Apparatus and method for testing bond stress between concrete and steel bar

Abstract

The invention discloses a test device for bonding stress between concrete and a reinforcing steel bar and a use method thereof; the device includes a concrete test block and the reinforcing steel bar;the reinforcing steel bar is arranged in the concrete test block, a contact part of the reinforcing steel bar and the concrete test block is provided with a plurality of graphene strain units, both sides of each graphene strain unit are each provided with a plastic soft catheter, and the plastic soft catheters are arranged in the concrete test block and are leaded out from the edge of the concrete test block; the plastic soft catheters are each internally provided with a strain sheet guide wire, and one end of each strain sheet guide wire is connected with the corresponding graphene strain unit, and the other ends of the strain sheet guide wires are connected with an electrical test device. In use, an electrical device communicates with a graphene-cement mixed colloid buried in a test specimen, the resistance change [delta]R of the graphene-cement mixed colloid under different load effects is acquired, and a strain value epsilon of each point of the reinforcing steel bar along the buried length is calculated by using the following formula described in the specification. The test device has the advantages of simple test method, convenience and fastness, and no damage to the reinforcing steel bar.

Description

technical field [0001] The invention relates to the technical field of bonding stress testing, in particular to a bonding strain testing device for bonding between concrete and steel bars and an application method thereof. Background technique [0002] The bond between steel bar and concrete is a complex interaction between steel bar and concrete, relying on this action to transfer the stress between the two to ensure the coordinating work of steel bar and concrete. The axial pull-out test is usually used to determine the distribution of bond stress along the longitudinal direction of the steel bar. The bond stress at each point can be calculated approximately by dividing the stress difference of the steel bar between two adjacent points by the contact area. In order not to damage the bond between the steel bar and the concrete contact surface when measuring the stress, the method usually used in the past is to cut the steel bar into two halves in the longitudinal direction,...

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Problems solved by technology

[0003] Although the patch method of slotting inside the steel bar can measure the strain in the steel bar well, it also has its obvious shortcomings. The test method of cutting the steel bar and milling the slot through the length will cause great damage to the steel bar itself, resulting in The performance of itself has changed greatly, and the test results may be distorted, and this method can only be applied to deal with thicker steel bars, and thin steel bars cannot be used at all. Due to the large wound surface of steel bars, the scrap rate in previous tests using strain gauges was high.

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