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Method for modeling and calculating unbonded rib limit stress increment in prestressed concrete beam

A technology of ultimate stress and calculation method, applied in calculation, special data processing application, instrument, etc., can solve problems without considering the main structure type, key parameters of damage signs, loading mode of non-bonded tendon arrangement form, number of spans, and no impact Problems such as the accuracy of the ultimate stress increment of bonded tendons

Inactive Publication Date: 2015-04-01
HARBIN INST OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problems that the existing unbonded prestressed concrete beams and slabs do not consider the main structure type, damage signs, key parameters, unbonded tendon layout, loading mode and number of spans, which affects the unbonded concrete beams and slabs. In view of the accuracy of the ultimate stress increment of bonded tendons, a modeling and calculation method for the ultimate stress increment without bonded tendons in prestressed concrete beams and slabs is proposed

Method used

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  • Method for modeling and calculating unbonded rib limit stress increment in prestressed concrete beam
  • Method for modeling and calculating unbonded rib limit stress increment in prestressed concrete beam
  • Method for modeling and calculating unbonded rib limit stress increment in prestressed concrete beam

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specific Embodiment approach 1

[0036] Specific implementation method one: the modeling and calculation method of the ultimate stress increment of the unbonded tendon in the prestressed concrete beam slab, which is characterized in that the modeling and calculation method of the unbonded tendon ultimate stress increment in the prestressed concrete beam slab is specifically according to the following steps Achieved:

[0037] Step 1, taking the edge strain of the concrete pressure zone of the mid-span control section reaching the ultimate compressive strain as the sign of the ultimate state of the bearing capacity of the simply supported prestressed concrete beam slab;

[0038] Step 2. For simply supported prestressed concrete beams and slabs, the ultimate stress increment △σ without bonded tendons p1 When modeling: when a plastic hinge appears in the mid-span control section, the overall deformation coordination condition of the beam and slab is introduced to solve this problem. The plane section is no longer...

specific Embodiment approach 2

[0040] Embodiment 2: This embodiment differs from Embodiment 1 in that: after the plastic hinge appears in the mid-span control section in step 2, the bending moment-curvature nonlinear analysis method is used.

[0041] Other steps and parameters are the same as those in Embodiment 1.

specific Embodiment approach 3

[0042] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is: the limit stress increment △σ of the unbonded tendon in the simply supported prestressed concrete beam slab described in Step 3 p1 The calculation formula is:

[0043] The different loading forms are single-point loading in the span, three-point loading and uniform loading;

[0044]

[0045] In the formula, β p is the reinforcement index of prestressed tendons, β s is the non-prestressed tendon reinforcement index, L / h is the span-to-height ratio;

[0046] The formula for calculating the ultimate stress without bonded tendons is:

[0047] σ p = σ pe +△σ p1 (2)

[0048] The design value of ultimate stress without bonded tendon can be taken as:

[0049] σ pu =(σ pe +△σ p1 ) / 1.2 (3)

[0050] Design value of ultimate stress without bonded tendon σ pu Conditions that should be met:

[0051] σ pe ≤σ pu ≤f py (4)

[0052] where f py is the design v...

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Abstract

The invention relates to a method for modeling and calculating unbonded rib limit stress increment in prestressed concrete beams and aims to solve the problems that accuracy of unbonded rib limit stress increment in the prestressed concrete beams is affected due to the fact that main structural types, destroy signs, key parameters, unbonded rib arrangement forms, loading patterns and span number of existing unbonded prestressed concrete beams are not considered. The method includes the following steps of step one, simply supporting the prestressed concrete beams, step two, performing modeling, and step three, calculating delta sigma <p1>; step one, calculating the unbonded rib limit stress increment in continuous prestressed concrete beams on the basis of a failure mode I, step two, performing modeling, and step three, calculating delta sigma <p2>; step one, calculating the unbonded rib limit stress increment in the continuous prestressed concrete beams on the basis of a failure mode II, step two, performing modeling, and step three, calculating delta sigma <p3>. The method is applied to the field of unbonded rib limit stress.

Description

technical field [0001] The invention relates to a modeling and calculation method for the ultimate stress increment of unbonded tendons. Background technique [0002] The ultimate stress without bonded tendons refers to the stress without bonded tendons when the prestressed concrete beam slab reaches the limit state of the normal section bearing capacity, and the difference between the ultimate stress without bonded tendons and the effective prestress is the ultimate stress increase quantity. Since the unbonded tendons can slide relative to the surrounding concrete, the assumption of a plane section in section analysis is no longer applicable. Therefore, the reasonable calculation of the ultimate stress increment of unbonded prestressed tendons is the key to accurately calculate unbonded prestressed concrete structural members. The basis of normal section bearing capacity and ultimate load. [0003] The analysis of the test results of nearly a hundred unbonded prestressed ...

Claims

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Application Information

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IPC IPC(8): G06F19/00
Inventor 王英王晓东郑文忠周威
Owner HARBIN INST OF TECH
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