Handbook for Bridge Inspections - TSP2

9.2 CONCRETE ELEMENTS
203 Deformation of Concrete
Element
The type of damage "Deformationy" covers bridge elements which have developed bowing whencompared
to their original shape. They can consequently have been subj ected to additional loads or
now have reduced carrying capacity. The consequence can be pennanent deflection of, for example,
the main carrying element or the bridge deck etc.
Cause of Damage
• Design fault - under-designed elements or incorrect assumptions.
• Construct ion fault - settlement of the scaffolding during construct ion; unintentionally applied
loads.
• Loads - overloading due to heavy vehicular loads; too thick an asphalt layer.
• Accident impact - traffic colli sions.
• In-service impacts - c.g. secondal)' damage due to subsidence for example.
Possible Measurements
• Levelling.
Degree of Damage & Consequences
Deformation of load bearing elements can be an indication of too Iowa carrying capacity or of
overloading.
The degree of damage assigned must be based on the severity of the defonnation and its probable
further development.
So far as continuous span bridges are concerned deformat ion of the superstructure due to subsidence
in abutments/columns will affect carrying capacity . Calculations must be undertaken before
deciding the degree of damage. In many instances differential subsidence has been taken into
account during the design period and should therefore be included in the process of deciding the
degree of damage.
Deformation due to subsidence can also affect future maintenance costs since the long-term deformation
of concrete caused by creep will make jacking procedures more difficult.
Carrying capacity will not be affected by subsidence of scaffolding.
Both traffic safety, maintenance costs and the environment can be affected byabnormallong-tenn
deformation due to the bridge's fully laden weight.
150 Handbook for Bridge Inspections