Claims
- 1. A method of constructing a concrete roof on top of a large structure having an open interior with the aid of a plurality of prefabricated elongated sector-shaped form members, each sector-shaped form member having a wide end and a narrow end with each being disposed at a different opposite end portion of the length thereof, each form member having a sector-shaped upper surface for receiving and supporting a layer of reinforced concrete and an integral supporting beam extending below the upper surface between the ends thereof to enable the form to resist bending mounts applied thereto either by the weight of the form when the form is suspending from a single suspension point disposed intermediate with respect of its ends or by the weight of a layer of concrete on the top surface of the form when the form member is supported only at its ends, the method including the steps of:
- erecting a staging extending vertically to a predetermined height above the structure in the center of the interior of the structure, the staging being self-supporting and independent of the structure;
- successively positioning each sector-shaped form member with its wide end being supportably engaged by the upper portion of the structure and with the under side of each form member adjacent its narrow end being supportably engaged by the erected staging, such that the upper sector-shaped surface of each form member extends inwardly and upwardly from the structure and is adapted to receive and support a layer of reinforced concrete, each form member being otherwise unsupported, and each form member being flanked by adjacent form members to provide a substantially continuous upper surface having a centrally disposed access opening therein which is substantially in alignment with the narrow ends of the form members;
- covering the upper surfaces of the form members with a layer of reinforced concrete to form a roof having an opening corresponding to the access opening in the continuous upper surface provided by the form members and that is large enough to permit removal of each form member intact through said opening;
- suspending each of the form members at said single suspension point from the roof after the concrete has cured to a predetermined strength, thereby enabling the roof to carry up to all the weight of each form member that was heretofore carried by the structure and the erected staging;
- removing the staging from engagement with the form members and from the interior of the structure through the opening in the roof, the suspending of each form from the roof supporting each form member upon the removing of the staging;
- applying a lifting force to a form member at said suspension point thereof to remove the load of the form member at said suspension point away from the roof;
- disengaging from the structure the wide end of the form member to which the lifting force is applied;
- reducing the lifting force on the form member to which the lifting force is applied to lower the form member out of engagement with the inner surface of the roof;
- repeating the steps of applying a lifting force, disengaging the wide end, and lowering for each of the form members; and
- removing each form member intact through said opening in the roof.
- 2. A method of constructing a concrete roof in accordance with claim 1 in which the step of lowering each form member includes engaging the form member substantially at the predetermined location thereon from which the form member is suspended from the roof.
- 3. A method of constructing a concrete roof in accordance with claim 1 in which the step of
- lowering each form member out of engagement with the roof comprises lowering each form to the floor of the interior of the structure.
- 4. A method of constructing a concrete roof in accordance with claim 1 and including the additional steps of:
- attaching a lifting line to each form member after its disengagement from the roof, the lifting line being attached near its narrow end such that the form member will hang suspended from the lifting line with the wide end of the form approximately directly underneath the narrow end; and hoisting each form member by the lifting line through the access opening.
- 5. A method of construction according to claim 1 wherein each form member has a lifting means attached at said suspending location of the form member, said suspending location being located approximately on a vertical line through the center of gravity of the form member when the form member is positioned on the structure, and the suspending step includes suspending the form member by said lifting means from the cured concrete roof.
- 6. A method of construction according to claim 1 wherein each form member has an elongated lifting means extending above its upper surface approximately coaxial with a vertical line through the center of gravity of the form member when the form member is positioned on the structure, the lifting means carrying a stop element spaced above the upper surface of the form member, wherein the step of suspending the form member after the layer of concrete has cured comprises:
- placing a bearing means on top of the concrete layer adjacent to the lifting means and spaced below the stop element carried by the lifting means, the bearing means being adapted to distribute the weight of the form member to the concrete roof when engaged by the stop element of the lifting means, and
- retracting the height of the central support staging by a distance sufficient for the stop element to engage the bearing means.
- 7. A method of construction according to claim 6 comprising the further steps of:
- attaching one end of an elongated tension member to the lifting means; applying a predetermined upward force to the lifting means through the tension member; and
- removing the bearing means from the way of the stop element.
- 8. A method of construction according to claim 7 comprising the additional step of:
- placing a stiff cylindrical collar on the upper surface of each form member in radially spaced relation around the elongated lifting means before covering the form member with the layer of concrete to facilitate disengaging the form member from the circumscribing wall and lowering the form member to the bottom of the structure.
- 9. A method of construction according to claim 8 wherein the wide end of each form member is supportably engaged with the structure by means of at least one angle bracket bolted to the inner face of the supporting structure, and the step of disengaging the wide end of the form member from the structure comprises:
- unbolting the angle bracket from the structure; and
- shifting the suspending location radially inward to permit the form member to move away from the inner face of the wall for performing the subsequent lowering step without hitting the wall.
- 10. A method of construction according to claim 7 comprising the additional steps of:
- placing a cylindrical collar on the upper surface of each form member in radially spaced relation around the elongated lifting means before covering the form with the layer of concrete; and
- filling the space between the collar and the elongated lifting means with hardenable material to hold the collar in place and provide support for the lifting means, the collar material being such as to provide a low shear strength joint between the hardenable material and the surrounding layer of concrete to permit separation of the plug from the roof when the form member is lowered after the concrete has cured, thereby providing a clearance space around the tension member to facilitate disengaging the wide end of the form member from the circumscribing wall and lowering the form member to the bottom of the structure.
- 11. A method of construction according to claim 10 wherein the wide end of each form member is supportably engaged with the structure by means of at least one angle bracket bolted to the inner face of the supporting wall, and the step of disengaging the wide end of the form member from the circumscribing wall comprises:
- unbolting the angle bracket from the wall; and
- shifting the suspending location radially inward to permit the form member to move away from the inner face of the structure for performing the subsequent lowering step without hitting the wall.
- 12. A method of construction according to claim 1 wherein each form member is positioned on the structure by the steps of:
- applying an upward force to the form member at a point such that the form member hangs suspended in approximately the attitude desired when it is in position on the structure, lifting the form member to a position directly above its intended location on the structure; lowering the form member further and simultaneously guiding the narrow end of the form member until it rests on the center staging; and
- lowering the former member further and simultaneously guiding the wide end of the form member until it is supportably engaged by the wall.
- 13. A method of construction according to claim 12 comprising the steps of:
- connecting a walkway near the wide end of each form member for pivoting movement about an axis parallel to said wide end; pivoting the walkway upward against the inside of the form member before lifting the form member into position on the structure to minimize the possibility of damage to the walkway and facilitate clearance through the access opening; and
- pivoting the walkway downward to a horizontal position below the end of the form member after it has been positioned on the structure to provide an integral work platform to facilitate the supportable engagement of the succeeding form member by the structure.
- 14. A method of construction according to claim 1 comprising the additional steps of:
- covering the upper surface of each form member with a pliable sheet of plastic material, before the form member is positioned on the structure, the sheet being provided with a multiplicity of spaced studs extending from its upper surface, and
- overlapping each joint between adjacent form members after they are positioned on the structure with a strip of plastic material for sealing the joints when the forms are covered with the concrete layer, the studs serving to anchor the plastic sheets to the underside of the layer when the concrete has cured,
- whereby the plastic sheets facilitate stripping of the forms and provide a lining for the roof.
Parent Case Info
This is a continuation of application Ser. No. 586,366 filed June 12, 1975, now abandoned.
US Referenced Citations (6)
Continuations (1)
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Number |
Date |
Country |
Parent |
586366 |
Jun 1975 |
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