Which types of structural framing systems and materials are most commonly used in the US for residences? For office buildings?
In the US typical residence buildings (single family units) use timber framing whereas commercial buildings are a mix of concrete and steel (typically steel is used for larger structures like high rises). Timber is used for residence buildings because these structures will be subject to much smaller loads in comparison to commercial buildings. Additionally, timber framing is much quicker and more cost affective in these small scales. Larger buildings, that have heavier loads require high strength materials like concrete and steel.
How do you think design coordination was done before we started using digital models?
Prior to digital models, design coordination most likely had to all be done in-person and through drawings/plans (which were all done by hand). This meant that architects, engineers, clients, and all other major parties involved in the design\construction, had to coordinate\communicate through paper plans and physical models. Without the use of digital models, there is a huge constraint not only in time\convenience, but also limitations on physically seeing how different elements of the structure may interact with one another. Since a physical scaled model cannot be constructed, issues that may not be able to clearly spot through a 2D representation may not be found until construction.
At what point in the project development process should design coordination start?
Generally, I would think that design coordination should begin after a solid conceptual design has been created along with a preliminary design of the structural system. If we begin design coordination too early in the process, before a solid design has been discussed\some what finalized, there is the danger that a substantial change take place in the design that significantly impacts wall placements, structural element placements, utilities, etc. However, we also should not wait to long, to a point where things that have been modeled are difficult to manipulate and alter if certain changed do need to take place.