When the planting bar depth is required by the structure, the tensile anchorage depth of the bar is lower than that under compression. What is the reason? The minimum structural anchorage length of tension steel bar is max{0.3ls; 10d; 100mm}, and the minimum structural anchorage length under compression is max{0.6ls; 10d; 100mm}.

For cast-in-place reinforced concrete components, the transfer of force between the steel bar and the concrete is through the adhesion, friction and mechanical occlusal force of the contact surface between the steel bar and the concrete.

For the planted bar components, the force transmission between the steel bar and the concrete is realized through the bonding shear strength of the planted bar adhesive.

The elastic modulus of the adhesive for planting bars is small, and the deformation is small under compression. The end of the anchor bar is topped on the concrete base material as the main force transmission method of compression. The elastic modulus of the anchor bar and the concrete base material are relatively large, so the deformation is relatively small. With such a small deformation, for the adhesive with a large elastic modulus, it has not yet been able to exert its shear resistance. It is somewhat similar to the difference between end bearing piles and friction piles. If the pile tip is in bedrock and there is almost no deformation, the side resistance of the pile will hardly be brought into play.

If the adhesive has not been able to exert its shear resistance effect, the local pressure of the end of the anchor bar on the matrix is still large, and the concrete at the edge of the compressed steel bar is prone to local punching failure.

1—Punch cutting destroys the oblique section of the most unfavorable side of the vertebral body;

2—The local pressure N of the anchor bar on the concrete;

3—Anchor bar;

4—Matrix

In addition to the above reasons, what other reasons do you think? Welcome to leave a message to discuss.