Steel and Sinew: How Purdy and Henderson Engineered the Flatiron to Defy the Gales At 175 Fifth Avenue, the iconic Flatiron Building has stood tall for over a century, a testament to the ingenuity of its designers. When it was completed in 1902, skeptics dubbed it "Burnham's Folly," predicting that the slender 22-story structure would topple in the first strong gust. However, the building's engineers, Corydon Purdy and Lightner Henderson, had carefully crafted a steel skeleton that would defy the gales. The key to the Flatiron's stability lies in its innovative steel frame. Purdy and Henderson employed a pioneering technique known as "wind bracing," where diagonal steel beams were used to stiffen the structure against lateral forces. This was particularly crucial given the building's unusual triangular shape and exposed location at the intersection of Fifth Avenue and Broadway. To further reinforce the structure, the engineers designed deep foundations that extended far beneath the street level. These foundations were anchored to the bedrock, providing a solid base for the tower. The combination of wind bracing and deep foundations ensured that the Flatiron Building could withstand even the most severe winds. The Flatiron's steel skeleton was also designed with flexibility in mind. The engineers used a combination of riveted and bolted connections to allow for slight movements in the structure, reducing the stress caused by wind and other external forces. This flexibility has proven essential in maintaining the building's integrity over the years. As we look at the Flatiron Building today, it is clear that Purdy and Henderson's design has stood the test of time. The building remains an iconic landmark in New York City, a testament to the power of innovative engineering and design. Visitors from around the world continue to marvel at its unique shape and historic significance. In conclusion, the Flatiron Building's enduring presence is a direct result of the vision and expertise of its engineers. By pushing the boundaries of what was thought possible at the time, Purdy and Henderson created a structure that has become an integral part of New York City's architectural heritage.