Inspection of Timber Piles at St. Helena Annex 



The initial evaluation of the proposed sampling criteria was con- 

 ducted during one phase of the inspection of facilities at the Naval 

 Shipyard in Norfolk, VA. These inspections were conducted by Childs 

 Engineering Corp. under the direction of CHESDIV Code FPO-1 as part of 

 the Specialized Inspection Program. This evaluation was conducted on 

 four timber piers (Figure 16) . The piers are about 80 feet wide and 

 650 feet long, with 110 to 120 bents, each bent having from 20 to 22 

 piles. The total number of support piles per pier ranges from 2,133 to 

 2,240 (see Table 2). Each pier has a concrete deck surface and two 

 standard gauge railways. Pier 12 also has a relieving platform and an 

 extra railway for a large crane. 



Table 2. Pier Characteristics 



Pier 



Year 



Length 



Width 



Total No. 



No. 



Constructed 



(ft) 



(ft) 



of Piles 



11 



1941 



705 



81 



2,133 



12 



1941 



665 



82 



2,175 



13 



1941 



650 



80 



2,175 



14 



1941 



643 



80 



2,240 



The purpose of this field inspection was to test several proposed 

 statistical sampling plans and evaluate their results. Specifically, 

 four sampling plans were used. A different plan was tested on each of 

 the four piers. The following list summarizes the methods of selecting 

 the samples (the piers are listed in the order in which they were 

 inspected) : 



(1) Pier 14 - Random selection of 10 piles in each of 3 pile 

 categories (30 samples) . 



This was the first pier inspected. The pier was divided into 

 three strata: (1) batter piles, (2) bearing piles supporting 

 crane rails, and (3) bearing piles not supporting crane rails. 

 A Tandy Model 100 computer was used to generate 10 sorted ran- 

 dom numbers within the range of piles for each stratum. 



Using the pier plan drawings, the 10 pilings in each stratum 

 were located by first selecting a corner of the pier as a 

 starting point (a unique beginning piling for each stratum was 

 chosen) and then numbering each pile in consecutive order 

 throughout the stratum. The pile number (determined by the 

 random number generator) was then located on the pier plan 

 drawing and the process was continued until all 30 piles in 

 each of the three strata were identified (Figure 17). 



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