Distressed bridges and schedule of inspection by official

Distressed bridges and schedule of inspection by official.

Definition of distressed bridge:- A distressed bridge is one which shows some physical deterioration of its physical condition, indicating the need for rehabilitation through special repairs strengthening or rebuilding (including replacement of griders).

Classification of distressed bridges

Category - i: Those requiring rehabilitation to be done immediately, say within a year’s time. Category-ii: those requiring to be kept under observation and to be taken up for rehabilitation on a programme basis. Signs of distress for Group I bridges:

I. Foundation: Settlement of foundations, deep scour around pipers/abutment,

II. Piers and abutment: Crushing of masonry, tilled piers and abutment, wide cracks in abutment/piers, crushing of masonry.

III. Bed block and bearings: shaken/displaced/cracked bed blocks, cracks or any other distress in bearings,

IV. Arches: Diagonal cracks in arches, transverse in cracks arches, distortion of arch, displacement of brick/stone from arch ring, 

V. Misc.: Progressive loss in camber of prestressed concrete/steel girders, wide cracks in Reinforced Cement Concrete/prestressed concrete members. Crack/ heavy corrosion in load bearing members of steel girders, weak/corroded weak/ corroded/ cracked piles, particularly cast iron crew pipe, snapping of rivets.

 Sings of distress for Group II bridges

I. Abutments, piers, wing wall and return walls: cracks in return walls/wing walls, slight tilting/buging of masonry in return wall/wing walls, perceivable deterioration of stone/brick masonry,

II. Arches: wide longitudinal cracks in arches, abutments and piers, cracks/lean/bulge in parapet walls of an arch, bulging or separation of spandrel from arch barrel,

III. Misc.: Spelling of concrete in beams and slabs, loose rivets above 20% at any point, observations of any excessive vibration in part of the bridge.

Category Inspection by Periodicity

 I. 

(a) Inspector (concerned) - Once in a month

(b) AEN or ABE Once in two months

(c) DEN or Sr. DEN  Once in three month 

II.

(a) Inspector (concerned Once in three months

(b) AEN or ABE Once in six months

(c) DEN or Sr. DEN Once in a year