Tensioning method for bonded and unbonded combination prestress concrete beams at post-cast strip

Abstract

The invention relates to a tensioning method for bonded and unbonded combination prestress concrete beams at a post-cast strip, which is characterized by including the following steps of 1) setting one ends of bonded prestress stranded steel wires at haunching concrete positions on two sides of a frame beam below a floor slab, fixing one ends of unbonded prestress stranded steel wires on the upper side of the floor slab, and fixing the other ends of the bonded prestress stranded steel wires and the unbonded prestress stranded steel wires to a side post or a side beam of a building; 2) casting concrete and the haunching concrete to the frame beam and then casting the concrete of the floor slab; and 3) tensioning the unbonded prestress stranded steel wires on the floor slab firstly when the design strength of the frame beam and the floor slab reaches 75%, and then tensioning the bonded prestress stranded steel wire below the floor slab. By the tensioning method, construction period can be shortened, loss of prestress of prestress concrete members can be reduced and the respective advantages of the bonded prestress stranded steel wires and the unbonded prestress stranded steel wires can be developed.

Description

technical field [0001] The invention belongs to the technical field of tensioning of bonded and non-bonded combined prestressed concrete beams at the post-casting belt, and in particular relates to a tensioning method for combined prestressed concrete beams with bonding and non-bonding combined at the post-casting belt method. Background technique [0002] The use of new materials and new technologies is vigorously promoted by the state in the construction industry. The energy-saving (steel-saving and cement-saving) design of buildings is being vigorously promoted. The large-span prestressed structural form has been widely used in various building structures and has become a modern The direction of design research and construction technology research has been gradually promoted and applied. However, in actual engineering use, a single bonded or unbonded prestressed structure is used. Although a certain design effect has been achieved, the single prestressed structure has th...

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Problems solved by technology

[0003] 1. Due to the friction in the bellows of the bonded prestressed steel strands (the friction between the steel strands, the friction between the steel strands and the pipe wall, the friction between the steel strands and the bellows), the prestressed large loss;

[0004] 2. The bonded prestressing effect is better, but the stress loss is larger with time;

[0005] 3. Although the unbonded prestressed steel strand has a protective cover and less prestress loss, this technology has higher requirements on the quality and performance of the anchorage at the tension end;

[0006] 4. The unbonded prestressed steel strand can slide due to the protection of the sheath, and its strength cannot fully play its role in the beam

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