What You Need To Know About The Tension Of Prestressed Anchors

Pre-stressed tensioning is to add tension in advance in the component, so that the pre-stressed tensioning component will bear the tensile stress, and then cause it to produce a certain deformation, to cope with the load of the steel structure itself, including the load of the roof's own weight, Wind load, snow load, earthquake load, etc. Generally, steel strands, jacks, anchor plates, and clips are used for tensioning. Today, the editor will tell you what Zhang La works.

Before the engineering structural components bear the external load, pre-compression stress is applied to the steel strands in the tension module to improve the bending resistance and rigidity of the components, delay the occurrence of cracks, and increase the durability of the components. For the mechanical structure, it means that stress is generated in advance. The advantage is that it can increase the rigidity of the structure itself, reduce vibration and elastic deformation. This can significantly improve the elastic strength of the tension module and make the original resistance stronger.

The pre-stress adopts the two-end symmetrical simultaneous tensioning, tensioning force and elongation dual control method, and the lifting and pressing of the jacks at both ends, drawing lines, elongation measurement, and pad insertion are carried out together. After the jack is in place, first fill the main cylinder with a little oil to make it tight, so that the pre-stressed steel strand is stretched straight. When the steel strand reaches the specified initial stress σ0, stop the machine to measure the original gap and draw a line as a mark .

The technical editor of Qiangli Group found that the tension sequence of the steel strand should be determined by combining the following factors: First, avoid excessive eccentric stress on the cross section of the member during tension, and not cause tensile stress on the edge of the concrete; Second calculation And compare the pre-stress loss value of the batch tension; the third is to minimize the excessive camber of the beam body to prevent the beam body from cracking or serious deformation. After comprehensive comparison, a two-stage force-transfer anchoring method is used for tensioning, that is, after the strength of the T-beam concrete reaches 90%, the N1-N4 steel strands anchored at the beam end are first tensioned, and the channels of the 4 steel strands are grouted. , And then save the beam; in order to reduce the creep and camber of the T beam, the N5-N7 steel strand anchored at the top of the beam is stretched and grouted before the beam is erected, and then the beam is erected. Another advantage of using the two-stretching process is: first stretch a part of the steel strands, apply a lower prestress to the beam body, so that the beam body can bear the load of its own weight, and move the beam out of the production beam position in advance, which can greatly shorten the production pedestal Use cycle to speed up the construction progress.