Architecture 517 - Final Analytical Project

FORTH RAILWAY BRIDGE | Queensferry, U.K. Eric Heckman, Nathan Sands, Casey White Image Source: http://stlouispatina.com/firth-of-forth-bridge-scotland/

FORTH RAILWAY BRIDGE | Introduction

Architect/Engineer: Sir John Fowler and Sir Benjamin Baker | Constructed by Sir William Arrol & Co. Dates: Construction started in1882 | Bridge opened in 1890.

Location: Queensferry, U.K. Carries: Rail Traffic Crosses: Forth of Firth Length: 8,296’ Width: 120’ at piers | 32’ at center Height: 361’ | 150’ above water Longest Span: 1,700’

Stretching a total of 8,296 feet, with main structural elements spanning 1,710 feet in length, the Firth of Forth Railway Bridge was the most prominent steel structure when it was commissioned in 1890.

Documented to hold 14.6 million tons of rail cargo, the bridge encounters 190-200 rail passes daily. With such a prominent form and structure, the question arises of how the bridge resolves load forces encountered through railway activity, as well as how the structure was constructed during the 1800’s.

Utilizing 54,000 tons of steel, the superstructure consists of three seperate, double cantilever sections, supported by large granite piers.

To construct such a feat, builders used a double cantilever philosophy to their advantage, constructing outward from the central piers, while balancing progress on both sides. Utilizing a workshop in South Queensferry, large steel members were bent and rolled into desired shapes, developing upon the new found technology of rolled steel support members.

Structurally, rolled steel members, acting in compression, formed the structural skeleton of the structure, while lattice girders, spanning between the rolled steel members, acted in tension, preventing torsion and bending throughout the bridge’s structure. As structural and live loads of the structure are transferred through the framework of the long spanning bridge, granite piers and caissons, spanning 70 feet in diameter, acted as the foundation of the structure. These foundations supported the bridge’s structure, while transferring loads into the riverbed.

Image Source: https://www.thetrainline.com/trains/scotland

Image Source: https://en.wikipedia.org/wiki/Forth_Bridge

Image Source: https://www.urbanrealm.com/news/3547/Forth_Bridge_nominated_for_World_Heritage_Status.html

Image Source: http://photoeverywhere.co.uk/britain/edinburgh/slides/forth_bridge_tower.htm

Image Source: https://www.luxurytrainclub.com/trains/belmond-royal-scotsman/

FORTH RAILWAY BRIDGE | Construction Details

Image Source: https://www.pinterest.co.uk/agnesdrjewelery/south-queensferry-pics/

Details of Piers

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Erection of Cantelievers

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Erection of Cantelievers

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Erection of Towers

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Details of Junctions at Top of Towers

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Connections of CentralGirders and Centilevers

Image Source: https://www.theforthbridges.org/forth-bridge/construction-g

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

gallery/

FORTH RAILWAY BRIDGE | Structural Advancements

The Firth of Forth Railway Bridge was a marvel of engineering during the 1800’s that sought to break railway bridge records for it’s long spanning abilities. The structure, originally proposed to span the Firth of Forth River, utilized a revolutionary double cantilever design that implemented advancements in steel construction and bracing methods. Additionally the bridge used developments in caisson technology, plunging deep into the waters of the river, while supporting the multi-toned structure over 150 feet in the air.

The Firth of Forth Railway Bridge was constructed during a shifting era of technological advancement in the realm of architectural design.

The concept of rolling steel had just been established, allowing for hollow, structural members to be created. These hollow structural members not only lightened the structure of the bridge, but they also maintained the strength and stiffness of previous cast and wrought iron bridges in history.Furthermore, the fabrication process of rolling steel became more efficient in terms of construction. For example, as structural members of thesteel were being fabricated in a nearby facility, on-site installation could occur simultaneously, lessening the time frame of construction for the massive project.

CONSTRUCTION

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

Image Source: https://www.theforthbridges.org/forth-bridge/construction-gallery/

STRUCTURAL TESTING

Image Source: https://publicdomainreview.org/collections/the-forth-bridge-building-an-icon/

To demonstrate the double cantilever, three tower system to skeptics, the engineers developed a simulation, using two people acting as the double cantilever, while a person simulated the the center suspension span.

Weights were incorporated at the ends of the human demonstration to simulate the base anchors, bringing the cantilevered structure into a state of equilibrium.

Our group recreated this historic demonstration to help others, as well as ourselves, understand the forces acting upon the Firth of Forth Railway Bridge. We wanted to be able to actually encounter and feel the forces acting on ourselves, using our bodies as the tensional members, resembling the cantilevered portions of the bridge that are in a state of equilibrium. Additionally, our group tested different angles, lengths in span, and weight distributions to see if more optimal configurations for the bridge could be developed, given the advancements in technology and structural loading programs.

STRUCTURAL FORCES DIAGRAMS Dimensions 680’

Compression Members Tension Members

145’

680’

350’

680’

26

60’

1700’

145’

680’

FORTH RAILWAY BRIDGE | Structural Model

Using the information we learn from our physical testing, we created a scale model of the Firth of Forth Railway Bridge. This model acts as a structural model that tests possible point loads, stress levels, and failure points, amongst other forces, throughout the supporting and spanning members of the bridge. During our initial investigation, we discovered that the bridge utilized advancements in both steel construction and connections between spanning members.

To create a structural model of the Forth Railway Bridge, our team incorporated 3D printed structural joints, combined with 1/8� steel rod, acting as the structural members of the bridge. We recreated ONE of the cantilevered sections of the bridge, allowing for play and examination of various structural members.

During the construction process of the model, we do not incorporate every structural member, but instead, we included as many members needed to express the structural integrity of the railway bridge at the scale that we will be working at. The structural members included within the model examine main structural areas of the bridge in reality.

Our intentions were to test the limits of the current bridge’s design to determine the highest amount of load that can be enacted on the structure before it fails.

Model Scale | 1:32