A variety of other methods of connectingthe panels are also used. A BUTTED con-nection, using grout or a gasket, can beused if the wall does NOT contribute anystructural strength to the structure. Steelcolumns are welded to steel angles or platessecured in the wall panel. Precast columns canalso be used. Steel angles or plates are secured inboth the columns and plate and welded togetherto secure the panel.When panel connections that do not actuallyhold the panels in place are used, the panelsare generally welded to the foundation andto the roof by using steel angles or plates.All connections must provide waterproof joints.This is accomplished by the use of expansion jointmaterial.FinishesTilt-up panels may be finished in a variety ofways similar to any other concrete floor or wall.Some finishes may require the panel to be pouredface up; others will require face-down pouring.This may affect the manner in which the panelsare raised and set.CONCRETE CONSTRUCTION JOINTSAND CONNECTIONSConstruction joints are divisions betweenconcrete work done at intervals spaced widelyenough to allow partial hardening. They areused between the units of structure and placedwhere they will cause the minimum amount ofweakness to the structure. It is safe to assume thatconstruction joints are located where theshearing stresses and bending moments arerelatively small or where the joints will besupported by other structural members. Forhorizontal work, such as floor slabs, constructionjoints should be in a vertical plane; whereas, forvertical work, such as columns, the joints shouldlie in a horizontal plane (fig. 7-20).Foundation walls are bonded to footings withvertical reinforcing steel called “dowels, ” whichare placed in footings and extend about 3 to 4 ftup into the wall. A wedge-shaped through, calleda keyway, is built into the footing to strengthenthe bond between footings and walls (fig. 7-21).Contraction JointsThe purpose of contraction joints is tocontrol cracking caused by temperature changesFigure 7-20-Location of construction joints in beams, columns, and floor slabs.7-16
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