Bracing for Disaster: Earthquake-Resistant Architecture and Engineering in San Francisco, 1838–1933 (review)

The field of construction history is making good progress, if the roughly 180 papers presented at the Second International Congress on Construction History in 2006 are any indication. Those who contribute to the field come from diverse backgrounds—academics in a variety of disciplines, engineers, architects, and tradesmen, for example—and they have a range of research interests. Yet two questions are central: how did people actually build, and why did they build that way? Stephen Tobriner asks these very questions in his book about San Francisco. Published in the centennial year of the great 1906 earthquake and fire in that city, Bracing for Disaster is a history of the techniques architects and engineers used to safeguard their buildings in the event of earthquakes.

Tobriner is an architectural historian who has studied the reconstruction of buildings following early modern earthquakes in Europe, and he has been a member of teams that investigate damage to buildings from modern-day earthquakes. His book begins with the settlement of the city and ends in 1933, when California enacted a comprehensive earthquake code; but in keeping with his interest in "earthquake-resistant architecture and engineering," the focus is on buildings during and after two major earthquakes, in 1868 and 1906. In that interim, architects, engineers, and materials manufacturers introduced a variety of solutions to the problem of how to protect structures in an earthquake zone. One of Tobriner's main goals is to show that the city's architects and builders, joined at the end of the nineteenth century by engineers, tried to deal with the problem even though they had limited knowledge of the causes and nature of earthquakes. He contests assertions that San Franciscans minimized or ignored earthquake danger: "most building professionals were seriously trying to see and understand, not to deny or conspire" (p. 220).

Efforts to take earthquake hazard into account in design began at an early date in San Francisco. The most interesting part of the book deals with the various measures introduced from the 1850s through the 1880s. These were voluntary and experimental, but creative and in some cases effective. One solution was to build masonry buildings with self-supporting walls and separate internal frames made of timber, which carried the buildings' loads. In theory, the more flexible frame could ride out an earthquake even if the walls cracked and fell. Another strategy was to put horizontal iron bars into masonry walls and tie the bars together at corners, so as to unite the structure. Bond iron or timbers were practically universal in brick walls built in England in the eighteenth and early nineteenth centuries, and a number of San Francisco's early architects came from Britain and Ireland. There, the bond timbers simply kept a building together during construction, but in San Francisco the idea was adapted to reinforce masonry walls.

During the 1890s, the city's designers apparently lost interest in earthquake-resistant design. Tobriner discusses the seismic features of some of the early steel-frame buildings, but later ones had no such features. He writes that engineers believed steel frames designed to resist wind would also survive earthquakes. Yet many buildings had no special wind bracing. Moreover, the steel-frame buildings made up only a fraction of the city's stock. So, what was being done to make the great majority of the city's buildings safe? Very little, Tobriner acknowledges.

Several chapters are devoted to the question of how various types of buildings in San Francisco were affected by the 1906 earthquake. This is a complicated matter because fires that broke out soon after the quake destroyed buildings that had survived the quake and obscured quake damage in buildings that survived the fires. Yet Tobriner attempts to assess the effect of the earthquake on buildings, using contemporary photographs and reports about the condition of buildings after the quake and before the fire. His main conclusions are unsurprising: buildings...