PEDESTRIAN STEEL BRIDGE INSPECTION

The first pedestrian bridge was built to provide a transportation facility to commute from one place to another place which was made of wooden material before the 2nd century BC. This pedestrian bridge was constructed during the 20th century over a tube line and it was 0.2 miles away from Upton Park tube station, London, United Kingdom. The main purpose of this bridge is to provide easy transportation possibilities for pedestrians and cyclists ( dismount before entering required). The first warren-type truss bridge was constructed during the mid-nineteenth century by James Warren and Willoughby Monzoni. The inspected bridge is similar to a subdivided warren-type truss bridge. The pedestrian bridge weight is equally divided by an equivalent triangular diagonal bracing system and the low weighted frame structure was named as subdivided warren truss bridge because patented by James Warren who invented it in 1846. This inspection was carried out as an assignment submission according to visible inspection from the footpath, all the content of this website is not accurate as per standard.

As shown in figure 1, Bridge itself seems like a subdivided warren truss bridge whereas, the superstructure was fully material of steel and its elements as listed above and the construction form is bolted connection throughout the structure resting on steel bearing of each side. The total length of the span is approximately 22m and the width of the walkway is approximately 1.8m and the type of bridge bearing looks like a spherical bridge bearing. Three subs confined span was given to decrease the weight of the bridge and provide the predominant relentlessness to the substructure component and the upper and lower chord bracing of the bridge which is interfacing with each side of inclining to brace was meddle its aggregate structure component and provide the security against wind oblige. Anti-skid steel deck provided due to provide sufficient grip who is using that bridge to cross the tube station and also steel sheet barrier provided both sides of the bridge to prevent the risk of falling outside for safety of pedestrian and cyclist.

From figure 3 to 10, the problem identified from the video and photograph such as, rusting, leaked, unequal sloping, vegetation, slippery surface of the walkway, bent vertical bracing, rusted bolt, corrode joint plate, missing brick, a wet portion of the abutment, cracks, etc.

Health & Safety

Lack of drainage line and uneven sloping induce the risk for users of the bridge, as per safety user code bridge was inspected according to considering life safety. Safety barrier provided to reduce the risk of falling down on railway line.

Risk Assessment Form

Bridge observation clearly shows that the primary deck element and secondary deck elements are in average condition so it was categorized as 2C (1.2) as per visual inspection. There is minor corrosion on the nuts and joints plate of the transverse beam and the primary deck seems good but no proper sloping was provided on the bridge due to that water was not drain-off and it may cause by rusting the deck element.

5.2 Load Bearing Structure

5.3 Durability element

5.4 Safety Element

5.5 Ancillary Elements

• Rainfall

• The uneven slope on the primary deck

• Accidental Damage of vertical bracing member

• Missing of the drainage system substructure

• The coating is not sufficient on the bracing element

• Overloading on abutments

• Damaged abutment like wet bricks, cracks, missing brick, vegetation growth

• Loading on corrode steel bearing of the structure

• Windstorm effects on the bracing elements

• Repaired wing walls

• Bolt missing on modular joint

• Bolt cap missing on joint plate of bolt connection

According to considering above all causes of defects, the structural behavior of the bridge is good because it's only used by pedestrians and cyclists. So that's the reason of bridge is in working condition. There will be some displacement shown if necessary was not taken as early as possible and it may cause major loss of structure later on. Slight Displacement is recognized in structural behavior from the considering joint position and bolt missing on the plate it creates unequal loading on abutments ultimately defects increase in the substructure elements. Also, crack is a factor of structural deterioration due to the leakage of water. Structural behavior can be improved by taking necessary steps like coating, joints, and exchanging corrode plates to improve the life of the bridge and the safety of users.

According to considering above all causes of defects, the structural behavior of the bridge is good because it's only used by pedestrians and cyclists. So that's the reason of bridge is in working condition. There will be some displacement shown if necessary was not taken as early as possible and it may cause major loss of structure later on. Slight Displacement is recognized in structural behavior from the considering joint position and bolt missing on the plate it creates unequal loading on abutments ultimately defects increase in the substructure elements. Structural behavior can be improved by taking necessary steps like coating, joints, and exchanging corrode plates to improve the life of the bridge and the safety of users.

Testing & monitoring of all elements was required to evaluate the proper bridge defects and how critical condition of it was? So, various testing & monitoring methods are required to do for effective analysis of structural behavior and getting critical information of the bridge to provide safety for pedestrians. Some of the testing & monitoring methods that are recommended after the bridge inspection are listed below.

1. Vision-based monitoring method ( Photographic )

2. Impact testing on joints ( To check yield stress capacity

3. Sound testing on abutments & modular joints

4. Magnetic particle testing on corroding elements of the truss ( To identify losses of section )

5. Vibration method ( Displacement checking )

6. Radiographic testing ( Lower part not visible so )

7. Laser testing ( due to lack of visibility, to identify cracks )

The recommendation for maintenance, repair, or strengthening required for various bridge elements is listed below.

1. Repainting and coating of safety barrier and modular joints.

2. Reinforce steel section which is not in proper condition by welding techniques.

3. Filling techniques of the cracks in masonry abutments and wing walls.

4. Repair the cracks in abutments by concrete filling in the gaps.

5. Maintain by cleaning the exposure area of the bridge drain-off the water from the upper deck surface.

6. Replacing loss bolts and nuts for strengthening.

7. Repainting complex joints which are in the initial stage of corrosion.

8. Resurfacing of anti-skid steel sheet to provide better slope to drain-off water from upper surface.

9. Replacing rusted joint plate to provide better stability and strengthening of structure.

10. Extra bonding plate if require after monitoring structural behavior.

The pedestrian bridge was inspected according to considering health and safety factors and only safe visible inspection through the footpath. From overall inspection of the bridge, the bridge looks like average condition and marked some critical points which described in inspection sheet and categorized in priority work required list to improve serviceability of that bridge not only this but also various testing and monitoring technique recommendation listed to identify the possible structural behavior to measures the working condition of bridge element and identify the repair techniques which is listed in section 8 as a recommendation which was helpful to improve the life of the bridge.