This invention relates to the hingeable connections required for the method of construction in which walls and ceiling slabs are cast horizontally on site and in which ceiling slabs are positioned over a group of wall slabs and the wall slabs are hingeably connected to the ceiling slabs from a position on top of the ceiling slab, by a hingeable connection which is inserted thru an access slot and attached to a pivot means secured in the hinge edge of the wall slab, and the connection provides for the clearance required to permit the end of the wall slab to rotate under the ceiling slab, and for the pick up of the weight of the wall slab, and the connection device provides for the guidance of the ceiling slab as it is lowered to bear on the upper edge of the wall slabs.
This method of construction is set forth in my copending application Ser. No. 519,082.
Hertofore connection devices for foldable concrete slab construction have been made as disclosed in Johnson U.S. Pat. No. 3,494,092 in which reinforcing bars were cast embedded continuously between ceiling and wall slabs and these bars were allowed to bend during the lifting operation. These bent bars were suitable for one story construction, and for conditions where the walls were cast in an outward position in the same plane as the ceiling slab. There were spalling problems however that required considerable expense to over come. In addition, the Engineers calculating the strength of the joint were not satisfied that the spalling could be completely overcome. In addition the transfer of vertical loading thru the joint was a problem. Johnson '092 disclosed the use of eye bolt and links also but these disclosures were not completely developed as to exactly how to handle all the loads thru the joint. Johnson '092 also disclosed walls cast under the ceiling slab with the joint made by a bendable bar. This was subject to the same problems but in addition, resulted in a condition completely inaccessible for repair if something went wrong.
Verner U.S. Pat. No. 3,785,095 disclosed flat bars extending from the edges of both ceiling and wall slabs, with a substantial length of the bars embedded in the slabs as required to generate a cantilever for the hinge. Verner '095 also disclosed a slot in the wall portion of the hinge to assist in generating a clearance for rotation. To make this hinge work required extensive reinforcing, and was usable only for the condition of the walls being cast outward from the ceiling slab. The premise of the hinge was to keep the ceiling slab off from bearing on the wall slabs. This was used by present inventor on a twelve story building successfully, but cost a good deal of money, and was resisted by the engineers reviewing the design of the building for code compliance. It did provide a good pocket for grout under the wall, but this kind of connection is not adequate for current revised uniform building code standards, unless the edges of the walls are especially roughened to produce 1/4 inch reveal. This is not practical.
Miram U.S. Pat. No. 3,789,455 disclosed a removable two piece hinge suitable for connecting ceiling slabs cast in the same plane as the wall slabs. A hinge member was secured to opposing edged of wall slab and ceiling slab, and the slabs had to be in perfect position and perfect spacing to make the connection. This resulted in the same problems as encountered in assembling ordinary precast slab construction, and was very difficult. It had the advantage of saving most of the cost of the hinge in that the hinge itself was reusable, but the cost of the hinge, and the cost of the labor to install, to remove, and the attendant anchor required to secure the wall made it uneconomical so far as present inventor knows. In addition, it was not adaptable to an underlying wall assembly being assembled to an overlying ceiling slab, and especially for interior walls.
Greenhalgh U.S. Pat. Nos. 3,527,008 and 3,600,870 disclosed cable lines inserted down thru hollow bore bolts to connect to walls hinged at the edge of a ceiling slab. This required outside access to the wall slab edge, and did not provide the means to make the connection from above the ceiling slab, nor a precise positioning of the wall slabs in the erected position. This relied on "winding up" the cable to bring the wall up to the ceiling slab. This is not adaptable to the needs of the present method of construction.
There are other various means of hingeably connecting ceiling slabs to wall slabs thru the use of some sort of bendable metal. Present inventor does not know of their being reduced to actual practice.
It is the object of the present invention to disclose a connection device that can be used with precast ceiling slabs, and wall slabs, and provide the means to easily assemble the slabs, and to have a tolerance to overcome errors in workmanship; and to provide the means to adjust the final position of the wall slabs in the erected position. It is a further objective to provide a pivot means located at the center of gravity of the wall when the wall is in a vertical position, to assist in the erection of the building.
It is a further objective to provide an accessible connection device which can be visable inspected, and which is adaptable to the nested slab configuration of ceiling slabs when the undersurface of the ceiling slab is not always in the same plane.
It is a further objective of the present invention to provide a connection where the connection to the pivot may be done by hand reaching down thru the access hole rather than `fight` the problems of blind hinges where they are cast in place for interior underlying walls.
It is a further objective to eliminate connecting devices which have extensions beyond the surface of the slabs that interfer with casting, finishing, and are prone to the knocked out of line by the workmen during the casting operation.
It is a further objective to reduce the waiting time of the crane during erection by facilitating the means of the field work.
It is a further objective to disclose a design that is not subject to freezing by the grout that has penetrated the presently used types of Flat Bar hinges.