Elements - Exposure Classifications

BridgeStation Knowledge Base > BridgeStation Web Edition > Structures
 
Exposure Environment Exposure Description Typical Element Location
Mild
Structure and/or elements of a structure:
 
  • Generally exposed to mild weather conditions, i.e. may be sheltered or in an environment that results in little or no exposure to severe weather conditions; and/or
  • Not exposed to any aggressive agents, e.g. no exposure to road de-icing salts or greater than 8m* away from traffic spray, not exposed to or buried in aggressive soil agents, no exposure to contaminated water, etc.; and/or
  • With no ventilation or condensation problems or where poor ventilation or the level of condensation are unlikely to increase the rate of deterioration.
  • Elements protected from salt spray with cladding or by a protective enclosure.
  • Deck soffit and piers of integral bridges where the obstacle crossed is not a road, i.e. elements are not subjected to spray from salted road.
  • Tenanted arch bridges.
  • Half-joints or hinge joints overlaid with functional expansion joints.
Moderate
Structure and/or elements of a structure exposed to:
 
  • Moderate (normal) weather conditions, e.g. direct rain, moderate humidity or condensation, some freeze-thaw action etc.; and/or
  • Moderate de-icing salt spray and airborne chlorides; e.g. within 3 to 8m of traffic spray on routes with de-icing salts; and/or
  • Low to moderate river flow.  But elements are not exposed to or buried in aggressive soils.
 
 
  • Top of roadside bridge pier or abutment subject to light vehicle spray from salted road. 
  • Bridge deck soffit subject to light vehicle spray from salted road.
Severe
Structure and/or elements of a structure exposed to:
 
  • Continuous or regular severe/extreme weather conditions, e.g. hot and cold extremes, high freeze-thaw action, severe humidity or condensation, etc.; and/or
  • Severe de-icing salt spray, e.g. within 3m of traffic spray on routes with de-icing salts; and/or
  •  Run-off and/or ponding on routes with de-icing salts; and/or
  • Aggressive soils, i.e. completely or partially buried in aggressive soils that are contaminated with acidic water or water containing sulphates; and/or
  • Marine environment and/or abrasive action of seawater or completely immersed in sea water; and/or
  • Corrosive fumes in industrial areas; and/or
  • Medium to rapid river flow and flooding.
  • Roadside bridge abutment, parapet upstand or deck edge beam subject to heavy vehicle spray from salted road.
  • Section of bridge deck near a leaking expansion joint or gutter e.g. deck end or crosshead.
  • Half-joints or hinge joints overlaid with non-functional expansion joints.
Protected Protected' refers to a finish 'freezing' deterioration of the component/material type.  
 
* The 8m limit is based on DMRB BD 43/03.
Article ID: 209, , Modified: 11/9/2016 at 2:59 PM

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