Jembatan Golden Gate | Puncak Teknik

Summary

The Golden Gate Bridge, a stunning feat of engineering, overcame numerous challenges during its construction, including harsh environmental conditions, complex design issues, and the need for innovative solutions. The suspension bridge design, with its iconic main cables and towers, solved problems like horizontal forces, thermal expansion, and deep-water foundation construction. The project required meticulous planning, precise assembly, and constant attention to worker safety. Despite the risks, the completed bridge stands as a symbol of engineering excellence, enduring both time and extraordinary stress, like the 50th-anniversary crowds, demonstrating its resilience.

Takeaways

• 😀 The Golden Gate Bridge is a suspension bridge designed to span the 2.7 km gap between San Francisco and Marin County, California.
• 😀 A key challenge in its design was to avoid obstructing shipping lanes, which led to the use of a suspension bridge system rather than a traditional beam bridge.
• 😀 The suspension system relies on two main towers and a network of cables to support the bridge deck, with the cables hanging in a parabolic curve.
• 😀 To counteract the tension and horizontal forces from the cables, the engineers designed a solution to anchor the cables to the ground and positioned the towers closer together.
• 😀 One of the most significant engineering challenges was preventing the towers from bending due to horizontal forces, which was addressed by optimizing the cable thickness and positioning.
• 😀 Expansion joints were incorporated into the design to manage the thermal expansion of the bridge, allowing it to expand and contract with changes in temperature.
• 😀 The foundations for the towers were built on solid rock beneath the ocean floor, requiring complex underwater blasting and excavation techniques.
• 😀 The main suspension cables are made up of 27,000 smaller steel wires, and assembling these cables required workers to build a catwalk system across the bridge.
• 😀 The bridge deck is constructed with a combination of steel and concrete, with workers fabricating and assembling the sections on-site.
• 😀 Worker safety was a priority during construction, with nets installed below the bridge to catch any falling workers and careful coordination to handle the construction in hazardous conditions.

Q & A

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

The suspension bridge design was chosen because it efficiently handles the long span between two shorelines (2.7 km) without obstructing ship traffic below. Alternative designs, like the conventional beam bridge, would have required costly foundations in deep water and would have been impractical.

What problem does the horizontal force on the towers create, and how is it solved?

The horizontal force from the tension in the main cables causes the towers to bend inward. To counteract this, the solution was to anchor the cables further into the ground and reduce the distance between the towers, which also allowed for thinner cables and more efficient use of resources.

What challenge did the engineers face with the concrete deck expansion due to thermal changes?

Thermal expansion of the concrete deck and steel structure presented a risk of immense pressure on the towers, potentially causing damage. To solve this, engineers incorporated expansion joints, which allowed the deck to expand and contract without damaging the bridge.

What role do the 'finger expansion joints' play in the Golden Gate Bridge?

The 'finger expansion joints' allow the concrete deck to move when subjected to extreme temperature changes. These joints are placed every 15 meters and can accommodate up to 1.2 meters of expansion to prevent structural damage.

Why are taller towers more effective for suspension bridges like the Golden Gate Bridge?

Taller towers are more effective because they reduce the tension in the suspension cables. A steeper angle in the suspension cables of shorter towers would increase tension, potentially causing the bridge to fail under heavy loads.

What was the difficulty in constructing the southern tower foundation of the Golden Gate Bridge?

The southern tower foundation posed a significant challenge due to the need to build it on solid rock 50 feet below the Pacific Ocean. Workers had to overcome strong ocean currents and dangerous conditions, involving underwater blasting and precise excavation techniques.

How did the engineers protect the foundation from the dangerous ocean currents?

The engineers used a clever method of constructing a concrete slab (called a 'dome') beneath the water, which protected the workers while they dug into the rock foundation. This also helped to prevent the structure from being damaged by strong ocean currents.

What is the composition of the main cables on the Golden Gate Bridge?

The main cables of the Golden Gate Bridge are made up of 27,000 individual wires, totaling 129,000 kilometers of steel wire. These wires are twisted together to form a large, strong cable that supports the bridge deck.

What unusual event occurred on the Golden Gate Bridge's 50th anniversary?

On the 50th anniversary of the Golden Gate Bridge, more than 300,000 people gathered on the bridge, which caused the deck to sag by nearly 2 meters due to the excessive weight. Despite this, the suspension system held strong and prevented catastrophic failure.

What innovative method did engineers use to build the towers of the Golden Gate Bridge?

Engineers used a modular approach, constructing the towers from hollow steel cells that were carefully assembled on-site. This made the construction process more efficient and allowed for the necessary structural strength while minimizing costs.