Conceptual Architectural Sketching
According to my engineer, to build a 27 meter cantilever canopy, you simply need 2 structural trusses about 7 meters deep, that is secured back on 2 pairs of columns 32 meters apart. Actually these dimensions are adopted from the architectural plans. No big deal, and a quick free-hand sketch visualize the concept quicker than an expert CAD operator could draw.
The engineer further proposes that the 7-meter deep canopy be designed with a space frame between the two main supporting trusses to support the roof surface. However as the trusses span over the entry podium triple height volume it seemed odd to me that the space frame should obscure the effectiveness of a glass roof there. Again the conceptual sketch illustrates how effective the glass roof could be with the space-frame removed.
Quick free-hand sketches explored how the 7 meter deep main trusses could be covered and enclosed, but if their detailing were built to be exposed that could be ideal.
It soon became obvious that a complete glass roof over the atrium could lead to an elaborate structural system to cope with supporting the “glass roof” over such huge spans. By visualizing through quick plan and section sketches I was able to invent a beam system that incorporates simple skylight systems in the designed voids through the roof system.
Interesting to note that these sketches are not drawn to a particular scale but rather to illustrate an idea and concepts which I invented as I continue to chat with the engineer.
Sketchingjourney's Blog 
Reblogged this on Archi Blog.
Very impressive. You definitely have the visual as well as structural senses, quite a gift . . . To be able to view it 3D definitely helps the collective exploratory process.
Thanks Daphne, it comes after years of experience. After years of observing and analyzing structural systems one gets the essence of how structural members individually and collectively will perform under analytical conditions. The trick is to visually interpret how members will respond to various condition then counter the action with opposite reaction thus creating stability.
After years of experience some visual sense of how things work becomes natural although many times are not exactly correct, but allows discussions to be initiated. It also helps in the development of your creative spirit. That is the essence of the reason to explore ideas with free-hand sketching. It frees your efforts from being exact in what you are trying to illustrate.