Golden Gate Bridge | The CRAZY Engineering behind it

Summary

This video explores the engineering marvel behind the Golden Gate Bridge, focusing on its design and construction. The suspension bridge was chosen for its efficiency in spanning the 2.7 km distance without obstructing ship traffic, unlike beam or arch bridges. The video discusses key challenges, such as balancing cable tension, constructing stable foundations in the Pacific Ocean, and addressing thermal expansion. It highlights innovations by chief engineer Joseph Strauss, including cable systems, tower designs, and safety measures, emphasizing the bridge's resilience even under extreme conditions.

Takeaways

• 🌉 The Golden Gate Bridge is a suspension bridge that spans 2.7 km over the Pacific Ocean, using a parabolic cable system for support.
• ⚠️ Without the suspension cable system, the bridge would fail due to the lack of structural support.
• 🏗️ Joseph Strauss, the chief engineer, chose a suspension design because beam and arch bridge designs were either impractical or costly for this location.
• 🔗 Suspension bridges rely on tall towers and cables anchored to the ground to balance tensile forces, preventing the towers from bending inward.
• 🔧 Strauss solved the issue of concrete cracking by connecting the suspension cables to a steel structure, which provided a strong and flexible connection.
• 🛠️ The bridge deck was divided into seven sections with finger expansion joints to allow for thermal expansion, preventing damage from temperature changes.
• 🏔️ Constructing the south tower foundation was challenging due to its location in the deep and turbulent waters of the Pacific Ocean.
• 📏 Taller towers in suspension bridges reduce tension on cables and increase bridge strength, which was key in the design of the Golden Gate Bridge.
• 🔩 The main cables were created by spinning 27,000 smaller wires, resulting in a total steel wire length of 129,000 km.
• 🎉 On the bridge's 50th anniversary, it successfully supported a massive crowd of 300,000 people, sagging by 2 meters but remaining structurally sound.

Q & A

What would happen to the Golden Gate Bridge if its suspension cable system was not present?

Without the suspension cable system, the bridge would collapse, as the cables provide crucial support to the road deck, distributing the weight and ensuring the bridge’s stability.

Why was the suspension bridge design chosen for the Golden Gate Bridge?

The suspension bridge design was chosen because it allows ships to pass underneath and avoids the need for costly underwater piers in deep water, making it an efficient solution for the 2.7 km distance between the coastlines.

How did the engineers resolve the issue of inward bending of the towers caused by the tension in the main cables?

The engineers resolved the issue by extending the main cable and anchoring it to the ground via an anchorage system. This balanced the horizontal forces acting on the towers.

Why did Mr. Joseph Strauss move the towers closer together, and how did this impact the cable design?

By moving the towers closer together, the length of the unsupported bridge deck was reduced, lowering the tension in the cables. This allowed for a reduction in the cable's cross-section area, optimizing costs.

How did Mr. Strauss address the issue of the suspension cables causing cracks in the concrete deck?

Mr. Strauss addressed this by connecting the steel suspenders to a steel structure beneath the road deck, as steel-to-steel connections are stronger and prevent the formation of cracks in the brittle concrete.

What solution did the engineers use to handle thermal expansion in the Golden Gate Bridge?

The engineers used finger expansion joints between the road deck sections to allow movement during temperature changes. These joints prevent stress on the towers and road deck caused by expansion and contraction.

Why is the height of the towers crucial in a suspension bridge design?

The height of the towers is crucial because taller towers reduce the tension in the cables by increasing the angle of the cables. This reduces the overall stress on the structure, making the bridge stronger.

How was the south tower foundation constructed, and what challenges did the engineers face?

The south tower foundation was built on bedrock 50 feet below the seabed. Engineers faced challenges from the violent Pacific Ocean currents. To overcome this, they built protective fender walls and an RCC slab to safely carry out the construction beneath the water.

How was the main cable of the Golden Gate Bridge constructed?

The main cable was constructed by spinning 27,000 smaller steel wires over the towers and clamping them together. The wires were pressed using a hydraulic press and then bound into a single large cable.

What happened to the Golden Gate Bridge during its 50th anniversary celebration when it was overloaded with people?

During the 50th anniversary, the Golden Gate Bridge sagged by almost 2 meters due to the weight of over 300,000 people, but the suspension system held strong and prevented any structural failure.