The forces imposed by windloading on a fixed berthing facility can be resisted easily by 

 almost any adequately designed structural system. It is only necessary to check the 

 resistance of the array of supporting bearing piles to determine if they can take the lateral 

 loading in cantilever bending or if cross bracing is needed. 



i. Interconnection of Floating Components. A floating system requires considerable 

 analysis of the internal forces imposed by the various types of loading to which it may be 

 subjected. As has been pointed out, each floating finger must be considered separately, and 

 the design lateral load in many locations will be great enough to require considerable 

 strengthening of the commonly used stringer and crosstie deck systems and the connections 

 of fingers to headwalks. 



Pull tests made at Marina del Rey, California, in the early 1960's on certain proprietary 

 flotation systems that had been accepted without structural check elsewhere revealed 

 weaknesses that required major modification of structural systems. One problem involved 

 buckling of fingers due to the eccentricity of shear -stressed members with compression and 

 tension members under lateral loading. Corrective action included increasing the size of the 

 stringers to resist torsional forces and the addition of a system of cross struts and tie rods. 

 Some of the clip angles attaching fingers to headwalks failed in internal bending and had to 

 be strengthened with gusset plates. Other cUp angles held but caused failure of the headwalk 

 stringers to which they were attached. Some bolted splice-joints failed for lack of enough 

 bolts or insufficient end distance in the joining members. An important lesson learned was 

 that measurable strengthening can be effected in any flotation system tied together with 

 timber stringers by the addition of cross struts and tie rods under the deck at frequent 

 intervals (Fig. 92). 



The wave-produced vertical deflections of any floating system can be dealt with in either 

 of two ways. One is to join fairly short, rigid components with hinged connections. Unless 

 the hinges are quite massive and kept well greased, this procedure usually results in rapid 

 wear and ultimate failure of the hinges by a peening action, which progressively elongates 

 the holes of the hinged connections. This peening action caused by repetitious reversal of 

 stress becomes noisy as the situation worsens and may be a source of irritation to people in 

 the harbor. The other method is to join all components semirigidly by continuous headwalk 

 stringers and bolted finger connections; a modification is to join the fingers to the main 

 walk by extending the finger stringers under the main walk, joining its components in a 

 crosslocked system (Fig. 93). 



The semirigidity of any extensive floating system without hinges sets up some rather 

 severe vertical bending stiesses in the connecting stringers when waves pass under the 

 structure, especially in heavy systems such as those with concrete floats or decks. In a basin 

 of 10-foot depth, e.g., a typical local wind wave of, say, 5-second period, wiU have a 

 crest-to-crest length of about 80 feet. If this wave is 2 feet high (about the maximum 

 allowable for any floating system) and approaches along the axis of a headwalk, the 



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