Age of Steel

The prevalence of solid masonry began to wane in Western societies in the late 19th century, with the introduction of steel frame construction. While effective for low-rise construction, solid masonry buildings were inadequate to meet the needs of industrialized cities, which began to grow vertically.

The Monadnock Building (1891) in Chicago exemplifies the difficulties of building tall structures with load-bearing walls (Fig. 5.1). Its 16-story north half is the tallest conventional building in the United States that is supported solely by solid masonry walls.

Figure 5.1 - Monadnock Building

 

The building is structurally traditional, employing cast iron and wrought iron framing only for window spandrels and the internal frame. Consequently the walls at ground level had to be six feet thick to carry the upper floors; this massive bulk then rested on an immense iron and reinforced concrete raft. Six-foot-thick walls at the base of the Monadnock Building support the great weight of the masonry above. The building's tremendous weight caused it to settle nearly 20 inches (50 centimeters) into the ground before stabilizing, making it necessary for occupants to step down from the sidewalk to the ground floor.

Solid masonry construction was also expensive and labor intensive. In contrast, steel frames were cheaper and could be erected in a fraction of the time. Remarkably, construction of the Empire State Building (1931) took almost a full year less than that of the Monadnock Building, despite rising 86 stories higher (Fig. 5.2)

 

Figure 5.2 - Empire State Building

 

Although structurally different, early steel frame buildings still had thick masonry walls. While the steel frame provided the primary structural support, the exterior ("infill") walls of early steel frame buildings were composed of several wythes of masonry. The masonry surrounded the steel frame, or was connected to the frame using rigid components, creating composite wall systems.

This combination of old and new building techniques became known as "transitional masonry." Like their load-bearing predecessors, these buildings relied on the storage capacity of the exterior masonry to control the elements.

This construction style posed several problems. Because the steel frame was rigidly connected to the exterior walls, without provision for differential expansion, contraction, and deflection between the disparate materials, movement of the building frame could lead to cracking and buckling of the masonry.

In addition, corrosion of the steel frame due to exposure to water in the damp masonry could also cause masonry displacement. Unfortunately, such problems took many decades to become apparent. New York's first facade inspection ordinance, prompted by a fatality from falling masonry, was not written into law until 1980.