Citto, C., Woodham, D., & Feinberg, J., The Evaluation of the Historic San Juan Fortification Walls, Proceedings of 12th North America Masonry Conference, Denver, Colorado, May 2015.
The original construction of the San Juan fortification walls began in the middle of the 16th century. The fortifications were constructed with the single purpose of defending the City of San Juan and its harbor from attack, principally by sea, and eventually surrounded the entire city. Over a four-century period of construction and reconstruction, the fortification walls evolved from one construction typology into at least ten identifiable types. The walls investigated in this study are 2,600 feet long, range to 50 feet in height, and include two bastions and the San Juan Gate.
The challenging task of evaluating such complex structures required the synergism between historic research and diagnostic techniques to develop a deep understanding of the history, materials, and structural behavior of the fortification walls. In addition to historic research, the 21st century technologies selected to evaluate the walls included laser scans, digital photo-documentation, wall coring, remote visual inspection of the core interior, microwave radar scans, thermography, characterization of stone and mortar types and strength and finite element modeling.