Placing concrete in shells is hard work for the placing crew who must work on a sloping surface and often shovel heavy concrete uphill, so every effort should be made to make the operation simple and convenient, with an adequate number of workers and finishers. This trick makes an interesting under surface of the shell. It must be specified and detailed by the engineer, and may be expensive. Construction time and cost • The construction of a reinforced concrete shell involves many problems, the design and construction of forms, reinforcement selection and placing, concrete materials and placing, and curing and decentering. The sheer mass of the concrete is able to block out most external noise a concrete shell. The objective of concrete placing is the production of a smooth dense solid texture on the under surface of the shell with no pockets or honeycombing. One cannot make an out-of- hand judgment that shells are too expensive for a particular design. There is a general agreement among engineers that concrete should be placed from the bottom of the shell upward. The first, concrete-shell construction, permits the erection of vast vaults and domes with a concrete and steel content so reduced that the thickness is comparatively less than that of an eggshell. Precasting has the advantage that material and construction conditions are under the best control, forms may be constructed for repeated use, and concrete materials may be better controlled. Shell Contracting Southwest Florida Construction is fully Licensed and Insured. It there is too much water, the concrete will run down the slope, and if there is too little, the concrete becomes unplacable. with multiple additional patents pending. The optimum number of uses appears to be from 6 to 10, depending on the total length for the time of construction, and the curing time between uses. A Concrete Shell is manufactured at your site. The overriding element in the cost, is the forming system. The screed rails are removed as soon as the surface is established, and the depressions left by the boards and blocks are filled up so there are no marks on the under surface. Too early removal of forms may not affect the strength, but may have serious consequences for deflections, especially for thin cantilevers at the corners of an umbrella shell. The use of lightweight concrete for shells may save some weight, but this saving will result in little reduction in stresses, so there will be little reduction in the quantity of reinforcing. The most convenient and least expensive material for the surface of the forms is plywood. combination works equally well in the winter and results in year-round energy savings that you can see The mechanical ingenuity of the contractor is very important for proper design of this type of forming system. Our concrete The engineer should, during construction, be free to make decisions on plans and specifications that will expedite the construction without any reduction in quality. The team specializes in concrete driveways, sidewalks, pavers, slabs, tie beams, footers, and many more concrete services. The critical advantage of thin-shell construction is how it uses the least material to enclose a given volume. structure. The shells are most commonly flat plates and domes. Serve. Except for very steep slopes and thick walls, top forms are unnecessary. Instead, his firm has been a leader in the development of utilitarian concrete shell forms, such as egg-shaped concrete Concrete ships and barges have utilized shell technology for over half a century. We spend more time up front on blueprints and assembly drawings which allows us to complete projects faster and at a higher level of quality. Our revolutionary Multi-Flex Forming system allows us to cast our buildings from concrete; the floor, It is important to have available more panels and shores than required for each concrete placing operation, otherwise this system will have no particular advantage in terms of labor efficiency. With curved surfaces, it is easy to underestimate the length of bars. The engineer must be aware of the economic factors in shell construction. However, rapid decentering may be directly involved with the economy of the project, especially for industrial buildings where large areas are to be covered. A basement is an option for all shells and we can easily handle varying Even in your utility bills. They are thin and do not generate or retain heat, so cold weather protection, both above and below the surface is essential. A Concrete Shell is manufactured at your site. drawings which allows us to complete projects faster and at a higher level of quality. There are several methods to establish the thickness of the shell as the concrete is placed. be drawn on a piece of paper. All of these problems must be understood in order to make the structure safe and economically feasible. Modern thin concrete shells, which began to appear in the 1920s, are made from thin steel reinforced concrete, and in many cases lack any ribs or additional reinforcing structures, relying wholly on the shell structure itself. The weight and cost of steel structures. Large span concrete shell roofs are an ideal solution and is a result of a unique synthesis between architecture and structural engineering. The Monolithic Dome shell is so thin that it’s proportionally thinner than an egg shell 1. The specifications must be carefully written to reflect the problems in thin shell construction. The reinforcing should be detailed so the bolsters are vertical. Concrete Thin parabolic shell vaults stiffened with ribs have been built with spans up to about 300 ft (90 m). These are outlined in the codes, standards, and publications of the American Concrete Institute. envision), entirely out of concrete. Then the contractor can make his decision on the type of concrete and the rapidity of movement of the forms. Our concrete shells are built to stand the test of time and will look stunning for years to come with minimal upkeep. There are certain industries, particularly food handling and processing, where such dust free surfaces are most desirable. On relatively small inverted umbrellas, where movable forms are used, the enclosure may be part of the forming system. Our prices are comparable to wood framing, but with much more value added. Instament, Inc. providing Concrete Shell Construction in Hollywood, Florida. We build concrete slab foundations for a variety of residential projects ranging from single-family to multi-family, sidewalks / walkways and more for builders all over the state of Florida. The shell was virtually plastered. The normal standards for the construction of concrete structures are, of course, absolutely necessary for shells. It top forms become necessary, the most convenient method is to use wire mesh or metal lath panels that can be removed as soon as the concrete has been placed, so that the surface can be finished with the rest of the roof. Single use forms should be considered if there are fewer than, say, 4 units. Address: 1701 Rogers Avenue Suite 40, San Jose, CA 95122, Concrete Shells 2019 | All Rights Reserved. A concrete shell, also called “thin shell” concrete structure, is composed of a thin shell of concrete formed in such a way as to be self-supporting, often with no interior columns or exterior buttresses. Shells operates at a higher level of technology than most other builders. Projects range from large custom residential homes to complex commercial and industrial projects. The vibrator operator must be given precise directions. The joint efforts of the contractor and engineer will create a structure bringing pride and a sense of accomplishment to all parties. you can imagine. In hot weather, the thin surface is susceptible to plastic cracking, so precautions must be taken. We are a licensed shell contractor that carries a certified building contractor license. The strength of a skyscraper in every We are proud to say most of our supervisors have been with us 20 years plus. Then the concrete will not sag downward and cause pockets. The selection of the type of placing equipment, whether by pumping, by bucket and mobile crane, by movable wood runways and carts, should be the decision of the contractor, based on factors such as the equipment available, the steepness of the slopes, the form and shape of the shell, and the distance above the ground. Get Concrete Shell Construction Deals and Reviews. The surface of the earth mound is covered with a suitable contact material such as plywood to make the under surface of the concrete acceptable. The vibrator should be placed at the center of each square for only a short time. This criterion is not always useful, because it is difficult to define the best building, especially if there are intangibles that cannot be evaluated in terms of money. Concrete Shell Structures has a $10,000 bond with Indemnity Company Of California. Shells are so thin that the under surface will not have the advantage of the weight above the surface as in beams or columns, so extra care must be taken. The economy of long span shells depends on many factors. Light interior surfaces may reduce the cost of lighting and bright interiors may be better for the morale of the workers. The unyielding power of mother nature has met its The accepted standards for the curing of concrete apply to the construction of shells. Precasting should be considered only for small units. Particularly, the production, placing, and curing of concrete must be under firm control. The entire cost of the building, must be considered, and not just the cost of the structure. A Concrete Shell creates tranquil space. The disadvantage is that it is usually necessary to transport the shell units over a considerable distance if the are built in a precasting yard. For example, for hyperbolic paraboloid (HP) umbrella shells, the average thickness per square foot of projected area is about 3.5 inches and for a gabled HP shells or saddle shells, 4.5 inches including the edge members. Spengler Construction & Masonry’s focus is primarily commercial, industrial and multifamily projects, offering a full range of concrete construction services from on-time estimating, establishing budgets and value engineering to utilizing the latest in construction technology to complete any project. Shell construction began in the 1920s; the shell emerged as a major long-span concrete structure after World War II. The factor next in importance is the cost of formwork; the contractor must use his ingenuity to devise form systems that can be erected, moved forward and re-erected at minimum cost. He should use a competent superintendent, one with mechanical ingenuity and perseverance. A seasoned Foundation Subcontractor that exceeds expectations The only answer to the economic question is to take bids from contractors on several competitive systems. However, there are some cases where high early strength concrete becomes necessary in order to move forms rapidly for maximum production. It is important that the concrete be placed on the form at the place where it is required. They may run either horizontally or vertically, and should be close enough together so that the screed board will rest on the rails. It is covered with concrete and a second membrane is placed on top. An advantage is that it is not necessary to have an elaborate schedule of sequential forming, reinforcement pacing, concrete placing, curing, and decentering. Without the savings of multiple use forms, the economy may be lost. For example, the use of a shell structure may raise or lower the cost of heating, lighting, and finish materials, so the cost of the structure alone is no measure of the economy. These joints should be planned and specified by the engineer, and indicated on the construction drawings, together with the details of the method of stress transfer such as the inclusion of keyways, special reinforcing, and possible thickening of members. The contractor and the engineer should fully agree upon the schedule for removal of panels and shores. If the shell membrane is thin, usually the stresses are fairly small, and no special reinforcing is required at construction joints. Concrete Shell serves to stabilize the interior temperature on even the hottest days. Other structural systems may require large additional costs for hung ceilings. it! Some of the built-in shores should remain in place until adequate concrete strength precludes excessive deflection from overloaded young concrete. The approach to disaster-resistant home construction requires that the entire exterior shell (walls, floors, and roofs) of the house be monolithic reinforced concrete in character. In general, for any concrete structure, the longer the forms remain in place, the better the results. For inverted HP umbrella shells, for example, forms for one unit can be constructed in quadrants so it is necessary to decenter only a few inches. We are a family owned and operated construction company based in Pompano Beach, FL. Most of the structures built in this manner have been domes. However, for umbrella shells, the corners may tend to sag, so re-shores should be used at these places. The use of concrete as a building material reduces both materials cost and the construction cost. complex roof configurations and round sections can be constructed! Both the contractor and the crew may resist placing from the top down. concrete shell elements characterized by extreme control in curvature, sectional features and surface detailing. A large shell will require a single use form unit unless there are many repeated uses. It requires a large amount of forming materials in comparison to the final area of the shell. This method requires a considerable investment in mechanical equipment such as long hydraulic jacks or the repeated use of short jacks. Loose boards may look better to the architect, but they are considerably more expensive, and must be replaced more often. 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