The Existing Unbonded Prestressed Steel Strand Anchor Truncation Technology Research And Practice

With the changing urban planning,many existing buildings in order to meet the development of urban construction or the use of new functional requirements,the need to establish a non-cohesive stress on the floor of the hole or the overall structure is not satisfied with the use The demand part of the transformation or removal to meet the new needs of the building,for this need to cut off the existing prestressed tendons.But the previous construction process is directly cut off the prestressed tendons,due to excessive prestress loss,may lead to the construction of the original building there is a large security risk.In this case,a special open anchor is required.In this paper,through the experimental research and practice,this paper proposes a new method for the construction of steel wire rods with unbonded prestressed concrete structure.After the reconstruction and implementation,the pre-stress of the original structure can be maintained No loss or loss is small.The key to the construction method is to develop a simple and efficient open anchorage,namely the tool anchor(with a screw inside the cup)and a working anchor(double cup),the working anchor is a permanent anchor,the tool anchor is repeatable Use the tool anchor.In this paper,static tests,long-term anchoring tests,repeated load tests and strand breaking tests were carried out on open anchors.In order to study the internal force and deformation of the open anchor structure and the stress change before and after the steel strand was cut off,the finite element ABAQUS software was used to simulate the three-dimensional non-linearity of the open anchor and the strand.And the stress distribution of steel strand.Combined with the specific test and finite element theory analysis,the existing unbonded prestressed concrete structure of the steel strand anchor anchor construction of the specific construction method to do a detailed introduction and the Huiyuan Building podium demolition project done information monitoringThe theoretical analysis shows that the results of the finite element simulation of the open anchorage test with the unbonded prestressed steel strand are closely related to the experimental results.The experimental study and engineering practice show that the work anchor and the tool anchor should be used in order to achieve the best anchoring effect when the strand is cut off.It is better to use the two tool anchors with one working anchor.After the cutting is completed,the tool anchor is detachable use.Combined with the dismantling of the skyscrapers of Huiyuan Building in Changsha,the construction method and information monitoring program of the existing anchorless truncation technology of unbonded prestressed steel strand are put forward.