Chengtao Zhang

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

Residential:

• Light wood framing is the most common
• Wood is one of the most abundant, renewable, and low-cost materials in the U.S., an it is easy and fast to construct
• Wood’s design flexibility can accommodate different layouts, and openings
• Wood has relatively low thermal conductivity

Office buildings:

• Structural steel framing and reinforced concrete framing are the most common
• Both materials have high strength-to-weight ratio, which allow for longer spans and larger opening
• They are both fire resistant and durable to comply with building codes
• Both allow for rapid and safe erection in the process of construction, while being able to carry heavy vertical loads for multistories buildings

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? 

• Before digital models, 2D drawings on paper were implemented by architects, structural engineers, and MEP engineers. They all produced separate 2D drawings, and they used to place transparent drawings directly over one another on a light table to compare and detect conflicts.
• Frequent coordination meetings were required to discuss conflicts because there was no single centralized model

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

• Digital BIM tools have automatic clash detection between architectural, structural, and HVAC elements that reduce human errors.
• BIM has one centralized model shared between all stakeholders, which reflect real-time updates and errors to prevented outdated drawings.
• BIM’s 3D views feature help with understanding and visualization of complex spaces and spatial relationship between floors and elements

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? 

Design coordination should start as soon as more than one discipline is involved in the design. Early coordination can resolve issues early on before they become expensive or impossible to resolve.

Is it ever too early?

It is never too early to coordinate, as key high-level topics such as initial building massing and designs should be discussed and aligned before proceeding with greater details.