Port Works Design Manual : Part 2

40flow circulation. Mathematical modelling may be applied to determine the necessity ofopenings and the required spacing in the catwalk.For a piled deck catwalk, the number of supports and foundations for the beams can bereduced if steel sections are used instead of reinforced concrete beams, because of the longerspan that steel beams can sustain. The steel sections and the concrete deck slab may bedesigned in accordance with BS 8110: Part 1 and BS 5400: Part 5 to form compositeconstruction. Adequate corrosion protection measures, such as enclosing the steel sectionswith concrete and coatings, should be applied to ensure the durability of the steel in marineenvironment. Where cathodic protection is to be installed, it is necessary to ensure electricalcontinuity of the steel sections and any embedded reinforcement. Refer to Section 3.6 ofthis part of the Manual for further details of corrosion protection. The designer shouldevaluate the suitability of this type of construction with respect to the project conditions.3.9 Construction3.9.1 GeneralThis section addresses particular aspects of construction of piled deck piers. Forinformation on the materials, workmanship, quality control and other construction aspects,refer to the General Specification for Civil Engineering Works (GS) (Hong KongGovernment, 1992).3.9.2 PilingThe location of all temporary setting-out marks and the levels of all temporary tide gaugesshould be checked before any piling or construction works start on site. For a driven pile,the location and the rake of the pile should be checked after pitching but before drivingcommences, and for a bored pile, the location of the casing should be checked before anyboring commences.When checking the design of any temporary staging and temporary works, care should betaken to ensure that the effects of wind pressure, wave loads including possible uplift,dynamic or impact loads, construction materials, formwork and falsework, plant equipmentand workmen have been taken into account in the design. Temporary staging for pileinstallation plant should take particular account of pile weights during pitching and during theinstallation of raking piles.