Which types of structural framing systems and materials are most commonly used in the US for residences? For office buildings?

What factors determine why these are the most used materials?

Steel and wood are two of the most commonly used materials in the US for residences. Concrete, in addition to the two forementioned materials, are used more often in the design and construction of office buildings. Brick and masonry are also used in residential/commercial construction, abeit less often. Steel, wood, and concrete are used more commonly due to resource availability, the advancement of technology, and the experience that the design and construction industries have developed with the use of these materials.

Why do different teams of designers and subcontractors link and share their models during the design process? 

What are the advantages of linking models?

Are there any disadvantages to linking models?

How do you think design coordination was done before we started using digital models? 

What advantages does doing this coordination digitally have over previous methods?

Before digital models became more commonly used, I think that design coordination was implemented via in-person meetings, which included the relevant design teams and the contractors. The architects, engineers, and contractors (e.g. various trades) would have probably brought their plans and performed a visual inspection of the placement of the different systems that would be going into the building to check for conflicts and resolve any issues that may arise. This may create delays in the project timeline if any issues come up during the design coordination phase, and future coordination meetings will probably need to be set up to ensure that there are no conflicts remaining. On the other hand, digital coordination presents many advantages over the analog method. Design teams and contractors are able to resolve conflicts that arise during the coordination phase in real time by making the change directly, or identifying the conflict and assigning to someone else to rectify it. Additionally, other people can also be assigned to be included in the update of the coordination conflict, which allows for better communication between the stakeholders in a project. All of this combined can help to alleviate any potential issues that may arise later on in the project, and streamline the project towards completion.

What strategies can design teams use to find and avoid clashes prior to the start of construction? 

What can be done besides sharing the models digitally?

At what point in the project development process should design coordination start? 

Is it ever too early?

Design coordination should begin early on in the project development process to reduce the number of coordination conflicts that may arise throughout the project design/construction phase. In the begining stages of the project development process, the design coordination efforts will probably only primarily involve the architects and the engineers as they develop the architectural and structural designs of the building, respectively. As the design phase progresses, more trades will get involved as the design of the building/site becomes more refined per the project/design constraints.