Slide 16 of 45
- Untightened Nuts
- The nut must be tightened securely on the hold-down rod.
- If not properly tightened, the wall will begin to uplift during an earthquake before it engages the hold-down.
- This movement can split both the sill plate and the hold-down post.
- When the nut is not properly tightened, shear wall overturning will cause damage to the building.
- The figure shows an untightened nut found in an earthquake damaged building. This allowed the building to slip up.
- Shrinkage does occur in new buildings. The wood will lose approximately half of its water content during framing. It is important to tighten all the bolts after framing is complete.
- We have discussed: types of hold-downs, how they resist uplift force during earthquakes, how to install them properly, and common installation errors.
- Now we will discuss connections throughout the building, from top to bottom, that resist shear forces.