General Requirements of Self Drilling Anchor Bar’s Tension
The purpose of self drilling anchor bar’s tension is to make free section produce elastic deformation through tensioning equipment, which can exert prestress value for anchoring structure. Its general requirements are as following:
1. Tensioning equipment should be chosen according to material and locking force of self drilling anchor bar.
2. Before tensioning, tensioning equipment should be calibrated.
3. Before installing, accessories of self drilling anchor bar should be checked strictly.
4. Before tensioning, concrete strength of anchorage section and bearing plate should be reached to designed strength. At the same time, surface of bearing supporting member should be leveled, pedestal and anchorage device should be installed and vertical with axial direction.
5. Tensioning should be carried out according to certain procedure and designed speed (generally 40kN/min). There are two pretensions before the formal tension and tensioning force should be 10%-20% of designed tension. Load of formal tension should be exerted by different levels, not to lock-in load at a time.