BUILT

Looking at the history of structures through “the eyes of an engineer.”

For those who wonder why tall skyscrapers don’t tip over and long suspension bridges don’t collapse, structural engineer Agrawal has some answers. Written in a personable, friendly style featuring the author’s own hand-drawn illustrations, the book acts as a guide to “our ever-changing, engineered universe…full of stories and secrets.” Agrawal cut her engineering teeth on a footbridge for Northumbria University, assiduously checking and rechecking the forces her bridge would need to withstand; “as engineers,” she writes, “we can’t afford to make mistakes.” In the chapter on “Force,” she looks at the effect of gravity on various structures. In 1907, the Quebec Bridge, which spanned the St. Lawrence River, collapsed, killing 75 workers; the engineer underestimated the bridge’s weight. Addressing the effects wind or earthquakes can have on buildings, Agrawal explores the Taipei tower in Taiwan, which has a 660-ton steel pendulum near its top, the “heaviest in any skyscraper in the world,” which absorbs the tower’s movement. In “Fire,” she notes that the twin towers’ engineers had planned for the effect of a Boeing 707 crashing into the building. Three decades later, when two much larger planes struck them, fires from their fuel loads collapsed the buildings’ steel columns. “Clay,” “Metal,” and “Rock” examine building materials. The author notes how she loves to “stroke” concrete and feel its texture. When Henry Bessemer revolutionized the steel-making industry in the mid-19th century, 200,000 tons per year were produced. By 1898, it was 12 million tons. Without Elisha Otis’ elevator, writes Agrawal, buildings would not have been able to go higher and higher: “the equivalent of the entire world’s population is moved in an elevator every 72 hours.”

A delightful introduction to the science of engineering and those key in its development, from Brunelleschi and his Duomo in Florence to Emily Roebling’s Brooklyn Bridge to Fazlur Khan’s monumental Burj Khalifa in Dubai, the world’s tallest building.