Tilt up

Last updated
A finished tilt-up building Tilt slab finished.jpg
A finished tilt-up building

Tilt-up,tilt-slab or tilt-wall is a type of building and a construction technique using concrete. Though it is a cost-effective technique with a shorter completion time, [1] poor performance in earthquakes has mandated significant seismic retrofit requirements in older buildings. [2]

Contents

With the tilt-up method, concrete elements (walls, columns, structural supports, etc.) are formed horizontally on a concrete slab; this normally requires the building floor as a building form but may be a temporary concrete casting surface near the building footprint. After the concrete has cured, the elements are "tilted" to the vertical position with a crane and braced into position until the remaining building structural components (roofs, intermediate floors and walls) are secured. [3] [4]

Tilt-up construction is a common method of construction throughout North America, several Caribbean nations, Australia, and New Zealand. It is not significantly used in Europe or the northern two thirds of Asia. It is gaining popularity in southern Asia, the Middle East, parts of Africa, Central and South America.

Concrete elements can also be formed at factories away from the building site. [5] Tilt-up differs from prefabrication, or plant cast construction, in that all elements are constructed on the job site. This eliminates the size limitation imposed by transporting elements from a factory to the project site.

Construction

A tilt-up building during construction. A cast wall section is being righted. Other sections are visible in their forms. Tilt slab construction.jpg
A tilt-up building during construction. A cast wall section is being righted. Other sections are visible in their forms.

Tilt-up construction requires significant organization and collaboration on the building site. The chronological steps that need to be taken for a tilt-up project are: site evaluation, engineering, footings and floor slabs, forming tilt-up panels, steel placement, embeds and inserts, concrete placement, panel erection and panel finishing. [1] [6] Once the pad (casting surface or floor slab) has cured, forms are built on top. Dimensional lumber, a high quality plywood or fiber board that has at least one smooth face is typically used, although aluminum or steel forms are also common. Carpenters work from engineered drawings designed for each panel or element to construct on site. They incorporate all door and window openings, as well as architectural features and other desired shapes that can be molded into the concrete. Studs, gussets and attachment plates are located within the form for embedding in the concrete. The forms are usually anchored to the casting surface with masonry nails or otherwise adhered to prevent damage to the floor slab. [7]

Next, a chemically reactive bondbreaker is sprayed on the form's surfaces to prevent the cast concrete from bonding with the slab. This allows the cast element to separate from the casting surface once it has cured. This is a critical step, as improper chemical selection or application will prevent the lifting of the panels, and will entail costly demolition and rework.

A rebar grid is constructed inside the forms, after the form release is applied, spaced off the casting surface the desired distance with plastic "chairs". The rebar size and spacing is generally specified by the engineer of record. [8]

Concrete is then poured, filling the desired thickness and surrounding all steel inserts, embedded features and rebar. The concrete is then settled through vibration to prevent any voids or honeycomb effects. The forms are removed when the concrete is cured; rigging is attached and a crane tilts the panel or lifts the element into place. In circumstances when space is at a premium, concrete elements can be cast one on top of the other, or stack cast. Quite often a separate casting pad is poured for this purpose and is removed when the panels are erected. [9]

Cranes are used to tilt the concrete elements from the casting slab to a vertical position. The slabs are then most often set onto a foundation and secured with braces until the structural steel and the roof diaphragm is in place.

Structure

Concrete tilt-up walls can be very heavy, sometimes over 300,000 pounds (140 t). [10] Most tilt-up wall panels are engineered to work with the roof structure and/or floor structures to resist all forces; that is, to function as load-bearing walls. The connections to the roof and floors are usually steel plates with headed studs that were secured into the forms prior to concrete placement. These attachment points are bolted or welded. The upper attachment points are made to the roof trusses. Interior walls may be present for additional stiffness in the building structure as necessary, known as shear walls.

Insulation can be applied to either side of the panels or cast as an integral part of the panel between two layers of concrete to create sandwich panels. Concrete has the ability to absorb and store energy and is high mass, which regulates interior temperature (thermal mass) and provides soundproofing and durability. [1]

Like all concrete construction, tilt-up buildings are fire-resistant. In addition, wall panels can be designed to sag inward when damaged, which minimizes collapse (this can also be done with prefabricated panels). [1]

Uses

Schindler House is an early example of tilt-up house construction Schindler-Chase house (Rudolf Schindler), 1922 c.jpg
Schindler House is an early example of tilt-up house construction

Tilt-up was first used in America circa 1905. In 1908 Robert Akin patented the tilt-slab method of concrete construction used in the construction of the Schindler House. [11] Early erection was done using tilt tables, but the development of the mobile crane and truck mixers allowed tilt-up construction to grow. Tilt-up gained widespread popularity in the post World War II construction boom. [12] [13] Tilt-up was not used successfully in Australia until 1969. [14] [15]

Most early tilt-up buildings were warehouses. Today the method is used in nearly every type of building from schools to office structures, houses to hotels. They range from single story to more than seven and can be more than 29 metres (96 feet) in height. [16]

An early example of this method is found in the innovative Schindler House, built in 1922 in West Hollywood, California. Architect Rudolf Schindler claimed that with the assistance of a small hand-operated crane, just two workmen were needed to raise and attach the tilt-up walls.[ citation needed ]

The first tilt-up built home in Ontario, Canada was built in 2017. [17]

Appearance

Early tilt-up architecture was very minimalist and boxy. Recent techniques have expanded the range of appearance and shape.

Many finish options are available to the tilt-up contractor, from paints and stains to pigmented concrete, cast-in features like brick and stone to aggressive erosion finishes like sandblasting and acid-etching. Shapes are also a feature that have become dominant in the tilt-up market, with many panels configured with circular or elliptical openings, panel tops that are pedimented or curved, facades that are curved or segmented and featured with significant areas of glazing or other materials.

The school's architectural design highlights the flexibility offered by tilt-up concrete construction. The building's tilt-up panels include brick veneer and concrete finishes that incorporate recessed images of children's artwork. Public School, Ottawa, ON Design Highlights Tilt-Up Construction.jpg
The school's architectural design highlights the flexibility offered by tilt-up concrete construction. The building's tilt-up panels include brick veneer and concrete finishes that incorporate recessed images of children's artwork. Public School, Ottawa, ON

Association

The Tilt-Up Concrete Association (TCA) is the international trade association for tilt-up concrete construction. TCA is a membership-based association, with nearly 500 members worldwide. [18] TCA members can be contractors (general contractors or tilt-up subcontractors), engineers, architects, developers, consultants, suppliers, specialty trade firms, educators and students.

TCA offers primarily educational, networking and exposure benefits to its members. TCA also offers an Achievement Awards program annually, recognizing the best examples of tilt-up construction over a variety of end uses. [19]

Risks

In the wake of the 2011 Joplin tornado in which seven people were killed in a Home Depot when the 100,000-pound (45 t) panel walls collapsed after the store was hit by an EF5 tornado, engineers in an article published in The Kansas City Star criticized the practice. They said that once one wall falls, it creates a domino effect. Twenty-eight people in an un-reinforced training room in the back of the building survived. According to a study of the collapse, the tornado hit the south corner of the store and lifted the roof up causing the west walls to collapse into the store. The walls on the east side (where the people survived) collapsed out. Only two walls remained standing. Engineers said that stronger roof-to-wall connections might have tempered the collapse. Two other big box stores at the corner that had concrete block construction (an Academy Sports + Outdoors and Walmart) lost their roofs but the walls remained intact. Those buildings were not directly hit by the tornado but the Home Depot building suffered a direct hit. Three people died in the Walmart, but 200 survived. The engineers told the Star that when concrete blocks fail they usually break apart, and do not come down in huge slabs. Home Depot, which has hundreds of stores built with tilt-up, said it disagreed with the finding and that it would use tilt-up when it rebuilt the Joplin store. [20]

Shortly after publication of the Kansas City Star article, the technical committee of the Tilt-Up Concrete Association (TCA) formed a task force to investigate the claims presented in the article. With the cooperation of Home Depot, the task group performed detailed engineering calculations, research and investigation of the claims posed in the article. This task force consisted of a nationwide group of practicing structural engineers with a diverse range of experience in tilt-up construction and "big box" buildings. The final report was published on January 12, 2012. "The information provided in these findings will help Association efforts to promote the benefits of site cast Tilt-Up construction and dispute many of the claims presented in The Kansas City Star article." [21]

Findings of the Task Force

"The Task Force's findings to date include:

  1. The failure started in the structural steel, steel joist and wide-rib deck roof system. This roof system is one of the most commonly used systems in commercial buildings, including those with masonry walls, precast concrete walls, and almost all forms of wall construction.
  2. The Tilt-Up concrete panels performed very well and survived the extreme loads of the EF-5 event only to collapse after the roof failed due to lack of bracing mechanism.
  3. Tilt-Up construction methods played no role in the failure.
  4. The perception that the nearby Wal-Mart store performed better because it was concrete masonry is false. The Wal-Mart took a glancing blow from the storm and the Home Depot took a direct hit." [22]

One of the conclusions of the Task Force's report was "Recommend to ICC and direct to building owners the use of storm shelters in lieu of designing buildings for high winds. The TCA should develop specific Tilt-Up based storm shelter designs for winds of up to 200 MPH that would compete against alternative masonry, precast, or cast-in-place designs. Storm shelter design is addressed in 2009 IBC, section 423 and ICC-500." [22]

See also

Related Research Articles

<span class="mw-page-title-main">Reinforced concrete</span> Concrete with rebar

Reinforced concrete, also called ferroconcrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel bars (rebar) and is usually embedded passively in the concrete before the concrete sets. However, post-tensioning is also employed as a technique to reinforce the concrete. In terms of volume used annually, it is one of the most common engineering materials. In corrosion engineering terms, when designed correctly, the alkalinity of the concrete protects the steel rebar from corrosion.

<span class="mw-page-title-main">Rebar</span> Steel reinforcement

Rebar, known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression, but has low tensile strength. Rebar significantly increases the tensile strength of the structure. Rebar's surface features a continuous series of ribs, lugs or indentations to promote a better bond with the concrete and reduce the risk of slippage.

<span class="mw-page-title-main">Foundation (engineering)</span> Lowest and supporting layer of a structure

In engineering, a foundation is the element of a structure which connects it to the ground or more rarely, water, transferring loads from the structure to the ground. Foundations are generally considered either shallow or deep. Foundation engineering is the application of soil mechanics and rock mechanics in the design of foundation elements of structures.

<span class="mw-page-title-main">Seismic retrofit</span> Modification of existing structures to make them more resistant to seismic activity

Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries and late 1970s for many other parts of the world, many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example.

This page is a list of construction topics.

<span class="mw-page-title-main">Multistorey car park</span> Building designed for car parking

A multistorey car park or parking garage, also called a multistory, parking building, parking structure, parkade, parking ramp, parking deck or indoor parking, is a building designed for car, motorcycle and bicycle parking and where there are a number of floors or levels on which parking takes place. The first known multistory facility was built in London in 1901, and the first underground parking was built in Barcelona in 1904. The term multistory is almost never used in the US, since parking structures are almost all multiple levels. Parking structures may be heated if they are enclosed.

<span class="mw-page-title-main">Ingalls Building</span> United States historic place

The Ingalls Building, built in 1903 in Cincinnati, Ohio, is the world's first reinforced concrete skyscraper. The 16-story building was designed by the Cincinnati architectural firm Elzner & Anderson and was named for its primary financial investor, Melville E. Ingalls. The building was considered a daring engineering feat at the time, but its success contributed to the acceptance of concrete construction in high-rise buildings in the United States. It was converted to a hotel, the Courtyard by Marriott Cincinnati Downtown, in 2021.

<span class="mw-page-title-main">Insulating concrete form</span>

Insulating concrete form or insulated concrete form (ICF) is a system of formwork for reinforced concrete usually made with a rigid thermal insulation that stays in place as a permanent interior and exterior substrate for walls, floors, and roofs. The forms are interlocking modular units that are dry-stacked and filled with concrete. The units lock together somewhat like Lego bricks and create a form for the structural walls or floors of a building. ICF construction has become commonplace for both low rise commercial and high performance residential construction as more stringent energy efficiency and natural disaster resistant building codes are adopted.

<span class="mw-page-title-main">Concrete slab</span> Flat, horizontal concrete element of modern buildings

A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Steel-reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs may be used for exterior paving (see below).

<span class="mw-page-title-main">Formwork</span> Molds for cast

Formwork is molds into which concrete or similar materials are either precast or cast-in-place. In the context of concrete construction, the falsework supports the shuttering molds. In specialty applications formwork may be permanently incorporated into the final structure, adding insulation or helping reinforce the finished structure.

<span class="mw-page-title-main">Precast concrete</span> Construction material

Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels for tilt up construction. In contrast, cast-in-place concrete is poured into site-specific forms and cured on site.

<span class="mw-page-title-main">Voided biaxial slab</span>

Voided biaxial slabs, sometimes called biaxial slabs or voided slabs, are a type of reinforced concrete slab which incorporates air-filled voids to reduce the volume of concrete required. These voids enable cheaper construction and less environmental impact. Another major benefit of the system is its reduction in slab weight compared with regular solid decks. Up to 50% of the slab volume may be removed in voids, resulting in less load on structural members. This also allows increased weight and/or span, since the self-weight of the slab contributes less to the overall load.

Studcast concrete, also called "pre-framed concrete", combines relatively thin concrete layers with cold formed steel framing to create hybrid panels; the result is a panelized system usable for cladding, curtain walls, shaft walls, and load-bearing exterior and interior walls. Studcast panels install in the same manner as prefabricated steel stud panels. The technology is applicable for both factory prefabrication and site-cast (tilt-up) wall construction on almost all types of buildings, including multifamily housing, schools, industrial, commercial and institutional structures.

<span class="mw-page-title-main">Ironworker</span> Tradesman who works in the ironworking industry

An ironworker is a tradesman who works in the iron-working industry. Ironworkers assemble the structural framework in accordance with engineered drawings and install the metal support pieces for new buildings. They also repair and renovate old structures using reinforced concrete and steel. Ironworkers may work on factories, steel mills, and utility plants.

The Filigree Wideslab method is a process for construction of concrete floor decks from two interconnected concrete placements, one precast in a factory, and the other done in the field. The method was developed during the late 1960s by Harry H. Wise as a more efficient and economic construction process than conventional cast-in-place technologies.

<span class="mw-page-title-main">Prefabs in the United Kingdom</span>

Prefabs were a major part of the delivery plan to address the United Kingdom's post–Second World War housing shortage. They were envisaged by war-time prime minister Winston Churchill in March 1944, and legally outlined in the Housing Act 1944.

<span class="mw-page-title-main">Stadthaus</span>

Stadthaus is a nine-storey residential building in Hackney, London. At nine stories, it is thought to be the second tallest timber residential structure in the world, after the Forte apartment complex in Melbourne, Australia. It was designed in collaboration between architects Waugh Thistleton, structural engineers Techniker, and timber panel manufacturer KLH.

Tornadoes, cyclones, and other storms with strong winds damage or destroy many buildings. However, with proper design and construction, the damage to buildings by these forces can be greatly reduced. A variety of methods can help a building survive strong winds and storm surge.

<span class="mw-page-title-main">Lift slab construction</span>

Lift slab construction is a method of constructing concrete buildings by casting the floor or roof slab on top of the previous slab and then raising (jacking) the slab up with hydraulic jacks. This method of construction allows for a large portion of the work to be completed at ground level, negating the need to form floor work in place. The ability to create monolithic concrete slabs makes the lift slab construction technique useful in quickly creating structures with repetitive form work, like parking ramps.

References

  1. 1 2 3 4 Glass, J. (August 2000). "Wall panel renaissance: the benefit of tilt-up concrete construction" (PDF). Proceedings of the Institution of Civil Engineers - Structures and Buildings. 140 (3): 277. doi:10.1680/istbu.2000.32599. Archived from the original (PDF) on 2007-09-28.
  2. ↑ Reitherman, Robert (2012). Earthquakes and Engineers: An International History. Reston, VA: ASCE Press. p. 347. ISBN   9780784410714. Archived from the original on 2012-07-26.
  3. ↑ "Woodland Construction Company". Archived from the original on 2010-11-22. Retrieved 2009-10-24., Woodland Construction Co. 2010
  4. ↑ "CON/STEEL - About Tilt-Up". Archived from the original on 2009-03-25. Retrieved 2009-10-24., CON/STEEL,2010
  5. ↑ Collins, J (2002). "Tilt-up dominates Australian construction". London Concrete Society. 36 (3): 36–37.
  6. ↑ "Woodland Construction Company". Archived from the original on 2011-07-18. Retrieved 2009-10-24., Woodland Construction Co., The Tilt-Up Process, 2010.
  7. ↑ "Woodland Construction Company". Archived from the original on 2011-07-18. Retrieved 2009-10-24., Woodland Construction Co., Forming Tilt-Up Panels, 2010
  8. ↑ "Archived copy" (PDF). Archived (PDF) from the original on 2012-03-14. Retrieved 2009-10-24.{{cite web}}: CS1 maint: archived copy as title (link), CON/STEEL, The Tilt-Up Construction Process, 2010
  9. ↑ "Woodland Construction Company". Archived from the original on 2011-07-18. Retrieved 2009-10-24., Woodland Construction Co., Panel Erection, 2010
  10. ↑ "Heaviest Tilt-Up Panel". Archived from the original on March 26, 2007. Retrieved 2007-06-13.
  11. ↑ Schindler House
  12. ↑ "Tilt-up Construction: An Old Idea for General Contractors With New Innovations". Archived from the original on 2007-09-29. Retrieved 2007-06-13.
  13. ↑ "The basics of Tilt-Up construction - The Korte Company". www.korteco.com. 2018-10-03. Retrieved 2023-07-07.
  14. ↑ Davis, Malcolm (2005). "Tilt-up development in Australia". Concrete Engineering. 9 (1).[ page needed ]
  15. ↑ "CON/STEEL - Tilt-Up History". Archived from the original on 2012-03-14. Retrieved 2009-10-24., CON/STEEL, Tilt-Up History 21 Oct 2010
  16. ↑ "Tallest Panel". Archived from the original on March 26, 2007. Retrieved 2007-06-13.
  17. ↑ "Ontario's First Concrete Tilt-Up Built Home, the Future for Home Builders?". Archived from the original on 2017-11-05. Retrieved 2017-03-02.
  18. ↑ "History of the TCA | Tilt-up Concrete Association". Archived from the original on 2009-11-21. Retrieved 2009-10-24., Tilt-Up Concrete Association, History 21 Oct. 2010
  19. ↑ "About the Tilt-Up Concrete Association". Archived from the original on 2009-11-11. Retrieved 2009-10-24., Tilt-Up Concrete Association, 21 Oct 2010
  20. ↑ "Experts challenge Home Depot building design, codes after Joplin tornado". KansasCity.com. Archived from the original on 2011-06-27. Retrieved 2011-06-28.
  21. ↑ "Task Force Completes Investigation". TILT-UP TODAY. Tilt-up.org. 2011-12-19. Archived from the original on 2013-11-11. Retrieved 2014-04-25.
  22. 1 2 Tilt-Up Task Force Report Archived 2016-03-04 at the Wayback Machine , Jan. 2012
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.