only the current issues should be used. The standards are published under the general title of 



"Standard Grading Rules for ," "Official Grading Rules for ," or "Standard 



Specifications for Grades of ," with the dashed Une being the type of timber covered, 



such as Douglas Fir, Sitka Spruce, Southern Pine, and Tidewater Red Cypress. Some of 

 these standards are repeated in the Uniform Building Code (1970), or in the most current 

 edition. Wherever a timber bulkhead of more than minimal height or length is required, the 

 designs discussed in the AWPI Technical Guidlines (App. B) should be checked against the 

 latest grading standards for the type of timber used. 



Timber bulklieads often fail because of corrosion, abrasion, or fatigue of metal 

 connectors, or because of abrasion of the wood by loose connectors and not as a result of 

 deterioration of the wood members. For marine exposure, all hardware should be galvanized 

 and the following minimum sizes used: 



In or Below Splash Zone 



Bolts 1 -inch diameter 



Plates 0.5-inch thickness 



Washers Ogee (standard size to fit bolt) 



Above Splash Zone 



Bolts 0.75-inch diameter 



Plates 0.375-inch thickness 



Washers 0.25-inch plate (ogee operational) 



In general, the exposure of bolts to the atmosphere should be reduced to a minimum by 

 using only one washer or plate per unit. Adjacent timbers should be in contact with the bolt 

 to prevent exposure. Boltholes should not exceed the diameter of the bolt by more than 

 0.062-inch. Drift bolts or spiral bolts should have a driving fit. Washers should bear evenly 

 and fully on the timber, and where the axis of the bolt is not perpendicular to the face of 

 the timber, beveled plates or washers used. 



Steel or aluminum sheet-pile bulkheading with an exposed face of not more than about 6 

 feet can be constructed quickly and at fairly low cost with special lightweight sheet-pile 

 sections (Fig. 50). Matching cap beams and deadman anchors of the same metal are available 

 for some of these Ughtweight sheet-pile systems. Their manufacturers claim that with proper 

 control of alloy content in the base metal, or application of preservative coatings, these 

 sheets can be resistant to seawater and a wide range of hydrogen-ion (Ph) values in 

 freshwater. The primary advantages of the lightweight sheets is that they require only the 

 simplest equipment for handling and driving, and yet provide a sandtight wall with 

 considerable tensile strength at interlocking joints. Manufacturers usually provide design 

 details that require only the simplest engineering analysis. Asbestos-cement sheet piles have 

 been used successfully for low bulkhead walls to avoid the corrosion problem. Because of 

 the low allowable fiber stress of the material, the active earth pressures should be checked 



95 



