In 1978, Diane Hartley, an undergraduate architecture student, made a startling discovery while working on her thesis. Her research focused on the Citicorp Center, a towering skyscraper in midtown Manhattan. As she meticulously examined the building’s plans, she uncovered a potentially catastrophic oversight that threatened to bring down the 59-story structure in one of New York City’s most densely populated areas.
Completed in 1977, the Citicorp Center was among the world’s tallest buildings at the time. Its sloped roof was a distinctive feature in the city skyline, but the building’s most remarkable aspect lay at its base. The construction site was already occupied by St. Peter’s Lutheran Church, necessitating the skyscraper to be built on columns, akin to stilts. While using stilts on a building’s corners was not unprecedented, the church’s location at the block’s corner required these supports to be placed at the center of each side.
Despite concerns from some backers, chief structural engineer William LeMessurier took extensive measures to ensure the building’s stability. The exterior was designed with v-shaped chevrons, forming a robust exoskeleton to support the skyscraper. This design not only provided strength but also reduced the building’s overall weight. However, it left the structure susceptible to strong winds, a challenge LeMessurier addressed with a state-of-the-art solution—a tuned mass damper. This 400-ton counterweight, controlled by computerized sensors, was designed to counteract any swaying.
With these safety measures in place, calculations indicated that each side of the building could withstand powerful winds, and the Citicorp Center opened for business in 1977. However, a year later, Hartley noticed an anomaly during her study. While the building’s broad sides were designed to endure strong winds, the unique base meant that winds striking the corners posed a greater threat. Traditional designs did not account for corner winds, leading Hartley to suspect that this risk had been overlooked.
Upon contacting LeMessurier’s firm, Hartley was initially reassured that the building could handle these winds. However, upon reviewing the plans, LeMessurier identified a critical issue. A change, made without his knowledge, had replaced the exoskeleton’s welded joints with cheaper, weaker bolted joints. Although the mass damper mitigated this risk, a power outage during a storm could deactivate the counterweight’s sensors, leaving the building vulnerable to winds of just 112 kilometers per hour. Given the weather data, such a storm had a one-in-sixteen chance of hitting New York City annually.
LeMessurier never informed Hartley of her discovery’s significance. Instead, he discreetly informed the architects and Citicorp executives, and together with city officials, devised a confidential plan. Without alerting the public, construction crews embarked on night-time shifts to reinforce the bolted joints. This delicate operation began in mid-August 1978 and was only halfway complete when Hurricane Ella threatened the city in September. City officials and Citicorp executives prepared an emergency evacuation for a 10-block radius, but the hurricane ultimately veered out to sea, sparing the city.
The secret evacuation plans were never executed, and the reinforcements were completed a month later. Remarkably, this covert construction went unnoticed due to a newspaper strike that coincided with the project. The public remained unaware of the near-disaster until 1995, when a New Yorker article unveiled the story to the city and to Diane Hartley. Although the article, like LeMessurier, failed to credit Hartley, she at least knew that her diligent work had saved countless lives.
Construct a scale model of the Citicorp Center using materials like cardboard, straws, and glue. Pay special attention to the unique base design and the placement of the columns. This hands-on activity will help you understand the architectural challenges and solutions implemented in the building.
Create a wind tunnel using a fan and a small-scale model of the Citicorp Center. Test how the building reacts to winds from different directions, especially the corners. Document your observations and compare them with the issues Diane Hartley discovered.
Research another famous building that faced structural challenges and present your findings to the class. Highlight the problem, the solution, and any lessons learned. This will help you appreciate the complexities of architectural engineering and the importance of thorough analysis.
Participate in a classroom debate on the ethical responsibilities of engineers and architects. Discuss whether LeMessurier and the Citicorp executives handled the situation appropriately. Consider the implications of keeping the reinforcement mission secret from the public.
Write a short story or essay from the perspective of Diane Hartley, detailing her discovery and the potential consequences if the flaw had not been addressed. This activity will help you explore the human element in engineering and the impact of individual contributions.
Engineering – The application of scientific and mathematical principles to create structures, machines, and systems that solve problems. – Engineering plays a crucial role in developing sustainable energy solutions for the future.
Architecture – The art and science of designing buildings and other physical structures. – The architecture of the new library combines modern aesthetics with functional spaces for community use.
Skyscraper – A tall, continuously habitable building with multiple floors, typically designed for commercial or residential use. – The skyline of the city is dominated by a stunning skyscraper that reaches over 100 stories high.
Stability – The ability of a structure to maintain its position and resist external forces without collapsing. – Engineers must ensure the stability of bridges to withstand heavy traffic and environmental conditions.
Winds – The movement of air that can exert pressure on structures, affecting their design and stability. – Architects consider the effects of strong winds when designing tall buildings to ensure they can withstand gusts.
Joints – The points at which two or more structural elements are connected, allowing for movement and flexibility. – Properly designed joints are essential in construction to accommodate thermal expansion and contraction.
Construction – The process of building or assembling infrastructure, including roads, bridges, and buildings. – The construction of the new sports complex is expected to be completed by the end of the year.
Design – The process of creating a plan or drawing that outlines the specifications and aesthetics of a structure. – The design of the new community center incorporates eco-friendly materials and energy-efficient systems.
Safety – The condition of being protected from or unlikely to cause danger, risk, or injury in engineering and construction. – Safety protocols are critical on construction sites to prevent accidents and ensure worker well-being.
Disaster – An event that causes significant damage or destruction, often requiring engineering solutions for recovery and rebuilding. – After the earthquake, engineers were called in to assess the damage and develop a plan for disaster recovery.
