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A formwork blockout or recess former fitted to the edge formwork of a post-tensioned concrete member, and that creates a temporary void space external to the prestressing anchor to allow the anchor block or similar to be fitted after formwork stripping. [3]: 32 anchor set See wedge set. anchorage assembly
Spiral columns are cylindrical columns with a continuous helical bar wrapping around the column. The spiral acts to provide support in the transverse direction and prevent the column from barreling. The amount of reinforcement is required to provide additional load-carrying capacity greater than or equal to that attributed from the shell as to ...
Forces on post-tensioned concrete with profiled (curved) tendon Post-tensioned tendon anchorage; four-piece "lock-off" wedges are visible holding each strand. Post-tensioned concrete is a variant of prestressed concrete where the tendons are tensioned after the surrounding concrete structure has been cast. [1]: 25
In the illustration of the column formwork above, the 'column clamps' are closer together at the bottom. Note that the column is braced with steel adjustable 'formwork props' and uses 20 mm 'through bolts' to further support the long side of the column. Some models of "permanent formwork" also can serve as extra reinforcement of the structure.
The height of the ribs and beams should be 1 ⁄ 25 of the span between columns. [3] The width of the solid area around the column should be 1 ⁄ 8 of the span between columns. Its height should be the same as the ribs. [3] Diagram showing waffle slab rib and Beam Heights rule of thumb formulas.
Structural loads from a column or wall are usually greater than 1,000 kPa, while the soil's bearing capacity is commonly less than that (typically less than 400 kPa). By possessing a larger bearing area, the foundation distributes the pressure to the soil, decreasing the bearing pressure to within allowable values. [ 2 ]
For a ground-bearing slab, the formwork may consist only of side walls pushed into the ground. For a suspended slab, the formwork is shaped like a tray, often supported by a temporary scaffold until the concrete sets. The formwork is commonly built from wooden planks and boards, plastic, or steel.
Completed falsework: Decking and some formwork has been added. The illustrations are of modern pipe-column falsework, used to support the formwork for a post-tensioned reinforced concrete flyover connector for the eastern span replacement of the San Francisco-Oakland Bay Bridge. When the supports are complete, wood beams and plywood or reusable ...