2.3.1 Live anchorages
The non-jacking end of the strand may be bonded in concrete, or it may be fitted with a pre-locked anchorage which has also been cast in the concrete. The anchorage at the jacking end is called a live anchorage whereas the one at the non-jacking end is termed a dead anchorage.
Protection to an anchorage is required only at the live end, the dead end is cast in the concrete. The live anchorage is housed in a recess, or pocket, which is wide enough for the stressing jack and deep enough so that there would be adequate concrete cover to the assembly when the recess is made good. After stressing, the strand is cut off close to the face of the wedge using a disc cutter and the whole assembly is sprayed with a corrosion inhibitant. The assembly is then covered with a grease-filled cap and the recess made good with mortar containing a non-shrinking agent.
A few decades ago most manufacturers had their own patent devices for anchoring tendons. They included bars with threaded ends, enlarged ends of wire which passed through holes in thick plates such that the button sat on the plate, wedges, concrete male and female cones gripping a number of wires arranged in a circle, and a toothed conical wedge in a barrel. The cone and barrel systern is now the most commonly employed device for post-tensioning floors and it is available from most manufacturers.
Figure 2.9 shows a typical section at the end of a post-tensioned member containing a monostrand anchorage assembly, complete including the corrosion protection and Figure 2.10 shows a typical multistrand anchorage. Their representative dimensions are given in Tables 2.10 and 2 11.
2.3.1 Live anchorages
The non-jacking end of the strand may be bonded in concrete, or it may be fitted with a pre-locked anchorage which has also been cast in the concrete. The anchorage at the jacking end is called a live anchorage whereas the one at the non-jacking end is termed a dead anchorage.
Protection to an anchorage is required only at the live end, the dead end is cast in the concrete. The live anchorage is housed in a recess, or pocket, which is wide enough for the stressing jack and deep enough so that there would be adequate concrete cover to the assembly when the recess is made good. After stressing, the strand is cut off close to the face of the wedge using a disc cutter and the whole assembly is sprayed with a corrosion inhibitant. The assembly is then covered with a grease-filled cap and the recess made good with mortar containing a non-shrinking agent.
A few decades ago most manufacturers had their own patent devices for anchoring tendons. They included bars with threaded ends, enlarged ends of wire which passed through holes in thick plates such that the button sat on the plate, wedges, concrete male and female cones gripping a number of wires arranged in a circle, and a toothed conical wedge in a barrel. The cone and barrel systern is now the most commonly employed device for post-tensioning floors and it is available from most manufacturers.
Figure 2.9 shows a typical section at the end of a post-tensioned member containing a monostrand anchorage assembly, complete including the corrosion protection and Figure 2.10 shows a typical multistrand anchorage. Their representative dimensions are given in Tables 2.10 and 2 11.
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