Special Types Of Bridge Bearings || Bridge Articulation

Figure-1: Metallic Plunger Type Hinge Bridge Bearing.

Special Types Of Bridge Bearings || Bridge Articulation: 

1. Metallic Plunger Type Hinge Bridge Bearing: 

Nowadays, this type of bridge bearing is not available. Metallic plunger-type hinge bridge bearing had been provided in old pattern bridges. This type of bridge bearing is mainly provided in box girder-balanced cantilever Bridges. It had seen in Mahatma Gandhi Setu in Patna, Bihar State (Across Ganga River) and Old Narmada Bridge which is known as Sardar Vallabhai Patel Bridge in Bharuch, Gujarat State (Across the Narmada River). Mahatma Gandhi Setu had been constructed in 1972 to 1982 and Old Narmada Bridge had been opened in 1977. 

But now-a-days, It is observed that the bridge design does not seem to take present-day loading pattern and making distress in bridge articulation zones due to moving present days loading vehicles. Distressed superstructure of Mahatma Gandhi Setu is replacing in current year.

Distresses in Articulation zones:

Figure-2: Gap due to hammer action of plunger head.

Figure-3: Damaged Bridge articulation due to hammering action of bearing.

                           The plunger type hinge bearing (The line contact zones) are subjected to quick reversal of stress during the passage of each vehicle, resulting in continuous hammering action and also subjected to wear and tear caused by frequent reversible longitudinal movement of the bridge deck due to sway during the passage of each vehicle. This dynamic effect aggravates the continuous impact, which together with the wear and tear at the line contact zone quickly produces a gap between the plunger head and the Steel angle plates due to fatigue. Within short period there is developed no hinge condition. Anchor nuts are in loosed in all bearing and some anchor nut-bolts have been damaged due to the combined effect of shear stress and tensile stress along with continuous hammer action. Additional plates have been provided in most of the bearings and articulations have been repaired and rehabilitated before our inspection time but continuous hammer action in no hinge condition, the additional plates has been compressed and displaced in some bearing along with damaged the articulation. So, providing additional plate in gap between the plunger and the plates is not successfully rehabilitation process for the bearings. In that condition, replacement of metallic plunger type hinge bearing by central hinge bearing is more suitable and successful.

2. Central Hinge Bridge Bearing: 

Figure-4: Central Hinge Bridge Bearing

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