Masonry Magazine September 2002 Page. 19
By
Maria Viteri, AIA
Director of Program Development
And
Matthew Stokes Redabaugh
Special Projects Coordinator
International Masonry Institute
Bethesda, Md.
One of the oldest construction elements, the masonry arch, is the perfect example of form following function. Known for simplicity, elegance and their ability to span areas and support loads, masonry arches are one of the most flexible and basic of all design elements. There are several compelling reasons why masonry contractors should give serious thought to making greater use of these marvels: case of construction, improved building performance and overall project savings.
The historical success of arches is based on an understanding of the structural advantage the use of compression in dealing with loads and stresses. The aesthetic appeal is based on flexibility related to form. A masonry arch can take on a variety of shapes, all the while responding to balance, proportion and scale in design. A masonry arch's great resistance to compression makes it the most efficient structural element in dealing with spanning openings.
Arches have been historically constructed with unreinforced masonry. In an unreinforced state, the masonry arch has been used to span various size openings and across considerable lengths. Due to the curvature characteristics of the arch design, it provides great structural efficiency that successfully transfers vertical loads and vertical forces. Because of masonry's compressive strength, masonry arches can support considerable load.
However, while history points to hundreds of masonry-only examples of arch construction, today we are seeing a combination of materials. While typical, this trend is usually not necessary, and may even have a compromising effect on building performance.
"Ask a brick what it wants to be, it will say an arch!" - Louis Kahn
If, as the saying goes, a brick wants to be an arch, why do we see combinations of materials? The possible answers range from general misunderstanding of arch design to a comfort level in the craftworker constructing the arch. Both issues can be addressed in a positive and more importantly, cost effective manner.
Masonry arches in their traditional application serve many sizes of openings without the need for additional reinforcement. It is not until very long spans or very small rises are incorporated in arch design that reinforcement need be considered. A reduction in the area of masonry used as abutment might also require the use of reinforcement for load resistance.
Masonry arches are most easily constructed when designed according to the basic principle that arches are self-supporting and compatible material meets a higher performance standard. This means that masonry arches are not dependent on additional structural materials for their stability.
Georgian Court Bridge, Lakewood, NJ
Best in Category Restoration projects 1999
NJ Golden Trowel Awards