The Amazing Engineering Behind The Golden Gate Suspension Bridge Explained
Mr. Joseph Strauss, Chief Design Engineer, created the intricate engineering marvel that is the Golden Gate Bridge, a suspension bridge across the Pacific. Ships can pass under the bridge thanks to its suspension cable system, which enables it to resist the ocean’s lethal currents. Two towers are built at either end of the ocean as part of the bridge’s construction, and a lengthy cable is slung between them. A concrete road surface supported by pillars runs the length of the wire, which can be roughly modelled as a parabola. The road deck is secured against failure by use of suspension cables that run the length of the bridge and are connected to the main cable.
The potential of the towers bending inward because of the main cable’s extreme tensile load is one of the many difficulties the bridge’s design has had to overcome. In order to resolve this problem, the engineers made the decision to lengthen the main cable and secure it using an anchorage system to the earth. The length of the unsupported bridge deck was shortened by the engineers’ closer tower placement, which produced a cable with a smaller cross-section area in order to maximise financial resources.
But because concrete is brittle, there would be cracks in the deck if the steel braces were directly attached to the concrete. Mr Strauss attached the braces to a sturdy steel structure in order to remedy this issue. The road deck is positioned atop this construction, which shows the specifics of the relationship between the braces and steel structure.
The misty and windy conditions at the bridge’s location made assembly challenging. Ships were used to transport the prefabricated truss members to the construction site. Their connections were fastened with rivets, and assembly was completed with the aid of a derrick. To protect workers, a net was positioned beneath the bridge deck.
Suspension cables were employed in 250 pairs of vertical cable to link the structure to the main wire. Workers needed to install this system evenly and concurrently in two directions for each tower in order to keep equal loading on the wire. The entire bridge deck was suspended from the main cable, which was connected to 250 pairs of vertical cables on the bridge.
On top of the solid framework, concrete was built by erecting wooden form work, fastening steel bars to the steel sections beneath it, and then using a needle vibrator to pour and compact the concrete. Even though the bridge looks great right now, it is not yet prepared to handle car traffic.
In order to address the issue of thermal expansion, Mr. Strauss separated the deck into seven sections, installing finger expansion joints in between the joints during periods of high temperature. The elegant answer to the thermal expansion problem is offered by these joints, which move by nearly 4 feet. But the steel has a somewhat greater differential expansion than the concrete, which could be problematic for the concrete deck. Because of this, the Golden Gate has microscopic expansion joints spaced 50 feet apart to reduce the effect that thermal expansion has on the concrete deck.
A major obstacle had to be overcome by Lesex principal engineer Mr. Joseph Strauss in order to develop the Golden Gate Bridge. He tried out two distinct bridge designs: a short journey design with a tiny sag and a tall tower design with a significant sag. The angle of the cable tension in the vertical component of the cable tension and the load to be carried were the primary differences between the two systems. Although the tall tower design required more money to build, it decreased the tension in the wire.
Mr Strauss talked about building the south side tower and how difficult it was to build the Golden Gate Bridge in the film. In order to build a tower foundation on sturdy bedrock known as hard strata, the south tower had to cross the ferocious Pacific Ocean. To improve the structure’s surface, professional divers were engaged to detonate bombs underwater. Fender walls were built by pouring concrete, and water was pumped out from within.
Because of the ocean currents, which made the work extremely dangerous, building the fender walls was difficult. Placing material shafts, worker shafts, and blasting tubes inside the fender walls was a brilliant idea that Mr. Strauss came up with. To hold the fender walls and shield workers below from lethal currents, a substantial reinforced concrete slab was built.
The hard strata were levelled, and then an RCC foundation and steel structure were constructed. Deadly waves were deflected from the main foundation by the fender walls.
Hollow steel cells were used to build and rivet the steel foundation plate when the construction of the enormous towers got underway. The tower’s construction was finished, and these cells were intended to be robust and affordable.
Cable saddles, consisting approximately 130,000 km of smaller wires total, were used to lay down the main cables. Before the wires were secured by workers and passed through the cable saddle over the tower one by one, they first built a catwalk bridge for themselves. The wires were then woven together using galvanised steel wire after being firmly compressed using a hydraulic press.
Next came the laying of the road’s concrete and the deck structure. On the Golden Gate Bridge’s 50th anniversary, an unusual incident happened as more than 300,000 people congregated on the bridge. Suspension bridges can sag or even bend inward when they are overloaded, as was the case that day. Even yet, Mr. Strauss’s suspension bridge held up well, thanks to technological advancements made 89 years prior to the bridge’s construction.
To sum up, the design and construction of the Golden Gate Bridge by Mr Strauss represented a major advancement in the field of civil engineering. In addition to showcasing the cutting-edge technology created by Lesex for the bridge’s design and construction, the movie highlights the significance of weighing the advantages and disadvantages of various building techniques.