TRAIL BRIDGE INSPECTION.ppt

TRAIL BRIDGE INSPECTIONBRIDGE INSPECTION PROCEDURES Objectives: Learn the different inspection methods Learn a standard procedure to conduct routine bridge inspection Learn what to look for during an inspection Bridges Inspection Methods There are three basic methods used to inspect a timber bridge. They include: Visual Physical Advanced inspection techniques Visual Inspections For timber members, visual inspections reveal areas that need further investigation such as checks, splits, shakes, fungus decay, deflection, or loose fasteners. Types of Visual Inspections Cursory Inspection Involves reviewing the previous inspection report and visually examining the members Involves a visual assessment to identify obvious defects “Hands-on” Inspection. Requires the inspector to visually assess all defective timber surfaces at a distance no further than an arm’s length Timber surfaces are given close visual attention to quantify and qualify any defects. Physical Examination Once the defects are identified visually Physical procedures are then used to find out the extent of the deterioration or decay The basic methods for physical examination are: Pick Test Sounding Pick Test Probing with a pointed tool such as an awl will locate decay near the wood surface. Decay will be evidenced by excessive softness or lack of resistance to the probe penetration and the breakage pattern of the splinters. A brash break indicates decayed wood, whereas a crisp splintered break with the splinter hinging from one end indicates sound wood. Pick Test Sounding Sounding the surface by striking it with a hammer is one of the oldest and most commonly used inspection methods. Although sounding is widely used, interpretation is VERY subjective. Soundings are based on the tonal quality of the ensuing sounds and the rebound of the hammer Practical experience has shown that sounding is only useful for members less than 4 inches thick. Sounding Interpreting Soundings: Sound timber gives