-wide authority on post-tensioning and is dedicated to expanding post-tensioning applications through marketing, education, research, teamwork, and code development. As you are aware, there are many arguments for each case, it depends on your priorities. Built in 1964, the Baltimore Garage is a 270,000 SF split level button head post-tensioned garage located in Detroit’s New Center neighborhood. Millions of square feet of cast-in-place, post-tensioned parking garages are built in the United States each year. The foundation used poured in … Unbonded post-tensioning (commonly used in the construction of buildings and parking structures) remains separated from the surrounding concrete except where the load is transferred at the anchors. Regarding cast-in-place, post-tensioned parking garages, based on the number of post-tensioned structures we have repaired, I'm very reluctant to recommend any such system for parkades, even for the newer extruded sheathed tendons. While upfront costs for a post-tensioned parking structure can be higher than for precast, maintenance and repair costs are considerably lower. The stair/elevator cores utilize … During the spring of 2007, external PT was used to strengthen two damaged PT beams at a government facility parking structure in the Washington D.C. area. Using rebar for shrinkage and temperature reinforcement in parking garage slabs. 4. We’ve budgeted $70,000 for those tendon repairs if the topping work can’t be done in 2021. The selection was based on STRUCTURAL’s years of experience and knowledge of post-tensioning repair procedures as a specialty contractor. Repair Post-Tensioned Bridges. As a result, the decks are virtually crack free. The more movement a structure experiences, the more likely cracking and connection distress will occur. Park Plaza Post‐Tensioned Parking Structure Demolition Presenter: Michael Lussier, Structural Technologies ‐VSL Our Future | Vision PTI envisions a future in which post-tensioning is the first choice for reinforcing all structures. Keep in mind, every situation/structure is different. The Post Tensioning Institute is even developing a barrier cable specification, which is available since 1996. This project encompassed a 5-year This was accomplished with relative ease, and the Chicago area got its first precast, post-tensioned concrete garage. These are mostly parking garages and mid-rise buildings erected in the 1960s and 1970s. The use of PT reinforcement in these structures greatly reduces the amount of cracking and possible leakage to the structure and also allows economical long-term construction. Understanding the technical challenges of repairing post-tensioned cables and the safety issues relating to the structure, the patrons, and the workers when highly tensioned cables are repaired, the owner selected STRUCTURAL to perform the work. In continuous or indeterminate post-tensioned structures the moments due to the prestressing Post-tensioning is a method of reinforcing (strengthening) concrete or other materials with high-strength steel strands or bars, typically referred to as tendons. ... engineering and solution implementation for the parking structure. Post-Tensioned Concrete Structure Evaluation By Michael Tabassi P ost-tensioned concrete structures often reveal very little about their lifetime condition until failure of the post-tensioning becomes evident. Post-tensioned parking garages can be either stand-alone structures or one or more floors in … A typical The number and timing of broken strands In some cases, depth reduction is an essential factor in meeting code height restrictions. Here’s how both processes are combined: In wall panels , vertical post-tensioning strands pass from the top of the wall to the base of the structure through plastic sleeves cast into the panel. Additional benefits are obtained when the post-tensioned reinforcing is installed in a draped profile instead of running in a straight line. The new parking structure expansion was designed and constructed as a cast-in-place and post-tensioned concrete structure at the East end of the existing parking structure. Over the life cycle of the building, precast is often the more expensive approach. So, starting the work in 2021 will save us at least 2.5% on the total costs. Post-tensioning is the system of choice for parking structures since it allows a high degree of flexibility in the column layout, span lengths and ramp configurations. I am designing a Post-Tensioned concrete parking structure (flat plate) with ramps between levels. Post-Tensioned Garage Repairs J ust north of the provincial capital of Toronto is the growing city of Markham, Ontario. Use of post-tensioning reduces the depth of the floor system by one third or more in comparison to some alternative systems. Understanding the technical challenges of repairing post-tensioned cables and the safety issues relating to the structure, the patrons, and the workers when highly tensioned cables are repaired, the owner selected STRUCTURAL to perform the work. The structure has (3) isolated stair/elevator cores constructed steel with composite deck framing. To further complicate construction, beams extend diagonally from the core to the extreme corners of the ramps. Post-tensioned concrete construction is a little different than standard reinforced concrete construction. 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Today, post-tensioned and precast concrete systems dominate the market. Cast-in-place, post-tensioned structures reduce the amount of sealant joints and exposed connections that require regular maintenance making it the best choice for the owner. I was involved in the rehabilitation of a large, unbonded, post-tensioned parking structure where the slab tendons were de-stressed, removed and replaced. Car Parks; Structural Repair Solutions; Why we are different. Post-tensioned concrete provides a structurally efficient, reliable, and cost-efficient solution for the construction of concrete parking garages. By eliminating closely spaced joints found in other construction methods, properly designed post-tensioned parking structures are virtually crack-free, maintenance free and offer great aesthetic freedom and flexibility for today's architectural designs. This system is the most economical because of its high strength to weight ratio. Invalid Email Address. LEARN ABOUT OUR COMPANY. Revenues from your retail customers can remain as there is no loss of parking space. Doing so will eliminate the need to repair the post tensioned cables in that structure. Before discussing Bringing the six-story, 500,000 square foot post-tensioned structure back into full operation with a cost-efficient, sound repair with minimal down-time was critical to the Owner. Retrofit Post-Tensioned Slab Buildings. "Parking Structure with a Post-tensioned Deck," Engineering Journal, American Institute of Steel Construction, Vol. Final delivery was by truck. The benefits of post-tensioning include: More Strength. The structure is made of precast concrete columns and tee beams. PT precompression and load balancing permits thinner slabs and improves durability by reducing slab cracking. The steel-framed parking structure provides the opportunity to use any of the three concrete deck systems, a major advantage in choosing structural steel for a parking structure. A review is made of significant features of the design, construction, and maintenance as they relate to the deterioration. Originally post-tensioned, two-way slab framing systems were constructed with column and middle strips, similar to those used in conventionally reinforced two-way slabs. The foundations consist of spread footings. The reinforced concrete, post-tensioned garage is, to the contractor's knowledge, unique in that it is a double helix design with a crossover core in the center. I personally witnessed the de-stressing of upwards of a thousand tendons. In simple span beams the primary post-tensioning (P/T) moments induced by the prestressing force are directly proportional to the eccentricity of the tendons with respect to the neutral axis of the member (i.e. Park Plaza Post‐Tensioned Parking Structure Demolition Presenter: Michael Lussier, Structural Technologies ‐VSL. We recommend using PT for temperature and shrinkage reinforcement. Post-tensioning cable ends extending from freshly poured concrete 5. Fewer Materials. Properly designed and detailed, cast-in-place post tensioned concrete parking structures are virtually crack-free, maintenance free and offer great aesthetic freedom and flexibility for contemporary architectural designs. I personally witnessed the de-stressing of upwards of a thousand tendons. ... Understanding the technical challenges of repairing post-tensioned cables and the safety issues relating to the structure, the patrons, and the workers when highly tensioned cables are repaired, the owner selected STRUCTURAL to perform the work. Post-Tension Parking Garage Repair. Parking Structures:Recommended Practice For Design and Construction 1-1 Parking structures have become important elements in today’s urban and suburban environments. Among many condominiums built in the mid-1980s is 275 Bamburgh Circle. I have obtained a few publications from PTI about the topic but my main question doesn't seem to be answered in them. 8. Post-tensioning allows almost any shape of structure to be constructed while reducing environmental impacts, construction time, materials and costs." Post tensioned structures are a growing solution to meet this need. Built in 1964, the Baltimore Garage is a 270,000 SF split level button head post-tensioned garage located in Detroit’s New Center neighborhood. Post-tensioned parking garages continue to gain market share in terms of both the number of structures built and volume (number of spaces). The monolithic construction inherent in post-tensioned garages helps reduce building movement from both gravity and lateral loads. There exists a niche in the market, which DSI intends to exploit in the Western United States. The steel-framed parking structure provides the opportunity to use any of the three concrete deck systems, a major advantage in choosing structural steel for a parking structure. The parking structure of a government office building in Washington, D.C. suffered failure of two post-tensioned beams as a result of overloading. Cast-in-place post-tensioned floor slabs utilizing steel cables to compress the slab after curing by placing the cables or tendons in tension. Post-Tensioning for Buildings & Parking Structures STRUCTURAL TECHNOLOGIES is the exclusive manufacturer of VSL post-tensioning products and construction systems in the United States. We recommend using PT for temperature and shrinkage reinforcement. At PT slabs in underground parking structures, however, restraint from foundation Post-Tensioning for Bell Parking Garage: Cover Story. Understanding the causes of some of these problems should help contractors build better post-tensioned structures. Whether you call them precast parking garages, parking structures, parking ramps, parkades or car parks, structured parking made of precast concrete is the leading choice for designers in the United States for speed, economy and low life cycle cost. Cast-in-place post-tensioned floor slabs utilizing steel cables to compress the slab after curing by placing the cables or tendons in tension. Post-tensioning now is used extensively in bridges, elevated slabs (parking structures and residential or commercial buildings), residential foundations, walls, and columns. Post Tensioning Repair Robinson Parking Garage. POST-TENSIONING SYSTEMS In the U.S. and Canada, post-tensioned buildings and parking garages are typically constructed with seven-wire, 0.5-in.-diameter (12.7 mm), unbonded single-strand (monostrand) tendons. There are several construction issues with post-tensioned concrete that are found consistently among engineers and contractors. Level 1 & 2 Unbonded PT Installer & Inspector, Level 1 & 2 Multistrand & Grouted PT Specialist, Level 1 & 2 Multistrand & Grouted PT Inspector, Copyright 2021 by Post-Tensioning Institute, Level 1 & 2 Unbonded PT Ironworker (Accelerated), PTI DC20.7-01: Design, Construction and Maintenance of Cast-in-Place Post-Tensioned Concrete Parking Structures, PTI C30.1-03: Level 1 Unbonded PT Field Installation, PTI DC20.8-04: Design of Post-Tensioned Slabs Using Unbonded Tendons, PTI M10.4-07: Specification for Seven-Wire Prestressed Steel Strand for Barrier Cable Applications. The superstructure consists of post-tensioned slabs with concrete columns. This would allow expansion of a terminal building that was landlocked by runway offsets and roadways. There is no functional compromise, which can be the case with other framing systems. REINFORCED AND POST-TENSIONED CONCRETE FLAT PLATE STRUCTURES A Dissertation Presented By LEILA KEYVANI To The Department of Civil and Environmental Engineering In partial fulfillment of the requirements For the degree of Doctor of Philosophy In the field of Structural Engineering Northeastern University Boston, Massachusetts January, 2015 . The scope of the project included providing extensive general concrete repair and maintenance and post-tensioned repair. This was accomplished with relative ease, and the Chicago area got its first precast, post-tensioned concrete garage. Prestressed and post-tensioned concrete are often used together in the construction of wall panels and parking decks. The post-tensioning system includes complete strand encapsulation. A parking structure is either an independent, freestanding structure, or is an integral part of a multi-use structure. Post-tensioned (PT) concrete deteriorates due to corrosion of post-tensioning strands. Reduced structural depth enhances both the appearance and economy of post-tensioned concrete parking structures. DYWIDAG Post-Tensioning Systems are known around the world for their superior load-carrying performance, durability and simple design. This results in lower maintenance costs over the life of the structure. Post-tensioned slabs (PT slabs) (2) Specific design consideration regarding to PT structures Sketches from PT-structures.com The slab has to be able to shorten freely at jacking (elastic shortening due to the compressive forces) When unfavorable cases occurs, specific execution details can be adopted to maximize the compression force in the slab. Bakota, John F. (1988). 119-125. Deterioration of existing surface parking, plus … 25, pp. Post-tensioned (PT) concrete construction is popular for parking deck floor slabs. STRUCTURAL also had access to VSL® post-tensioning products and engineering support through STRUCTURAL TECHNOLOGIES. The structure stems from the University’s objective to push parking to the perimeter of the campus to enhance the internal pedestrian paths and open space. Post-Tensioned Corrosion Mitigation & Concrete Repair. A thorough evaluation of the existing condition is essential to the safety and stability of the structure Provide Post-Tensioning Consulting . When all of the factors are evaluated, it is easy to see why cast-in-place, post-tensioned concrete parking garages are the system of choice for the nation's hospitals, universities, developers, parking operators, commercial owners and public institutions. The post-tensioning system selected made use of long 8-wire grouted tendons that were cast and tensioned in the 5 inch thick slab. The project involved amputating a significant portion of an existing post-tensioned airport parking structure to allow the airport owner to move a roadway closer to the parking structure. This project consists of (5) levels of above grade and (1) level below grade parking structure. Precast concrete columns and tee beams were shipped by rail from Nebraska to a storage yard 3 miles from the construction site. With over 20 years of experience as a post-tensioning system supplier and installation contractor, SDI has both the technical proficiency and practical know-how to perform any repair or retrofit operation. The aging structure showed significant signs of structural degradation as well as the need for architectural improvements. The current trend toward structural steel parking structures with a pre-stress deck evokes many design questions. Its high strength to weight ratio your retail customers can remain as there is no one-size-fits-all solution for deck. For supporting the rolls of tendons while awaiting ramp forming were used feet of cast-in-place, post-tensioned structure with pre-stress... 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