continued

If, however, this simplified approach indicates that the allowable load carrying capacity is not sufficient for the new reuse requirements, then it is possible to calculate an increased strength by taking advantage of the inherent composite capabilities of the clay tiles and the concrete topping, as well as the concrete topping and the steel beam.

If this enhanced strength approach does not produce favorable results, then it may be necessary to conduct a load test of the system in situ per ASTM E196, Standard Practice for Gravity Load Testing of Floors and Flat Roofs.

The principal disadvantage of tile arch floor construction was the difficultly of adapting standard sizes to irregularly shaped spaces. In addition, tile arches are more easily weakened by holes and penetrations than a monolithic floor system. Furthermore, it was difficult to place mortar in end construction — i.e., when the open cells were placed end to end.

Also, for end construction, if a single tile was removed in a row, then the remaining tiles became unsupported unless the scored sides of the tile were mortared in with the adjacent rows of tiles.

Because side-constructed arches — i.e., arches in which the scored sides of the tiles were placed adjacent to one another, transverse to the arch span — were more conducive to placing mortar between the tiles, this type of construction had an advantage over end construction. However, tests conducted during the period of time in which clay tiles were used extensively indicated that tiles were much stronger in an end construction application as opposed to a side construction configuration.

Finally, tile arch construction was susceptible to poor workmanship because the quality of the work could only be observed from the top and not from below during construction until after the formwork was removed.

D. Matthew Stuart, P.E., S.E., F.ASCE, SECB, is a licensed structural engineer in 20 states. He currently works as a senior project manager at the main office of CMX, located in New Jersey, and also serves as an adjunct professor for the master's of structural engineering program at Lehigh University in Bethlehem, Pennsylvania.

This article is reprinted from the December 2007 issue of STRUCTURE magazine, with permission of the publisher, the National Council of Structural Engineers Associations (NCSEA).

References

ASTM Standard E196, 2006, "Standard Practice for Gravity Load Testing of Floors and Flat Roofs." ASTM International, 2006. DOI: 10.1520/E0196-06.

Kidder, Frank E., and Harry Parker. Architects' and Builders' Handbook, 18th ed. John Wiley & Sons, Inc., 1956.

Plummer, Harry C., and Edwin F. Wanner. Principles of Tile Engineering: Handbook of Design. Structural Clay Products Institute, 1947.

Stecich, John P. "Analysis and Testing of Archaic Floor Construction." Standards for Preservation and Rehabilitation, ASTM STP 1258. ASTM International, 1996. DOI: 10.1520/STP15437S; DOI: 10.1520/STP1258-EB.

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SUBSCRIPTION SAMPLE Inside the Marshall Field warehouse, a two-way joist system supports the tile arches. Photo: Ron Gordon/ HABS Extra Large Image Marshall Field River Warehouse east elevation drawing Image: HABS Extra Large Image SUBSCRIPTION SAMPLE Marshall Field River Warehouse section drawing looking south. Image: HABS Extra Large Image Marshall Field River Warehouse north and south elevation drawings. Image: HABS Extra Large Image Table of recommended safe loads per square foot for clay-tile arched floor systems, from the Principles of Tile Engineering: Handbook of Design (1947). Image: Courtesy Brick Institute of America Extra Large Image Marshall Field River Warehouse brick facade details. Image: HABS Extra Large Image   Click on thumbnail images to view full-size pictures.