Handrails.ppt

TRAIL BRIDGE INSPECTION TIMBER DETERIORATION DECAY TIMBER DETEROIRATION DECAY Types and Causes of Timber Deterioration Types and Causes of Timber Deterioration NATURAL DEFECTS OF TIMBER Fungi Mold and Stain Brown and White Rot Brown and White Rot Insects Insects tunnel in and hollow out the insides of timber members for food and shelter. Some common types of insects include: Termites Carpenter ants Powder-post beetles or lyctus beetles Caddis flies Termites Carpenter Ants Powder-post Beetles or Lyctus Beetles Caddis flies Marine Borers Marine Borers Marine Borers Types and Sources of Deterioration Delaminations Delaminations occur in glued-laminated members when the layers separate due to failure within the adhesive or at the bond between the adhesive and the laminate. They provide openings for decay to begin and may cause a reduction in strength. Other Types and Sources of Deterioration Delaminations Types and Sources of Deterioration Loose connections Loose connections may be due to shrinkage of the wood, crushing of the wood around the fastener, or from repetitive impact loading (working) of the connection. Loose connections can reduce the bridge’s load-carrying capacity. Types and Sources of Deterioration Loose connections Types and Sources of Deterioration Surface depressions Surface depressions indicate internal collapse, which could be caused by decay. Types and Sources of Deterioration Fire Types and Sources of Deterioration Impact or Collisions Severe damage can occur to truss members, railings, and columns from floating debris or ice. Types and Sources of Deterioration Abrasion or Wear Types and Sources of Deterioration Types and Sources of Deterioration Overstress Types and Sources of Deterioration Overstress Types and Sources of Deterioration Weathering or Warping Other Types and Sources of Damage NATURAL DEFECTS OF TIMBER NATURAL DEFECT DEFINITIONS Defect - Check Defects - Split Defect - Shake Review of Natural Defects WHAT CAUSES D