Example Of The Clifton Suspension Bridge Report

The Clifton Suspension Bridge stands out as one of the historic bridges which span the Avon George and the River Avon joining Clifton in Bristol to Leighwoods in North Somerset. The bridge opened in the year 1864 and was designed by the engineering quintessential Isambard Kingdom Brunel. This paper seeks to analyze the engineering and construction challenges that faced the designers of this most historic suspension bridge.
The construction of this bridge took almost a total of three decades that is, from the first laying of the foundations stone in the year 1836 to the year 1864 when it was initially opened for traffic. The first challenge faced by the designers was the construction of the abutments and piers which took a painfully long time and was also a relatively long process. Further, designers were particularly faced by challenges of lack of sufficient funds which caused delays to the construction of the bridge. Further, delays were also caused by the interruptions that resulted from the riots that took place at the time in the area. During the construction of the bridge, a total of six wires were strung across the gorge side by side and bound with planks to from a temporary footbridge with two ropes that were 3 foot and 6 inches above the planking to act as a handrail. More so, there was another wire that ran above this footbridge. Constructors attached a small cart to allow for the individual links form the chains to be taken from the piers and to the men that were constructing them. It is also the case that the chains were built from the anchorage plates towards the outside and from the piers towards the inside. As a result of joining of the chains at the middle, the packing was lowered and the chain took its own weight thereby reliving the stage from its action. Another engineering challenges that confronted the designers was the attachment of the suspension rods as well as the cross girders. This was made possible by the use of apparatus which was made by the contractors. The apparatus was a mobile crane that travelled on a railway on top of a base frame which weighed in excess of 5 tons. It was designed and constructed in such a way that when it moved to the edge of the abutment, it would carry a cross girder with the section of a longitudinal attached to its intended position where the rods and the chain were fixed to it. It is then that the planks were then laid to linking the abutment to the cross girder. The railway was then advanced with the process being repeated till both ends met at the middle. The removal of the planks enabled the remaining cross girders to remain fixed in their place.
The other critical challenge that faced the designers of the Clifton Suspension Bridge concerns the temperature effects. It is well known in engineering that fluctuations of temperature have an effect on the design of any metallic construction more so a bridge. This is because the contractions and expansions associated with fluctuations in temperature cause the bridge material to develop residual stress within its structure which is dangerous to traffic. In this case, the effects of temperature changes in the timber decks were minimal as compared to the effects caused by temperature fluctuations with respect to the wrought iron chains and the deck frame. The designer of the bridge Brunel well knew this challenge of temperature fluctuations and how the same would affect the bridge structure. As a result, Brunel had estimated that the changes in length of the chains would cause a decrease or an increase in the length of the chains. This was subsequently accounted for by the ensuring that the towers were built high enough to allow for such movements in the deck that would be caused by the then change in dip of the chain. This also was to allow for the movement of the chains over the saddles. Another critical and extremely essential aspect of assessing a bridge is the assessment of the natural frequency of the bridge. It is notable that at the time of the building and designing of the bridge, the natural frequency assessment was not considered an essential aspect of a bridge design as it is today. Indeed, if such an aspect is overlooked, it could lead to a possible collapse of the entire bridge structure. For instance, in modern day, the fundamental frequency of a superstructure is required to fall within the limits greater 5 Hz and less than 75 Hz. It is the case that if natural frequency falls below 5 Hz, then a mere gust o9f wind or a pedestrian walk may create a lot of problems to such a structure. Yet, at the time, this crucial aspect was only a matter of a personal opinion on the part of the designer. Without doubt, this was a formidable challenge.