Tilt-up, tilt-slab or tilt-wall is a type of
building
A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and fun ...
and a
construction
Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...
technique using
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
. Though it is a cost-effective technique with a shorter completion time,
poor performance in
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
s has mandated significant
seismic retrofit
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 exp ...
requirements in older buildings.
With the tilt-up method, concrete elements (walls, columns, structural supports, etc.) are formed horizontally on a
concrete slab
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 ...
; 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.
Tilt-up construction is a common method of construction throughout North America, several Caribbean nations,
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, and
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
. 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. Tilt-up differs from
prefabrication
Prefabrication is the practice of assembling components of a structure in a factory or other manufacturing site, and transporting complete assemblies or sub-assemblies to the construction site where the structure is to be located. The term is u ...
, 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
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.
Once the pad (casting surface or floor slab) has cured,
forms
Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens.
Form also refers to:
*Form (document), a document (printed or electronic) with spaces in which to write or enter data
* ...
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.
Carpenter
Carpentry is a skilled trade and a craft in which the primary work performed is the cutting, shaping and installation of building materials during the construction of buildings, Shipbuilding, ships, timber bridges, concrete formwork, etc. ...
s 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.
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
Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a Tension (physics), tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concr ...
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.
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.
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, as much as or more. 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
A truss is an assembly of ''members'' such as beams, connected by ''nodes'', that creates a rigid structure.
In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assembla ...
. 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
A sandwich is a food typically consisting of vegetables, sliced cheese or meat, placed on or between slices of bread, or more generally any dish wherein bread serves as a container or wrapper for another food type. The sandwich began as a po ...
panels. Concrete has the ability to absorb and store energy and is high mass, which regulates interior temperature (
thermal mass
In building design, thermal mass is a property of the mass of a building that enables it to store heat and provide inertia against temperature fluctuations. It is sometimes known as the thermal flywheel effect. The thermal mass of heavy structura ...
) and provides
soundproofing
Soundproofing is any means of impeding sound propagation. There are several basic approaches to reducing sound: increasing the distance between source and receiver, decoupling, using noise barriers to reflect or absorb the energy of the sound wav ...
and durability.
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
Prefabrication is the practice of assembling components of a structure in a factory or other manufacturing site, and transporting complete assemblies or sub-assemblies to the construction site where the structure is to be located. The term is u ...
panels).
Uses
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
The Schindler House, also known as the Schindler Chace House or Kings Road House, is a house in West Hollywood, California, designed by architect Rudolph M. Schindler.
The house serves as headquarters to the MAK Center for Art and Architecture ...
. 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
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
construction boom. Tilt-up was not used successfully in Australia until 1969.
Most early tilt-up buildings were
warehouses
A warehouse is a building for storing goods. Warehouses are used by manufacturers, importers, exporters, wholesalers, transport businesses, customs, etc. They are usually large plain buildings in industrial parks on the outskirts of cities, town ...
. 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.
An early example of this method is found in the innovative Schindler House, built in 1922 in
West Hollywood, California
West Hollywood is a city in Los Angeles County, California, United States. Incorporated in 1984, it is home to the Sunset Strip. As of the 2020 United States Census, 2020 U.S. Census, its population was 35,757. It is considered one of the most ...
. 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.
The first tilt-up built home in Ontario, Canada was built in 2017.
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.
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. 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.
Risks
In the wake of the
2011 Joplin tornado in which seven people were killed in a
Home Depot
The Home Depot, Inc., is an American multinational corporation, multinational home improvement retail corporation that sells tools, construction products, appliances, and services, including fuel and transportation rentals. Home Depot is the l ...
when the panel walls collapsed after the store was hit by an
EF5 tornado
The Enhanced Fujita scale (abbreviated as EF-Scale) rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States, Canada, China, and Mongolia.
The Enhanced Fujita scale repl ...
, engineers in an article published in ''
The Kansas City Star
''The Kansas City Star'' is a newspaper based in Kansas City, Missouri. Published since 1880, the paper is the recipient of eight Pulitzer Prizes. ''The Star'' is most notable for its influence on the career of President Harry S. Truman and as ...
'' criticized the practice. They said that once one wall falls, it creates a
domino effect
A domino effect or chain reaction is the cumulative effect generated when a particular event triggers a chain of similar events. This term is best known as a mechanical effect and is used as an analogy to a falling row of dominoes. It typically ...
. 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
A concrete masonry unit (CMU) is a standard-size rectangular block used in building construction. CMUs are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them.
Tho ...
construction (an
Academy Sports + Outdoors
Academy Sports + Outdoors is an American sporting-goods store chain with corporate offices in the Katy Distribution Center in unincorporated western Harris County, Texas, United States, near Katy and west of Houston. For 74 years, it was a priva ...
and
Walmart
Walmart Inc. (; formerly Wal-Mart Stores, Inc.) is an American multinational retail corporation that operates a chain of hypermarkets (also called supercenters), discount department stores, and grocery stores from the United States, headquarter ...
) 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.
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."
Findings of the Task Force
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."
[
]
Gallery
Image:Temporary-casting-pad.jpg, Cast panel on temporary casting pad (foreground), with panels being erected in background. Small retail shop, Northern Australia.
Image:Stack-cast.jpg, Stack-cast panels.
Image:Tilt-panel.jpg, Panel being hoisted into position.
Image:Form-section.jpg, Extruded aluminium form section.
Image:Tilt-slab-base-detal.jpg, Base detail of tilt-slab sat on strip footings. Finished floor level will be approx. 75mm higher than blue inserts. Inserts take threaded rebar into floor slab.
See also
*Lift slab
Lift slab construction (also called the Youtz-Slick Method) 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 con ...
References
External links
Tilt-Up Concrete Association
Tiltup.com
Tilt Up Panels Safety Procedures
{{DEFAULTSORT:Tilt-Up
Building engineering
Structural system
Building
Concrete