User:Juslynch/sandbox

For the Timber Roof Truss article entry, I plan to add some information about current solutions to timber roof truss structural issues. The section would explore how pre-fabricated trusses compare with trusses that are are manufactured on site. I could also add some information about innovation in permanent bracing design for wood trusses, as well as the process one should take in assessing historic wood trusses. A bibliography for these topics is listed below:

Salvadori, Mario and Robert Heller. Structure in Architecture The Building of Buildings. New Jersey: Prentice-Hall, Inc., 1963.

Underwood, C. R., Woeste, F. E., Dolan, J. D., & Holzer, S. M. (2001). Permanent bracing design for MPC wood roof truss webs and chords. Forest Products Journal, 51(7), 73-81. Retrieved from                         https://proxy.library.upenn.edu/login?url=https://search.proquest.com/docview/214664013?accountid=14707

Branco, J., Sousa, H., & Tsakanika, E. (n.d.). Non-destructive assessment, full-scale load-carrying tests and local interventions on two historic timber collar roof trusses. Engineering structures, 140. doi:10.1016/j.engstruct.2017.02.053

Cotton, Lyndsay. 2016. "The benefits of pre-fabricated timber roof trusses." Civil Engineering (10212000) 24, no. 7: 47-48. Business Source Complete, EBSCOhost (accessed November 8, 2017).

Bracing
It has been proven that permanent bracing designs can improve the lateral stability of roof trusses, specifically with j chords. Continuous lateral braces can prevent negative effects of lateral forces by being diagonally set in to brace the chord. However, there are variable effects of permanent braces on the truss web, given that the length of the chord would determine the number of brace locations.

Pre-Fabricated Wood Trusses
Pre-fabricated wood trusses offer advantages in building construction through machine-made accuracy and tend to use less timber. However, this does not take into account site-specific design alterations that require customized truss design.

Historic Wood Trusses
The challenges of maintaining wood trusses are not limited to newer building projects. Visual grading can be used to conduct condition assessments for historic trusses. This along with load carrying tests, can be used to determine the best possible solutions to repairing older truss systems. Metal plates and correct, period material can be used to repair, although 100% recovery of the material may be hard if the wood truss has deteriorated. MPC wood trusses are typically made from lumber, rather than timber.

Connections in Wooden Trusses
The earliest wooden truss connections consisted of mortise-and-tenon joints and were most likely crafted at the construction site with the posts. Since most early most early trusses were made from unseasoned posts, the subsequent shrinkage would create cracking at the mortise-and-tenon joints. Additionally, the mortise-and-tenon joints in older trusses were located at the weakest point in the post, accelerating failure. Much of the early truss connection designs anticipated structural behavior under loads. This is why holes were drilled slightly off-center, allowing the peg to naturally pull the posts together with gravity.