Small answer to the construction details of planting reinforcement glue (3)
Date：2020-04-06 09:40:00 Share：
1、 How to locate the planting bar accurately?
Answer: rebar planting is the drilling construction on the existing components, and the original structural rebar shall not be damaged when drilling, so the rebar position detection instrument must be used to detect the position of the original structural rebar before drilling.
2、 How to make the hole diameter accurate?
Answer: the bond between steel bar and base material mainly depends on the bond force of planting steel bar glue. Therefore, when selecting the hole diameter, it should be ensured that the hole diameter of the planting bar is slightly larger than the diameter of the steel bar, so as to ensure that the planting bar adhesive has a certain thickness to provide sufficient adhesive force. In a certain range, the increase of the aperture can increase the pull-out resistance of planting reinforcement.
In practical engineering, because of the small elastic modulus of the binder, the increase of the pore diameter will lead to the increase of the slip of the structural system, which will not only increase the amount of the binder for planting reinforcement and the difficulty of drilling, but also make the strength of the original structure significantly reduced and cause greater damage if the drilling is too large.
Therefore, considering many factors such as creep of bond, difficulty and economy of planting reinforcement under long-term load, combined with numerical simulation study, it is considered that the drilling diameter D is generally taken as the reinforcement diameter (D + 2) mm ~ (D + 10) mm.
3、 How to determine the drilling depth of planting reinforcement?
Answer: the depth of planting is an important factor to affect the effect of planting. The pullout resistance of steel bar is mainly provided by the bond between steel bar and adhesive and the bond between concrete and adhesive. Therefore, the depth of planting steel bar directly determines the pullout resistance and failure form of planting steel bar.
In order to ensure the safety of the structure, it is necessary to ensure that the failure mode is cone bond composite failure, that is, the steel bar and the base material slip, resulting in the pull-out failure of the mixed interface, and the planting steel bar yield, which can give full play to the tensile strength of the steel bar without brittle failure.
The drilling depth of rebar planting directly affects the quality of rebar planting, so the hole of rebar planting must be checked one by one. There are also quite a lot of information about the depth of planting steel bars, including highly professional books, which regard 15d as a feasible anchoring depth of tensile steel bars in engineering, while as a structural designer and site management personnel, there should be an accurate concept and correct judgment on the depth of planting steel bars, otherwise it is very easy to be brought into the ditch.
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