This past fall semester, MARTOS Principal Christian Martos had the honor of working with The City College of New York Spitzer School of Architecture students to construct and perform load testing on balsa wood bridges. The lesson is part of Christian’s role as an Assistant Adjunct Professor at CCNY, where he teaches seminars including Introduction to Design of Timber and Masonry Structures, Elementary Structural Analysis and Behavior, and Introduction to Design of Steel and Concrete Structures. The video above shows Christian explaining the structural implications involved while load testing the student constructed balsa wood bridges. By discussing the design and structural failure analysis, the students gain a visual demonstration beyond standard classroom instruction.

The objective for the project was to explore the structural and architectural design of a roof structure through both theoretical and experimental modeling. The criteria for the assignment was as follows:

• Span = 18” (center to center of supports)
• Supports Dimensions = 4”x4”
• Max. height = 15” (measured from top of supports to top of structure)
• Max width of structure = 6”
• Max total length = 24”
• Material = Balsa Wood
• Max Individual Member Cross Section = 0.25 sq. in.
• Clearance Below Structure = A clearance 4” tall x 12” wide had to be provided between the supports, measured from the top of supports and
centered between supports
• Connections = No Glue or other such materials were permitted
• Min. Weight to support = 100 lbs.
• Loading criteria requirements = The roof structure was to be loaded at center span. To allow for loading, the model must have provided for
a 4”x4” block to be placed at top of structure were load was applied.