Massachusetts Institute of Technology, Building NW21
Building NW21 at the Massachusetts Institute of Technology (MIT) was constructed in the early 1900s and now houses the Plasma Science and Fusion Center. The center, which is a vital part of the university, performs roughly $30 million in experimental research annually. When MIT personnel observed large cracks in the interior plaster finishes and binding interior doors at Building NW21, the university asked SGH to investigate the cause of the distress.
We found that portions of the structure were settling due to deterioration of timber piles that support the load-bearing brick masonry structure. The settlement caused distress to interior finishes along with cracks in the exterior brick masonry walls.
SGH helped MIT develop and administer a pile repair program to stop deterioration-related settlement while allowing them to continually use the facility. We conducted photographic and level surveys, and implemented movement monitoring of exterior walls using crack gauges to assess the extent of distress and prioritize repairs. MIT implemented pile repairs at certain critical locations. Our recommended repairs included:
- Excavating and removing top sections of timber piles deteriorated by decay fungi
- Replacing deteriorated piles with new concrete-filled steel posts bearing on the remaining sound portions of the piles below the groundwater table
- Encasing the top sections of the piles in concrete pumped from trucks into the building’s crawl space during normal working hours
We also developed remedial work to repair and stabilize distressed masonry walls including the following:
- Rebuilding brick masonry walls with severe cracking and out-of-plane displacement and repairing cracked stone foundation walls
- Using CFRP bars to strengthen brick masonry walls and stitch wide cracks
- Installing external steel reinforcement to stabilize severely distressed walls