‘Gutsy, masculine and industrial’, SOM’s John Hancock Center showcased its engineer’s ingenuity and confirmed Chicago’s continuing status as an incubator for new design.
The bold articulation of the massive X braces that criss-cross the façade emphasise the engineer’s contribution to the design (photo: pigprox – stock.adobe.com).
“It’s not easy to come up with a new system every day,” Fazlur Rahman Khan once said. Perhaps he was just being modest: for the prodigiously talented structural engineer, the rate of invention seemed nearly that rapid, and he sure didn’t make it look hard. Born in present-day Bangladesh under the British Raj, trained in the US courtesy of a Fulbright scholarship, Khan possessed an almost uncanny ability to perceive solutions through intuition that others would only arrive at through laborious mathematical calculation. As his daughter Yasmin Sabrina Khan (herself a trained engineer as well as an author) once observed, Fazlur could somehow experience “empathy… with the structure under load,” literally feeling what it was like to be a building.
This almost comic-book superpower reached peak intensity with the John Hancock Center, the 100-storey, truncated- pyramid tower that stands as one of the most recognisable fixtures on the Chicago skyline. It does not stand alone: together with his architectural counterpart Bruce Graham and their collaborators at mega- firm SOM, Khan was responsible for many of the most prominent skyscrapers in the city, including the Sears (now Willis) Tower, the tallest in the world for much of the latter 20th century. A number of Khan and company’s other projects were no less important in terms of innovation, not the least being the nearby DeWitt-Chestnut Apartments (1962) and Cook County Administration Building (1964), which previewed many of the structural techniques that would make the team’s subsequent oeuvre possible. Neither the largest nor the first of its kind, it is still Hancock above all that shows how daring Khan’s vision really was, and how much potential it had to reshape the urban landscape.
Over a thousand feet tall at its flat-topped roof, and with its signature antennae adding another five hundred feet more, the building’s singular silhouette is a bold presence on the Chicago skyline (photo: rabbit75_fot – stock.adobe.com).
It did not, in its initial conception, promise to do quite that much. Insurance giant John Hancock had intended to finance the development of two buildings on the site on North Michigan Avenue, towards the upper end of the glittering retail corridor known as the Magnificent Mile. If realised according to the original scheme, the results would have been predictable: a low-rise commercial structure facing the main street, and behind it a high-rise residential tower, the arrangement already planned (though not yet executed) for what would become Water Tower Place immediately across the street. But the rote Modernist strategy of separate functions in separate volumes would be upended when one of the existing occupants of the parcel refused to vacate. The architects would have to squeeze the hoped-for suite of condominiums, offices, shops, and amenities into a much smaller site.
Graham – the dynamic, Peruvian-born architect who would lead SOM’s flagship office for four decades – was the first to recognise that two towers would no longer be suitable. But it was Khan who figured out how to compress all the projected programs into a single envelope. The instrument he used was one he had already demonstrated at DeWitt-Chestnut, and then developed further with Cook County: where a typical skyscraper relies on a solid centre core to carry the bulk of the vertical load, Khan determined that perimeter members, properly spaced and rooted in the ground, would be sufficient for the same purpose, turning the skyscraper into a sort of giant cantilever. The deployment, as Khan termed it, of “the hollow thin- walled tube with punched holes” would have the added advantage of requiring fewer and less bulky materials to attain the same heights as conventionally-built towers. It was exactly the system needed on North Michigan.
The tubular breakthrough did not solve every problem at once. Early in the project’s development, a group of consulting engineers attempted (unsuccessfully) to hijack Khan’s scheme and make detrimental changes; partway into construction, the contractors discovered they had miscalculated the soil settlements, resulting in huge financial losses and the bankruptcy of the initial developer. The setbacks were only temporary, however, and the building that ultimately emerged was astonishing: “gutsy, masculine and industrial,” in Graham’s words. The architectural expression given to Kahn’s gigantic black wedge puts an emphasis on the engineer’s contribution, in particular through the bold articulation of the massive X-braces that criss-cross the façade from top to bottom. Over a thousand feet tall at its flat-topped roof – and with its signature antennae adding another five hundred feet more – the building’s colossal presence and singular silhouette was as bold an announcement as any that Chicago, the birthplace of the modern skyscraper, was still an incubator for new design.
The architecture profession was a little slow to notice – in her touching memoir of her father, Yasmin Khan notes that Hancock was denied award after award by the AIA until the 1990s – but its place in the canon seems secure by now. Among other things, the layering of apartments on top, workplaces below, and public attractions at ground level was arguably the first full-blooded expression of the multi-use high-rise, now a staple of American cities and a substantial break with the single-use towers of the early postwar years. That achievement wouldn’t have been possible without Khan’s insight; nor, for that matter, would a great deal else. From the Shanghai World Financial Center, to the Burj Khalifa in Dubai, to the Petronas Towers in Malaysia, Khan’s tube has become the system of choice for tall buildings in our time. It is remarkable to consider that such a self-effacing man should have helped create so many monuments.
