Slide 9 of 67
long, low shear walls resist uplift better than tall, short shear walls
- Discussion of figure
- The length and width of the shear wall dramatically influence the amount of uplift experienced by the shear wall during an earthquake
- Figure shows two identical buildings.
- Only difference is shear wall length.
- The top building
- Shows a long low shear wall with a height to width ratio of ˝ :1 (or for every 2 feet in height, the building must be 4 feet in width)
- Point out the shear wall = shear wall is 16 feet wide and 8 feet high
- This is the Retrofit Prescriptive Standard with ˝:1 height/width ratio
- Note the uplift of 0 lbs.
- The bottom building
- This shows New Construction Code Standard with 2:1 height-to-width ratio
- The shear walls are on the corners
- Note the uplift of 1600 lbs. – this building will be less stable due to tipping and rocking during an earthquake
- Note the importance of hold-down anchors
- Why is the Retrofit Prescriptive Standard different from the New Construction Code Standard?
- New construction is usually engineered and retrofit is usually NOT engineered, so it is more conservative