girliestructure
Structural
- May 3, 2015
- 1
We have a one story 18'-0" tall rectangular existing tilt-up building with wood roof, the owner want to add a basketball court to the 1/4 of (E)building. So we are going to raise the roof of 1/4 of the building to 30'-0" for the basketball court.
We are designing the project with new added concrete shear walls to support this new roof since the existing lateral system is concrete tilt-ups. This way R of the lateral system is consistent.
We are considering this building is a one story structure with the vertical offset in roof diaphragm with disrupted chord. The design concept is portion of the new concrete wall above the existing roof will act as a transfer element for vertical offset at the roof. In short this is a single roof with the offset. Please see attached PDF.
The owner's contractor who is a professor turned contractor is insisting on using steel frames to support the new roof because of the added weight of new concrete walls. He is also insisting that code allows the portion above existing roof to be designed for higher R, so we can use SCBF or BRB for raised 12'-0" of the new portion. I could not find anything is ASCE 7-16 except for the section 12.2.3.1 for Vertical combination of later system. But per my understanding we can only use vertical combination like upper or lower system if we have two stories. We do not have diaphragm in new potion at 18'-0" level ((E)roof level).
What is the correct way of designing for this project? Is the one story approach I am using not correct? Please help
We are designing the project with new added concrete shear walls to support this new roof since the existing lateral system is concrete tilt-ups. This way R of the lateral system is consistent.
We are considering this building is a one story structure with the vertical offset in roof diaphragm with disrupted chord. The design concept is portion of the new concrete wall above the existing roof will act as a transfer element for vertical offset at the roof. In short this is a single roof with the offset. Please see attached PDF.
The owner's contractor who is a professor turned contractor is insisting on using steel frames to support the new roof because of the added weight of new concrete walls. He is also insisting that code allows the portion above existing roof to be designed for higher R, so we can use SCBF or BRB for raised 12'-0" of the new portion. I could not find anything is ASCE 7-16 except for the section 12.2.3.1 for Vertical combination of later system. But per my understanding we can only use vertical combination like upper or lower system if we have two stories. We do not have diaphragm in new potion at 18'-0" level ((E)roof level).
What is the correct way of designing for this project? Is the one story approach I am using not correct? Please help
